Earthquakes, floods, sea-level rise and sudden shifts in river courses threaten many of the 150 million Bangladeshis living in the low-lying Brahmaputra River delta. Scientists from Lamont-Doherty, Dhaka University and other institutions have begun a five-year project to understand the hazards and the possible hidden links among them. Lamont seismologist Michael Steckler keeps us up to date on the work.
Here in Bangladesh, we are combining fieldwork using magnetotellurics (MT) to examine the structure and faults below the surface in this earthquake-prone region, together with a mini-Field School of 11 U.S. and Bangladeshi students for the last 2 weeks. Magnetotellurics uses the sun’s electromagnetic radiation to probe the subsurface. It requires carefully recording the electric and magnetic fields with sensitive equipment. However, we have had difficulties finding places far enough away from power lines, and had rats and foxes eating the cables. Our solution has been to deploy in tea gardens (plantations) and to bury the cables. Rain and flooding has also hampered our search for good sites for MT. We have now completed our work from a base in Srimongal in southern Sylhet, so we drove north to a resort on the Sylhet anticline.
After settling in our hotel in the hills, a group of 4 of us went out to scout a remote area in NE Sylhet. We hope the tea gardens there will work. To collect MT data, we need 2 simultaneous sites, we are hoping for one of the tea gardens here on this anticline and another farther to the NE. Heading out on the main road, we saw the extensive flooding that has already happened with early rains. Many areas are under water and we saw people collecting money to help those flooded. Usually, rice fields are flooded, but home and roads are elevated above the normal flood level and remain dry. Now, we can see homes and schools that are flooded even before the monsoon begins next month. Continuing on, we headed onto progressively smaller roads. As we got close to our target site, we reached dirt roads that were not passable by a van this time of year with deep muddy ruts that we could not drive through. I had hoped the tea gardens would maintain good road access, but I was wrong. We had to abandon the scouting and head back.
Since it was still relatively early, we headed to Shahjalal University of Science and Technology (SUST), Shofique’s university. It is a little west of the city at the edge of the Sylhet anticline. We toured the school, Shofique’s office, a GPS site (not mine), and the local Shaheed Minar on top of a hill. The Shaheed Minar is a monument to those killed during the Bengali Language Movement in 1952 when Bangladesh was still East Pakistan. It was a poignant precursor to the eventual 1971 War of Independence. The Central Shaheed Minar is near Dhaka University, but there are local ones throughout the country. They are central to the annual Language Day celebrations, including a week long fair in Dhaka celebrating the Bangla language with plays, poetry, readings and a book fair.
We were all unsatisfied with our hotel and in the morning we switched to a much nicer one in Sylhet City itself. This was also our last day for scouting and installing any MT sites or they would not be deployed sufficiently long for our purposes. Unfortunately, it proved to be another rainy day. Scouting and deploying electrical equipment in the rain is never a good idea, so instead we spent the day completing most of our lectures for the mini-Field School. Rashed Abdullah of Jahangirnagar University and I lectured in my large room. I have the largest room of the group and it is just large enough for all of us, 10 students and 3 professors (since a few people had to leave early), to squeeze in while projecting the PowerPoints on the wall.
Our two remaining days in the field were focused on seeing the geology, with some last lectures in the evening. We started at Jaflong, at the Indian border with the massive 2-km high, 300-km wide Shillong Massif on the other side. This is the Indian state of Meghalaya, which means Abode of the Clouds and it is the rainy place on earth. The Shillong Massif is thrusting over the Sylhet Basin pushing it down. It creates thicker sediments and many low swampy areas in northern Sylhet. Traditionally, the Dauki Fault separating these two regions is placed at the border, the break between the mountains and the flat plains. However, we have long suspected that this is not the main Dauki Fault ever since Nano Seeber and Ellie Ferguson mapped here some years ago. It cannot accommodate the ~7 km of vertical motion along the fault here. It was good to argue with some of the Bangladeshi students who have long been taught that this is the Dauki Fault.
We visited outcrops of Eocene (~50 million year old) limestones and younger shales. This area has been built up since I was last here, with new stone steps and many tourist shops going down to the river. Jaflong is a mixture of an industrial site mining the rocks carried down the rivers from Shillong as a source of aggregate for making concrete, and of tourism to see the steep mountains and the rivers flowing out of them. We scrambled among the rocks and worked our way farther east stopping at outcrops at Tamabil and Jaintipur. Jaintipur is a center for the Khasia people, a matriarchal society from Shillong. We had lunch in Jaintipur and then walked through outcrops in the surrounding area, including a government agricultural center adapting various crops for the climate of Bangladesh.
The next day we continued with a boat ride along the Shari River. No trip to Bangladesh is really complete without riding on a wooden boat. Unfortunately, many of the outcrops are underwater this time of year. We were still able to see the stratigraphy and deformation of the beds. We also got out and walked nearly to the Indian border. After the boat trip and some green mangos, we drove to some more outcrops, including some beds that were nearly vertical. These reinforce our belief that the Dauki Fault is blind and extends much farther south. The deformation we see could well be the effect of a fault below. This interpretation will be consolidated with future research.
After the outcrop geology, we visited the site of gas field where there was a blowout in 1955. Then the relief well to stop the gas leaking out also had a blowout. Now, gas can still be seen bubbling up through the waters at the two wells, and nearby a flame continuously burns in a small cave. This was followed up by a visit to the Sylhet Gas Field company office. On the way back we visited Shofique’s home and met his wife and daughters. I thought he had just invited me, but when I saw the other cars, I realized that he had invited everyone. We were greeted with a fantastic spread of food and fruits. And we finally got to try ripe litchis and mangos.
After much needed showers, we went out for a buffet final dinner at a restaurant in Sylhet City. Then we returned to our hotel for a “lungi party”, with all the men in lungis while photos of our trip flashed on the wall. It was a nice end to the mini-Field School. The next morning was the long drive back to Dhaka. The first stop was Bangladesh Open University (BOU) where our other equipment from the March cruise is being stored. The original crew of Masud, Arman and Biplab and I stayed behind to pack it all up the next day for shipment to the U.S. Everyone else headed back to Dhaka to their homes, relatives, or a hotel.
While the students got together in Dhaka University to show the Americans around town the next day before their flights, my crew spent the day cleaning and repacking the equipment. After arranging the 1400 lbs. of equipment on 3 pallets, a team from a furniture factory wrapped it in plastic and then rope for shipment back to the U.S. Then, we final few could head back to Dhaka. I spent my last day visiting Dhaka University and attending part of a meeting about the Bangladesh Delta Plan 2100, a major initiative to create a sustainable delta over this century. Now all that was left was the long flight home. While the MT data acquisition encountered many difficulties and our acquisition plan had to be greatly scaled back, I am still hopeful that it will yield important information to complement our seismic data. The mini-Field School, despite its loose organization dictated by the on-the-fly MT logistics was a complete success. Both the students and I learned a lot both in the classroom and in the field thanks to the contributions of the mixture of U.S. and Bangladeshi professors.
I am in Bangladesh this time to collect magnetotelluric (MT) data. This electromagnetic method can look deep underground to help image the sediments and faults beneath the surface. It will help us assess the earthquake hazard in this densely populated country. Deploying an MT station consists of laying out electrodes in the north-south and east-west direction, 50 to100 meters apart, and burying magnetometers pointing north, east and vertical. Struggling with cable-biting rats and foxes, and interference from ubiquitous power lines, we have learned the hard way that tea gardens and buried cables are the most successful way to collect good data.
Now we are entering a new phase of this trip. We have added to more students and professors to our team and will conduct a mini-field school in conjunction with the deployment. COVID derailed our plans for a full field school, but we are managing a smaller number of students and using the funds saved to support the MT deployment. We have four U.S. students from three universities and seven Bangladeshi students, also from three different universities. Teaching, we have three American and two Bangladeshi professors, all from different places. We will be traveling around in four vans and currently are storing our equipment in a small truck.
For the first day, we took everyone, minus the US student who missed his flight, out to deploy an MT site. Half of us are now very experienced at deploying MT, and the newcomers shadowed us to learn how to do it. Finishing before 1pm, we decided to hike to the nearby Hum-Hum waterfall in one of the anticlinal hills. After some preparation, we started hiking in with a guide. The forest was beautiful and surprisingly noisy. After crossing several streams on bamboo bridges, the trail started becoming more vertical as the day heated up.
A few of us decided to turn back after realizing that it would take another 1.5 strenuous hours to reach the waterfall. We headed back and look the late arriving student to a very late lunch. Some of the others turned back near the top of the anticline when thunderstorms could be seen approaching. The remaining few made it all the way to the falls. All but my first group got caught in the downpour and needed to carefully make their way back down the mountain. A number of people got leeches as well.
The following day, the lectures got underway. During the morning, I presented an overview of the history and tectonics of the region and why we are doing MT. Then Samer presented an overview of what MT is and can do. Following lunch, we changed hotels from Tea Heaven to the Tea Museum at the beginning of the hills and tea gardens. The Tea Museum has multiple bungalows of several rooms, which nicely promotes mixing of the participants. The pool is also a good place for socializing. There are also more extensive grounds. We eat our meals in a temporary screened-in tent, which is almost like eating outside. There is a monkey that wanders the grounds. I share a bungalow with Paul and the students Alex and Martin. Since our bungalow has the largest living room, this is where we are doing presentations. Later in the afternoon, one group went out to retrieve an MT station, while the rest of us settled in.
The next day, we spent the morning reviewing more details on the MT method by Samer and regional geology by Paul. After lunch, we split into three groups. Samer led a group scouting for sites far to our east and visiting geologic outcrops. Oliver led a group retrieving a nearby MT site. I led half of the people to visit one of my GPS sites at a school. After arranging access to the school’s ladder, we went up to the roof, where the equipment is. I explained the setup and downloaded all the data since Sanju and I were last here. The data telemetry for this site is not working. Next month, Sanju will come here with parts I brought to repair it. Meanwhile I can use the site for a demonstration. By the time we finished, the MT group was done, but we still went to the site simply because it is the most beautiful of our deployments, with a kilometer walk through hills covered in tea to get to it.
After we returned, Shofique, Oliver and I did some scouting locally. We need a site to do a deployment with the field school in case the other team did not find a site. We returned in time for me to visit the pool to cool off after the hot roof. The other scouting team didn’t arrive back until close to 9pm bearing jackfruit and pineapple. They had found a potential site.
The site was in an anticline about two hours to the east. We left early and got breakfast on the way. Paul, with Rashed’s assistance, led the students through the geology while they all made measurements of the strike and dip of the strata. We could see the geometry of the beds change as we progressed through the anticline, including very steeply dipping beds and deformation bands of crushed rocks. Paul and Rashed did a great job and really engaged the students. After a break for lunch, we were ready to deploy in a tea garden in the middle of the anticline, until it started raining.
Deploying electrical equipment in a potential thunderstorm is never a good idea, so we went back instead. In the evening, Paul was able to continue his next set of lectures. The morning was also rainy, so it became a classroom day. We started with Samer completing his lectures on the MT method and how it works. Then, using the measurements the pairs of students made, Paul led then them through the first steps of the analysis, and I lent my computer to assist some of the teams. After lunch, Samer, Paul and Oliver left to return to the U.S. As the long-period (LP) instruments are leaving with him, we no longer need the truck that is with us. After they left, Alex, Paul’s student continued the instruction. As we continued, a complete analysis proved too ambitious, but the students still got the gist of the structural analysis.
That night we got a call that one of our MT receivers had been stolen. A group of us immediately went to the police to file a report. Then, after a scant five hours sleep, we went back to the police station and then went to the site with them. Whoever did it unscrewed the magnetometer cables, but snapped the string holding the cap, so at least we didn’t have more cut cables. We found one of the two batteries ~100 m south of the sight and farther along, we found the other battery under a tea plant. They must have been too heavy to carry. Still, no trace of the expensive receiver. We suspect teenagers, as adult thieves would have certainly taken the valuable batteries and carried them easily, and a teen was seen there the day before. We learned that there were only three guards taking turns instead of four, so that there was a few hours gap between the day and night guards.
After packing up the remaining equipment, we met local officials and the townspeople who will mobilize to find our equipment. The guards refused payment for their time until the receiver is found. After a while, Shofique and I went back to the Tea Museum, as without speaking Bangla I could not help beyond showing some pictures of the receiver. Rashed and others stayed to keep the search going. The local police initiated a house-to-house search. Everyone there is motivated to find our stuff, which is quite heartening. We are hopeful that it will turn up.
In the morning, we were driving to the police station to finish filing out report when word arrived that the receiver, nicknamed Chinstrap, had been recovered. After picking up the policeman, we headed to the site. The receiver had been left anonymously by the hospital in the early morning. However, when I examined it, the SD card with all the data was missing. The village will continue searching to recover the SD card. We headed back semi-satisfied.
We lost 1.5 days of the field school due to the lost receiver. We completed our time in Sremongal with me lecturing about my GPS work here, then we went to the Monipuri Market for 7-layer tea, a local specialty where teas of different densities are layered in a glass, and shopping. Tomorrow we drive north to the Sylhet anticline near Sylhet City for more geology, lectures, and hopefully some last MT stations.
We are installing magnetotelluric (MT) stations around northeast Bangladesh to image deep below the surface. Each is out for a few days at a time. They use the sun’s radiation to probe beneath the surface of the earth. We need to lay out long lines of electrodes in the north-south and east-west directions to record the electric field plus three magnetometers pointing north, east and vertical. The instruments are very sensitive to pick up effects from kilometers below the surface and they need to be far away from any power lines. In densely populated Bangladesh, this is difficult to do. Power lines and roads crisscross everywhere. We hope to image the depth to the megathrust fault, with the potential for generating a large earthquake, and the thickness of the sediments. Perhaps we can image the base of the crust, but that is less likely with interference. Because we cannot get far enough away from electric lines, we are giving up on using harvested rice fields.
The first site we tried in Sylhet, as northeast Bangladesh is called, was a place where we previously had a seismic station installed. It is on a tea garden (plantation) on the flank of an anticlinal hill. Sylhet is where the sediments of the Ganges-Brahmaputra Delta are folded up into hills by the long-term movement of the megathrust underneath. Tea plants grow in well-drained soils, so they are mainly planted along the flanks and sometimes tops of anticlines. Only near the Indian border, where the land slopes upward, does tea fill the valleys as well. Sylhet, with its tectonically active hills and valleys, is where most of the tea in Bangladesh is grown. The geology and tectonics are also why we are here. For me, it is my eighth trip to Sylhet.
The manager of the tea garden was very welcoming and we walked around with the assistant manager in brutal heat until we found a suitable site. With acres of tea plants, it is easier to find places away from power lines. We started deploying our instruments, although we couldn’t finish until Samer’s team returned from picking up the last two sites west of the Meghna River. Because of all the broken magnetometer cables, we don’t have enough without the ones from the other sites. With needing to trench and bury all the cables, it was a tough day, although the tea garden staff did a lot of the trenching. By the time the others arrived we were exhausted and let them finish the site.
Our new paradigm is deploying in tea gardens. We are also burying all of the lines in shallow trenches. Just enough to keep the foxes from nibbling on them. We have shortened the distance between electrodes from 100 meters to about 50 meters. Just burying ~130 m of cable is plenty of work — 230 m would be too much. Our pattern is now an L instead of an X, with two long and two short electrode cables. While longer is better for measuring the electric field, it is also more sensitive to local electrical noise.
The next day, I was feeling under the weather, so stayed at the hotel while multiple sites were scouted by the two teams, including another tea garden that has had a seismic station. Permission for the tea garden came through in the afternoon, and they started deploying. When a few people returned to the hotel to get some more equipment, I joined them for the end of the deployment, although it took a little while to find them among the acres of tea plants. When leaving, we saw a fox, our nemesis, along the side of the road.
The next morning was pouring rain, so I used the time to prepare my lectures for the next part of this trip. We have four U.S., four additional Bangladesh students, and more professors coming, and we will hold a mini-field school in conjunction with continuing the MT survey. They will get hands on (and hands dirty) experience mainly in the cooler mornings and lectures and field trips in the afternoons. In the afternoon, two teams went scouting as I continued my preparations. At dinner, we had some of the jackfruit that was bought during the scouting. The fresh jackfruit is amazing.
It was drier the next day, so we picked up the equipment from the first tea garden and installed it at a third tea garden farther east. The trenching had worked. All of the cables were intact. I am becoming more optimistic that we will get sufficient data to make an impact. This time the deployment was in an open meadow within a tea garden, with cows grazing nearby and steeply sloping hills of tea. As before, workmen from the tea garden did most of the trenching. With the kodal, they cut into the grass and soil and overturned a segment in one or two strokes. Even the two 40- to 50-meter-long cables do not take them long. In the evening, we had fresh salad that one of the drivers made, as well as more jackfruit.
The next day was raining again, so we took the time to finally repair the broken cables that the rats and foxes had bitten. In the afternoon, Sameer and Masud went scouting. I continued to focus on my lecture preparation. That evening, it was fresh pineapple and oranges as well as a delicious juice from Bael with lemon. This is one reason to come to Bangladesh this time of year — all the tropical fruits are ripening and I hope to be sampling them most nights.
The following morning we all went to our fourth tea garden in the anticline just east of our hotel. This is the most beautiful one yet as we drove through valleys with steep slopes of tea all around us. We had to walk most of a kilometer from our cars to the site as the cars could get stuck if there was a sudden downpour. However, it was easy to pull the cart and appreciate the landscape at a slower pace. We took our time and the drivers greeted us with a giant bowl of fresh pineapple when we were done.
Now, Babu and I took off for Dhaka to pick up the students and professors for the field school tomorrow morning. Everyone else stayed behind to continue scouting, and retrieving and deploying MT. We stopped at Ujan Vati, where we had stayed not that long ago, for a quick 3:30 lunch. We got to Dhaka for the evening. In the morning we met or picked up the Bangladeshi students and professors, and got the Americans from the airport for the long drive back to Srimongal in two cars, this time stopping for lunch at the same place a little after 3. Tomorrow we switch from purely MT to a mixture of MT and field school with 11 students, five professors and five drivers.
On the morning of the Muslim holiday of Eid al-Fitr, we had a downpour. We could not eat the celebratory breakfast by the Humayun’s garden at the vice-chancellor residence, although it was still outside. On most days we have breakfast at 5:30 am so we can get an early start before the heat of the day. For the Eid, we got to sleep in with breakfast around 9 after prayers.
The Eid gave us a late start for another day of installing magnetotelluric (MT) instruments in northeast Bangladesh. These instruments use the sun’s electromagnetic radiation to look into the earth and see more conductive and resistive layer below the surface. We are doing multiple day deployments to image the subduction megathrust, the thickness of the sediments, and depth to the Moho, the base of the crust. To record the data, we must lay out electrodes and magnetometers around a central recorder.
We started by going to a site we scouted the day before. It is in a slightly uplifted area where reddish, older Pleistocene sediments are exposed. We believe that this is uplifted because of a folding of the sediments as they enter the subduction zone. The rivers in this region have been widened by people to create broad flat areas for rice cultivation. We drove and walked through the more forested uplands with lots of jackfruit trees, and into the rice fields. We found that the field we had picked out the day before now had an inch or two of standing water. We needed another place. With more rain in the forecast, we were now concerned about flooding in all of our sites.
Luckily, the farmer who was going to watch the site for us owned some nearby forest land that was not settled. Although there were rice fields nearby that were not flooded, we opted for the forest since there was more rain in the forecast. We went over found the patch of forest was just large enough to fit our array if we shortened the electrode wires. Since this deployment would take a long time, we left it for the next morning. We headed farther east to the site that Samer and Arman scouted.
Here was a site along a small river along a path that the mighty Brahmaputra River used to flow. The archeological site of Wari-Betashwar is not too far. It was built on the uplifted forest land, which doesn’t flood, with access to the Brahmaputra. It flourished as a trading center from 450 BCE to 600 CE, when the Brahmaputra shifted channels and another city replaced it. It shifted again before a larger avulsion shifted the entire Brahmaputra River system up to 100 km west to its current position a little over 200 years ago.
Due to the former presence of the Brahmaputra, the ground is sandy. This means it drains well and won’t flood our equipment. This site is closer to a village and lots of kids joined our team. One of them helped when we had to run an electrode wire under a frame growing squash. He and his friends then helped dig the hole for the electrode itself as well. We were successful, but still concerned about finding sites that will not get flooded.
The next day, we went out to pick up our first site and deploy it farther along the transect. What we found was that one of the electrode and magnetometer cables had been cut. It was possibly a fox, but most likely rats, which are very large here. We also heard from one of the watchmen at another site that wires had been cut. Now we had a new very serious problem. The electrode wires are coated in a substance that rats do not like. What we are finding is that they take a first bite, decide that they don’t like it and leave the other cables. However, by then the damage is done. Once one of the electrode or magnetometer cables is cut, the data cannot be used. While the single wire in the electrode cables is easy to repair, the magnetometer cables with eight thin wires is much more difficult.
After retrieving the first site, we went to the other broken site and picked that one up as well. We tried to scout for a new site, but was unsuccessful. The area was too heavily populated with too many electric wires crossing every which way. We drove back to Bangladesh Open University (BOU), where we were staying, but it was too late to pick up another site. We just stopped for some food along the way.
The next morning, we prepared to move to another hotel. Our line is extending too far east of BOU. We hired a small truck and packed up everything. We stopped at our first LP site and found both that it was closer to an electrical line than we thought and that one of the electrodes was cut. At the next site, the first we had installed, we found more cut wires. We were now getting concerned about collecting sufficient good-quality MT data here. Plus we were working from 5:30am breakfast and not returning until 8-8:30pm in the evening. Our pace is not sustainable.
The next site we needed to pick up early because they needed to harvest the rice because of the rain. It was intact, at last. Perhaps it was because the wires went into rice fields and were suspended on the rice plants instead of on the ground. We were a little buoyed but still concerned about how to keep the wires safe from rats and foxes. We drove across the Meghna River and checked into our hotel around noon.
We finally had a sit-down lunch for the first time since we arrived. We lowered our expectations. We need to slow down and put more work into keeping the wires safe. Samer, Masud and I went shopping for neem oil, which rats don’t like, but could not find it. Instead, we will try chili oil. If that doesn’t work, there is encasing the wires in PVC tubes or burying them.
We split up to visit our last two remaining sites west of the river. I went to the forest site while Samer went to the sandy site near a river. We found it still working. Just in case, we buried the magnetometer cables and covered parts of the electrode cables with dirt. Samer’s team found that foxes had severed some of their cables. They spread chili oil over the wires. While they managed it, they found it wasn’t practical, too large a chance for people to get chili oil on them and then rub their eyes. The next day, we picked up the two sites and headed across the Meghna River to Sylhet.
We are working at a pace that is not sustainable, trying to install two sites per day. We are going from 5:30 am to 8:30 pm. We are going to cut back to one site per day, or less with scouting. We also need to be more careful about the site locations and power lines, particularly for LP sites. We are going to have to trench all of our cables to avoid the rats and foxes chewing on them. Although they don’t like the taste, their first bite ruins the site. We will have fewer, but more carefully selected sites as we continue to the east. With our revised plans, the next day, we picked up the two sites and headed across the Meghna River to Sylhet.
I am on the campus of Bangladesh Open University (BOU) in Bangladesh with Eid al-Fitr celebrations later this morning. Last night the month of Ramadan, when Muslims fast during daylight hours, came to an end. Our group was on the way back from the field at sunset when Ramadan ended and the Eid festival began. We stopped at a restaurant in Gazipur and had large plates of biryani. Those in our group who are fasting had not eaten since 3:30 am this morning.
I have returned to Bangladesh once again. I am taking advantage of the magnetotelluric (MT) instruments that were shipped here for my last trip to collect more electromagnetic data in northeast Bangladesh before they have to be returned to the U.S. In addition to the four broadband (BB) instruments that we used in March, Samer Naif from Georgia Tech, is bringing four long-period (LP) ones that can see even deeper. This time, we are deploying the instruments for three (BB) to six (LP) days at a time. The longer deployments can better determine lower frequency signals that can see deeper into the earth. With the BB, we expect to see the entire 15-25 km of sediments here. With the LP, we will see 30-40 km to the Moho, the bottom of the crust.
We are doing this experiment in a part of Bangladesh that is tectonically active. The same fault that ruptured in the 2004 Sumatra earthquake continues into Bangladesh, but is buried by the thick sediments here. We want to image the fault, the subduction megathrust, within the sediments, and the bending of the crust as the Indian plate is subducted beneath the IndoBurma subduction zone. Both are poorly known, but impact our assessment of the earthquake hazard here.
Fieldwork during May, the hottest and most humid month before the monsoon rains start in June, is not ideal. Neither is trying to work through the end of Ramadan and the biggest holiday of the year. However, we are limited by the cropping season and the need to return the BB MT instruments. We are trying to work between the harvesting of the spring rice crop and the planting of the summer crop since our instruments have to be buried in the fields over a 100-meter by 100-meter area.
Our plans in Bangladesh always have to be flexible, this time from the very start. Samer missed his flight from the U.S. trying to deal with travel paperwork and the seven pieces of luggage containing the LP MT instruments. Oliver, his student, and I arrived on time on the morning of April 29 and were met at the airport by Masud, Arman and Biplab, three Dhaka University students who were with me on the last trip, and thus are familiar with installing MT instruments. However, instead of a boat, we are traveling by vans driven by Babu, our long-term driver and Sumon. We all continued from the airport north to the main BOU campus, where my long-term collaborator, Humayun Akhter, is now the vice-chancellor. The BB MT were stored here. We spent our first afternoon retrieving the instruments and getting set up in the BOU guesthouse, where we will be staying.
We will deploy the instruments in a 200-kilometer-long transect from here to the eastern edge of Bangladesh across the subduction zone and the many folds and faults that deform the sediments. We will also do a shorter north-south transect to capture the northward tilt of the deformation. Once the instruments are installed, we plan to shift 1-2 of them each day for most of a month. Since the LP MT are at each site longer, and must go back to the U.S. when Samer leaves, we will have many fewer of those stations. Our plan to start installing the LP MT right away was foiled by Samer missing the plane.
The MT instruments include electrodes that must be placed about 50 meters from the recorder in each of the cardinal directions to measure the electric field. The BB MT have three magnetometers that must be buried facing north, east and vertical. Burying the 1-meter-long coils is the hardest part of the deployment in the heat. The LP instruments have a smaller magnetometer that measures all three components, but must be carefully oriented in its hole. They are both powered by large car batteries — one for the LP, and three for the BB.
To install the MT without disturbing crops, we need places where the rice has been harvested, at least for the central recorder and the magnetometers. Having a rough spatial arrangement for the array in mind, we pick promising sites from Google Earth images of the fields and Chris Small processing of satellite data to show vegetation, water and soil. Unfortunately cloud cover obscured recent images for the first part of our deployment, so we have been flying blind.
To avoid the heat and accommodate Ramadan, we are working early. Those observing have breakfast at 3:30 am before morning prayers and a nap. The rest of us have breakfast at 5:30 am. We then all meet at 6 am to pack for the day and head off to the field. The morning after we arrived, we set off for our target area and scanned the fields along the way. On our first try, we got lucky. We spied a promising area from the main road, then took local roads to get as close as possible. We hiked into the fields and found some fields that had recently been harvested. A local farmer directed us to the owner, and soon we were deploying. We hired the other farmer to protect the instruments.
We finished out first site, just in time for Masud and me to head to the airport to get Samer. Since he got through customs quickly, we were able to install an LP MT in the afternoon. For that site, we tried a field that we had spotted on the way to the previous site and had similar success. On that first afternoon, the temperature was 94 degrees, but the humidity made it feel like 110 degrees. Despite the problems and the heat, it was a good first day of fieldwork.
The next day also went well. For one, the initial try was no good because of nearby power lines, but we were able to find an excellent place on the second try. There was a harvested field in the middle of a larger set of fields. We could put the recorder, battery and magnetometer there, while the electrodes extended into the still-maturing rice around it. For the second site, we drove down a local road then tried a barely passable road as far as we could go. It was far enough for us to walk to the open fields. In the end, we succeeded in putting in two more LP sites.
Our third day, the last of Ramadan, started off well. In our target area we drove along the only local road wide enough for our van. It didn’t go where I was hoping, but it did lead us to a good site after about 2 kilometers of driving. Then our good luck ran out. For the second site, we found a possible field, but the farmer didn’t give permission. Samer and Arman went to repair a cable that an animal had bitten trough, while the rest of us kept looking. Four more tries later, we gave up. This area was just too densely populated, and the few potential sites had high-voltage power lines across them. We decide to put in an extra site farther east and went to scout there. Samer and Arman fixed the problem and they also scouted another site. We met up and drove back, breaking the Ramadan fast along the way. The scouting means that we should be able to install two sites tomorrow, instead of the one we expected due to the holiday.
Having finish deploying magnetotelluric stations (MT) on land to image the distribution of fresh and saline groundwater along two rivers in Bangladesh, we now turned to a complementary towed TEM (transient electromagnetic) system to improve the imaging. Where the surface and groundwater are fresh has a huge impact on the agriculture. We are also imaging deeper freshwater, below the saline groundwater, which can be tapped for drinking water.
Before we started the TEM, we first had to pick up the MT stations deployed the day before. Because of the high winds, my team went to the last site by road. The country boat took us to the nearby bridge with the main road south. There, our guide Romeo hired two autorickshaws to drive our team to the equipment. While the main road was fine, the smaller road along the channel that led to our instrument was pretty bumpy. Eventually, we got there, packed everything up and made it back to the Kokilmoni. Another team picked the other two instruments using the country boat.
By the time we returned, Kerry had started assembling the raft that will carry the instruments. There is a rectangular frame made of Kevlar with ropes to tighten it. Coils of wire are wrapped for the transmitter and receiver wires and a smaller receiver will be towed behind on an inflatable kayak. The entire frame is mounted on inflatable boats, tubes and kayaks. Assembling it took the rest of the morning.
We towed it out to the Kokilmoni using the country boat and set up the tow lines. Then the debugging process started. We sailed up the Andharmanik River and started to get a feeling for how fast we could tow it. The round floats tended to flip and had to be secured better. We also added weight with 5-gallon jugs filled with water as ballast. We spent the entire day doing this and still hadn’t started the survey, so we were falling behind schedule.
Overnight the crew went ashore and purchased long bamboo poles. When we towed the Rube Goldberg device back to the starting point of the survey, we stopped and the crew added them to the frame greatly strengthening it. We started heading north, but now the kayak with the smaller receiver kept flipping over. We added one and then two outriggers with plastic jugs. Finally, a life preserver under its bow kept it from diving under the water.
Still, fighting the tide, we could not safely tow the system very fast. We found that 5 km/hr was approaching the limit for the speed we could towing it and were mostly going slower than that. Even using my contingency day, it was uncertain whether I could get back to Barisal on time. We didn’t get out of the Andharmanik River and into the larger Tetulia Channel until the late afternoon. It had taken us over a day and a half to build the towed TEM system and get it working. It was collecting good data, but our progress over the ground was very slow.
Then things started to change. The larger channel was rougher, but we caught the rising tide and suddenly we were going 9 km/hr. With the following sea we started making up time. At the end of the day, the captain decided to keep going after dark to take advantage of the tide while we could. We headed for a good location to spend the night.
We were almost there when the Kokilmoni ran aground. Parts of the river are very shallow and we hit a submerged sand bank. We spent a tense ½ hour keeping the TEM raft safe while trying to maneuver the Kokilmoni to get free. Finally, we did and headed back south to go around this shallow part of the river. We almost made it.
A little short of where we had previously crossed to the deeper water, the Kokilmoni had to swerve to avoid a fishing boat. As a result, we ran aground again while going pretty fast in the dark. This time we were solidly stuck although there is deeper water just a little to our side. We could not get free. Instead, we had to wait for the next high tide in the morning to get free, or so we thought. The two high tides of the day are unequal. We had gotten stuck during the higher tide. The morning tide did not reach a level to allow us to get free, so we had to wait for the evening high tide. Getting a few extra hours of travel with the tide now cost us an entire day.
We disconnected the TEM raft for getting the boat free, which happened easily once the water level was high enough. The next morning we reconnected everything and restarted our voyage north. Because, we had lost so much time, Adrien and I left shortly after breakfast on the speedboat, along with Céline and Masud, who will do gravity stations by land and meet the Kokilmoni in Khulna at the end of the cruise. To save time, we will motor directly to Patuakhali, which is closer than Barisal, and meet Sanju and 2 others there. They arrived in Barisal from Dhaka that morning on the overnight ferry. It turned out to be more of an adventure than we expected.
The speedboat had to frequently slow for fishing nets, so our speed was slower than expected. Then we encountered a sand bank where the water was too shallow. It took a while to get back to deeper water, including Romeo getting out and pushing the boat. Then we circled to the other side of the river. As we did the wind picked up and the waters became choppy spraying us with water. When we got to the other side, we sheltered in a small side channel.
At that point, after almost 3 hours of traveling by speedboat, we turned out to be only 5 km ahead of the Kokilmoni. She had caught the rising tide and rode it north at a good clip. She picked us up and gave us a ride. Since time was going by, we changed plans. The car continued east from the university hosting our GPS, while we sailed north and across the river on the Kokilmoni, then through a set of channels and a small river on the speedboat to meet the car with Sanju.
We then drove back to the GPS station. The problem turned out to be a faulty cable. We did not have a spare, so with the help of Sarah Doelgar at UNAVCO in Colorado, we got the receiver in a position that worked while Sarah monitored it in the middle of the night in the US. We then rushed north to Barisal University, where I gave a talk, delayed by our mishaps.
To end the fieldwork, Sanju, Adrien and I traveled from Barisal to Dhaka on one of the overnight ferries, something I had long wanted to try. It did not disappoint, and we arrived in Dhaka early in the morning. After two successful GPS repairs and our extensive EM survey (MT and TEM), the first of their kind in Bangladesh, it was time to return home. After a Rapid COVID test and meetings in Dhaka, we headed to the airport to fly home.
As we head south along the Tetulia Channel in southern Bangladesh on the M/V Kokilmoni, the landscape is changing. The northern part of this channel contained many chars (sandy river islands) that were excellent for deploying our magnetotelluric (MT) instruments. We are using them to image the groundwater in coastal Bangladesh. In many places the groundwater is saline, but beneath the saline water there is freshwater from the last ice age. Since the electrical conductivity of fresh and salty water is very different, we can use electromagnetic techniques to map them.
As we continued, the chars gave way to farm fields. We had been looking for fallow fields with cows grazing on the grass. Now we found very few of them that were dry enough for the equipment. However, we found that there were patches of fallow land for the cows surrounded by crops. We were able to put the central recorder and battery in the fallow field surrounded by the three magnetometers, which have to be buried. The electrical electrodes are placed 50 meters away in the four cardinal directions, but they are small and can be buried without disturbing the crops.
We were concerned about Cyclone Asani, a rare March cyclone, but it made landfall well to the south of us. Still, we stayed in small protected channels each night rather than the 5-kilometer-wide Tetulia Channel. One morning, the weather looked concerning, so the Kokilmoni stayed in place until the weather cleared around 11 am.
As we continued downstream, we stopped finding fallow patches. Everyone was growing watermelons in all the available land. Luckily for us, the farmers agreed to let us deploy in their watermelon fields. The fields are cut by irrigation channels and we could bury the three-foot-long magnetometers in those. There are also large enough gaps between plants to position the recorder and the electrodes. Furthermore, in the fields that were ripe, we got fresh watermelons as well. You can’t get fresher than eating just picked watermelon in the field it was grown in. The farmers are giving us watermelons several times a day.
Thus, everything was going smoothly. We had deployed 18 stations in five days. Then the weather changed and it became very windy. The wide channel that we are traveling opens to the Bay of Bengal and the 20-knot winds were raising whitecaps. After picking up our stations in the morning, we headed into a more protected side of the channel.
While waiting on the weather, I installed the campaign GPS at a geodetic monument I visited in 2020 just before COVID. These monuments were installed in 2002 by the Survey of Bangladesh. Remeasuring them in 2020 reveals how much they have subsided in the intervening 18 years. Since we are nearby, we headed over and installed it to get another measurement.
The wind looks like it might continue for several days, but we need MT stations here to see the transition to saltier water as we approach the Bay of Bengal. It was already lunchtime and we had not installed any new stations. In Bangladesh, you always have to be flexible and resilient. We had turned into the Andharmanik River to get out of the wind in the wide main channel. We decided to continue along its course and follow it out to the sea. It was much calmer in this narrower river in the middle of a large island. We managed to get two stations in before dusk.
As we are getting closer to the Bay of Bengal, the water is becoming more saline. We can see salt deposits on the dry soil. The lush watermelon fields have given way to fallow rice paddies. Here they can only grow rice when the monsoon rains and overflowing rivers bring fresh water. During the winter and spring, the lands lie fallow. There is no lucrative watermelon crop here.
The next day, we continued along the Andharmanik River and put in the final three stations of this transect. For the last station, we took the country boat up a small channel filled with fishing boats. This channel is just a few kilometers behind Kuakata Beach. We had made it to the end of the line. We even sailed passed some mangrove forest near the coast, but decided the open fields were better than fighting our way through the forest again.
We have finished 23 MT stations along this transect for a total of 44 stations. At the end of the cruise there will be a few more done near Khulna, but I will have left the boat before then. We will now switch to a different type of electromagnetic measurement that will be towed behind the boat.
We finished our line of magnetotelluric (MT) stations along the Pusur River to map the distribution of fresh and saline groundwater. This electromagnetic geophysical method can distinguish them because saline groundwater is much more electrically conductive. A preliminary look at the data is consistent with there being fresher water beneath the shallow saline groundwater here. We then headed to Barisal and the Tetulia Channel farther east where the water is fresher. It took an entire day to traverse the winding channels of the Sundarbans Mangrove Forest.
Where we emerged from the Sundarbans at Sharankola is close to where I have a GPS station that stopped working. The plan was for Sanju and me to go there via our speedboat and then rejoin the Kokilmoni. However, it was once again very foggy, so instead we went to the ghat (dock) to get motorcycle taxis to cover the 4 km to the site. Masud and the captain came along as well. Since it was early Friday morning, taxis were scarce, so Sanju and I shared one, while the others continued waiting.
When we arrived, Bacchu, who watches over our equipment, met me with big hugs. He unlocked the school that hosts the GPS and we went to work swapping the old GPS unit for another one. After some checks, and fiddling with the modem, which had trouble connecting to the network at first, we left. We had tea at a stall before extra motorcycles arrived for our caravan back.
We spent the rest of the day continuing on to Barisal where Hasnat and his student joined us, while Sanju and Shohan left us. At Barisal, the Kokilmoni refueled and reprovisioned. The next morning we began the transit to our first station at 5:45 am with no fog.
While our maps show very little bare ground, we found that the chars, as sandy islands are known, were covered with many grassy fields. Although we saw some crops growing, such as watermelons, squash and peas, many areas had cows lazily grazing. Seeing cows grazing was a good sign. It meant that the land had not been planted with vegetable crops but was still fallow. It also meant that some of the green areas on our satellite maps were good for deployments.
We are developing a new protocol for finding sites. We pick out an area that looks promising about 5 km downstream from the last site. Then, as we approach it, Kerry and I go to the ship’s bridge and look for promising sites. Sometimes when we visit them, they are too wet and we need to shift to a different site. We have the luxury of picking and choosing because we have become so efficient at installing sites.
On the flat open chars, we can walk out to bury the electrodes 50 m from the recorder in the north, east, south and west directions. Digging holes to bury the 3 magnetometers is also easier in the sandier soils on the chars. The ship’s crew does much of the heavy lifting and carrying, and digging. Kodals, essentially large hoes, are much better than shovels for digging trenches for the horizontal magnetometers. The post hole diggers we brought are great for the vertical magnetometers. We can now install a station in less than a half an hour. Sometimes arranging a watchman for the overnight deployment takes longer than the installation.
For picking up the instruments, we split into two teams. The speedboat picks up the two farther sites and the Kokilmoni picks up the two nearer sites. We have now been able to deploy four instruments a day for two days in a row for the first time — and had enough daylight leftover for a swim call.
However, just when we felt that we were on a roll, Cyclone Asani started forming in the Indian Ocean. It is well to the south of us, forming near the Andaman Islands and expected to make landfall in the Irrawaddy Delta of Myanmar. So far, only a little increase in winds. Still, the Kokilmoni is playing it safe and anchoring each night in protected channels to keep us safe. Then they start sailing at 5:30 am to get us back to position for the day’s work.
As we worked our way south, it became harder to find good sites. The chars here are too low and wet for our purposes. On the more stable land, we sometimes have to walk a long way to find a good location. For our last site on March 21, we ended up stopping at a ghat (dock) and explaining what we were doing to the townspeople and walked out to their freshly planted fields to deploy using some fallow patches and the raised borders between the fields. Since this procedure takes longer, we finished only three sites with the last as the sun was setting. We are also followed by lots of kids and many of the villagers, attracted by what we are doing. Still, it is nice to walk through villages, something we have had little of traveling by boat.
Even with the changes due to the cyclone and changes in finding appropriate sites, we are all quite happy with the progress that we are making.
The first two days went very smoothly so that we were ahead of schedule. On the third day we started by going up a small river between the Sundarbans Mangrove Forest and settled land, watching monkeys playing on the shore of the forest side. On the settled side, we found our open field. At this site and the last few before this, some of the rice fields have recently been planted with watermelon. This area grows the best watermelon in Bangladesh and it is their most valuable crop. Still, there were enough fields that were not yet planted for us to succeed.
The second site of the day was more problematic. We could not enter the Sundarbans until the next day, so we have to work on the land on the left bank. When we went to what we thought was a fallow field, it turned out to be a large construction site with backhoes moving around imported sand. After what seemed like forever in the hot sun, we finally found a site in two dry rice ponds that was far enough away from the heavy machinery for good measurements. By the time we finished, it was too late for a third site. Still, I have walked almost 7 miles for the two sites.
In the evening, the speedboat went to Mongla to drop off Anwar and a journalist traveling with us and pick up Céline Grall and Sanju Singha. Céline is my former postdoc and is bringing equipment for additional scientific measurements. Sanju has been working extensively with me on my GNSS (GPS) work. We will visit two sites later during this trip.
To save time, we split up in the morning for the site retrieval. I went back to the first site with the speedboat, while the country boat took people to the second site. On the way back we picked up our two forest guards and the permission to work in the Sundarbans Mangrove Forest. With only two sites to pick up, we were ready to start deploying early and succeeded in installing four sites.
Deploying in the Sundarbans, the world’s largest mangrove forest, is different from working in populated areas. We simply pick locations at the correct distance downstream and enter the forest. We hike through the bush using deer trails when possible and try to find enough of a clearing to set up the central receiver location. For the magnetometers, the challenge is finding a spot of the correct orientation that is free of tree roots, especially the aerial roots that allow mangroves to live in salt water.
The electrodes now became the slowest part of the deployments. Having to go directly N, S, E or W, we could not follow trails, but had to go straight through the trees and brush. We also cannot see 50 m through the forest and had to find more creative ways to position the electrodes, such as having intermediate people with compasses. For distance we need to use a tape measure as the laser rangefinder will not work. We also needed one of the armed guards to go with the group to the electrodes because of the risk of tigers. On our last site of the first day we came across pugmarks — tiger tracks — probably from that morning. We saw pugmarks, some old, at about a quarter of our sites.
Despite this, we manage to install four stations in the Sundarbans the first day. Only having to pick up two sites from the previous day gave us more time for installing new stations. The next day was the reverse. We had to pick up four stations. We were able to split into two groups by picking up two extra forest guards, but they had to return to their station after the pickup. The afternoon went very slowly because the Goran species of mangroves at that site formed a very dense forest. We had to hack our way through with a hatchet.
Since tigers like this type of forest, we had to be extra cautious. Our crew makes lots of loud noises to help keep the tigers away. Since there are plenty of deer here, the tigers in this part of the Sundarbans are not very aggressive and the noise is sufficient to keep them away. At least, we hope so. Almost all tiger attacks are farther west than where we are working. Still, we have established a clear safety protocol. Everyone stays in groups of at least four people with an armed guard. We make sure we have everything we need as one person cannot go back alone to get something that was forgotten. We continuously make lots of noise.
Once a day, we are also deploying a gravimeter that Céline brought along with one of my precision GPS. While the accuracy of the GPS with all the trees will be low compared to my geodetic work, it will be precise enough for the gravity measurements. Generally, Sanju and I set up the GPS, while Céline does the gravimeter, all with an armed guard watching over us.
We had hoped to have four guards instead of the two with us. However, we have been able to get a third (and once a fourth) guard most days. As always in Bangladesh, we adjust our schedule based on the difficulty of the sites and number of guards we have. Some days we are able to split up for the much faster retrieval of the instruments. One group takes the speed boat to the farther sites, while the country boat and Kokilmoni cover the other sites.
In the evenings, after fieldwork and showers we watch for wildlife in the forest until it becomes too dark. We have seen deer, a crocodile, a wild boar, egrets, a stork and monkeys — but no tiger. For two nights we got to stay in one of my favorite sites in the Sundarbans, near the place called Kokilmoni that our boat is named after. The smaller channel gives us a beautiful view of both banks.
I am learning to tell the different mangrove species apart as well. We try to avoid the dense Goran forests, preferring the more open Gewa or Sundari forest. Our maps do not differentiate the forest type, so we sometimes cruise along the coast looking for the more open forest. On one site we unsuccessfully took the country boat up a tidal creek to find more open forest. On our last site in the Sundarbans nearly to the Bay of Bengal, we deployed on a slight sandy rise of the tidal flats. It should not be flooded until the spring tide in a few days, but we placed the recorder and batter in plastic bags on top of the metal box just in case.
On our final morning in the Sundarbans, we were delayed by dense fog. We had to wait for the fog to burn off before we could pick up the last three sets of equipment. The speedboat crew that went to the last site found the slight rise with the recorder and magnetometers stayed dry, although some of the electrodes were underwater, which is fine. In the end, we completed 12 MT stations during four days on the Sundarbans. We then sailed through the Sundarbans toward Barisal, finally enjoying most of a day off during the transit.
I am now on a boat in southwestern Bangladesh, the M/V Kokilmoni. However, getting to this point involved some of the most complicated logistics of any project I have had here. We faced problems with insurance, shipping the equipment, getting the right batteries, visas, and the list goes on. Finally, everything got sorted out and we have been able to start our 25-day cruise only a few days late. On this trip, we are doing a new kind of measurement for me that will investigate a different issue than I usually study.
In large parts of the coastal zone of Bangladesh the groundwater is salty. This limits rice growing to just the rain-fed Aman rice in the summer to fall. For drinking water, they have to store the monsoon rain in ponds. However, deep in the earth, in sediments from the last ice age, fresh water can be found. It is used in some places, but a well deep enough to reach it is too expensive for most farmers. Another issue is that little is known of the extent of this deep freshwater aquifer. I have teamed up with a new set of colleagues to image the saline and fresh groundwater in coastal Bangladesh.
Since salt water conducts electricity much better than fresh water, we will be using two electromagnetic methods to image the distribution of fresh and saline groundwater along two rivers in Bangladesh. To do this, we have shipped 1400 pounds of equipment here. Kerry Key, also from Lamont, is our electromagnetic expert and Mark Person from New Mexico Tech, the head of this project, is our groundwater expert. We are here with their students, along with Anwar Bhuiyan and several students from Dhaka University.
We arrived a few days early in Dhaka for meetings and to make sure we got the equipment released from customs in time. With the help of Anwar, we were able to get it the night before we were due to leave Dhaka. On the day we left, we had to wait until we got the correct deep-cycle batteries before leaving. We then headed out on the long drive to Khulna to meet the boat. With Anwar’s help, we got VIP treatment at the ferry crossing the Padma River, as the combined Ganges and Brahmaputra are called, and did not have to wait long for a ferry. We even got invited for tea by some government officials on the ferry. The new bridge across the Padma is almost done and will be opened this summer, significantly shortening the time to drive to Khulna.
We arrived in Khulna around 6 pm and our caravan of three vans and one truck drove straight to the ghat (dock). The ship’s crew met us and carried the multitude of equipment boxes and luggage to the waiting wooden country boats. We settled in, had our first dinner on the Kokilmoni, and started finalizing the locations of our sites. Chris Small back at Lamont processed Sentinel-2 satellite data to show percentage of vegetation, water or shadow, and substrate (soil) for each 10-m pixel. That let us pick the exact locations of the barren fields for our deployment.
We are focused on training for our first day so the entire group of 12 stayed together. Only a few of us have experience with this type of measurement. The magnetotelluric (MT) instrument uses radiation from the sun to image the structure below the instrument. High frequencies give shallow results and lower frequencies give deeper results. As we are focused on the upper few hundred meters, we will only be deploying the instruments overnight.
At each site we have a central recorder and battery. These are connected by cables to north-south, east-west and vertical magnetometers. These are cylinders about three feet in length that need to be buried. The most difficult is the vertical and we brought post-hole diggers to get them in the ground. Finally, there are small electrodes for the electric field that are placed approximately 50 meters away from the center in the four cardinal directions using a compass and electronic rangefinder. They also need to be buried to minimize noise.
Arriving at the first site, we found a large fallow rice field in which to install the MT station. Kerry explained all the components and the procedure for installing them, and we slowly went to work. At each site we hired a local farmer to watch over the equipment overnight. It is important that nobody goes in the 100 m x 100 m area of the deployment as the equipment is sensitive enough to detect people walking by. By the second site, we were noticeably faster at getting everything deployed. In fact, we became efficient enough that we managed to install a third site on the first day. At the second and third site, we discovered one problem that Chris Small’s satellite images could not capture: cows and goats. Not only could they result in distortions of the signals, but especially the goats could eat the cables. Choosing the fields that minimized grazing livestock became as important as other aspects of choosing sites.
On the second day we circled back and recovered the stations, learning how to properly do it so they are ready to be deployed again at the next station. We spent the morning recovering the three sites and paying our overnight guards. Then, in the afternoon, we deployed three additional sites. One of the sites is at the home village of one of our boat crew. We met his mother and uncle while working at that site. Our original plan was to split into two groups for recovery and deployment. However, with so many people, and especially the help of the crew of the Kokilmoni, both deployment and recovery are very fast, so we decided to try to continue as one team. The ship’s crew is doing all the heavy carrying of the equipment to and from each site, and digging the holes for the magnetometers.
Meanwhile, Kerry took a preliminary look at the data from the first sites and they look good. We are all excited about the potential success of this new method, which has never been used in Bangladesh before this.
In the evening, we headed to the ghat (dock) around 8 pm. It was as hectic as usual, with many people coming and going from ferries and private boats, stands hawking food, and lots of honking vehicles. Bachchu, the boat owner, led us to the right place on the ghat. The wooden country boat of M/V Bawali, our home for the next week, arrived and helped the previous travelers off. Then the crew quickly helped load all our gear and luggage onto the wooden boat. Once we were settled, they crossed the channel to where the Bawali awaited us.
The Bawali, which means wood cutters, is a 60-foot long Sundarban tourist boat with six cabins, one for each of us. We were originally to join her in the morning. To make up time for the delay, she cruised overnight so that we can reach our first stop by morning. We got on board, settled in and had dinner, a buffet of multiple delicious dishes as usual. Still, it was several hours before we got underway. After the long drives of the last days, this will be a much more relaxing, although slower, way to travel. We spent the evening chatting and swapping stories before turning in. We were still in the Pusur River heading south toward the world’s largest mangrove forest.
When I awoke the next morning, we were deep within the forest, arriving to our goal after breakfast. Katka is a much visited tourist site in the Sundarbans and we saw a number of other boats. However, we were going to an RSET site inside the forest. I do not have a GNSS site here, so this was my opportunity to see the RSET measurements being done. As always, we were accompanied by two armed guards to protect against tigers, occasionally yelping to scare them off.
With Pinky and Masud in charge, and Ira, Sanju and out two boatmen assisting, it went relatively quickly. Masud and Ira added the measurement arm to the monument and made the 72 measurements of the elevation around it. Meanwhile, Pinky and Sanju located the sedimentation tiles and measured the thickness of the deposits. The difference between the change in elevation and the sedimentation will yield the shallow subsidence above the base of the rod. Both sites were done by 11:30 am.
Since the weather turned rainy, we missed the opportunity to go for a walk on the beach, and started off for our next destination. The boat sailed out of the river into the Bay of Bengal and into the next channel to head back west towards Hiron Point. Around sunset we passed the spot known as Kokilmoni and hove to near Tinkona Island.
We waited until the next morning to cross the 10-km-wide channel to Hiron Point. The Bawali waited outside the channel while we took the country boat in. The walkway to the tide gauge has broken since our last visit, so we will not visit it this time.
Instead, we went to the forest ranger station and started work on our GNSS. As usual, the batteries were bad and we changed them. They lasted until the end of October until they started failing. We also brought a modem now that Hiron Point has phone service and successfully got it online for the first time since it was installed in 2012. When we finished, two wild boars were wandering around the grounds.
When we finished, we took the country boat across the river to the RSET team, who were finishing up. We all then took the elevated forest walkway to the observation tower about a kilometer into the forest. The wooden slats are in bad shape and many are broken. We all carefully walked over the concrete frame, easily located by the nail heads. It was a beautiful walk through the forest, with a few deer along the way.
After returning to the country boat, I was surprised that we sailed upriver. When we continued that way, I learned that we were going through the maze of channels to the next main channel to the north. Along our 1.5- to 2-hour boat ride, we saw lots of deer, a few monkeys and a crocodile. Near the end, we harvested the fruit of a golpata tree (Nipa palm), and hacking it open with a machete, we got to try its fruit. We rejoined the Bawali just in time for our usual 2:30 lunch and headed to the next site.
The first part of the ride was through a narrower channel, which let us watch lots of deer in the woods. After a couple of hours, we entered a larger river a kilometer wide and headed north to our next destination. We stopped for the night and arrived at Jorshing in the morning. Pinky, Masud and Ira went to the RSET, Chris went to photograph the vegetation, and Sanju and I went to the school with the GNSS. After finishing, the RSET team headed to their second site outside the polder. Sanju and I went to find Chris and then took the speedboat to the RSET among the mangroves.
When done, we started the transit to our last site. During the journey, we spotted monkeys in the Sundarbans and freshwater dolphins in the large Shibsa River. We first headed to our GNSS site in the northwest corner of Polder 32, then to the RSETs on the south side. Our last GNSS to service on this trip is also in a primary school. We walked the half mile to the sites and set to work, with Pinky and Ira along to see the GNSS site. This last site also went well and we headed back to the Bawali feeling satisfied after tea with the headmaster.
We have now visited all of our southern coastal sites measuring subsidence of the delta. All are online and transmitting data back to the U.S., although one is having trouble locking satellites. I may have to visit it during my next trip here in March. The RSET team still have eight sites to visit over the next two days at Sorbhatkhali on the south side of Polder 32. Four are in the Sundarbans and four are within the polder.
Chris and I, however, are heading home. First, we will meet the smaller M/V Mowali (Sundarbans honey collectors) to take us back to Khulna. Then, the next day we travel back to Dhaka and finally catch our flight back to New York, after the required COVID test.
My GNSS network is working once again, collecting data to better determine the tectonics of the subduction zone in northeast Bangladesh and the subsidence of the delta in the southeast. Together they will refine our estimates of the hazards from a potential large earthquake in eastern Bangladesh, and from sea level rise and climate change in southwestern Bangladesh. My meetings in Dhaka between the two service runs will help establish new projects for continuing our research here. It has been a successful trip and I am ready to return home.
Having finished servicing our two GNSS and RSET sites south of Barisal, we now headed west to Khulna to service the rest of these sites measuring land subsidence and sedimentation in the Ganges-Brahmaputra Delta. Many roads in Bangladesh radiate outwards from Dhaka. There aren’t as many good roads going east-west in southern Bangladesh. That made for slow driving through rural Bangladesh. Near Pirojpur we had to cross the wide Baleshwar River by ferry. From the ferry ghat (dock), I could see a large new bridge nearing completion.
There is a tremendous amount of construction going on all over the country. With 7% economic growth per year for the last 4 years, the country is booming. New roads and bridges, a metro in Dhaka and new train lines are all underway as Bangladesh moves from being a low income country to a lower middle income country.
About halfway to Khulna we turned south to our sites at Sonatola in Sharankhola District. Here, we installed two GNSS stations. One is on top of a primary school, like many of our others, the other is installed on an RSET rod. The RSET (rod surface elevation table) measures sediment accumulation, elevation changes and shallow subsidence relative to the 80-foot rods we pounded into the ground.
The GNSS will measure the absolute movement of an identical rod, giving us the deep component of subsidence. The two GNSS here have only been in place for 2.5 years, too short for reliable rate estimates, but they have consistently shown faster subsidence by ~1 mm/y on the building, which is less deeply rooted than the rod.
It required another ferry crossing to get to this land on the edge of the Sundarbans Mangrove Forest. We had to drive around the island using the road on top of the embankment, as the interior roads are not suitable for our vans. To get our equipment from the embankment road to the school and then the open field nearby, we hired a rickshaw van.
We were also met by Bachchu, the local farmer who allowed us to put our equipment in his rice fields and a member of the school council. We were both happy to see each other after over two years. The first site at the school, SNT1, looked pretty good. Although we lost contact in late October, the receiver continued recording data into December, when the battery got too low.
We then checked the grounding rod. To our relief, it was still in place, but the wire to it cut off. We only had to splice in a new piece of wire. SNT2, with its receiver box in Bachchu’s garden, was even better. The battery was low, but still running. We replaced the battery with a new one anyway to be safe. As we edged around the central pond of the garden, Bachchu gave me fresh cucumbers. This site went surprisingly smoothly, but the RSET team still beat us as we had two GNSS here.
Now, we reversed our route back to the main road and drove past the historic city of Bagherat, founded in the 1400s, to Khulna. We crossed the Pusur River that we will sail down in a few days and entered the city. As our driver did not know Khulna well, we followed Google’s directions to our hotel, which took us over an awful road. We slowly bumped over the road to our hotel. The long drive and diversion to the sites at Sonatola meant we arrived at 7pm — another 12-hour day.
Our site for the next day was a long drive to the southwest. We originally estimated three hours to get there, but wrong directions from Google and a terrible brick road at the end meant it took four. We ended up getting out of the car and walking to lighten the load for the car. Besides, we could walk faster than the car could go over this road. Still the long drive had more variety of rice, shrimp, and other crops in different stages of development that Chris took three times as many photos as in the previous three days combined. We could see the fall rice crop being harvested and the spring rice crop still in its seed bed, or just transplanted, and everything in between. The area of this site is primarily Hindu, and we passed many temples and shrines.
After walking to the school, which doubles as a cyclone shelter, we met with the headmaster and went up to the roof. To our surprise, we found the receiver working and still recording data. When we changed the batteries, we found one of the old battery cases was split, so they weren’t long for this world. However, there was one tall tree that sprung up between the GNSS and the open field with the RSET. We want to try a new technique here called GNSS-IR (interferometric reflectometry). It uses the bounce from a river or the ground to determine its elevation below the GNSS antenna. It can potentially give us continuous measurements of the surface subsidence and seasonal variation, but not if a tree is blocking the view.
The headmaster initially suggested that we wait for when the electric company comes to trim trees near the power lines, but eventually, a local boy climbed the tree with a machete and started chopping off branches. We was able to get about three-quarters of the offending branches; the rest will have to wait for the electric company. For the first time, we were done well before the RSET team. We had tea and Sanju bought candy for all the local kids. We then leisurely walked back down the red brick road to the embankment road, talking with the farmers along the way. We left the RSET team and headed back, stopping for a quick lunch around 5 pm, just as the RSET team was finishing its work.
The RSET team was now done with their land sites, but our boat wouldn’t be ready until 7:30 pm. We had one site at nearby Khulna University. We finished it before noon. Sanju, Chris and I then went to the Divisional Archeological Museum to meet with the regional director, Afroza Khan Mita. When we arrived in an autorickshaw, we found her and her entire staff waiting in a line at the entrance to welcome us with flowers.
She then gave us a tour of the museum and we met in her office over tea and snacks. She organized a web seminar series I was part of on the archeology of deltaic ecology. It included both archeologists and geologists. With the people I met in this series, I hope to expand my measurements of subsidence to include more archeological sites. It was great to meet her in person and we are both excited about the potential collaboration. This meeting finished the third part of my trip. The final part will be reaching the remaining GNSS and RSET sites by boat.
I spent the past week in Dhaka, the capital, in numerous meetings with colleagues and partners, limited only by the terrible Dhaka traffic. Two events stand out. I traveled north to Gazipur to stay with my colleague of over 20 years and primary partner in Bangladesh, S. Humayun Akhter. Last summer he became vice-chancellor of Bangladesh Open University, the seventh largest university in the world. The vice-chancellor is the equivalent of the university president in the U.S., as the chancellor is a ceremonial position. He now has an enormous office and residence, where I stayed with him.
The real highlight of the week came on the last night, when Chris Small, now arrived to join me, and I attended Nafis Sazeed’s wedding reception, my first in Bangladesh. Nafis is a graduate student at New Mexico Tech and part of a project that will bring me back to Bangladesh in March — using electromagnetic tools to map saline and fresh groundwater. We have many times spoken by Zoom and email and I am on his thesis committee, but due to COVID this was also the first time I have physically met him. As it turned out, Humayun was also at the wedding. Georgina, his now wife, as well as Nafis, were students at the Department of Disaster Management at Dhaka University. Humayun was invited by her.
Early the next morning, we set out for southern Bangladesh, where I will spend the rest of this trip. I now have nine GNSS stations in this part of Bangladesh, and the batteries at all of the stations appear to have failed. We will change the batteries and see if anything else is amiss that could have caused the problem. These stations are examining the subsidence of the land of the Ganges-Brahmaputra Delta. All deltas sink due to the weight of the accumulating sediments and due to compaction of the sediments. The rate of the sinking is even greater than the rate of sea level rise, greatly exacerbating the problem in this densely populated, low-lying land. However, here the Ganges and Brahmaputra Rivers still bring an enormous supply of sediments to fill in the newly created space. As a result, Bangladesh is still gaining land, but due to the shifting positions of the rivers, some areas get sufficient sediments while others are facing problems due to a lack of sediments.
This investigation is currently supported by the Bangladesh Water Development Board as part of the “Long Term Monitoring, Research and Analysis of Bangladesh Coastal Zone (Sustainable Polders Adapted to Coastal Dynamics)” project. In Bangladesh, they use the Dutch term polders for the embankments protecting coastal islands.
In addition to Chris, who will be validating his remote sensing observations, Sanju and I are joined by five others. Masud Rana and Sharmin (Pinky) Akhter from Dhaka University will be servicing the RSET-MH (Rod Surface Elevation Table – Marker Horizon) equipment that we installed with the GNSS in 2019. These devices measure the elevation change and sediment accumulation. The difference gives the shallow subsidence above the 80-foot depth of the rods at the sites. The GNSS, on the other hand, measure the deep subsidence, but miss some of the shallow subsidence due to the foundation of the buildings that they are installed on. The combination is a very powerful way to understand the dynamics of the delta. This work is the basis for their master’s theses.
We recently published a paper on our results to date here. In addition, Pinky has brought another female student with her, Tanjina Fedous Ira. Finally, two employees of the Institute of Water Modeling, one of our partners in this project, are also coming along for the land part. Sheikh (Nahid) Nahiduzzaman and Upal Mahamud are along to be trained in our methodology and equipment as part of the technology transfer part of the project. Nahid was also with us in 2019. The two of them will visit New York and Louisiana for further training in April.
There are two ferry crossings of the Padma River, as the combined Ganges and Brahmaputra are called — one at Mawa, south of Dhaka, and one at Aricha, near the confluence of the three rivers. Although Mawa is closer and a shorter overall drive, the drivers elected to cross at Aricha because to the heavy delays at Mawa. While, this route will be overall time-saving, we did not arrive at Kuakata on the coast of the Bay of Bengal until 9 pm. Stopping at Barisal University, we picked up my colleague Hasnat Jaman and one of his students.
Now we could begin work on the sites. We headed back north towards Barisal, stopping at two sites on the way. Masud and Pinky’s team would service the RSETs and Sanju and my team would do the GNSS sites. The RSET team was worried about completing all their sites and making it to Barisal, so they left at 7 am. We followed more leisurely after an 8 am breakfast. Since we have a campaign GNSS kit with us, we stopped at the tide gauge near the GNSS site at Khepupara. We originally put the GNSS here to be close to the tide gauge, which showed irregular and sometimes high subsidence. On my last trip here in 2019, we welded a monument pin to the tide gauge. Now, we will put a campaign GNSS here while we work on the continuous site. After a few phone calls for permission, we used a ferry boat to go to the steel structure and it set up, hoisting the equipment by rope. GNSS recordings of the signal bouncing off the water will allow us to determine the offset of the local datum for measuring the tides from mean global sea level.
We then went to the continuous GNSS at a local weather radar station. Other than the batteries being dead, everything seemed to be in working order. The logs looked like it slowly failed last summer. The likely explanation is that with days of rainy and cloudy weather, the solar panel could not recharge the batteries. The battery charge was drawn down enough to damage the batteries. A quick call to Keith Williams at UNAVCO in Colorado confirmed everything was in working order. We packed up, recovered the campaign kit from the tide gauge, and headed north feeling confident.
We stopped for a relaxed lunch, instead of the snacks we often had on the road, and arrived at our second site at Patuakhali Science and Technology University and went to work. We changed the batteries, flipped the switch and … nothing. After much testing and some false starts, we determined the solar charger had failed and we replaced it. Now we had power, but the modem wasn’t able to connect to the network. Luckily, we had another spare modem and changed it as well. With running up and down from the fourth floor office hosting the receiver, I got lots of exercise. Finally, we installed a new grounding rod as the copper rod was stolen and we were done. It took us four hours. By the time we finished, the RSET was long settled in the hotel in Barisal. We were the late team. Sanju and I finally had dinner at 10 pm.
Due to the COVID-19 pandemic, it has been almost two years since I was last in Bangladesh. During this time, all of the GNSS (GPS) receivers that we set up in 2018 and 2019 for two different projects have stopped working. As a result, I will be here for three and a half weeks to visit and repair them all with the help of Dhaka University graduate Sanju Singha. He has been critical in maintaining the stations.
The first stage of this trip is visiting our five stations in Sylhet, in the northeastern part of Bangladesh. This is the area where the sediments of the delta are being folded up by the IndoBurma subduction zone. The folds form hills whose tops are covered by forests. The flanks are used for tea plantations, generally called tea gardens. The intervening valleys are covered by rice paddies. Beneath the folds lies the nearly horizontal subduction megathrust, a fault that could potentially rupture in a great earthquake. Over years, our GNSS stations can measure the motion of the ground down to rates of 1 mm/year or better, to better understand the fault movement.
The stations in Sylhet have failed because the first set of batteries we used leaked battery fluid. Sanju was able to replace the batteries with better ones and clean the equipment box as well as he could and replace some of the parts inside. I have brought a bunch of replacement parts: solar panel controllers, modems, cables, wiring blocks. Most of the equipment was supplied by UNAVCO, a consortium that assists U.S. universities with geodetic measurements.
Sanju and I left Dhaka, the capital, on December 29 with Babu, who has been our driver whenever we can manage it since 2005. On the way to Srimongal, where we will be staying, we stopped at our first station in Chunarughat. It is in the middle of one of the valleys at a college. Now I got to see how bad things looked inside the equipment box. The waterproof box kept all the leaked fluids inside and the acid fumes corroded everything.
The wood was nearly black, exposed connectors were all green, as were the ends of the copper wires. The corrosion meant the solar panels weren’t supplying power and the batteries were drained and ruined. We even found that the SIM card in the modem was corroded and had to be replaced, along with the modem. We spent hours cleaning and replacing everything. Amazingly, the expensive GNSS receiver, despite the corrosion on the unused connectors, worked fine. UNAVCO was able to remotely program the new modem. The station is now up and running again. Success!
We headed to Srimongal and picked up Shofiqul Islam, a professor at a university in Sylhet city at the train station. Shofique spent 7 months at Lamont in 2021 working with me on the folding and thrusting of the hills in Bangladesh.
The next day we headed east to service the two farthest stations. The ICPS station is on the roof of a primary school on the flank of one of the hills reached through driving on bad roads in a remote area. The roads are barely wider than our van, so passing other vehicles is always a challenge. This time, we could get the receiver working, but were missing a key cable connecting the receiver to the modem. Without a replacement, we had to leave it without a being able to transmit the data. However, it is recording the data internally. On my next trip, I will bring the needed parts and Sanju will complete the repairs.
We took a short cut to the JURI station on the other side of the hill. Instead of going around the hill, we went across it through the tea gardens and then an eco park. This station is in a medical clinic. They would like us to move the receiver out of the birthing room, but this will have to happen on another trip. This time the modem was ok and after the repairs, JURI is back online. The problem at this station is that trees growing around the clinic are blocking antenna’s view of the sky. This has been a problem at this station before. Betel nut trees are partially blocking the view to the north, but the worst is a tree whose branches overhand the antenna. Sanju will have to speak to the clinic director next week about cutting down, or at least trimming, the trees. Looking at the previous data from the site, I can see the recent data is about three times less precise than the older data.
The fourth station, SSPS, also on a primary school, was vandalized by someone to steal the batteries. The broken box was no longer waterproof and the rain ruined the receiver. However, a sixth site had to be removed because they expanded the school it was on, adding a new floor where our antenna was mounted. We installed the KGPS receiver in place of SSPS, but relocated the box to inside the school in a secure storeroom. This made for a longer job. We had to reinstall the solar panel, and add a grounded lightning protector to the antenna cable for safety before it enters the school. Still, we were able to finish in time to get Shofique to his train back to Sylhet. The SSPS site is in a beautiful location, but hard to get to. The concrete culverts over the little streams stood above the dirt road making it challenging for the van to drive over. We had to get out several times to lighten the van and at one site we made a brick roadway so the van could drive across. It worked and we could drive up to the site instead of having to carry the batteries and equipment the last half mile.
After finishing, we had tea and cookies, along with some hard-boiled eggs that Sanju ordered from a nearby store, in the mud and bamboo home of the head of the school maintenance committee. Then, for New Year’s Eve, we stopped for an afternoon snack at a fancy resort with its own tea garden followed by tea at a local tea shack. The contrast in style and price was striking.
Our final station was also at a school. It is on the top of the hill nearest to Srimongal, the tea capital of Bangladesh. The repairs were similar, except for a mix-up about the solar panel that cost us time. We are now on our way back to Dhaka. While we were there, the school children arrived to get new books for New Year’s Day. We have repaired all five GNSS stations and restored remote data transfer at three of them — overall, a pretty successful first phase of my trip. Now I will spend the next week in Dhaka, culminating in attending a Bangladeshi wedding before heading south to visit nine more stations by car and boat.
The data from these stations are helping to refine our estimates of the rate at which subduction is occurring. They are being used by graduate student Bar Oryan at Lamont as part of his thesis. The longer the time series of the data from the GNSS sites, the more accurate the estimate of the subduction rate and overall tectonics. The results are already showing the rate is a little slower than I previously estimated, which hopefully means a longer time between potentially disastrous earthquakes.
Our surveying of scores of old geodetic monuments installed by the Survey of Bangladesh in 2002 is going well. By determining their exact elevation with precision GPS, we can determine how much the land has sunk, or subsided over the last 18 years. This is of critical importance in the low-lying coastal zone of Bangladesh. The balance of sea level rise, land subsidence and sedimentation will determine what land loss the region could experience in the future.
We have worked our way south to the beach town of Kuakata on the Indian Ocean. Since installing the GPS just behind our hotel took longer than expected, we split into two teams to install our equipment at the other two sites near here. My group was to do the site to the northeast. The challenge was how to get there. While there are roads that directly go there, they are probably not passable for our van. Instead, we headed north.
We will have to take ferries to get to the corner of the island where the site is. After a lot of asking around, the best route turned out to be to drive east to the new large Deep Sea Port that is being constructed with a wide new road leading to it. We then went along the crumbling embankment road to a local country boat ferry. There were wooden boardwalks at each end to get to the boat for the short trip across.
On the other side, we were able to get a rickshaw van for about a third of the way to the school with the monument. The four of us had to walk the remaining half a mile. We were shown the monument adjacent to the school, which was surrounded by shallow water from an unused rice field. At least that meant that it had an excellent sky view. We took off our shoes and sandals, rolled up our pants and waded to the monument through foot-deep water.
The monument was in good shape and the set up went quickly. The only challenge was making sure the tripod was stable in the soft mud. After meeting the local school headmaster and having tea, we walked back to reverse our route. The other team was able to drive to their site, which was also in the middle of water with only the top of the monument sticking out. Unfortunately, it had sewage from latrines draining into it, so they decided to skip it.
Since they could not install that one, they got to pick up the GPS that was set up the day before. Since it was set up late the previous day, they had time to eat lunch and visit a beach. When we finished and made our way back, we had some free time in the evening, unlike the last few long days. We returned too late to catch the sunset, but were still able to enjoy a walk on the beach. When I was here in the summer, the water at the beach was fresh instead of salty.
This is due to the enormous water flow from the Ganges and Brahmaputra Rivers during the monsoon. The flow pushes the salty ocean water away from the coast. Now in the winter, the water was somewhat salty, but still not at a level of the normal ocean. We also had an easy morning, at last. We needed to wait until 11 AM to pick up the station outside our hotel, so we had plenty of time to pack and check out. Then the entire team went to our site from yesterday.
I opted to stay on the school grounds and let others wade through the water to pick up the equipment. When that was done, we were free to head back north to Barisal. Since it was the weekend, traffic was light and we got there in the early evening. With Hasnat and his students trained, it was time for me and most of the others to return to Dhaka. Céline will stay a few more days to work with them. We rearranged all the equipment in the cars, so we could install a site on the way back to Dhaka. Mondal, Sober, Salam, Masud and I went with the two GPSs returning to Dhaka and one to install. Hasnat, Nahin, Saif and Céline went to install two other sites. This time, the site was in a jute factory not too far off the main road to Dhaka. With both professional surveyors in our car, the installation went quickly, the factory manager arranged for security and showed me the facilities.
Based on expected traffic, we took a longer route and took the shorter ferry at Aricha near the confluence of the Ganges and Brahmaputra Rivers. While the route was longer, there was little traffic until we reached Dhaka and not much wait at the ferry. With 5 people and equipment to drop off, we had multiple stops in Dhaka. We spent almost as much time (almost 4 hours) in Dhaka as getting to Dhaka from the last site (4.5 hours. For me now, there are a few days of meeting in Dhaka, then the long trip home.
Meanwhile, Hasnat and his students will continue to survey the geodetic monuments for the next two months. Today, while I am in Dhaka, they installed one more site and picked up the equipment from the previous day’s three sites. I will pick up the equipment I brought in March. The trip has been very successful, with the usual rearranging the schedule on the fly.
The next day we all went to two sites to the southeast of Barisal. Our team of nine people are resurveying old Survey of Bangladesh (SoB) monuments to determine how fast the coastal zone of Bangladesh is sinking. Bangladesh, home to the world’s largest delta, is sinking, as are all deltas, worsening the effect of sea level rise. Here, unlike the Mississippi Delta, the rivers still bring a amount of sediments to fill the area and maintain the land. But with increasing sea level rise, it is important to know the rates that the land is going down.
Getting to the day’s sites involved two ferry crossings. The first was on the busy main N-S road over the large Bighai or Payra River.
A huge bridge is under contraction, but until it is done, a ferry is needed. The second ferry was on a smaller river heading east. Both would eventually cause problems. When we finally made it across the rivers and finished the long drives and got to the site, we found it under lots of trees. The landowner had told the SoB that he was going to build his house and garden there back in 2002 when the monuments were installed.
However, they did not listen and shift the monument to the site he suggested in an open field. We could not cut down enough trees to make it a good site. After many discussions and phone calls, the Institute of Water Modeling was able to arrange for a surveyor to join us tomorrow. We put the GPS in a nearby open field with a good sky view. When we return, the surveyor will do a leveling survey.
He will determine the elevation difference between the monument and the GPS with the temporary mark we created. The delays meant it was already after 2 PM before we finished the site. We headed south along a bad road to the next one. We weren’t sure of the road to take, but both Google Maps and local guides took us to a dead end. There was a large tree fallen across the road. People slowly sawing it into pieces. Clearing the road would take days.
We looped back and found the site off a road that was on no map. At least it had a very good sky view. We installed the site and arrange for guards as darkness fell. We had managed two sites that were difficult to get to. Unfortunately, they were also difficult to get back from. My car left early to pick up the site near Barisal University on the way home while the others finished the installation. However, we first found the large ferry near the city of Patuakhali was jammed with traffic.
It took hours to get across and with the extra stop, we didn’t reach our hotel until after 10 PM, around the same time as the other team. We gave up picking the rest of the previous days sites and arranged for security to continue another day. Knowing how long cooking food takes at the hotel restaurant, we asked our floor boy what could be made quickly. As a result all nine of us had chicken biryani for dinner.
That convinced me that it was time to move to Kuakata, a beach resort town on the coast as our base. No ferries. The three river crossings now all have bridges. It is a long drive from Patuakhali, but no longer than the time we spent waiting for a ferry. To make this work, the teams split up. One car headed south to install stations on the way to Kuakata, while my team first headed north to pick up the two earlier sites.
We had a late start from checking out and trying to fit everything into the vehicles. The pickups went well, but the drives took longer than I expected. With the wait at the ferry, we got to the first site late in the afternoon. The surveyor went to work and made an excellent tie between our GPS in the field and the monument, getting the height difference with a uncertainty of 1 millimeter. We dropped him off at his nearby home town and got to the other site after dark.
We made the required checks and measurements by flashlight. Returning to the main road, this time our problem was the small ferry. A truck broke its axle and it took hours to get it off the ferry. We spent the time waiting at the ferry terminal drinking tea and watching cricket. It was almost two hours before we got to the other side. We stopped for dinner in Patuakhali and finally reached Kuakata a little before midnight. The other team also had bad luck.
The quickly picked up the station at the university and headed to a site in Patuakhali. It had a different, taller monument and our tripods would not work. The SoB will lend a different tripod to Hasnat for occupying that site later. They then drove to the next site and found it tilted and in the river. It was now good for helping people climb out of the river after washing, but useless for us. They finally got to install a site along the road to Kuakata.
Still, they finished well before us and had fresh barbequed fish at the hotel for dinner. With the late nights, we all slept in a little and had breakfast at 8. The next site turned out to be 100 feet from the back of our hotel on the road parallel to the beach. I hadn’t spotted it during a morning walk. That was because it was in a squatter’s home. The walls, trees and rooftop squash were a problem for the sky view. The person living there was very accommodating with changing his home.
He cut back some trees and lowered netting that had squashes growing on it. We tried several different configurations with different tripods to finally get the one that was both stable and gave us the highest antenna. We needed to be above all the walls and squash for the sky view. It took a while and we had to stand on stools to use the tribrach for leveling and centering the tripod. Most of the morning was gone and we still had two more sites to do today. Each team picked one and we all headed off.
The first one done would pick up the previous days site. Even so, it would be a shorter day than the last two, and we were in a beach resort town, if we ever managed any free time.
Overnight, our last team members arrived: Céline Grall, who just left Lamont for a permanent research position in France, and Abdul Muktidir Sober, a GPS specialist from the Institute for Water Modeling (IWM). Since they left Dhaka late in the evening, they only arrived in Barisal, Bangladesh at 5 AM. We let them sleep in.
The rest of our team consists of Hasnat Jaman, a professor at Barisal University and his students Saiful Islam and Nahin Rezwan, Shaikh Nahiduzzaman (Nahid) from IWM, Ershadul Mondal from the Survey of Bangladesh (SoB), Masud Rana, a student from Dhaka University (DU), and myself. Nahid and Masud were with me on the trip this past summer. I have been in the field with Hasnat several times back when he was a student at DU.
Following up on our first successful day, we attempted to install three GPS to the north of Barisal. We decided to go to the farthest site first, the other two being near the main road and easy to get to. All of monuments at these sites were set up by the SoB in 2002. Resurveying them will give us a measure of how much the land has sunk over the last 18 years. To reach the site, we needed a ferry to cross the Arial Khan River.
Since no car ferry was there, we debated whether to take one of the frequent people ferries and hire a vehicle on the other side. While we talked, the car ferry appeared. However, when we talked to the operator, we found it was not due to leave for two hours. We negotiated a sooner crossing, but could not arrange anything for the return trip to avoid a long wait on the way back.
We gathered everything we would need and took a crowded people ferry. While we were crossing, the car ferry also started crossing, but we probably made the correct decision. On the other side, we were able to rent a laguna, a covered pickup truck with two rows of seats facing each other in the back. The seven of us piled in with the equipment for the hour-long ride the rest of the way to the site.
It was at a school where we were welcomed warmly with tea and cookies. We found the monument, but it was next to a tree and a corrugated tin building. When SoB measured this site, they used a 10-meter pole for the antenna, something we don’t have. They cleared a wood pile, some vegetation and a tin canopy, but the site will still be of poor quality.
We set up the GPS anyway, continuing to train Hasnat and his students on all aspects of the set up. The school set up barricades to keep the children away. With our work done, we got back into the laguna for the long ride back to the ferry. After the crossing, we had snacks and tea with fresh hot milk while waiting for our cars. It was a treat where most rural town have only powdered milk or sweetened condensed milk. It was now after 3 PM and we could only do one more site before dark.
This site, off the main road, was not near a facility. Nahid and I went to find the local district chairman to arrange for guards to protect the equipment. We went to his office by foot and then his home by motorcycle to find him. Our van picked us up and took us to the site where he quickly arranged for the site to be watched and protected. We finished by going back to the previous day’s installation and retrieved the equipment in the dark.
A quick check of the data we collected showed that the first day’s data looks very good. The next day went very quickly. We quickly set up a GPS at Barisal University on a monument we had installed last summer. We went to a nearby site to the west. Since it was next to a busy road and overshadowed by banana trees, Nahid and I, with Nahin, who must learn to do this, went to find the landowner. We located him, got permission to cut back the trees and arranged for two people to guard the site through the night.
Then we drove north to another site. This was in a banana field next to a school. Working with the owner, we are able to trim the large banana leaves rather than cut down any of the small trees. We finished by having tea and cookies with the headmistress of the school.
It was early enough that we decided to split up. One team went to install the GPS at another site, while I went with the team to retrieve yesterday’s instruments.
We drove to the ferry, grabbed the tools we needed and left the van. There was some problem with the ferry, which sat at the dock without going. We left it and went on a speedboat across the river for less than 50 cents extra each. On the other side, a laguna van was not available. There had been an accident involving one, so all lagunas were grounded for the time being. Instead, we took a smaller and slower three-wheeled autorickshaw.
Once we got there we double-checked that the tripod was still level and centered on the point, and remeasured the height. Everything was fine and we packed everything up and got back in the autorickshaw for the hour’s ride back to the ferry, arriving after dark.
The other team found the next site in the middle of a stand of bamboo. As the owner lived elsewhere, the area was not maintained and the plants were wild.
We went ahead and set up the system, but we are not at all sure the data will be of sufficient quality. Then on their way back, an accident blocked the road. Two pedestrians were killed, including a beloved Freedom Fighter from the 1971 War of Independence. It would be 2.5 hours before they could get by. Thus, after crossing the ferry, we went to yesterday’s other site, paid the guard and packed up. We finally met up back at the hotel around 8:30 pm. A long, but successful day.
I am back in Bangladesh once more for another part of the Coastal Embankment Improvement Project Phase 1 (CEIP-1). The maintenance of the Ganges-Brahmaputra Delta depends on the balance between sea level rise, sinking of the land, and the filling of the space with sediments. Understanding this balance, as well as the shifting of the river positions through time are needed to design the embankments (Bangladesh uses the Dutch term polders) that protect the land in the southwestern part of the delta.
Despite dire predictions for the future of Bangladesh with sea level rise, the delivery of fresh sediments from the Ganges and Brahmaputra Rivers is helping the country keep pace with sea level rise. However, the future depends on whether India and China proceed with dams and river diversions upstream. My role in this large project is developing a better understanding of subsidence, the sinking of the delta. All deltas sink, increasing the effect of sea level rise. We are trying to understand to processes and rates.
Last summer, our team installed and rehabilitated GPS and installed Rod Surface Elevation Tables (RSET) to measure both the subsidence and sedimentation rates at a number of places. I have returned to make additional measurements of subsidence. Back in 2002, the Survey of Bangladesh (SoB) installed a large number of geodetic monuments around the southern half of the country. Their positions where measured by GPS, but they haven’t been remeasured since.
I have identified 55 monuments in my field area. This trip, I will start to reoccupy some of those sites with new GPS measurements and train Bangladeshis to continue measuring to complete the survey. With our precision GPS, I expect to be able to determine the elevation to ~1 cm (0.4 in) to determine how much the sites have subsidence over the last 18 years. While the data from only two short campaign GPS surveys 18 years apart will not be as precise as the continuously recording GPS we have, the number of sites, 55 evenly spread across the land will provide a broader picture than the 9 continuous sites I have.
After spending New Year’s Eve in the air, I arrived in Dhaka the following afternoon to find one of our safe-to-fly AGM batteries was taken from a GPS case in Dubai, and another one missed the connection. Between the delays dealing with the luggage and traffic, I made it to my 8:30 dinner meeting a little after 10:00 pm. Amazingly, they were just serving the soup and I was able to join in.
The next day was filled with meetings. I gave a talk at the Project headquarters at the Institute for Water Modeling (IWM), and went to the SoB and Dhaka University (DU). I met the Surveyor General, from a line that goes back to Sir George Everest and beyond. We finished the arrangements for the trip, prepared 2 additional DU campaign GPS, renewed old acquaintances and make some new ones. My last GPS case arrived at my room about 11 pm, also minus a battery.
The next morning, Nahid (IWM), Masud (DU )and Mondal (SoB) converged on my hotel for the long drive south to Barisal, our base for the fieldwork. We caught a slow ferry, a barge pushed by a tugboat, for the Padma River crossing, so we arrived too late for any work. Instead, we had a planning meeting, along with Hasnat, our colleague at Barisal University (BU), and two of his students at the hotel. Having skipped lunch getting here, we had an early dinner and collapsed into bed early.
Today, was our first day of fieldwork. We started by training over 20 BU students in setting up the tripod and GPS. This also gave us a chance to take out and test all of the instruments. The instrument from the SoB has internal batteries that must be switched every 3 hours, so it will not work for our 24+ hour observations. We have 6 that we can use, but 3 of them need new batteries now. We spent the morning doing the training in a field at the University and taking selfies.
When that was finished, we headed back to Barisal to shop for materials to build a fence around each site and miscellaneous other things. We could not find appropriate batteries, but Sober, a SoB engineer who will join us tomorrow found them in Dhaka and will bring them. Finally, well into the afternoon, we headed out to our first site to try and get it installed before dark. When we got there, we could not find the monument, only a new school building close to where it was supposed to be. I was sure it was destroyed during construction.
However, some of the local people told us it was still there, just buried. Poking the ground with a piece of rebar and then digging with a kodel (a cross between a shovel and a hoe), we found it! I was amazed, and the brass center point mark was clearly visible. As it was now getting late, we had Mondal, a survey specialist from IWM (the Institute of Water Modeling) set up the tripod and tribrach, carefully arranging everything exactly over the mark and skillfully leveled. We carefully installed the GPS and solar panel, built a fence around the equipment and arranged for people to watch that it wasn’t disturbed. Complete success as darkness fell. A great end to our first field day.
The next morning we headed north and stopped at Khepupara. After seeing the site, the SET team continued on. Ashraf had to get back to Dhaka for an exam and they had to scout the next and last location near Patuakhali Science and Technology University (PTSU). John and Sanju climbed the structure to weld on the monument. I joined them with some additional materials after taking pictures.
Then, we also continued north to PTSU. We met our contact and he introduced us to the relevant professors. The old vintage GPS was no longer working. We would scrape everything but the monument and rebuild the station. While a seismometer site was on the ground floor, the GPS was on the third floor close to the roof. Removing the old dated equipment we went to work constructing a new one, with a break to meet with the Vice Chancellor of the University. We had a number of purchases to make with our dwindling supplies, so we left early to shop in Barisal, where we would be staying. The small city of Patuakhali could not accommodate us. This means we have a two hour commute, including a ferry each day.
Meanwhile the SET team had a difficult time finding good easily accessible locations for their equipment. Still, they managed to locate the two sites they needed. Since, we were now ahead of schedule, we have plenty of time for this installation.
We walked around the downtown with a local Barisal University student buying nuts and bolts and a box to keep the station in, and arranging for a solar panel. We saw various areas selling, steel, clothing, automotive parts, peppers and turmeric, shoes, jewelry.
This is known as retail clumping, where sellers of the same items are all near each other. However, we could not find any angled aluminum for the solar power frame after wandering a long time. We decided to take an auto rickshaw to an aluminum place we spotted outside of town after dropping our purchases at the hotel. Then, 100 m from the hotel, we found what we had been searching for, and got the rest of the stuff we needed.
The next morning the SET team tried to leave before dawn to be able to install the outside the polder (embankment) because of needing to work during low tide. While the driver of their van overslept so the got out late, they were still on the road well before the rest of us woke up. We got to the university at Patuakhali later that morning and set to work rebuilding the GPS station.
We ordered a good quality solar panel by a Bangladeshi brand we trust. Since they have no official distributor in Barisal, we had arranged for it to be sent by bus to Patuakhali, a short ride from the university. However, the shop owner wanted to go to Friday prayers before sending it and the bus would then take some time. We decided to drive ourself to the small town of Galachipa where his shop was to pick it up to save time.
The first part of the journey was on the main highway, but we then turned off onto some bumpy dirt local roads. We wound our way through then to the river and then continued south. At one point, we hit a bypass road around some road construction that had a line of waiting busses. We found we could just barely make it across the temporary bridge. We continued on and reached the ferry. The shop was in the town on the other site.
However, the car ferry was not running because the high tide submerged the dock. We hopped on a country boat people ferry, then an electric rickshaw and found the small shop. When we got back to the dock, a ferry had just left. To save time, we hired a boat for ourselves (less than $1) and crossed back. I suggested a longer route with better roads, but was told the bridge was out so we could not go that way. We went back the way we came, but now a Caterpillar backhoe was blocking the route.
We could not get by. We went to the other route that we had suggested and asked people along the way how to go. We found a small road around the missing bridge. It included crossing a bridge with holes in the concrete and squeezing through an open air cow market for the upcoming Eid al-Addha (Feast of the Sacrifice) holiday. We finally made it back to larger, more drivable roads and hurried back. This adventure had taken us over 4 hours, but given the ferry and bypass road situation was actually needed to get the solar panels.
When we got back, the GPS station was mostly assembled. We installed the solar panel on the roof and a few remaining bits of wiring and headed back. My long-term collaborator Humayun Akhter was in Barisal to supervise some exams. Importantly, he had brought an antenna and power cable we need to complete the station. When we got to Barisal, we found the SET team had competed both installations with their early start.
However, the second one had lots of leeches at the site. I’m glad I didn’t get there. We had a large celebratory dinner that included Humayun, some professors from Barisal University and our team.
The next morning we headed back to Patuakhali and completed the site while the SET team slept in. Later in the day, they visited the sights of Barisal, including a mosque and floating market. It took 2.5 hours to finish the site, although John was not able to doublecheck the VPN internet connection to UNAVCO. Back at Barisal University, we decided to install two GPS monuments using leftover material. One was a braced monument on the ground using leftover SET rods. This will give us a shallowly anchored site to compare to the deeply anchored site on a long SET rod at our first location.
We also put a threaded rod on the roof so we have a monument that matches most of our other sites in Bangladesh. Hasnat will occasionally borrow the Dhaka University campaign system to make measurements.
We were not done, almost. John found the VPN wasn’t working, so he and Sanju headed back to Patuakhali in the morning as the rest of us started the long drive back to Dhaka. They will take the overnight launch from Barisal and arrive in Dhaka at 6 am.
For me and the others, fieldwork was over. We had installed 4 new GPS stations and upgraded 5 others. Shortly, all but Hiron Point will have working data downloading to UNAVCO. We also added 4 unplanned campaign monuments. The SET team installed 12 systems at 6 sites and made the first measurements at a seventh. We also made new friendships among the people in the team and connections to others at the places we visited. It was a very successful trip, and amazingly it took exactly the amount of time we estimated.
We had feared nearly continuous rain working during the monsoon, but it has been a relatively dry monsoon season and we had good weather much of the time. Happily most of the heavy rains happened overnight or while we were driving and we caught in only a few downpours. We even saw the milky way a couple of nights in the Sundarbans. The trip will end with several days of meetings in Dhaka related to this and our other projects here before the long flight home.
The next day we went to Khulna University (KU). Since there was no SET installation, many of the students came with me to work on the GPS. We had installed an already obsolete GPS at KU back in 2003, but it never worked well. The GPS was fine, but it had very little memory so a PC had to be attached to store the data and that failed all the time. We installed a modern instrument in 2014 and fixed the old one so we could have overlap between the two sites in order to combine them.
However, my contact at the Environmental Sciences Dept. had retired and the new chairman did not like having the equipment in personal offices as people change offices. With the help of some professors, and meetings with the chairman and dean, and exploring the building for suitable sites, we finally found a location acceptable to all. It took 2 hrs. It is located on a balcony in a corner between two offices. With a larger crew, we set everyone to work, including sending people off to buy solar panels. It was going well enough that Salam and I went off to the Urban and Rural Planning Dept. that hosted the original GPS to find the data. The professor in charge of it was abroad, but I had a great discussion with the department chairman. After getting back to the other building, I helped finish the installation as the sun set.
The next morning we headed off to Barisal University. Two former Dhaka University students that I had worked with were now faculty there. Alamgir arranged for me to give a talk about what we were doing and my other work here. We hit bad roads and a slow route around them and just missed a ferry for a river crossing.
That gave me time to complete my powerpoint, including pictures from our field work. When my battery ran low, John set me up with one of the 12-volt batteries for the installation with a power converted. We only arrived a ½ hour before my talk, barely competed during the trip. We said goodbye to Salam and Barkat, who left to return to Dhaka. After greetings, introductions, snacks and coffee, we all went to my talk. The seminar had no shoes allowed, so this was my first barefoot talk. Afterwards, there were almost no questions except from my friends.
However, as soon as we went outside, I was peppered with good questions. The students were too shy to ask them in public. We stayed the night in Barisal and then headed south for Khepupara and Kuakata along the coast with Alamgir and Hasnat joining us.
For once, the roads were better than expected, we just caught a ferry and got to Khepupara much earlier than I inspected. I installed a GPS system here in 2012 very close to a tide gauge, as at Hiron Point.
The tide gauge showed periods of rapid subsidence, but also slower subsidence. The GPS should give us more reliable estimates. We brought a repaired GPS receiver, a modern modem and fresh batteries. We all thought this would go quickly and be done well be Carol, who had to drive farther south to near the coast and scout for a site before she could install her SET to measure elevation changes and sedimentation rates. We were about done, but the new receiver was not recording any satellites.
We started checking cables, the lightning protector and the antenna. When John got a signal at the antenna, we decided to change the cables and lightning protector. Howver, we had to wait for the van that had one to come. Carol and the SET team was about a ½ hour farther south at Kuakata. When it finally arrived, we set to work, but when we finished, the system still didn’t record satellites. We tried the other receiver and it immediately got them.
A few more switches showed that we had a bad receiver that only occasionally recorded satellites. We swapped the receivers, reset the system and were done. But now we are one GPS receiver short.
The next day, Carol and the SET team still had one more site to set up. Rather than take time off, John and Chris wanted to explore setting up campaign monuments near the coast, which is eroding quickly, 200 meters over the last 30 years.
With monuments set up, GPS units can be sent here periodically to measure the position of each one. We started driving west along the embankment road and found that it quickly became impassable for cars. We were told it was drivable in winter, but not during the monsoon. We tried two roads in the other direction. We got farther, but still could not enough to be useful. We were told the other side of the embankment to the north was similar.
After some discussion, we changed tacks and decided to try to find the actual Khepupara Tide Gauge and see if we could put a monument directly on it. The drove the ½ to the north and stopped along the southern bank to the Nilganj River, where my maps showed it to be. We saw nothing. We talked to the local people and they said it had been moved to across the river and pointed it out. We went over and found it next to the ferry ghat and met the shopkeeper who looks after it. We also got the history of the tide gauge. It had been moved several times due to siltation and then was shifted to the opposite bank in 2016. This year a new automatic laser system was installed on a new tide gauge next to the tilted previous one. This history probably helps explain the variable rate. We paid the ferry to take us over and climbed the tide gauge. Since it is steel, we can weld a nut and short piece of threaded rod on the top.
The arm that holds the radar is also stainless steel, so John decided that would be best. We talked to the person in charge and he agreed to allow us to install the very small monument.
We found that we only had one good battery with us, so could not weld. Rather than wait for a battery to be sent out with the other van, we went back to the hotel and welded the threaded rod and nut there.
We could attached it to the tide gauge in the morning when we drove back north to our last site.
We spent the evening going out to the beach at Kuakata. This peninsula is the only place to watch both the sunrise and sunset over the Bay of Bengal. The amazing thing about this beach in summer is, that the water is fresh not salty.
The waves rolled in and broke like other beaches, but this one is close enough to the mouth of the Lower Meghna River, with the combined monsoon flow of the Ganges, Brahmaputra and Meghna River, that the water is fresh. We walked along the beach, armored against further erosion with sandbags, including giant ones that looked like beached whales. We found the other team already there. Carol was sitting and talking to a family whose home was destroyed by the coastal erosion.
They now live farther north. As darkness and high tide set in, we walked back past the crowds visiting the beach and went to dinner.
Our last new site on the Bawali was farther north and west. We sailed north along the edge of the Sundarbans and turned west stopping for the night near a bridge. A lot of the land along the river we were seeking had been turned to farmland, so the Bawali could not continue much farther. As sediment is deposited along the river bank, people claim it, build low embankments and start farming rice or shrimp.
This is called khas land. It officially belongs to the government, but is squatted upon by the local people. In some cases, rivers are completely closed off. Carol estimated the amount of khasland being created and found it is equal to the land lost to sea level rise along the Sundarbans by Chris. When you add in the new land still being created by the sedimentation at the mouth of the Ganges-Brahmaputra-Meghna River, Bangladesh is still growing.
One of the Bawali’s crew went ashore and hired a local country boat for the rest of our journey. We boarded the next morning and continued on. We past the school I had picked but could see that it was surrounded by tall trees and not suitable for a GPS station. As we continued on, the river got narrowed due to the khasland. Twice fisherman had to move their nets so we could pass. Finally we could see that we could not make it upstream to the next school.
A few of us got off and sloshed through the mud to scout for a school. Salam talked to people we met. They confirmed that there we several schools a few kilometers up the embankment road, but they weren’t sure of they were concrete cyclone shelters. However, the new of a school two kilometers inland that was definitely a cyclone shelter. We hired two of the local pickup trucks – a flat wooden bed attached to a bicycle. Now these are electrically powered so each could carry 3 of us.
We bumped along on the bumpy, worn brick road until we could see the tall school jutting out above the trees. It was perfect and had rice, rather than shrimp fields in front of it for the SET.
We send for the headmaster and got permission to use the school. We sent word for the rest of the people and equipment to come and sent a flotilla of rickshaw vans to get them. After finding a ladder, we decided the small upper roof over the staircase was perfect. It was difficult to get to without a ladder and had an overhand that would shade the box from the sun. Meanwhile Carol negotiated for a site in the rice field and went to went back to the river to find a second site outside the embankment while her now experience team installed the first SET.
The GPS took longer than we expected, partly because we drained the battery of the hammer drill. Since Carol needed the spare for an angle grinder, we had a break while it was recharged by our large batteries for the GPS. It wasn’t enough and we had to send for the spare battery by motorcycle taxi. We had some tea, visited the local Hindu temple and chatted. The people were very interested in what we were doing, as at other site. They very much want to know if their land is sinking and at what rate. They are sure that our results would never filter down to them. Since a team must visit the SET every 6 months, we agreed to send word of our results as they develop. It was late in the afternoon when we finished and took the bumpy ride back. At the embankment, we found some of the others ordering snacks from a stand.
They fried piazu, onion and lentil fritters and potato-stuffed singara (pakoras) as the sun set and it became dark. We ate them on the country boat as it sailed back to the Bawali.
The next morning we stopped at my existing Polder 32 to do some upgrades. I have been to this site on an embanked island several times. It was flooded for almost two years when Cyclone Aila breached its embankment in multiple places. Sinking of the land inside the polders where it is not replenished by fresh sediment left the land inside 1-1.5 meters below the natural level so it was flooded every high tide. This is why we need to understand the dynamics of this part of the delta. After a few hours we were back on our way and headed to Khulna, the home port of the Bawali a day early.
We had two tasks in Khulna. One was to visit our sediment compaction site and provide some upgraded equipment to the family that does the measurements. We have 6 wells from 20-300 m that have optical fiber strainmeters in them. Since 2011, once a week, one of the four brothers used to use a laser device to measure the length of the fiber so we could track how the sediments compact leading to subsidence. Measurements had been interrupted by computer problems and I was bringing a new computer and upgraded laser device. When I was there in 2015, we watched as the small channel next to the wells was dredged to make it navigable again. The engineer tried to avoid them, after dredging the channel adjusted its shape. The tall GPS tower tilted over in 2017. Now Hafizur sent me photos showing the wells had collapsed into the river as well. We visited anyway.
Only one of the 6 wells was left. We pried off the lid and tried to make a measurement, but got zero length. The top was no longer connected to the fibers. At least we have enough data for some good results. We had a snack including fantastic fresh mango, chatted with the family I’ve known since 2011 and were on our way.
While most of us went to the compaction meter, John and Sanju returned to the first site by car to fix a few minor thingsAmazingly it took them only two and a quarter hours to get there from Khulna. The landowner, Bachchu, was thrilled to see them and gave them big bear hugs. They also returned his screw driver.
At the school, one of the children, Imran, showed how other students were playing with the ground wire and they fixed that as well.As it was Saturday and we could not go to Khulna University, we went to nearby Bagherat, home to the famous 60 dome mosque built in the 15thcentury. We saw the tomb of Khan Jahan who founded the area and built the mosque then continued on to the famous mosque itself.
John and Sanju, on their way back joined us there. When we were done, I wanted to visit two other historic mosques nearby that had been used as markers of subsidence. After a wrong turn, we found the correct road, but it was in really bad shape and we could barely drive it. We got to the first mosque as darkness and rain both started to fall and prayers were going on inside. After a little time there we abandoned going to the second one and headed back to Khulna.
We next went to the Forest Ranger Station at Hiron Point in the Sundarbans near the Bay of Bengal. The Bawali cannot cross the 12 km (8 mi) wide mouth of the Pusur River in the summer. Open to the nearby sea, it is too rough for our river boat. In the morning, Bachchu, our boat owner, arrived with a Mongla Port Authority vessel.
We transferred everything we needed, including overnight bags in case we needed to stay over to finish. We brought everything we might possibly need as there was no going back to the Bawali for anything. The crew brought all their cooking supplies as well as mattresses and pillows, in case we needed to stay.
Indeed, the 2-hour crossing was rough and Barkat threw up. When John saw the tide gauge station that measure water level, he suggested we make a GPS monument there to tie the tide gauge to the global network and directly measure its subsidence. Tide gauges measure the water level off the fluctuating river level for navigation. Long-term tide gauge records are used to measure sea level rise. However, they also see a mixture of sea level and land subsidence, but cannot separate the two.
Since a GPS measures absolute elevation, the combination allows them to be separated. This is why we put a GPS at the Forest Ranger station in 2012. Putting a GPS monument on the tide gauge, we would now get data from at the same point rather than 500 meters apart. When we reached the Forest Station, and offloaded the boat, John, Sanju, Nahid and I remained as it sailed to the Mongla Port Authority dock.
We walked over the boardwalk to inspect the tide gauge. It was better than we thought. The steel columns supporting the gauge were filled with concrete. We could drill and epoxy in a short piece of threaded stainless steel rod. We wired up a receiver in a waterproof box with a battery, attached the antenna and we were done by 11:30 am. We left most of our equipment on the boat and carried what we thought we would need to the Forest Ranger Station.
Carol and her team had already taken a country boat across the river to scout and install two SETs to measure shallow subsidence and sedimentation.
At the Forest Station, we removed the obsolete communication equipment that never worked in this remote site. We were too far from any cell tower. I have had to come here every year or two to collect the data manually. Recently, a cell tower for one company was installed nearby, so we would try to use that.
We also decided to rewire the ground wire and lightning protector to a better configuration. The work went slowly and we twice had to go back to the Mongla Port Authority dock to fetch things from the ship that carried us.
Things went very well for the SET team and they finished the two installations across the tidal channel by 3:30 pm. They had now developed an efficient scheme for preparing the rods.
They could pound them in without the problems they had encountered earlier. Critical was cleaning and testing the screwing together of the rods in advance. We were close to done, but could not connect to the internet with our modem. Sanju made several calls to customer service, we tried Nahid’s SIM card, but nothing worked. We needed to be done by 5 pm to be able to cross the Pusur before dark. With the deadline approaching, we decide to take the modem with us.
We trained several people on how to reinstall it by slipping it into its zip tie space and connecting the antenna, power and internet cables. A SET team must return every 6 months to make measurements. Now, we could finally eat the lunch that the crew had been cooking all day outside the room with the GPS. We took a group photo and John, Sanju and I ran most of the way to the tide gauge to disconnect the GPS.
John wirelessly downloaded the data and Sanju and I walked out to the gauge. We joined the ship and took it to the Forest Station dock to pick up everyone else and all the equipment. We started across at 5:30 and watch the sunset from the ship. We had done it all in one day.
We thought we were catching up to our schedule, but found out that the trip to the next site would be much longer than I anticipated.
The Bawali could not cross the Pusur River further upstream where it meets the Shibsha River. We would have to go much farther upstream and then travel west and south around the edge of the Sundarbans to reach the Koira district. Now completing all our tasks while we had the Bawali was becoming questionable. In case we could not finish our work in time, Bachchu offer use of his small boat, the Mowali, but it only sleeps five.
Still, it might work for the trip to our last stop.
We spent most of the day traveling upstream. We then continued west to the crossing of the Shibsa. While it was windy, the waves were small and we crossed and stopped for the night. The next morning we took a short cut through the Sundarbans and arrived at the next site. The school I had picked from the maps looked excellent.
The GPS team got off while the SET team shifted upriver to a place where new sediments were being deposited. Where we were, the coast of the island was eroding. At each site there are two SETs, one inside the embankments protecting the island and one outside near the river.
After a wait for school officials, we got permission to install the GPS equipment with many friendly hellos from the children. The work went smoothly and we finished around 3 pm. We went to join the SET team at their second site in a rice field near the school, but they had just finished, too. We met the Hindu family hosting the SET and helped carry equipment back to the boat. We could now start for the next site. Despite our worries, we had finally caught up to our schedule. The power drilled had once again shaved a lot of time off the SET installation.
With the power hammer, Carol managed to finish the first SET site. John and I finalized the location for the field and school GPS, but only got a little way into installation before darkness and fatigue from the 16 hour journey set in and we called it a day. To stay only one day behind schedule, we would have to finish the rest of the work in one day. We decided to have breakfast at 5 am so we could be onsite by 6 am. Carol’s team set to work installing a second of rods for our field GPS, while we set up shop next to a tea shop to start assembling the GPS. While the owner of the field suggested setting pole to keep the antenna wire off the ground, John thought buying it would be best. It would have to go well below the depth of plowing. To further protect it, on the first day Salam traveled 12 km to arrange for galvanized pipe to protect the antenna cable, only returning to the boat at 10 pm.
The next morning, we hired local laborers to dig the trench for laying the pipe and cable. With specialized tools, the four of them dug the 30 inch deep, 75 foot trench in only a couple of hours. Things were looking up.
With developing a new technique for using the power hammer, it took all morning and into the early afternoon to install the 20 rods. The short stub used to protect the rods from the hammer needed to be redesigned to work well.
Only when they were done could our team build the GPS monument over the rods. The SET measures subsidence of the ground relative to the deeply set fixed rod. With the field GPS we want to measure the subsidence of the rod system. The absolute elevation measurements of the GPS will provide values for the “deep subsidence” below the rods. However, the GPS needs to be will above the height that rice grows, but stable. Since the rods are thin, to brace it, we built a tripod with three diagonal rods welded to collar that the vertical rod could slide through. We needed the shallower 12-foot rods for stabilization to not impede the vertical motion of the long rod pounded into the ground. John was able to use three of our batteries wit jumper cables to do the welding. Then we had to thread the cable through the galvanized pipe and carefully lower it into the trench.
Finally, the laborers could fill the trench and restore the rice field. We washed up from the muddy field and had a lunch of noodle and egg brought from the Bawali. We got the GPS box in place, but it was now getting late. Sanju and I headed for the school as John finished programming the GPS. It was 4 pm and there were only 3 hours of daylight left.
In the meantime, Carol’s team scouted for an SET site outside the embankment where new land was accreting and being taken over for farming by the local people. It took them a while to finalize the selection between multiple options. Luckily, her team had now become experienced in using the power hammer and they sunk the rods in only 2 hours.
Back at the school, Sanju and I finished drilling the hole for the threaded rod in one of the reinforced concrete columns of the school just as John and the others arrived. We set to work as we needed to finish today to not fall farther behind schedule. With the antenna rod at one end of the building, the solar panel on the higher roof over the staircase, the GPS box inside the staircase and a grounding rod over the side, the work took time. It was well after dark when we finished using flashlights, headlamps and cell phones for light.
We still had to go back to the field site for some final touch ups. It was 10 pm when we joined the others on the Bawali and had dinner.
During the night, the Bawali took advantage of the ebbing tide to hear south to the Sundarbans. We awoke in the mangrove forest. Here at Katka, we were making the first measurements at an SET that Carol had installed in the spring. Hiking into the forest, we found the SET and Carol connected the apparatus that is used to make the measurements. The horizontal arm rotates in 8 positions and has 9 fingers that measure the elevation. While they were slightly hindered by the stiffness of the screws used to level the device, a pipe wrench held solve the problem. The apparatus was not properly clean after its last use.
In addition to making measurements at two SET, the also set 3 ceramic tiles around each SET so that they can measure how much sediment accumulates between each 6 month repeat measurement.
We finished early enough that we had time for a forest walk before sailing to where we will spend the night. I had done this walk once before, but now at high tide in the summer, it was a wet walk.
At one location, the water was over our knees, but for most of the time is was ankle to calk deep. Only about half of us took the wet walk, the rest staying on the boardwalk and beach. We saw lots of deer and after an hour reached tiger hill. It is a refuse heap from the salt making operation at the coast with lots of broken salt pots. It got its name because tigers like to visit to stay dry during high tide.
Unfortunately, the actual 300-year old salt kilns at the coast were underwater, a measure of the subsidence of the delta as the salt pans were placed at spring high tide level and the kilns above that. A group that worked on that site estimated ~4 mm/year of subsidence.
When we got back to the Bawali, we sailed to a location known as Kokil Moni. Here Bachchu, the boat owner will meet us with a Mongla Port Authority ship to take us across the wide estuary to Hiron Point tomorrow morning.
I am back in Bangladesh for a new project that has taken a long time to come to fruition. Consistent with the almost seven years since the project was first discussed our equipment was stuck in customs, and so we were delayed for starting our fieldwork. Still, it is a great project and it is good to be back here. Around the world, all deltas are sinking as the sediments that compose them compact. This exacerbates the problem of sea level rise, but is compensated for by the fresh sediment that fills the space. This project, part of a large
World Bank funded project to rebuild the embankments that protect the coastal areas of Bangladesh, will measure the subsidence of the land, the sedimentation rate, and the shifting of the rivers in order to better design new embankments.
During this trip, we will be installing precision GPS to measure the subsidence together with SET (Surface Elevation Tables) and MH (Marker Horizons) to measure elevation changes and sedimentation rates. In addition, Chris
Small with be collecting sediment samples and making observations of vegetation. Our team consists of 13 people. From the U.S. are Carol Wilson from Louisiana State University, John Galezka from UNAVCO and Chris and myself from the Lamont-Doherty Earth Observatory of Columbia University. We have been joined by 6 students from Dhaka University, including two I worked with last year. We also have two people from IWM, the Bangladesh Institute of Water Modeling, one of whom brought his son, a college student at Swarthmore. We will be visiting 10 sites in SW Bangladesh to
install new equipment, repair or upgrade existing equipment, or make measurements. Our first site is on the edge of the Sundarbans, the world’s largest mangrove forest, home to hundreds of Bengal tigers.
To get around for the first part of the trip we will be traveling by boat on the M/L Bawali. But first we have to get all the people and equipment there. With the equipment stuck in customs and already a day behind schedule, most of us
loaded into two vans with the equipment we hand-carried, had manufactured here, or had stored at Dhaka University. John, Salam and his son Barkat stayed behind to wait for the rest. It felt like the break up of the Fellowship of the Ring, but at least we can get the fieldwork started. Despite the reduced number of ferries crossing the Padma, as the combined Ganges and Brahmaputra River is called, due to the strong currents, the two vans managed to quickly get on
a ferry. Not so for the equipment truck. Nine hours after leaving Dhaka University, we arrived at the boat, planning to head to the field area as soon as the truck arrived. After dinner at 11:30 pm, we went to bed to wait for the truck to arrive. It didn’t come until 5:30 am when we hoped have already arrived at the first site. It wasn’t until 9:30 that we could finally disembark onto land to start scouting for a site.
Meanwhile, back in Dhaka, our shipment was finally released and it and the three others final hit the road at 9:00pm. Unfortunately, word of the ferry
problems at Mawa had spread, so they had a five-hour wait to get on the ferry at Aricha. John texted “it was the craziest free for all I’ve ever seen in Asia”. After the crossing and breakfast, the continued to drive to close as to our field site as roads would allow.
Despite all of the travel headaches, things started looking up once we go to the field. I picked primary schools from maps as potential GPS sites. We had great success using primary schools last year. They would be the only reinforced
concrete building in the area. Chris’s maps showed which areas were eroding and which were growing with new sediment. Together we picked a appropriate location and disembarked at the nearest ghat (dock) we could find. We were met by children on the docks and they quickly led us to their school. The Sonatola primary school looked excellent and we quickly got permission to install the GPS there. After talking to a number of people, we found a location nearby for the second GPS and the SET in a field belonging to a school council member, Bachchu. He even let us put the box with the GPS receiver and solar panel in his fenced-in garden. This was great as the SET and especially the GPS will permanently take some of the field from cultivation. Carol’s team went about setting up for pounding in the rod for the SET. The four-foot segments of the rod screw together and get pounded into the ground until refusal or 80 feet.
Since the gasoline-powered driver was in the shipment with John, a sledgehammer would have to do. Samiul went off with Chris to ground truth the remote sensing observations and collect sediment samples of all the different types of soils. For the GPS, there was not much we could do except measure the distance from the box to the field as the antenna cable is 30 meters long. The GPS and most of the equipment to install them were with John.
Finally, in the afternoon, we received word that they were almost at the meeting point. Sanju and I returned to the Bawali to pick them up. We met them at 3:10 pm, over 16 hours since they started from Dhaka. We sailed the exhausted group back to a hard to find ghat (dock) that was closer to the sites and brought Carol’s team the power hammer while we took GPS equipment to the school. At last our entire team was in place and getting our work done. The remaining question was could we still get everything done in our time here after
the initial delays. Luckily Bangladeshi are extremely resourceful and we were optimistic that we could find a way to get it all done with one less day on the boat.
I was able to go into the field with the seismologists one last time before moving on to Mandalay and Yangon. Eric’s team was going to move on to the next base at Konbalu, so I would have to go with one of the other teams. I decide to base my choice on the likelihood of getting food and perhaps coffee. Eric tends to work without eating all day, so forgets about food for others. After questioning the teams, I decided to go with Mike, Anna and Oo Than. However, when the schedule of my trip to
Mandalay switched from the next morning to that night, Eric thought I’d better go with Patricia, Derick and Tun Minn Oo. He was concerned that drive for the other team might be too long for me to get back in time for my ride.
Once again the teams started out at 6 am. The most direct route turned out to have bad roads cutting our speed as we swerved around potholes and bounced over the uneven roadway. We still got to the area so early enough that we were
able to stop for coffee. I think the extra time to get coffee is more than made up for by our being able to work faster. With a little hunting, we found the monastery, met the monks and were shown were the seismometer would go. We walked around a bit and decided on the exact location of the sensor, box and solar panel. We unloaded the car and Derick started marking out the location for the hole. We learned that we had 4 laborers for the digging. They did an extremely careful job of making a nice straight-
sided hole of the correct depth. While they did, I took the opportunity to eat my breakfast of fried rice with an egg, then went to work on setting up the solar panel. Tun Minn and I used the sledge to hammer in the two tripods of rebar and used zip ties to secure them and attach the panel. The GPS was attached to one of the rods. Meanwhile, the box was set up. When I started to make a trench for the cables to be buried in, the laborers took over and dug a better one. With the laborers digging the hole, I had time to explore and photograph the monastery’s
pagodas, and play with the kids and others who had come to watch.
When the 3-foot deep hole was finally done, Tun Minn and I mixed the cement for the pad. Since the ground was mainly mud, we mixed two batches to make it extra thick. When we finshed getting the sensor set up and covered with its protecting foam and fiberglass, it was time to lay down the metal cover, the tarp and shovel the dirt over the top. The laborers took over, making sure every
last bit of mud was shoveled back and making a neat job of it. They had a lot of integrity and refused to take more than a ridiculously small payment for the work. When the work was done we took off our shoes and met with the monk. He gave us tea and some snacks to eat at a low table. When I noticed has wasn’t eating I asked him about it. Monks do not eat after noon. It was 12:04. They eat breakfast and a brunch around 11:30, then fast the rest of the day.
For the way back, I suggested a longer route that I knew had good roads. We were back around 2. We started to go for lunch, but none of us were very hungry to we went to a coffee shop for coffee and naan. The other group joined us there about 3:30. So much for Eric’s driving estimates. Furthermore, after they completed their installation and met with the monks, they were invited to lunch in the home of the local council chairman. They got a real home-cooked Myanmar meal. My first choice to go with
Mike, Anna and Oo Than was right.
We made up for it that evening. It was my last day, so after loading the trucks and showering, we went out to a nice restaurant for a great meal. When we got back, I left on a 2-hour taxi ride to Yangon. I had breakfast in the morning with Soe Thura Tun and Myo Thant. Soe was part of the initial 2014 meeting in Aizawl, India where we developed this project. He is not taking direct part because he was elected to their
parliament, the Hluttaw, in 2015. He and Myo Thant, vice chairman of the Myanmar Earthquake Committee, were in Mandalay to lead a university field trip along the Sagaing Fault. It is a large strike-slip fault, similar to the San Andreas Fault. Here the Irrawaddy River runs along the fault. Soe and I have been trying to meet during this trip, but he was in Yangon when I was in Nay Pyi Taw and now he will be in Nay Pyi Taw while I am in Yangon. Luckily we were able to briefly cross paths in Mandalay.
I now had the unusual prospect of a free day before flying to Yangon to attend a conference. After resting and catching up on work and sleep in the morning, I headed out to Mandalay Hill. At 790 feet, it towers over the city. I started by visiting the
Kuthodaw Pagoda at its base. It houses the world’s largest book. The text is the Tripitaka, the entire Pali Canon of the Theravada branch of Buddhism practiced in Myanmar. It is written on 729 stone tablets (both sides), each housed in a stupa. It was built in 1860-1862 by King Mindon after he founded Mandalay as the last royal capital of Burma. The British conquered lower Burma in 1823 and took the rest of Burma in 1885.
I stopped for lunch as a nearby
restaurant then continued to the spectactular Kyauk Taw Gyi Pagoda. The center of the pagoda is a giant marble statue of the Buddha. It took 10-12,000 men to transport the marble block here to be carved. The pagoda grounds contain rows and rows of statues of the Buddha, supplicants, demons and other figures from Buddhism. I skipped the enormous palace grounds surrounded by a moat nearby. Most of the buildings were destroyed by the Japanese during
World War II and replicas are still being built.
It was time to begin the long climb up Mandalay Hill. The covered walkway has multiple pagodas along the way and benches along the sides for resting. It is 1729 steps to the top. With a rest in the middle and examining all the pagodas and shops along the way, it took me an hour and I was sweating like I had just dug a seismometer hole in the heat. The views at the top were as great as advertised. Given the exertion of getting up here, I decided to linger. I sat down and read a book for a while. When I looked up, the summit was now crowded with people. Everyone had showed up to watch the sunset. Enlarging the crowd was a group of 30-40 monks and students learning English. They come up here for 3 hours every two weeks to practice English with the tourists. It is the best spot
to find them. I spent time talking to a number of them, before I walked down with a group of monks and another tourist. We were some of the last to leave. A nice ending for the fieldwork part of this trip.
I now fly to Yangon in the Irrawaddy Delta in the south of the country. At 5 million people, it is by far the most populous city in Myanmar. Here I will spend several days attending a conference about the geology and
hydrocarbon exploration in Myanmar before flying home. It has been a long but satisfying trip. In a few years (with a lot of work), we will have a much better understanding of the structure of this region and its earthquake hazard.
It was a long drive to Mandalay; we only had time for a quick late dinner after checking into a hotel. Unlike the spread out capital of Nay Pyi Taw, Mandalay is a real city with lots of linear streets, tall buildings and historic sites. We had no time to see any of it, but returned to Nay Pyi Taw the next morning to end the GPS installation. When we arrived, we met the 6-member U.S. seismic team that will install the seismometers in Myanmar for our project. They had just finished testing their 33 instruments. All but one worked. Another day of preparation and
they would head to the field to start installing them. Keith flew home the next day since the GPS installation was done, but I joined the seismic team. I will stay with them until I have to head to Yangon of a conference. On the day we arrived, one of the trucks also showed up to carry the massive amount of equipment to local DMH offices to store them closer to where they will be deployed. The next day, the other truck taking the rest of the equipment came and was loaded up. Equipment for just one station remained for the entire group to install on the way
to Shwebo, their first base. When the preparatory work was done, we watched “The Himalaya Connection”, the PBS documentary that covered our previous project in Bangladesh and India. The film makers will arrive later to film the seismic installations.
In order to be sure of having enough time for installing the first seismometer, we left at 6 am the next morning, stopping at a highway rest stop for breakfast. The roads were good and we
arrived midday at the monastery. We had 10 people to do the installation, 3 Myanmari from our partners at DMH, 3 scientists from the University of Missouri, 2 from Louisiana State University, 1 engineer from PASSCAL, a facility that provides the equipment and technical support, and myself. With so many hands, the station was installed in only 2 hours. A broadband seismic station consists of three main components. The first is the seismic sensor, which is installed in a 3-foot hole that we had to dig. The bottom is leveled and then a ceramic tile is cemented to the bottom. The sensor is placed on the tile and oriented and leveled, then insulated with Styrofoam and fiberglass, then finally covered with metal plates, a tarp and dirt. The next piece is the equipment box that includes the recorder, a disk drive, batteries, and a power controller. It is covered with a tarp to protect it. The
last piece is a solar panel mounted on a rebar frame similar to the ones that we used in Bangladesh. The GPS antenna for timing is usually attached to the solar panel. Finally a fence is built around the entire system for security.
We then drove to Shwebo and had a late lunch of Myanmar food. We sat down and they brought out small plates of about a dozen different dishes and soup to try. Soup is served at pretty much every meal including breakfast. It is commonly included on the table along
with dipping sauces without ordering it. Traditional Myanmar meals include a few entrees and many side dishes. Our buffet had multiple meat and vegetable dishes to eat with rice. Our hotel is across the street from the DMH office in Shwebo, where our first stash of equipment was brought. We went over and loaded up the 3 SUVs. Each day, the group will split into 3 teams each installing a station. With the sensor and electronics in large padded carrying cases, one site’s equipment and tools, along with some
spares, fills the SUV.
The three teams again took off again at 6 am to get to the sites and dig the holes before it became too hot. I went with Eric Sandvol, the leader of the seismic, who is team from Missouri, Rasheed, a graduate student at LSU, Joe from DMH and Aung, our driver. We had the farthest station and the longest drive, about 4 hours including a stop at a security checkpoint. These first stations are in a restricted area for foreigners, but we had
permission. The people at the checkpoint were very friendly. I don’t think they get many foreigners. We continued on and the 3 cars diverged, each going to their respective sites.
We finally arrived at our site, a monastery that includes a large school. We were soon joined by an audience of many children, including monks in training. With only 4 of us and a heavy clay soil to dig through, it took about 3.5 hours to complete the job. In the heat,
we were quickly covered in sweat and went through many bottles of water. We were all pretty worn out by the end. We rested, and ate some food we brought, noodles and a fried egg. At least partially refreshed, I spent the rest of the time taking pictures and movies of the giggling kids during their breaks from the classroom. Then it was time for the long drive back. Although we were the farthest, we were the second to arrive back at the DMH offices. One of the teams had some equipment problems that delayed them. We then had to
reload the SUVs for tomorrow’s deployments, double checking with a list to be sure we had all of the dozens of individual components, from batteries to zip ties. When that was done, we could finally shower off the day’s thick layer of sweat and go to dinner.
While I will only do this for one more day, the rest of the group will continue repeating this pattern for another dozen days or so, matching west across Myanmar from one DMH office acting as
a storage depot to the next until all 32 stations are successfully installed. Then they will go back across revisiting the stations and collecting the week or two’s worth of data to make sure that everything is working and to check the quality of each site.
On the way back to Kale, we stopped at a Catholic church where one of the seismometers will be deployed. The seismic team is now in Nay Pyi Taw, the capital preparing for the dseismic instrument deployment. Eric Sandvol asked me to look into two stations that he did not visit in August when he scouted out the final locations for the seismometers. The church is right at the foot of the Chin Hills on our way. We met the catechist and he showed us the site uphill from the church. Eric was rightfully
concerned about the trees blocking the light for the solar panels. We shifted the site a little up the hill to minimize the number of trees that have to be cut down and gave the catechist the money to pay for it.
The next morning we started out for our next station at a Buddhist monastery in Thickegyin, a town 35 miles east of Kale. We picked up our equipment at the Kale DMH and strapped the rods to the roof, faster the second time around. We
followed the good road along the Myittha River to Kalewa and then crossed the new bridge over the Chindwin River. We went slower over the switchbacks through the hill east of the river and then still slower as we hit really poor bumpy roads. There was a better stretch of road near the end, but overall it took over 3 hours to drive the distance. Anticipating the long drive, I expected this installation to take multiple days because of the short workday due to the commute.
We met the head monk and made a donation to the monastery, then went out to look at the scouted site near the pagoda. It turned out not to be good. Too many tall trees and the pagoda building blocked too much of the sky view. Ideally, we like to see to within 10° of the horizon in all direction. We can accept some blocked view, but not this much. Keith and I wondered around the grounds looking for better locations. One spot was near the net for chinlone, which is like volleyball played with your feet
using a rattan ball, but too much risk of the ball hitting the antenna. Finally, we found a spot on a small rise covered in vegetation. Other than a couple of small trees, the view was good. Some workers quickly cleared all the vegetation and cut down the trees and we went to work. My main concern was whether the hill was natural or a manmade pile of sand. While I was assured it was natural, the rods went in way to easily for may liking, but there is little other choice. Thickegyin is in a small basin, so the hill may just be unconsolidated young sediments. With
the rods going in taking only a short time, we were amazingly able to complete the site that day. We had only one short break for coffee and dry cake. This time, we were joined by a group of children watching us, including a pet monkey. After the mandatory group photo, both with and without the kids, we headed back on the long drive.
Our last station was at another monastery still farther to the east. Far enough that we will stay at the small
town of Taze, not too far from the site. With such a long drive, we again shipped the rods. I thought we could take them with us as we did to Thickegyin and the last part of the road was good. I didn’t know what was ahead. Still, we are so far ahead of schedule, we again went to scout a seismic station to the south of Kale. After 45 minutes, we reached the church. Loosing track of the days while in the field, it wasn’t until we got there that it was Sunday and services were going on. We met the village leader who
showed us the site. I showed him pictures of installations in Bangladesh and discussed the burial of the sensor and setting up of the solar panel. Most importantly, I told him to expect the seismic team within 2 weeks.
Now came the long drive that will take up most of the day. Back north to Kale, then east to Thickegyin and beyond. We stopped for lunch in Kalewa and then went over the Chindwin River bridge and onto the bad stretch of road. After
Thickegyin, we entered some central highlands of the Burma Basin. They are along the trend of the subduction zone volcanoes to the north and south. The roads quickly became poor, with potholes and pieces of the road slumping off to the sides. We occasionally passed construction crews working on the road and plenty of large trucks that contributed to the poor shape of the road. For many stretches, we could only go about 10 miles/hour. So much for reaching the monastery mid-afternoon. We passed it in the dark
around 6 pm. No reason to stop in as the head monk was returning from Taze, our destination. After another hour driving and a little searching, we found the guest house. A building with a series of rooms with little more than a bed. Toilets and washrooms off to the side, no showers. As the rooms are open to the street, facing what I will generously call a plaza, we had to padlock them when going to the bathroom. We had dinner at a
nearby restaurant and went to bed.
We had Chin noodles for breakfast, picked up the rods at the bus station, and went to the Thukakari monastery. It is a beautiful site on a high overlooking the Irrawaddy valley below and dotted with stupas. The GPS is on a little ledge past a pile of stones where a new stupa will be built. The ground is covered with small balls of volcanicrock, some welded together into a hard bedrock. Keith took extra time to grind really good points on the rods. We again had laborers to help.
The muscular young men drove the rods in faster than I imagined. The solid sections must crack apart to the individual balls of rock when hit hard enough. We were now pretty practiced as installing the GPS. I took a try at welding the rods together and did a miserable job. It is a lot harder than it looks. During our lunch break, we had coffee and cake while the monks smoked cheroots, local cigars made mostly of corn silk. By mid afternoon, we were finished, took our final set of group photos and then the rain started. After waiting it out, we said our goodbyes, made our donation to the monastery, and headed out on the road to Mandalay.
Kalewa is about a 75 minute drive east from Kale on the other side of the Kabaw Fault. Driving around you realize that even though you drive on the right in Myanmar, most of the vehicles, including ours have the steering wheel on the right as well. They used to drive on the left as in Britain until they switched in 1970. However most of the cars, which are imported from Japan, still have the steering wheel on the right. That will be banned next year. In addition to cars, there are lots of motorcycles and scooters, more affordable and easier to get around with in many places.
Although seeing babies held by a sling is scary. I’ve also seen quite few sidecars for passengers or deliveries, too.
We started by loading the equipment we needed from DMH, including the GPS box, the generators, welder, etc. into the back of the truck. Then the four 12-foot rods we needed had to be strapped to the roof, with everyone having a different opinion of how to secure it. When it was finally settled, we headed off following the Myittha River as it passes through the mountains to the Chindwin River. The
path of the river is unusual; it flows north through the Kabaw Valley and then cuts through the mountains to the east. It strongly suggests that tectonics are shaping its route. Partway threw the mountains we followed a N-S valley for a while. It is actually following the Kabaw Fault. The shattered rocks of the fault zone are more easily eroded, so the river flows along it.
The Kalewa DMH office is on a hill near where the two rivers meet with a great view of the local monastery. The site for
the GPS is inside the compound with all the meteorological equipment. We had to make the monument a little taller so the antenna is higher than the fence. This time pounding in the rods was not so easy. A lot of the time we would only drive it a millimeter or less with each hammering. Luckily, with the DMH people, we had 5 people to take turns, and had multiple breaks for coffee, tea and snacks. The occasional drizzle kept us from overheating. At the end, the
head of the office poured water down the hole and that helped. Somehow, despite the long time for pounding the rods, we still managed to finish in one day. I was sure it would take two. The rain stopped long enough for the welding of the monument. We saved time by having me assemble the GPS box while Keith cut and welded the rods. The rain even stopped long enough for the welding of the monument. Still, it was dark by the time we packed up. We stopped for dinner on the way back to our hotel, but we are now well ahead of schedule.
Since the following day was clear, we could go west into the Chin Hills for the station at Tedim. It is not safe to drive the winding switchbacks when it is wet. During the monsoon, only specially built
homemade jeeps make the trek. Even now, we had the rods shipped by bus rather than take then on the steep roads tied to the roof. At one point we reached over 2300 m (7500 feet) elevation. At 1600 m we entered the clouds and drove through fog. It took us 3.5 hours to reach Tedim. It is less than 29 miles as the crow flows, but much longer and slower by road. The Chin people of Tedim and the Chin Hills are a distinct, at times persecuted, population in Myanmar with 53 separate officially recognized Chin
ethnic subgroups. They are closely related to the Mizo in Mizoram, India, where I have been on some past trips. In Myanmar the majority Bamar (Burmese) people live mainly in the central lowlands, while multiple other ethnic groups, such as the Chin, Kachin, Karen, Mon, and Shan occupy the surrounding mountainous regions. The Chin are dominantly Christian, with many of them Baptist.
We finally reached Tedim at lunchtime. In
the restaurant, our orders had to be translated from English to Myanmar to Chin. And had excellent Chin coffee. It is grown here and served ground with a cup of hot water, condensed milk and sugar for you to mix it yourself. You have to let the grounds settle like Turkish coffee. After lunch, we got to work. Keith made sure he made sharp points on the rods are we expected difficulty in these much older rocks. Luckily we had hired laborers which did most of the pounding, as well as carrying the heavy rods and
generator up the ~100 steps to the DMH building and farther up the hill to our site. While they did that, I did the less strenuous putting together and wiring the equipment box, progressing from doing it with Keith, to supervised by Keith, to soloing. The pounding turned out to be easier than we expected and we got most of the job done. We easily finished it in the morning and headed back down the mountain to Kale.
As we entered the Kabaw Valley, we
stopped at a Catholic church that will host a seismic station. While Eric Sandvol visited here in 2017, it was not visited during the main scouting trip a few months ago, so we needed to be sure it was ready. We checked the site up the hill behind the church and confirmed it needed trees removed for the solar panel. We shifted the site a little to minimize the trees removed and were assured that they will be gone before the seismic team arrives in couple of weeks.
In the morning our Toyota Hilux truck picked us and we went to DMH to load all the equipment. There are four of us, Keith, Zaw Min, a DMH staff member and Win Htut, our driver, and myself. The generator was too big, so it went separately by bus. Even so we could barely fit the rest. We needed to have the rear of the truck gate down and bought lots of rope to tie everything down. As a result we got out later than we expected and only made it to Monywa after a 6-hour trip. We stayed in the same fancy
hotel I used a year ago on my first trip to Myanmar. For the rest of the trip the next day, there were two choices. The direct route, which has really bad roads, and the longer route, which has better roads. We took the longer route, going west and then north rather than the diagonal. We crossed the basin, then climbed over the mountains and into the Kabaw Valley, both created by the Kabaw Fault that we will be studying. It took 9 hours. We finally arrived at the Kale DMH offices at 4:30. We were warmly greeted and shown around, unloaded the truck, and were served coffee, tea and snacks.
In Kale, or Kalay, our first proposed site at the airport wasn’t approved. That left a choice between a field at the DMH office that has some flooding after heavy rains, or a Buddhist monastery. Checking out the field, we decided it would be fine. Not more than ½ foot of water due to poor drainage. We will lay some bricks under the waterproof equipment box to raise it, just to be safe.
Finally, on our sixth day in Myanmar, we got to start installing the first GPS station. In Bangladesh where I have
many sites, almost all our stations are placed on reinforced concrete buildings. We merely have to drill a hole in a column and cement in a threaded stainless steel rod for the monument. Here, there are few such building in the mostly rural areas of our sites. Instead, we will build our monuments out of 4 stainless steel rods pounded about 6 feet into the ground and welded together at the top to make triangular pyramid with a taller central column. This is my first time doing this, but it is old hat for Keith.
First Keith used a grinder to cut the tips of four rods to a point. Then we started the work on pounding them into the ground. Since it has been drizzling for a day, the ground is soft and they went in pretty easily. The homemade post pounder with a sledge hammer head welded inside a pipe work amazingly well. In a short time we had all four rods in the ground, the central vertical and three diagonals for bracing. Keith then cut off the tips at an angle while I went to buy more grinding discs. He then welded the tops together along with some
triangular wedges and added a threaded cap to the central rod. The monument was done before the end of the morning. Kale in is the middle of a valley filled with young sediments, so this will certainly be the easiest site for pounding rods.
The remainder of the installation was more familiar to me. We added a leveling mount to the monument, leveled it and added the antenna. We did the remainder of setting up the GPS box adding the antenna and cellular modem
cables, wired in the batteries and grounding wires. We built the solar panel frame and used it to attach the panel to the top of the box at the correct angle. All of the junctions where wires and cables enter the box were made waterproof. Because site floods, we elevated the box on a layer of brick, but it was pretty wobbly. We re-leveled the spot, and added a third layer of brick. It still seemed unready to face a monsoon. Our host provided a wooden beam that we cut into lengths and hammers around each side of the box. Now it was finally
secure and ready. We made the final connections, tested the equipment and we were done before 3 pm. KALY is now up and running. It had taken less than a day and easily made up for the extra day of travel to the site.
Since the weather is still potentially drizzling for a few days, we will head east to Kalewa rather then up the windy mountain roads to Tedim in the west. We will commute the hour to Kalewa and stay here in Kale. We are in a new hotel that has not officially opened yet. It is quite nice except for the lack of hot water. So far in this short trip we have sampled food from Myanmar (Burmese, Chin and Shan ethnicities), Thailand, China and Nepal.
In February, a group of us went to Bangladesh to install equipment along to western side of our large geophysical transect across the IndoBurman subduction zone (red triangles on the map). This is the world’s only subduction zone that is entirely on land. Because of this and its slow rate of motion, it is often neglected or thought to not be active. However, we believe there is a significant earthquake hazard in this densely populated region. Thus, we developed this large project to study it using many geophysical and geologic tools. We are in the next stage of installing equipment for the project. I am now in Myanmar to install 5 GPS along the eastern side of the transect (white circles). Once again, Keith Williams, an engineer with UNAVCO is with me to provide support. The seismic team, this time from the University of Missouri and Louisiana State University will arrive in about a week to start their work installing seismometers at the green triangles. Keith and I will start installing GPS going from west to east along the transect. The seismic team will go east to west and we will cross and meet them later in the trip.
We have arrived in the Myanmar capital, Nay Pyi Taw, on the last day of a major Buddhist holiday, the Thadingyut festival. While the offices at our partners, the Department of Meteorology and Hydrology (DMH), are closed, stores are still open so we shopped for a few things, rested from the long flights and visited the Uppatasanti Pagoda. It is a copy of the famous pagoda in Yangon, but a foot shorter out of respect for the original.
The following day, we were able to work with our partners at DMH on preparations for the fieldwork. We settled the bills for the things they bought for our work, checked our shipped equipment, got supplies, such as a sledge hammer, pieces to make a post pounder, locks and chains to secure the GPS, SIM cards for the modems in the GPSs, and a
ladder. Along the way we drove on one of the amazingly wide roads here. There are 10 lanes in each direction, but we never saw more than about a half dozen cars in front of us. The new capital, only opened in 2006, is built on a huge scale and very spread out. As the center of the government, it now has over 900,000 people, but is not yet a vibrant city.
The GPS that we will install are a lot fancier than the ones in your phone or car. That can measure positions to 2 millimeters, about 1/12 of an inch. We will fix them securely to the ground and over the years, we will be able to see the plates moving and strain
building towards earthquakes. After shopping, we sent the 12’ steel rods that we will use for building the GPS monuments, the batteries and the ladder off to be transported to our basecamp by bus. Today, we finished our preparations, rewiring the GPS and welding the post pounder to help drive the rods into the ground. Tomorrow, we start early in the morning for Kale or Kalay, our initial base of operations, a 12 hour drive away. The five GPS will be
installed at a mixture of DMH offices and Buddhist monasteries.
Humayun and I arrived in Sremongal and were reunited with the others. After dinner, the gravity meter that Céline will use for measurements here after we leave finally arrived, making Céline very happy. It had been stuck in customs getting clearance for days as she impatiently waited for it to arrive. As time was growing short, Céline suggested that we should split into two installation teams and each do one of the far northern sites. Alissa, Humayun, Sanju and I went to BN05 while Celine, Nano, Paul and Karim went to BN04. Both are
2-3 hours away, but potentially longer if the roads are bad. Traveling through extensive fields of rice, the road was surprisingly good for someplace so remote and easily flooded. As was often the case, the scouted site was not good, so we called the chairman. While he wasn’t home, his brother was and after a long conversation with Humayun, offered his family’s home. It was large enough that there were several options, but one was clearly better than the others and we installed one of our smaller waterproof seismometers, just in
case of flooding. We were now experienced and completed it in less than 2 hours. More tea and photos and we were on the long road back. Céline’s team was also successful; two sites in one day put us back on track.
We again split the next day, with Céline, Alissa, Humayun and myself going to install B9, while the others went to look at the geology in the hills farther east. along the way they also stopped off at a tea garden to scout BN01. B9, officially BA09, had already been scouted, so we
quickly installed and took pictures with the family. After that was done, we went to service some stations, collecting the few days of data to make sure everything was working well and analyze the noise levels at the sites. We stopped at B10, where the owner treated us to his boroi, small apple-like fruits. Then we went to B8 located at a manager’s house in a tea garden. We wanted to do B7 as well, but they had important guests visiting and did not want us to come by today.
The next day was our last installation in this region, the Sylhet Division of Bangladesh. We again split into teams for the final installation, for doing field geology, and for servicing. Karim and I did the service runs. We did B3, outside a private home, then B2 in a tea garden manager house. We only saw the 6 servants that maintained the property. As we left, Karim pointed out that he thought two of them were transgender. Next was the long hard drive to B1. As we came close we called the manager to
ask about sending his jeep to drive the last stretch of road. However he had guests, so we had to walk the last mile to the tea garden. Along the way, we passed crews fixing the road. This time, we were invited to join his guests for tea and cookies in the gazebo when we finished. It was very welcome after the long walk in the hot sun. While we were having tea, our driver showed up. They had finished fixing the road sufficiently for our van to come up. The next people to visit for servicing will appreciate that. We ended the day servicing BN03 as B4 was also
having important visitors at the tea garden. We got back before the others and then went for a final dinner together.
The next morning, Humayun, Alissa and I headed to DUET in Gazipur, where we started this trip. We met Jim’s team and put all the empty boxes into storage. Then we dropped Jim and Alissa at the airport, while Chris and I dove into Dhaka. My first time here this trip. We have the final station to install in the morning and then we fly out the next
day. Nano and Paul and Sanju will do geology for a few more days then meet us in Dhaka. Nano flies out with us, Paul heads to India the next day. Céline will continue to stay in Srimongal doing a gravity survey with Karim for the next week.
The last station is south of Dhaka between the Dhaleshwari River and the Padma, the combined Ganges and Brahmaputra. It is at a health service complex. We met and had tea, then
looked around the grounds for a good site. The first were vetoed as not secure. Too many drug addicts near the clinic. Finally we found a good spot in the open near some people’s homes, including the night security guard. It went quickly and in the middle they climbed a tree and got us some fresh green coconuts. Coconut water is very refreshing on a hot day. We finished, but not earliy enough to visit the Padma. We still had to store the remaining equipment at Dhaka University. It has been a very successful
trip. As is my experience here, people find a way to get done what needs to be done. It is a country that is resilient out of necessity. We have installed 6 GPS, 28 seismometers, Céline is getting gravity measurements that have help up a project, and Paul has at least one good geological transect across an anticline with a few more days of work. Some of us have been working together for years, but others are new to our group and Bangladesh. Over 3 weeks in the field together will help change us into a team.
I spent two more days with Jim’s team. The first day we went to scout two of the sites and then install one that was already scouted. Humayun had sent a team of students out to scout the 28 seismometers we were installing, but some of the sites were good and some were not. B11 was too close to the highway and without an out of the way place with a good place for a solar panel. After tea and fruit, the owner walked around the village with us and we found a better site. It was at the edge of a yard next to the cow shed and at the edge of a slope. The family was ready to host it
there, so we moved on to Scout B12, the one site that was not scouted. I could see there were no roads to where I have located the site. I chose a new place as we tried to drive to it. We went as far out on the road as we could drive and started talking to people. We met the local chairman and walked around with him. There were a couple of larger, more elevation homes and we went to one and discussed it with the family. They were positive, but would make a final decision tonight.
We went on to B13, already scouted, to
install. It was on the other side of the Meghna River. We unloaded our gear and got ready, but the family backed out. He thought the installation was for 2 hours, not 2 years. We went looking for a new site. First locally, then driving a little farther afield, then as a school but we struck out. It was the end of the day and we have not put any seismometers in the ground.
The next day was better. In the morning we went to install B11. When that was
done we decided to try a different road for B12. We went out on it as far as we could and beyond that point there were no homes. We turned around and stopped at every house to inquire about putting a seismometer there. Actually, Sam did and without speaking Bangla, there was little we could do. Some weren’t interested or scared of the equipment, some had no good location. After about a half dozen homes, we waited outside one promising place, but the owner wasn’t home. Finally his brother said we could put it at his house.
Not quite as good, but it was a bird in the hand. That night Humayun and Sanju arrived with Paul, who flew in to see the geology on the way to NE India. After dinner, Paul and Sanju went east to join the other team, while Humayun joined ours.
The next day, Jim, Chris and Sam went build a fence at B11, while Humayun and I went to scout. I felt that with the problems both teams were having as some sites, we might not be able to finish
on time. Adding a third team for scouting would help save time and let the other concentrate on the actual installations. We went to the government building for B10. When it turned out to not be good, we went to the local chairman and he ended up offering his house, an excellent site. Then it was time for B13 once again. We tried on the other side of the Old Brahmaputra River. The Brahmaputra shifted about 60 mi west of here about 200 years ago leaving a smaller river and a broad low area with rice fields and
brick factories. We took smaller and smaller roads, ending in a heavily rutted dirt road. We saw a government building that looked good, but it was locked. We talked to the neighbor and decided to put the instrument there. Not an ideal location, but after 2 days of failed attempts to get B13, we took it and headed east to join the other seismology team, stopping to say goodbye to the team finishing up B10.
With the scouting done, we just that the installation of the final two GPS sites to do. Since we started drilling the hole for the antenna rod at Kalenga, we went there first to finish the installation. This time, the new road surface had dried enough for us to go over it. We arrived and went to work, becoming an experienced team for the installation. As promised, they had built us a ladder, a rickety one, but functional. After competing the job, we were surrounded by kids when we returned to the ground from the installation. We once again
handed out chocolates to all the students and teachers, had tea and went on our way.
It was still afternoon, so we drove to Chunarughat where the seismic team had just finished installing a station in the college where we reoccupied. We all had tea, some fresh pineapple, snacks and caught up. They went off to another site, while we went to scout two sites farther along that were on tea plantations. We had had problems
getting permissions as some were large corporations with headquarters in Dhaka. We headed to the first one, the Chundeecherra Tea Estate. We found the office and explained the situation. As first we were dismissed, but Sanju persisted, making friends with the assistant, who called the manager back and we were invited to his bungalow. We went there and discussed the project, and had tea and snacks. The Tea Garden and bungalow – a term meaning a house in the Bengali style – date from 1876. He
needed to confirm with his higher ups in Dhaka, but had been won over to allowing our deployment. In fact, later we received approval to place seismometers in any Tea Garden belonging to the National Tea Company.
He directed us to the next Tea Garden, although we got lost before finding the right place. While we call these places Tea Gardens, they can be miles of tea plants in every direction, major operations to run. We had trouble
finding the correct entrance. We again showed up at the manager’s house and were welcomed with tea and snacks. Sanju did his magic again, making friends and persuading him to allow us to install the seismometer at his bungalow. This tea company is privately held and the manager gave approval pending confirmation with the owner, his uncle. A productive day.
The next day we went back to install the last GPS station, again bringing chocolates for the students. The drilling was slow as the concrete was hard and the batteries didn’t last. We sent our driver to recharge them at the nearest town with electricity.
He went with the principal on his motorcycle. After finishing the job we took our last group photos and had tea and cookies with the teachers.
Again we went to stop at a Tea Garden for permission. This was at Finley’s a large multinational company. We were turned away at the gate. Sanju did not give up. He persisted and argued with them for a long time, although it seemed fruitless. He then tried going above them calling the local chief of police and elected representatives. He would not give up. Eventually the assistant manager came out and spoke to us. We explained our situation. He had previously spoken with the scouting team. He agreed that we needed to speak to the Chief
Operating Officer of Finlay. He would be in the next morning at 9. We had succeeded in getting out foot in the door thanks to Sanju’s determination. And with all of the GPS stations completed, we could turn our full attention to scouting the seismic stations for the one day before Keith leaves to return to the U.S.
The next morning we arrived and were let through the gate. We drove to the COO’s office and waited until he was free. Again we explained what we were doing, reassured him, as the others that the seismometers only listen to earthquakes from around the world. They do not interfere with anything or cause earthquakes. His concern was not being able
to provide security to watch the instruments, but we reassured him that we usually left them unattended. He tentatively agreed pending some paperwork. We headed to the offices of the managers of the individual Tea Gardens we would be installing in. We drove past miles of tea to the first. When we showed the manager to location, he pointed out that it was not in Finlay’s but another Tea Garden beyond their property.
We headed off farther into the hill. The roads got progressively worse, although the road cuts showed some good geology. Finally, we hit a rut we could not drive through and walked the last mile. After waiting for him in the gazebo to finish his shower, we again had tea and snacks. We got an agreement and chose a site in his yard next to the satellite dishes (after reassuring him it would not affect reception). Another site successfully done. We walked back and then got a ride the last part of the way
from his jeep, carrying the head of another tea company. We drove to the other site on Finlay’s property, but the manager was not home. He would be back in 2 hours at 4. We left and went to pick up some gift bags of tea that Sanju’s father had left for us. It was on top of the next anticline. After several wrong turns, and more cups of tea, we got our packages. It had only taken an hour and a half to get there. On the way back, we got a call from the manager, he would meet the COO tonight to discuss the seismometers, so no need to come today. We had done what we could today. This part of the trip was a success.
Columbia University researchers are part of a team that is exploring a plate boundary that crosses three countries: Bangladesh, India, and Myanmar. Click here to read the previous blog posts in this series.
After the drive yesterday, it was clear the car needed fixing. No need to rush out early in the morning and I got some much needed sleep for my jetlag and my cold. After a later (for us) breakfast, Bulbul, our driver took the car to be fixed. We took an autorickshaw to the first site to add the chain and lock security system and see the sky view without the trees. This time we had neither a ladder nor a truck to climb on. Keith and Sanju scaled the building, but I was still shaky from the cold and stayed
below. I worked on my blog until I ended up showing a group of kids my photos. That was where I was when they found me after completing the short job. My choice to stay down was reinforced by learning that Sanju had fallen on the way down. A piece of the concrete roof had broken off in his hand and he fell backwards onto the cut down tree. Luckily he was OK. His glasses frame was broken, his elbow banged up and had a some scratches from thorns, only minor injuries. With the car still being repaired,
we had some enforced free time. We went to a famous shop outside of Srimongal, past a rubber tree plantation, where they serve 7-layer tea. In fact, this was where it was created. Carefully pouring (I presume), they float 7 distinct layers of different colored teas on each other. Refreshed, we headed back to wait for the car, and Keith repaired Sanju’s glasses.
It was too late for an installation that was
an hour drive away, so we turned our attention westward. We were reoccupying a site at a college (high school) in Chunarughat, but we also had one more place to scout. This one was to be co-located with a seismic site, B4. The advance team found a home, but it would require constructing a monument. We went to see for ourselves if it would work for us, passing one of the two seismic teams joining us in Srimongal – Nano, Céline, Alissa and Karim. A few minutes of greetings and
we were both back on our way. Driving across the rice fields, with a few wrong turns, we found the direct road had a bamboo bridge we could not cross. We had to double back and take a longer, more roundabout route ending with bumpy dirt roads that were not meant for cars. Finally, we hit another bamboo bridge less than a kilometer from the site. We walked there and met the owner of the house. It would be usable
for seismometers, but there was no open sky view for us. We walked another kilometer farther, but this time we had no luck. The school was surrounded by trees. We were told that there was another school at a place called Kalenga with no trees. By now it was dark, so we headed to the dinner with the seismic team. They were having a more difficult time. Permissions were not finalized and appeared to be harder to get.
The next day we went to Chunarughat to do the reinstallation. I have been here a few times since the initial visit in 2007. The last time I saw the antenna, it was loose and assumed it was a problem with the mount. Instead, it was more serious. The rod itself was loose and had rotated. Two silver threads on the rod were visible
beneath the green weathered ones. Looking at my photos we pieced together that the antenna cable came loose and the straightening of the loops to relieve tension had rotated the antenna 1.5 times so the north end was pointing south. The unscrewing created a 3.5 mm increase in the height of the rod. I will have to look at the data carefully to see if we can figure out when it happened and correct it. Keith then carefully unscrewed it, added a really strong epoxy and screwed it back to its original level. Sanju and I took rickshaws into
town to buy more electrical wire for the solar panel and for grounding. After a while, Chunarughat was up and running again.
After some tea and snacks, it was time for the last task – finding the final GPS site. We went off in search of the now mythical Kalenga. I didn’t understand why everyone we asked seemed to know the direction to Kalenga until I realized there was a Forest Reserve of the same
name. We continued along progressively worse roads until the colorful school at Kalenga appeared. It was indeed open, surrounded on two sides by rice fields. Although it was on the anticlines, the rivers eroding it had created valleys suitable for rice. The school principal quickly agreed to the installation. We didn’t have more equipment with us, but we had the drill. That would save us some time tomorrow, so we drilled until the power ran out of the batteries. None of these schools had power, so instead of the large drill, we had to use the smaller battery-powered
one. We had been needing to recharge the batteries to do all the drilling, but with this early start, perhaps we would not. In any case, sites for all the GPS had been located and arranged. All that was left was the mechanics of the actual installation for the last two sites.
Columbia University researchers are part of a team that is exploring a plate boundary that crosses three countries: Bangladesh, India, and Myanmar. Click here to read the previous blog posts in this series.
We headed to the next area. One of Humayun’s students scouted for a location and found a reinforced concrete building, but it was not on the anticline as I wanted. It was farther west on the flatter land adjacent to the hill. It was on the wrong side of the rice/tea transition. We met the owner of the property and he accompanied us as we searched for another place. We could see why he stopped. Farther on the driving was more difficult and the houses were all thatch and tin. Walking around, we were shown a reinforced concrete building
under construction, but it wouldn’t be finished for two years. We kept hunting and then we found it. There, in a clearing, was a brightly colored primary school. Again, the headmaster quickly agreed to let us install the GPS on the roof. I even was presented to the classes. The students are a mixture of Bengali, Khasi and Garo. The later two are groups that are mainly in the eastern and western Shillong Plateau (Meghalaya). We are finding that many of the villages in the hills are part of the 2 percent of the non-Bengali population of Bangladesh. The Bengalis like the plains and rice farming, the others are hill people growing other crops. The Khasi here are Christian, we passed a church on our way in. Later we met their tribal leader.
This time a short ladder was found, allowing us to climb to the ledge over the window and then onto the roof. Much easier going up than going down
with the roof overhang. We again went to work, drilling holes in their roof and mounting the antenna, the solar panels and chaining the receiver box down for security. They had no electricity so we had to use the cordless drill until it ran out of power. Then we had to send our driver to the closest village to recharge them. Meanwhile, they served us tea and cookies on the roof. We couldn’t quite get the antenna rod as far in as I like, but plenty for stability.
The next day we had another site in a building that was too far from the hill. Again we went forward into the hills. This time, however, there was no local school. One of the Khasi villagers showed us around, but even the open fields had too many tall trees around. The best we could find was the corner of the rice of our guide. He would sell us the little plot of land we need, but it would be expensive since it would permanently removed it from productive rice farming. Sanju pointed out that there were some
Manipuri villages to the south, so we went back to the main road to try them. We discovered the maps of the area were not accurate; we failed to get to Islampur. We tried some other roads farther south. Our car could not make the direct route, so we took a detour that led us into dirt roads through a tea estate. It led us off in the wrong direction and our van was sounding worse and worse. It sounded like the CV joint was failing. We circled back to the main road on an unmapped road. We picked up someone who would show us how to
drive to Kolabonpara, our last option to the south. Beyond that is India. Again, there were no local concrete buildings. The best we could find was a newly planted field of tea. Since the tea is kept waist high, we could put the monument in the middle of the field. However, the only way to get to it was over a bamboo bridge. It would be very difficult to get a welder and generator over that. We took the name and phone number of the
manager, who was away in Dhaka, and headed off. On the way back north, we decided to make one last try by going to a village north of where we started. We got most of the way there and found a newly rebuilt section of dirt road. It was too soft for the van, so we walked the final half hour to the village. We went past the rice fields in through the beautiful woods next to the first high hill. Finally, at the end, we saw it: the land opened up and there in the clearing was another brightly colored reinforced
concrete school. Since it was Friday, it was closed, but we got the name, address and phone number of the headmaster and went off to meet him. He turned out not only to be Manipuri, but to also be Sanju’s “uncle”. With permission in hand, we headed back to our hotel. Scouting had taken the entire day, but we now had a location for the next GPS.
Columbia University researchers are part of a team that is exploring a plate boundary that crosses three countries: Bangladesh, India, and Myanmar. Click here to read the previous blog posts in this series.
Unlike the GPS in your car or phone that gets a location within about 10 feet, the much more expensive systems we are putting in will get daily position estimates to about 2 millimeters. To do that, they need a clear view of the sky in all directions. We have two options for mounting the GPS antennas. If we can locate solid reinforced concrete buildings, we can cement a stainless steel rod into one of the columns. If not, we can build a braced monument out of vertical and diagonal stainless steel rods driven into the ground and welded
together to make a solid base. We came prepared for either situation. The first can be done in a day, but the second requires at least two days and finding a local welder. This part of Bangladesh has the sediments folded up into linear hills where they grow tea and broad flat valleys where they grow rice. We will put six GPS devices on different parts of multiple hills and valleys.
Walking through the grounds of Lemon
Garden in the morning fog, there were no appropriate buildings and no sufficiently open space. We did find their grove of lemon trees (actually limes). We considered a hill nearby, but there was a tree at the top. As we saw later, the slopes are planted with pineapples that were being harvested. If fact, the hills here are either heavily forested or covered in tea. The tea plants are kept short for ease of picking leaves, but trees are scattered among them. We headed over to my backup for this area, a village
nearby where perhaps there might be some homes, government buildings or schools that would be suitable. As soon as we got to the village, we saw the local school. It is the only reinforced concrete building in the village. It seemed promising, but there were some trees around it that blocked the view. We met with the school officials and amazingly they agreed to cut down the trees. However, we needed final permission from the Upazila (county) Education Minister. We drove down to Srimongal, and got our permissions, along with cups of tea and cookies. It is amazing how accommodating the Bangladeshis are to us.
Our next hurdle was a ladder to the roof. When none was found, used the truck as our ladder, climbing onto its roof and then the building’s. It was now the afternoon, so we quickly went to
work, drilling an 18-inch hole in the roof and epoxying in the rod for the antenna, assembling the solar panel frame and attaching it to the roof, and finally setting up the waterproof box that will hold the GPS, the batteries, and the modem that will send the data to UNAVCO in Colorado. While we were working, the woodcutter arrived. Sanju is an ethnic Manipuri from the others side of this hill or anticline. He used his contacts to find a woodcutter, who arrived along with his uncle and younger brother. His tools
were a machete and a rope. Because we needed two trees cut down and he needed to avoid a nearby home, he raised his price. In the end, it cost us 1400 taka, almost $17, a tiny fraction of the cost in the U.S. Part of the tree falling killed a lemon tree, so we will have to pay the owner for the loss. Sanju is still negotiating the terms. As is almost always the case, it was dark before we finished the last part, installing the grounding rod for lightning protection.
The next day, we traveled two and a half hours to our farthest site. This is a reinstallation of one that was installed in 2007. The GPS, borrowed from UNAVCO had to be returned in late 2016. That makes this a simpler installation as the rod and cables are already in place. It is in a medical clinic with the equipment box located in the birthing room. The people I had met in 2007 have moved and there is a new doctor and his family living in the clinic. Since 2007, a number of trees have grown up. We again need to have trees cut down. Sanju negotiated with
the neighbor and she agreed to cut the tree for a fee, which she will sell for the wood. The branches of another tree will be cut back once the boroi fruit, like miniature apples are collected. Lunch was again tea and snacks. Two days and two sites installed. After delays of a few more days, the seismic group finally got their equipment and started testing them as we finished the second site. Things are going well for us.
I am back in Bangladesh to start deploying equipment for a large new project. Results from our last project showed there is a large earthquake hazard here. We demonstrated that the Sumatra subduction zone, where India plunges beneath Asia, continues to the north under Bangladesh. The subduction down at Sumatra caused the 2004 earthquake and tsunami that killed over 230,000 people. Even though the plate boundary comes onshore, which is unusual for subduction zones, is it still active with the world’s largest pile of sediments, the Ganges-Brahmaputra Delta, entering it. We have designed an experiment to investigate this plate boundary across three countries: Bangladesh, India and Myanmar.
Our first step is to install 29 seismometers and 6 GPS receivers in Bangladesh. To do this, we have a team of 11 people. Most of us will be here for three and a half weeks. There are five of us from Lamont, two engineers from PASSCAL and UNAVCO, organizations that provide support and equipment to NSF projects like ours, and four from Dhaka University. Ahead of us, we shipped over two tons of seismic equipment and carried over 300 pounds with us on the plane. Thanks to a two-hour delay due to fog in Dhaka, our flights lasted a full 24 hours, and longer for the two engineers coming from Colorado and New Mexico. We then spent the next several hours at the airport getting all our luggage, getting them through the huge backup at customs from all the delayed flights, changing money, and getting local phone numbers.
At a lunch stop, four members of our team who have never been here before tasted their first Bangla food. So far, they are all enjoying it. We then arrived at the Dhaka University of Engineering and Technology (DUET), north of that city to set up our base.
When we arrived we found out that the seismic equipment is being help up by customs. Since the packing list mentions the GPS antenna that gets exact time for the seismometers, customs referred it to the Telecommunications Regulatory Commission. Humayun went back to Dhaka and spent the day there dealing with it, while Alissa and I tried to find the documents he needed to show the antennae only receive signals and do not cause not interference.The paperwork is slowly going through the bureaucracy and we hope it will be released tomorrow.
Meanwhile, we spent the time running around Joydebpur shopping for the materials we need. The seismologists need to build underground vaults to hold the instruments, while the GPS team needed grounding rods and wire. Most of seismic supplies were bought or ordered, so they should be ready to move out ahead of schedule even with the delay, if they get it tomorrow. The GPS team finished our shopping so tomorrow we will pack up, hopefully be able to fit everything in one van, and take off. It will be Keith from UNAVCO, Sanju from Dhaka University and myself.
When they are done shopping and testing, the seismic team will split into two 4-person groups for the installations, starting with the dense central line of stations. We will hopefully see one of them by the end of the week when they arrive in the Srimongol area, where we are going. The other team will initially work from here at DUET. These are the two ends of the dense lines in Bangladesh and they will spend the following week deploying towards each other.
Of course we had too much stuff for the van, so the truck will come with us to carry our equipment and then return to DUET. We had the mandatory meet and greet with the president of DUET. In the end, our leaving first thing in the morning stretched to 12:30. We had hoped to stop at one of the sites on the way, but instead we went straight to the Lemon Garden Resort in the hills near Srimongal. The hills in Sylhet in the northeast part of Bangladesh are covered in tea estates. There are a growing number of resorts in the hills as well. Lemon Gardens has beautiful grounds, and tomorrow we will see if there is a good spot for a GPS.
From Khulna in the SW, we are heading to Rajshahi on the Ganges River, but first we are stopping at Kushtia, Humayun’s home town. Because the road on the more direct route is supposed to have bad road conditions, we took a longer route, way longer. It wiped out any chance to get to Rajshahi in time for some fieldwork, but it did boost my districts (states) of Bangladesh visited to 40 out of 64. After many hours on the road, we reached Kushtia and out goal – jordibaja, a fried noodle snack that is only available here. Chris bought 10 500 gram bags, about 11 lbs, at the bakery that makes
the best, of course. We then had a late lunch and continued to Rajshahi where we were once again joined by a police escort. Different teams stayed with us until we left the area. After finding our hotel, we all had our first hot water shower since we left Dhaka. Living on boats is great, except for the complete lack of hot water. Once cleaned up, we went to Humayun’s sister for a delicious dinner. After dinner, the commissioner of police, a former student of Humayun’s stopped by. He suggested we visit some of the chars (sandy river islands) close to Rajshahi rather than the places we went
to other years, an hour or more drive away. Chris and Dan checked their satellite images and found that the nearby chars would work, probably saving 2-3 hrs of driving.
The next morning, we headed off with out new escort, that included two policewoman. However, that had to switch off when we crossed from one precinct to another. Renting a country boat we crossed the Ganges to the chars. While Dan and Chris (with Humayun) made salinity, moisture and spectroscopic measurements, Liz and I
scouted for the proper sediment samples for her OSL needs. After wandering about the island we found what she wanted and collected a sample. Until now, her studies of the delta did not have any samples from the Ganges itself. For Dan and Chris to get the observations they wanted, we visited several chars before ending up back at the first one for them to study the transition from sandy sediments to rice fields. As soon as the chars have deposits of the right kind of sediments, people start planting crops. If the char continues
to grow and stabilize, they will move there as well. They are great places to live 9 months of the year, but a struggle during the high water of the monsoon season. The islands with migrate, eroding from one side while sediment deposits on the other. The char people have to move frequently as the chars move out from under their homes. Liz and I wandered off and found another place to sample. Now she have both a sand and a silt samples from the Ganges. It only took a few hours to accomplish the more specific tasks of this field program. When we first started visiting chars 12 years ago, we explored then from the morning
until dusk. We needed to see and explore all aspects of this new environment for us. Now, we are building on our work with much more focused activities.
Off the river by early afternoon, we drove across country to Bogra near the Jamuna River, as this part of the Brahmaputra is known. We were able to arrive around sunset, avoiding the sometimes frightening driving in the dark. For old times sake, we skipped the new hotel that was booked and stayed at the colorful Parjartan Hotel that we first used
in 2005. It is literally painted the colors of the rainbow, as well as having more character, even if everything is not quite working. This was the hotel where my room once had electric outlets of 4 different shapes, requiring every adapter I had to recharge my equipment. Now I always bring an outlet strip so I only need one adapter.
We had planned to go north to Gaibandha, but a new satellite overpass showed that we could get all the data we needed farther south at Sirajganj. We could cut out a day. As it turns out, this was fortuitious. I have a family
emergency and have to return to the U.S. From Sirajganj we could return to Dhaka, rather than stay at Tangail. Chris and the others can do the rest of the field work as day trips from Dhaka. It is more driving for them, but will enable be to catch the evening flight back to the U.S. We packed up and headed to the embankment at Sirajganj, which protects the city from the shifts in the Jamuna River. We walked down the embankment (the river level is about 7 m or 23 feet higher during the summer monsoon season). We headed for a large char that
we first visited in 2005. It has grown and become attached to other chars. It also has much more agriculture, they are growing rice, peanuts, lentils, corn and more. The complex history of changes in the char provides lots of different sediment types for Chris and Dan and plent of cut bank surfaces for Liz to get a good silt sample. A few hours of exploring, sampling, measuring and we were done. Since it is Friday, the Muslim holy day and the weekend here, traffic is light until we reach Dhaka. Near the university and our hotel, the streets are packed with people and rickshaws. Still we manage to get to the university to drop off equipment and for me to get 7
GPS receivers that finally have to be returned to UNAVCO after 10 years. This is the last of the 11 we were lent in 2007 by them. They provide geodetic data and services for NSF and allowed us multiple extensions that enabled us to get this much needed data for so long. It is the basis for our paper on the potential earthquake hazard in Bangladesh as we can see the slow motion of the surface (0-17 mm/y) that indicates the buildup of strain in the earth. Then back to our hotel to meet Dhiman and have a final dinner together before an Uber takes me to the airport. I am leaving to return
home, while they will carry on without me a few more days. They will visit the confluence of the Ganges and Brahmaputra Rivers, and the Padma, as the combined river is called. For me, my main goals for this trip were accomplished.
My critical equipment repairs were now done. Chris and Dan still had several days of work in the area, but Humayun and I were interested in traveling to Hiron Point near the coast in the Sundarban Mangrove Forest. We want to take advantage of being so close. We hoped we could do it in a day, with the tides and broad open channel to the south, it would take two, too much for Chris to spare. We worked out that Humayun, Liz and I could take Bachchu’s smaller boat, the M.B. Mowali. Mowali are the honey collectors in the Sundarban and Bawali are the wood cutters.
Before we leave, we have one day with Chris and the others. After, Matt and Tanjil, our forest guide from 2015 who stayed with us for a day, departed, I went out with them to Polders 32 and 31 for their afternoon run. They are making soil salinity measurements to see if it is possible to determine soil salinity from satellite imagery. Saline soils are a large problem in this part of Bangladesh. We took the country boat to shore and scouted for the appropriate place. At each one Chris and Dan laid out a grid of probes to measure salinity and moisture
content. Kingston and Zahan did similar measurements at the surface and at the root level. As always, we attracted a crowd of onlookers curious as to what these foreigners were doing.
Later, after dinner, the M.B. Mowali arrived and our group split once again. We traveled to the edge of the Sundarbans that night, to pick up our guide and our armed guard for the tigers. The Mowali is much smaller. I
haven’t seen her since she was renovated. Now there is one cabin, which Liz got, and a larger room for Humayun, myself and our guide. In the early morning we headed south. Once the fog lifted and we entered smaller channels, we started seeing deer and monkeys on the banks and in the forest. We stopped in a small side channel and had lunch before crossing the over 10-km wide estuary in our speed boat, a 40-min. ride. I could see that a lot of fresh land had grown at the mouth of the channel with the forest station and our GPS since the
last time I was here, two years ago.
We brought along lots of extra equipment in case anything had broken down. Humayun and I worked on downloading the GPS data while Liz and the guide went for a walk and climbed the observation tower. They got to see deer, wild boar and a monitor lizard, while Humayun and I sat in a dark room. As usual, we struggled to remember how to connect and download data exacerbated by unfamiliarity with the Windows OS on the PC we were using.
Eventually, we got it right and were happy to see that the system was working perfectly, with data files for every day since I last visited. Obviously, because we had brought all the equipment along, we didn’t need it. We downloaded all the data and then changed the SIM card in the modem. We had set up cellular communications when we installed the station, but the signal was too weak to collect any data. Now there is a good signal here from a different cell phone company. When we get back we will have UNAVCO check to see if it works. In any case, we now have enough data to measure the subsidence here. The sinking of the land exacerbates the impact of rising sea level. Only the vast sediment supply of the delta counters it to maintain the land. And that is at risk from human intervention.
We had tea and cookies with the forest ranger and then headed back before low tide trapped us in the channel. As things went well, we stopped on the newly emerged char land and Liz and I walked around examining the sediments, surprisingly sandy for a tidal estuary. Back in the speed boat, we crossed the broad channel and then paused to watch the sunset on the water. Once on the Mowali, we sailed to where we would spend the night in the Mangrove Forest, and now I got to see deer and boar on
the way before darkness descended. There was even a herd of nine or 10 just across from where we rejoined the Mowali.
In the morning, we started heading north. Because it was very foggy, we stayed in smaller channels for a few hours before entering the main channel of the Pussur River. I spent the early morning before breakfast watching the forest go by and spotted a few more
deer. By noon we were out of the Sundarbans and ready to drop off our guard. I actually hadn’t seen him for the entire trip. We continued past the Rampal power plant. This is a coal-fired plant being built less than 20 km from the Sundarbans. Most of the coal for it will likely be transported up the Pussur River through the Sundarbans. It is the subject of a lot of protests, including the hartal we had last week, but they are not likely to stop it from being built. A short time later we met up with the Bawali and
moved back across. Then, work here being done, both ships sailed up to Khulna for the night. Tomorrow morning we disembark for the next phase of the trip.
After a night in Dhaka, our group temporarily split up. Chris and Dan headed to Khulna in the SW at 4 a.m. to avoid the hartal (general strike) that was planned for 6 a.m.-2 p.m. Liz and I stayed in Dhaka for a day. I spent it mostly editing material for a new project. The next day, Liz, Humayun, my partner from Dhaka University, and I followed the others to Khulna, crossing the Padma (combined Ganges and Brahmaputra) River by ferry at Mawa. After waiting an hour, Humayun used a connection from a former student to get us on the next
ferry, a fast one. It is impressive how much the river has silted up since the last time I crossed here. Another few hours and we arrived at our compaction meter site SE of Khulna. We picked up one of the four sons from the family that takes care of the site. Mofizur, the second son, now a student at Chittagong University, is returning home for the first time in six months. Making the weekly measurements has been passed along from the oldest to youngest sons. It made for a great welcoming by the Islam family when we arrived mid-afternoon.
The last time I was here, the river adjacent to the site was being dredge and widened. It had gone from 200 m wide to just a few and was now too small for boats except at high tide. The widening cut into the bank that held our instruments. While the engineer tried to leave us enough room, it clearly didn’t work. The pillar that holds the GPS antenna is tilting badly towards the stream. They have secured it with ropes to keep it from completely falling over. We got hold of a ladder and removed the unusable antenna. Mofizur climbed up, afraid that I weighed too much for the fragile system. Next, Humayun and I surveyed the monuments for the compaction meter wells. We had to dig out the sediments
covering the base. Liz measured the thicknesses, which were 4-7 inches. We could clearly see the finely layered sediments deposited from before the river was enlarged to the thick muds that accumulated afterwards. The sedimentation rate had clearly increased due to the river widening. The survey will give us the relative heights of the wells. When we get back we will compare it to earlier measurement to see if the wells have shifted, too. Without the GPS we cannot determine the absolute elevations. Our last task was to measure the lengths of the optical fibers in the wells. We brought along a new laptop to work with the electronic distance meter (EDM), but we found the recharger was still in Dhaka. We had forgotten it. With a dead battery and no way to recharge it, the measurements will have to wait until Humayun can send the recharger.
While we were there, we were served lunch, a huge banquet. Three kinds of fish, chicken, rice, vegetables, two desserts. The three of us sat a table outside in the yard, while the family plied us with the delicious home-cooked Bangladeshi food. The more important the guests, the more food, and were were suitably overwhelmed. And since it was after 3 p.m., we were famished and did our best make a dent in it. Since the GPS is no longer usable, we left them the battery and solar panel that was powering it, doubling their electricity supply. Before we installed the
equipment in 2011, they did not have electricity at all. After some heartfelt farewells, we headed to Khulna to meet up with Chris, Dan and Matt Winters, my teaching assistant from the class I taught in 2015. Fluent in Bangla, he has been working with Chris on field observations for his master’s thesis at Columbia. He and some of his assistants will join us for a few days. The three of them had a dinner meeting, so my group headed to the M.B. Bawali, our home for the next four days. Smaller than the M.B. Kokilmoni, it is a perfect size for our group.
The next morning, we headed for Polder 32, the embanked island we have been studying. Humayun and I will visit the GPS station we set up there in 2012. It has a cellular modem so data can be downloaded remotely every day, but stopped working in November. It seemed that the receiver was not recording satellites, so we brought along replacement antennas, cables and lightning protectors. Another GPS station had a similar problem, and there the cable had to be replaced. When we arrived at the school, we found the receiver was tracking satellites. We didn’t
have to track down a break in the system. But why wasn’t it recording data? The best we could ascertain was the modem had hung up; rebooting it fixed the problem. It was working, but I don’t understand what happened enough to be sure it won’t happen again. Hopefully, now that it is working, the engineers at UNAVCO can log in and work on it. When we double checked everything, we found that the grounding wire was missing. This is unsafe. If there is a lightning strike, the lightning protector blows the connection
to the equipment inside and shunts the electricity down the grounding wire. We cannot put a school full of children at risk. The only wires we had were the coaxial antenna cables. We stripped the ends off a partial cable and wired it between the cut ends on the roof and near the ground. We made a visit to the Hindu goddess of education and headed back to the ship having done all the repairs we could, and satisfied that the school was safe.