Geohazards in Bangladesh
It was time to pack up and leave. Shofiq, who is from Sylhet, was dropped off near his home and the fellowship of the rocks was broken. We settled in for another long drive. We made an impromptu stop at one of the numerous brick factories scattered across Bangladesh. Here, the workers immediately started snapping pictures of us with their phones. We walked past the rows of drying unfired bricks to the massive kiln built from the bricks themselves. We saw them feeding coal into the hot, actively firing part and unloading bricks from the completed quadrant. This would be followed by loading of raw bricks for the 12-hour firing. This factory makes around 9,000,000 bricks in the six-month season. Although it was their lunch break, they demonstrated the mixing of the mud with a little sand and let me carry a half-full wheelbarrow load to where the bricks were
shaped. I spilled a full load when I tried to move it. The experienced brickmakers took about 30-seconds per brick.
We stopped for lunch at the same roadside restaurant, then went to find Wari-Betashwar. Getting to the archeological site was not easy, but a mixture of my hand-held GPS with a Landsat image and a Bangladeshi phone with completely inaccurate Google maps eventually got us there a little after 4 p.m. We toured the site with the chief archeologist, but all the excavations had been filled in to protect them during the off-season. As we walked around the 600m by 600m protective wall, Prof. Rahman explained the history of the site. This urban
center was founded around 500 BC on land slightly uplifted by one of the anticlines. The slight extra elevation protected the land from flooding. The site was by the side of an old path of the Brahmaputra River and was thus a major trading center. Artifacts from as far as Greece and Rome were found here. After a gap in the record, the city flourished again in the 7th century AD, before being abandoned. The rise and fall of the center may be tied to avulsions, or switches in position of the Brahmaputra, making the site an interesting confluence of tectonics, rivers and people.
Continuing on, the students got a taste of Dhaka traffic as we approached our hotel near the airport. Now came the real
splitting up of the group. The foreigners would stay overnight to begin our return home, while the Bangladeshis would fight the traffic to return to Dhaka University and their homes. Many of us spent most of the time until our 2:30 a.m. departure talking. Twenty-three of us and our luggage and equipment managed to squeeze into a 21-seat bus and made it to the airport. Now, once again problems with our tickets arose. While most of us were fine, almost half only got boarding passes as far as Abu Dhabi, or none at all. Eventually they fixed the problem for most of them, and all of us were able to board the delayed aircraft. The delays here and in the flight to New York and Chicago will mean that the vast majority will miss connections. At least my nightmare scenario of missed flights and connections was happening on the way back. Not the smoothest ending, but it has been a great trip and a very successful field school. Several of the students are trying to figure out how to get back to Bangladesh, and a lot of lasting friendships and connections have been made.
The drive from Tangail to Sylhet turned out to be grueling. We took a longer route that skirted Dhaka to avoid the traffic jams that people hit earlier in the week. Unfortunately, with the slower buses that route took 13 hours. We didn’t hit our lunch stop until 4:30 p.m., where Badrul and Ashraf had been waiting to join us for five hours. It was dark by the time we drove past the first anticlines, and we didn’t get to the resort until 11 p.m. We picked our roommates, got our rooms and had a very late dinner. Most field trips have a “death march” hiking a long way through forest, swamps, hills or deserts to get to a remote outcrop. We have a “death bus ride” instead.
The new resort where we were staying was tucked away in a corner of Bangladesh along the Shari River about a kilometer from the Indian border. With a cold pool and only slightly warmer not-hot tub, views of the woods and hills, this is by far the nicest place I’ve stayed in Bangladesh. Given the late arrival, we delayed the start of the classroom day by an hour. The classroom was in a separate building closer to the river The first classroom day covered the stratigraphy and structure of the sediments and rocks we would see the next day. With lots of questions, the day ran late.
We started early and argued over an outcrop on the driveway of the resort. We continued down to the Shari River, where I had previously visited the geology by boat. Numerous
country boats were mining and transporting sand from the river. We worked along the shore, climbing over and visiting outcrops. The beds dipped steeply into the ground, folded by the tectonics, but also provided evidence that a large braided river used to flow here. One possibility is that it was the Brahmaputra from a time before the uplift of the 2 km-high Shillong block pushed it 200 miles to the west. Eventually, we could not go farther along the river. We took an inland path farther north, but when we rejoined the shore, we were blocked again. A short time later, after a conversation with the Bangladeshi border guards stationed here, they flagged us a passing boat. It ferried us across the river, but not before
several on our party practiced their cliff jumping technique.
After spending some time on an outcrop where we were filmed last year, we took an inland path. Along the way we met Johnny the elephant, and a few groups of students got elephant rides. We continued past tea gardens and rice paddies and finally emerged to a large outcrop of shallow marine sediments along the river. At this earlier time, the coastline was north of us, and the delta was prograding to the south as a result of all the sediments eroding from the Himalayas. The younger river sediments we had seen earlier had been deposited after the coast had pushed past here. We stopped for lunch, looking across the river at the India-Bangladesh border and a pile of watermelons waiting for a
boat to take them downstream. Two students swam across and purchased two for dessert. Then Badrul flagged down a large boat to taxi us downstream back to where we started.
After a few geology stops along the way, we reached Jaflong. At this site, there is a mixture of mining of sands and gravels from the river, and tourists looking to view the massive Shillong uplift in India. We stopped at an overlook near our GPS and seismology stations. Then a group of us descended to some outcrops and the chance to join the tourists at the international border. The river had shifted a little since I last was here, and now the best viewing site was officially in India. The Indian and Bangladeshi border guard let us and everyone else cross the
border to the little spit of land for a better view. Many photos later, we walked back to the buses and returned to the resort. Dinner was delayed and about half of us took the opportunity for a dip in the freezing pool to rinse off the sweat and grime.
Our final classroom day conversation included multiple aspects of the interaction of the rivers and the tectonics that our project focuses on. We ended with several students presenting their research from places across the globe. The last item was a group photo close to the Shari River. The last field day took us farther southwest to Sylhet City itself. The Cricket Stadium is surrounded by outcrops that we walked around, passing a pet monkey as well. After lunch at the stadium and a peek inside, we had to make a decision. There was not enough time for
both the outcrops at the airport and shopping in Sylhet. The group split, and each bus went to one of the sites. I chose the outcrop. The river sediments at the airport were clearly different from the stadium and showed that the sediments were deposited while the 80m-high Sylhet anticline was growing. They were muddier where the anticline was tilting the land northwards, and sandier with gravels on the other side of the anticline where the southward tilting had steepened the river. We headed back, stopping to at least buy some tea from the region. However, we got back too late to hold the bus vs. bus cricket match. Just some practice would have to do, until the BBQ that evening.
It has been an incredibly busy week. We have had between 42 and 48 people here for the field school, including 35 students and 12 instructors (seven to 10 at a time). The first day was very light for the jet-lagged students, just a short introduction to the field school and some background, and then introductions all around as we started to get to know each other. The final group of nine students finally arrived around 9 p.m. They were the most worn-out, bedraggled bunch of travelers I have ever seen.
After a good night’s sleep we started on the first classroom day. Our full five days near the Brahmaputra River would focus on the river processes and the stratigraphy they produce. We stopped the lectures at 4 and all piled into the bus
to see the embankment built to protect the city of Sirajganj from the westward migrating river. As is often the case in the dry season, they were repairing the embankments from last summer’s collapses. We rented two country boats and sailed along the embankment and walked back to the buses on the top of it. It is an impressive structure, but in need of continual repair to keep up with the river.
The next two days were spent on the river and its mobile islands, called chars. Setting up the equipment for the river surveying was hampered by a lack of power for drilling holes. A Bangladeshi drill and bow solved the problem, but not before rearranging the schedule. On the first day we all visited the char near the 5 km
Bangabandu Bridge over the river. We spent the day viewing sedimentary structures and seeing the villages on this island that is almost entirely underwater during the monsoon. For the second day, we had to split the group. One contingent joined Jim Best as we surveyed the river with an ADCP, which measures water velocities from the top to the bottom of the river, and a sidescan that provides images of the bottom on either side of the boat using sound. The other, yielding to student requests, went to Tangail, the nearest city, for shopping. When everyone returned, we held a cricket match, with most Americans learning the rules on the fly. We finished the five overs per side as darkness fell.
We went back to the classroom the next day for more lectures on remote sensing of changes on the delta, stratigraphy,
subsidence and arsenic contamination. The hands-on experience was analysis of two sets of well samples that had been drilled the days before. Everyone had a chance to describe the samples, measure magnetic susceptibility and use a portable XRF machine to measure chemistry. We have found that magnetic susceptibility and strontium content are a good way to characterize whether sediments have come from the Brahmaputra River or not.
Finally, our last field day here was doing a resistivity imaging survey over the two bore holes and across the boundary between the Brahmaputra floodplain and the upland strata of the Madhupur tract. Generations have debated whether the transition is a fault contact or not. We would collect some data to try to answer the question. The students also got
to visit another tube well being drilled. Tube wells, drilled primarily for drinking water, is a local drilling method whereby a team of a handful of people can drill a 100m well in a day by hand. After everyone helped set up the 750m long resistivity line, most of the American students went to see the tube well drilling. The Bangladeshis, who have all seen tube well drilling, stayed with me to help run the resistivity line. As it turns out, Liz Chamberlain was pulled into a local villager’s home to have her hands tattooed with henna by a woman and her daughters. She missed the tube well drilling, but gained an exciting personal experience. It was also the first time the students were in a Bangladeshi village. We were the center of attention and many photos were snapped by both sides. We gathered up the resistivity equipment and then had informal student
presentations before the final night barbeque. We had successfully completed the first half of the course, and all the students (and instructors) were bonding.
Feb. 21 is Language Day in Bangladesh. It is a holiday, now adopted by the UN as International Mother Language Day. It commemorates a day in 1952 when a crowd of Bengali students protesting Pakistan’s adoption of “Urdu and only Urdu as the official language of Pakistan” were fired upon by the police. It marks the beginning of the move towards the independence of East Pakistan, the future Bangladesh, from Pakistan. It is a time of plays, book fairs and poetry reading celebrating the Bengali/Bangla language. There are also laying of flower wreaths at the Shahid Minar, the monument where the killings occurred near Dhaka University, and many smaller copies throughout the country.
For us, it was a travel day. A long eight-hour drive from Khulna in SW Bangladesh across the Ganges River and the Jamuna River, as this section of the Brahmaputra is known, to our home for the next week. The eight of us in our
party left the Bawali in two vans, stopped to pickup equipment, and settled in for a long uneventful drive, or as uneventful as driving in Bangladesh can be.
The next day my group went to Mawlana Bhashani Science and Technology University to try to install a new GPS. After various meetings and cups of tea, we explored the rooftops looking for the perfect site for the antenna. Unfortunately, the building we were in was not quite finished. It was a good site, except the columns on the roof were still a mass of rebar and the concrete was yet to be poured. More meetings, coffee, sweet desserts, and we checked out other roofs. Many buildings at the relatively new university are unfinished. The older finished ones are lower and the clear view of the sky we need is blocked by trees. The
first roof was the best choice, but would not be ready for three months. The best we could do was to set up the GPS box and leave all the equipment there. Humayun will come and finish the job in May. Without the installation work, we continued to meet people and have tea, lunch and more tea. We finally left around 4. Time to go back to the Elenga Resort, where we were staying, and prepare for the arrival of students for the Field School.
Our NSF grant from the PIRE (Partnerships for International Research and Education) has a large emphasis on providing American students with international research experience. One of the things we proposed was a two-week Field School in Bangladesh. We have 15 U.S. students, 15
Bangladeshi, a few other invitees (France, Singapore, India) plus the scientists and students from our project and our advisory board. Most were scheduled to arrive on Sunday. During the day, I started receiving messages about delayed and cancelled flights. My nightmare scenario was arrivals scattered over several days with no way to know where or when. Most of the delays were absorbed by the long layovers at JFK and O’Hare, where experienced Bangladesh hands would lead them to the promised Field School. Our travel agent shifted one of the cancellations to another flight.Then I learned that Steve Goodbred, leader of the JFK troop, had his flight cancelled and would fly a day later. Mike Howe, a grad student with one trip to Bangladesh, was in charge. Worse, the flight was delayed and could miss its connection in
Abu Dhabi. One student was MIA. I stayed up late to follow the flight and, yes, it missed the connection. I went to bed thinking that most of the U.S. students would be a day late.
I awoke early to find that they had been rebooked through Delhi and would arrive late afternoon. Better still, I learned that the missing student had been rebooked to the Chicago route. Then Humayun called and asked if I was meeting the on-time group for breakfast. I rushed out and Babu drove Chris and myself to the Parjatan restaurant across from the Martyr’s memorial. We got there just after they did. We had breakfast and then dodged traffic to cross the street to the memorial. While there, the Dhaka University contingent arrived for breakfast and we joined them. The Field School was on. Three-quarters of the people had arrived; most of the rest would be here by dinner. Only Steve and Ryan would be a day late.
When we got cell phone signal back, we found things did not go according to plan. Scott’s flight had a medical emergency that required a stop in London, so he missed his connection. So did the GPS box, so they both arrived the morning of the 18th. He was not in Khulna already working. He wasn’t working on the compaction site. Between the flight delays and the ship delays, we had lost a day.
Since I couldn’t meet Scott, it was best for me to go to Polder 32 to check on the GPS there. However, not knowing the situation, we had sailed up the wrong channel. We wouldn’t get to the Polder 32 site until the afternoon. Polder is a Dutch term for an embankment. They have been built around much of the land in coastal Bangladesh to protect it from flooding from the brackish water and
improve farming. An unexpected side effect is that the protected land inside the polder, with no flooding or sediments, has sunk by over a meter. It is lower than the land outside the wall and lower than high tide. When Cyclone Aila hit the area in 2009, it breached the polder and the island was flooded for almost two years. We are studying both the physical environment and the human impact. My part is measuring the subsidence with GPS. The receiver here has a modem so the data can be collected by phone, but it hasn’t worked since Jan. 1. We went to the school that houses it, and I managed to correct the problem.
Now it was time to join Scott. I left the boat for a bumpy 2.5-hour drive to Khulna and the hotel. We had allotted two days for servicing and installing GPS in Khulna, but we also wanted to visit a 400-year-old temple in the Sundarbans. It is being looked at to measure subsidence since it was built. We could only visit the temple if we could do the GPS work in one day. We started a 7 a.m., picking up Hafizur and heading to his family’s house, where the compaction meter is. We hoped to finish it quickly, but there were problems with the GPS. The solar panel controller was bad and had to be replaced. Then I found the settings of the GPS were bad; I couldn’t communicate with it. After a struggle, I managed. The system went bad last June and had recorded no data since then. Scott collected data from the compaction meter and surveyed the monuments, while
I got the GPS going again. When it was time to leave, we found that the Islamic family had prepared a huge lunch for us, and we had to stay and eat: sweet rice appetizer, two kinds of fish, chicken, vegetable, rice and a rice pastry in palm juice for dessert.
When we left to go to Khulna University (KU), our chance for the temple looked bleak. We met Professor Rakib Uddin, who did not get our sense of urgency. The GPS at KU hadn’t been working for years. Set up in the Urban Planning Department, the 20-year-old receiver needed constant care to keep going. We had installed these obsolete instruments when we first started working in Bangladesh and had almost no funding. We would be reestablishing the site, replacing everything.
Then we would install a new receiver in Rakib’s office in Environmental Sciences. As long as we had some overlap of the two receivers, we could combine the measurements for a longer record. After various formalities, we went to the office. We would need to buy some extra equipment, but the professor had to leave. We called everyone to say we could not do the temple. Then Rakib got the professor to leave the key so we could keep working. It was now a maybe. We arranged for the forest permits not knowing if we could use them. Allan and Towfique went shopping while Scott and I did what we could. By the time they got back and we finished, with multiple time-stealing problems along the way, it was dark. Rakib stayed late and Scott and I rushed to install the new GPS. The new ones are easier to work with, but
everything takes time. By the time we finished it was almost 9 p.m.
We rushed to the hotel and packed overnight bags. Bachchu’s other boat, the Mowali, would take us to the Bawali. We left at 10 p.m. after less than 24 hours in Khulna. It took 4 hours to reach the Bawali west of Polder 32. It was 2 a.m., but we made it. No dinner, but a chance to see the only Hindu Temple in the Sundarban. With two armed guards for tigers and a local guide, we sailed to a small channel south of the temple and took the launch to go into the forest. The channel got smaller, with branches occasionally sweeping across the boat. We got stuck, but the tide was rising. Then we had a long hike through the muddy forest, across a log bridge and more mud.
Finally we got there. After examining the temple, we decided more work was needed before we accepted the low subsidence rate estimated for the site. We also visited the rubble of the home for the local community and their protective wall. They were sent here to protect the region from Arakan and Portuguese pirates. They were the ones who built the Shakher temple. We could head back down the channel and return to Khulna on the Bawali. Despite all the problems, we had accomplished all of our goals for this part of the trip.
In Bangladesh we find that nothing ever goes according to plan, but we have always been able to accomplish our goals. So far on this trip, we have had to adjust from before we even got on the plane. The snowstorm on Feb. 13 cancelled Scott and his student Allan’s flights to New York from Wilmington, N.C. It looked like they would be delayed by a day, but then it worked out for them to drive to South Carolina to catch a flight. I was then able to pick them up on my way to take them to the airport for our flights to Bangladesh. There were seven of us going there together, but only six made it onto the plane. There were problems with his ticket, probably from the attempts to get to New York, and he couldn’t get it fixed in time to make the flight. Allan’s ticket was OK, though.
Not having Scott meant rearranging our plans. Plan B. We switched the order of things. Allan and I would go to Hiron Point in the Sundarbans mangrove forest first, since I could service the GPS there alone, but needed him for most of the other work. The silver lining was one of my equipment boxes didn’t arrive. It would not arrive until the next day when Scott could pick it up. I didn’t have to delay leaving Dhaka. After stopping by Dhaka University, I headed to Khulna to join Chris Small and others on the M/V Bawali. Chris was able to rearrange his work so we could sail to Hiron Point first. We got to the ship around 4 p.m. after a day of driving and a two-hour ferry ride across the Padma River, as the combined Ganges and Brahmaputra Rivers is known. We waited for Kushal and his students from Khulna University to arrive, then started the trip to Hiron Point near the coast.
We made good time and got to Hiron Point in the morning. We installed a GPS at the forest ranger station near a tide gauge. The tide gauge measures the water level relative to land, a mixture of sea level rise and subsiding of the land. Our GPS measures just the subsidence of the land, accurate to 8 mm each day. The combination of rising sea level and sinking land puts Bangladesh at greater risk of inundation. Thus the sediment deposited by the rivers is critical for maintaining the land and the mangrove forest. So far, it looks like sediment is keeping pace in the natural environment, but there are problems where man has made changes. We installed the GPS in October 2012. While we put in communication equipment, the site is so remote that there was no cell phone signal to download the data. Hence, our visit to collect it manually.
Everything looked fine, but when I tried to connect to the GPS, I couldn’t. The set-up for the communication equipment meant the settings were different and locked. After a frustrating hour of attempts, including a hard boot to reset the system, I finally found the right settings to talk to the device. The trip wasn’t in vain. Downloading the data, I found something had gone wrong last July. We had good data until July 19, then one giant file with a date in 2025. I hope that it actually contains good data, but I won’t know until I get back and can get it to someone to look at it. Even better, my hard reboot cleared out the problem, and the GPS started recording data properly again. Even if we have a data gap, we will still be able to see the data trend for the subsidence rate. Taking two days to come down here was worthwhile.
The next problem was that the Bawali couldn’t get out of the small channel by the ranger station until the next high tide. We were stuck for eight hours. We used the time to explore the channels, but we would not be able to get to our next stop on schedule. Time for another change in plans. We are up to Plan C. We decided to go back so I could get off the boat and join Scott, who has hopefully arrived. We will do our on-land work and then rejoin the Bawali in a day and a half, if all goes according to plan. Not a sure bet on this trip.