Hydrology EESC BC 3025

HYDROLOGY - Homework # 8 - due 3/29

1.) (12 points) Tucson water issues
Download the TAMA (Tucson Active Management Area) water use data (TAMA_projections.xls) and make (linear?) projections for population and related water demand for the next 40 years. Play with different scenarios, assuming you (a) do and (b) do not have access to CAP water.

Note the comments in the spreadsheet for explanation of the different uses of water.

How can you match supply and demand? What policy recommendations you would make for this region? Use a couple of graphs to support your argument.

Print out and attach the spreadsheet you used for your projections.

2)  (8 points) Bangladesh Arsenic issue

(a) Typical sediment in Bangladesh contain about 2mg/kg Arsenic. Assuming  a typical prorosity for sand (25%)  determine what the maximum As concentration in water could be if you dissolve all this As in the water in one instant. The density of the solid phase is the sediments is of the order of 2.6 kg/liter.

(b) As discussed in class, As is increasing linearly with the 3H/3He age. The slope of that relationship tells us that As is accumulated in groundwater at a rate of about 20ugL-1yr-1If groundwater would flow through the system at  a constant rate, how long would it take to remove all the Arsenic?

3) (8) CO2 sequestration
The US emission of CO2 from non-stationary sources amounts to 7 Gt/year.

(a) Imagine you were able to collect 50% of this CO2 and compress it to supercritical conditions (density of CO2 is then 0.47 g/cm3). How large a volume would this take up (in km3)

(b) If you had a formation 100m thick to store the CO2 in with a porosity of 10%, and you were able to displace all fluids currently in this formation with the CO2, how large an area would the CO2 saturated aquifer cover? What fraction of NY State would this represent?