Hydrology BC ENV 3025

HYDROLOGY - Homework # 10

1)  (10 points) Bangladesh Arsenic issue

(a) Typical sediment in Bangaldesh contain about 2mg/kg Arsenic. Assuming  a typical prorosity for sand (see lecture notes)  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-1.  If groundwater would flow through the system at  a constant rate, how long would it take to remove all the Arsenic?

2) (8 points) Unsaturated zone

a)   The infiltration rate is often decreasing during a precipitation event. What processes causing this behaviour can you imagine?  (Identify 3 of the potential processes).

b) Does this have any implications for flood forecasting?

3) (12 points) Future global water use

a) (4p) Type current population data into EXCEL and plot world population as a function of time. Which function fits the data best? Project the population for the year 2050 and 2100.  (data are from: http://www.census.gov/cgi-bin/ipc/popclockw).

Monthly World population figures:

07/01/02    6,228,394,430
08/01/02    6,234,672,164
09/01/02    6,240,949,898
10/01/02    6,247,025,125
11/01/02    6,253,302,860
12/01/02    6,259,378,087
01/01/03    6,265,655,821
02/01/03    6,271,933,556
03/01/03    6,277,603,768
04/01/03    6,283,881,502
05/01/03    6,289,956,729
06/01/03    6,296,234,464
07/01/03    6,302,309,691
07/01/04    6,372,797,742
08/01/04    6,379,026,080
09/01/04    6,385,254,418
10/01/04    6,391,281,842
11/01/04    6,397,510,180
12/01/04    6,403,537,604
01/01/05    6,409,765,942
02/01/05    6,415,994,280
03/01/05    6,421,619,875
04/01/05    6,427,848,214


b) (4p) If the whole world would consume as much water as a typical US American (1200 gal/day), what would the worlds water consumption be in 2050 and 2100 as a percentage of the total available freshwater (5*104 km3/y) on Earth

c) (4p) If it looks like there is plenty of water out there for all those people, why are we still concerned about the water future?