Running out of water in an aquifer is a real problem. Below is a diagram of the Denver system aquifer that supplies water for Denver and the surrounding area. While people think that an aquifer has unlimited water the amount of water an aquifer has is determined by a number of factors. The first factor is how much water can soak directly into the aquifer from rain and other forms of precipitation (recharge area). The second factor is how much water comes from other aquifers in interflow we will assume for this exercise none is on the interflow side. This gives the amounts that are in the plus side of the equation for total water now let’s look at the loss side of the equation. Aquifers loose water to by ground water withdrawal and runoff (natural discharge into rivers lakes and streams) As well as evaporation. Green arrows pointing up are evaporation, turquoise arrows pointing sideways are the loss to river and streams.
USGS Ground Water Atlas of the United States
We will be looking at the three aquifers for Denver region; 1. Dawson aquifer (light green), 2.Denver aquifer (light green with dark green dots) and 3. the Arapahoe aquifer (darker green).
4. The value of the ground water withdrawal from all three aquifers is _23.2________? 5. The total available water (recharge from precipitation) without withdrawal for the Denver area aquifers is?_____6.5_______
6. The total loss (surface run off + ground-water withdrawal for the three aquifers) is approximately ________40_____?
7. How many gallons is this aquifer short (recharge – withdrawal) One acre-foot is the volume of water sufficient to cover an acre of land to a depth of 1 foot, = 43,560 cubic feet, approximately 325,851 U.S. gallons ___________________________________
The final set of problems is to calculate an estimate of the number of people who could get all the water they would need all their lives from the Denver aquifer system (there is one more aquifer that Denver uses for water).
Assume that the aquifer system contains 15 trillion gallons of water (15,000,000,000,000). People use 150 gallons of water per person per day (this is total amounts from drinking to washing to laundry to bathing etc.). Humans live eighty years.
8. How many gallons does a person use per year?
9. How many people can the aquifer system support for their life time?
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10. When do you think Denver area will run out of water? Population for the region |
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REGION |
1990 |
2000 |
2010 |
2020 |
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Projection |
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DENVER |
1,986,250 |
2,595,707 |
3,066,952 |
3,546,080 |
