The Water Table

1. The Water Table A colloquium presentation by: Derrick Hwang

2. What is the Water Table? • Water Table: The top zone of soil and rock in which all voids are saturated with water.

3. What is the Water Table? • The level of the water table varies with topography, climate, and seasonal changes.

4. What is the Water Table? • Aquifer: An underground layer of permeable rock from which water may be extracted. • Perched Water Table: An aquifer that is formed above the regional water table.

5. How Does the Water Table Affect Us? • Without water, livestock cannot be grown and land cannot be cultivated. • Only 3% of Earth’s water is fresh water; however, humankind has access to only 1% of this fresh water. • The rise and fall of the water table has a very large impact on how and where fresh water can be distributed to the population.

6. The Importance of Equilibrium • High Plains Aquifer (174,000-square-mile area that includes parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming)

7. The Importance of Equilibrium Water is extracted from the aquifer using a pump that extends beneath the water table.

8. The Importance of Equilibrium At Equilibrium: Recharge (water entering) = Discharge (water leaving) Over-pumping occurs when more water is drawn from the aquifer than is returned.

9. Equilibrium Lost • What happens when the water table dropsbelow the level of the pump? • To obtain water, we will have to wait until the aquifer naturally recharges itself. • If the pump is near a sea coast, over-pumping will allow saline water to seep into the aquifer – mixing with and replacing the original fresh water.

10. Equilibrium Lost: Northern India • Net loss of 54 cubic kilometers of groundwater per year between 2002 and 2008. • Water table decrease of 10 centimeters per year.

11. Equilibrium Lost: California's Central Valley In 2002, produced one-twelfth of the nation’s crops. Now in danger: Over 20 cubic kilometers of groundwater pumped out since 2003. On average, the water table here has dropped 23 centimeters per year.

12. Equilibrium Lost: Ogallala Aquifer • In western Kansas and the Texas High Plains – supplies the United States with 1/5 of its agricultural harvest. The Ogallala Aquifer is being depleted at an annual volume of about 18 Colorado Rivers. 90% of the water pumped is used to irrigate crops. It will take 6,000 years for the aquifer to be refilled naturally.

13. Sustainable Solutions for Ogallala • It takes 1,000 gallons of water to produce 1 ton of grain. • Grow crops without groundwater:Eliminate wells and plant crops in harvest residue. • Develop less-thirsty crops: Drought-resistant corn could reduce amount of necessary water by 10 percent. Wheat does not require as much water as corn. • Evapotranspiration Measurement: Determine the minimal amount of water required to keep crops alive.

14. Sustainable Solutions • Take shorter showers: a 4-minute shower uses about 30 gallons of water. • Use a dishwasher or washing machine with full loads. • Check faucets and toilets for leaks.

15. Sustainable Solutions • Xeriscaping – replacing thirsty plants with less thirsty ones will save 750-1,000 gallons of water per month. • Fuel-efficiency: 1,700 gallons of water are needed to produce 1 gallon of ethanol. • Education: Producing a typical American Thanksgiving dinner for six people requires over 30,000 gallons of water.

16. Sustainable Solutions • Should the price of water be raised in order to promote water conservation? • The average price of water in the United States is about $1.50 for 1,000 gallons – or about a penny for one gallon of water. Is this a bargain we can keep? • Would eating lower on the food chain have any effect on water usage? • For 300 million Americans, a small reduction in meat, milk, and egg consumption would cut grain use by 30 million tons and water used for irrigation by 300 billion tons.

17. Bibliography • (2009). Water table. Columbia Electronic Encyclopedia, 6th Edition, 1. Retrieved from Academic Search Premier database. • Agricultural Water Table Management Systems, AEX 321-97. (n.d.). Ohioline. Retrieved March 8, 2010, from http://ohioline.osu.edu/aex-fact/0321.html • Ground Water Development, Sustaninability, and Water Budgets. (n.d.). USGS Publications Warehouse. Retrieved March 8, 2010, from http://pubs.usgs.gov/circ/circ1186/html/gw_dev.html • Is Your Garden Soil Too Salty?: Salinity Levels Can Affect Plants. (n.d.). Desert/Water-wise Gardens. Retrieved March 8, 2010, from http://desertwaterwisegardens.suite101.com/article.cfm/is_your_garden_soil_too_salty

18. Bibliography • Little, J. (2009). Saving the Ogallala Aquifer. Scientific American Earth 3.0, 19(1), 32-39. Retrieved from Academic Search Premier database. • OECD Glossary of Statistical Terms - Overpumping Definition. (n.d.). OECD Statistics (GDP, unemployment, income, population, labour, education, trade, finance, prices...). Retrieved March 8, 2010, from http://stats.oecd.org/glossary/detail.asp?ID=1979 • Perkins, S. (2010). California hit by irrigation drain. Science News, 177(2), 14. Retrieved from Academic Search Premier database. • Perkins, S. (2009). New data show quickening loss of groundwater beneath India. Science News, 176(6), 5-6. Retrieved from Academic Search Premier database.

19. Bibliography • Water Crisis: How Does it Affect Us? - A precious resource - Softpedia. (n.d.). Latest news - Softpedia. Retrieved March 8, 2010, from http://news.softpedia.com/news/Water-Crisis-How-it-Does-Affect-Us-71148.shtml • Water Conservation: 25 ways to conserve water in the home and yard. (n.d.). Eartheasy - Sustainable Living. Retrieved March 8, 2010, from http://www.eartheasy.com/live_water_saving.htm • Water Conservation. (n.d.). Mono Lake. Retrieved March 8, 2010, from http://www.monolake.org/about/waterconservation