1. Robert W. Christopherson Charlie Thomsen Chapter 9 Water Resources

2. The Hoover Dam on Colorado River The Lake Mead is 36 m lower in 2007 compared with that in 1983

3. Middle East: Jordan river A security issue South Asia India and Bangladesh over Gangs River India and Nepal over Mahakali River Mekong River Basin: China, Laos, Cambodia, Viet Nam US Western US: California/Nevada over Colorado River water. NC/SC: over water use from Catawba/Yadkin Rivers. SC Attorney General filed a lawsuit in 2007 NC in US Supreme Court to stop a NC plan to pump 10 million gallons a day by two NC cities. Both Catawba and Yadkin rivers flow into SC. Water Resources Conflicts

4. The Hydrologic Cycle Soil-Water-Budget Concept Groundwater Resources Our Water Supply Water Resources

5. Hydrologic Cycle Model Figure 9.1 Round and round as it goes, the rivers never stop flowing and the oceans never overflow. The flow of water linked the atmosphere, ocean, land, and living things through exchanges of energy and matter.

6. Earth's Water and the Hydrologic Cycle

7. Surface Water Figure 9.2 Evaporation Transpiration Runoff Infiltration Percolation Water Table

8. Transpiration/Photosynthesis Figure 9.2 CO 2 H2OH2O Losing water is the price to pay for gaining CO 2 Underside Stomata Transpiration is a biophysical process, plants control transpiration rate through regulating the aperture of a stoma. (1)When there is plenty of water supply during sunny condition, stomata open wide to absorb CO2, in the meantime, losing water. (2)During the nighttime, there is no light for PSN, plants shut their stomata to prevent water loss. (3)When there is a shortage of water, plants shut their stomata to prevent physiological drought

9. Why Is There a Water Table?

10. The Bucket Model Figure 9.3 Principle: Mass conservation Bucket volume= Maximum amount of water soil can hold ΔSΔS P T E ΔSΔS P T E R

11. The Soil-Water Balance Equation Figure 9.3 P: Precipitation which can in various forms such as rain, snow, hail, a complete list in Table 9.1. ET: evapotranspiration (evaporation + transpiration) R: Runoff water ΔS: change in soil water What are the other two balance equations we learned earlier?