Robert W. ChristophersonCharlie Thomsen

Chapter 9 Water Resources

The Hoover Dam on Colorado River

The Lake Mead is 36 m lower in 2007 compared with that in 1983

Middle East: Jordan riverA security issue

South AsiaIndia and Bangladesh over Gangs River

India and Nepal over Mahakali River

Mekong River Basin: China, Laos, Cambodia, Viet Nam

USWestern 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

The Hydrologic Cycle  

Soil-Water-Budget Concept  

Groundwater Resources  

Our Water Supply  

Water Resources

Hydrologic Cycle Model

Figure 9.1Round 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.

Earth's Water and the Hydrologic Cycle

Surface Water  

Figure 9.2

EvaporationTranspirationRunoffInfiltrationPercolationWater Table

Transpiration/Photosynthesis  

Figure 9.2

CO2

H2O

Losing water is the price to pay for gaining CO2

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

Why Is There a Water Table?

The Bucket Model

Figure 9.3

Principle: Mass conservation

Bucket volume=Maximum amount of water soil can hold

ΔS

P

T E

ΔS

P

T E

R

The Soil-Water Balance Equation

Figure 9.3

SRETP 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 waterΔS: change in soil water

What are the other two balance equations we learned earlier?