Water Resources

Chapter 13

Questions for Today

Why is water so important? Does everyone have access to clean and

healthy water Describe the three major zones of Groundwater. What are the major problems associated with

Freshwater in the US? What is Drought and what are the problems

associated with Drought? Who owns all the freshwater?

Freshwater Is an Irreplaceable Resource That We Are Managing Poorly (1)

Why is water so important?• Earth as a watery world: 71% (mostly Salt)• 60% of yourself is made from water• Freshwater availability: 0.024%

Hydrologic cycle • Movement of water in the seas, land, and air• Driven by solar energy and gravity

Water pollution• Degradation of the World’s Water Supply• Partly Because it’s Cheap• Taken For Granted

Freshwater Is an Irreplaceable Resource That We Are Managing Poorly (2)

Access to water is • A global health issue• Sanitation• 1.6 million people died in 2007

• An economic issue• Helps reduce poverty and produces food and

energy• A women’s and children’s issue• In developing countries, it is their job to carry water

back home• A national and global security issue• Tension between shared resources

Girl Carrying Well Water over Dried Out Earth during a Severe Drought in India

Most of the Earth’s Freshwater Is Not Available to Us

People divided into:• Water haves• Those that have a readily availably clean and

healthy water supply• For instance:

• Canada has 0.5% of the world’s people but has 20% of the world’s water

• Water have-nots• Those that do not access to clean, fresh water• For instance:

• China has 20% of the world’s people, but only 7% of the world’s supply of freshwater

Two Types of Freshwater:• Ground water• Water found in the pores between soil, gravel and

rock held between an impenetrable rock layer

• Surface Water

Ground Water Dissection

Zone of saturation• The point at which the groundwater is completely filled

Water table• The Top of the Ground water zone

• Falls in dry weather or unsustainable harvesting• Rises in Wet Weather

Aquifers• Two Types:

• Unconfined• Confined

Aquifer recharge: HAPPENS VERY SLOWLY• Natural recharge – from precipitation and percolation• Lateral recharge – from a nearby river or stream

Fig. 13-3, p. 316

Unconfined Aquifer Recharge Area

Precipitation Evaporation and transpiration Evaporation

Confined Recharge Area Runoff

Flowing artesian well

Well requiring a pump Stream

InfiltrationWater table Lake

InfiltrationUnconfined aquiferLess permeable

material such as clay

Confined aquiferConfining impermeable rock layer

Surface Water

Surface Water – Most Important Water Resource• Lakes, Rivers, Streams• Surface runoff – non-evaporated precipitation• Watershed (drainage) basin• A collection area for Surface water

We Use a Large and Growing Portion of the World’s Reliable Runoff

2/3 of the surface runoff:unusable, lost by seasonal floods

1/3 runoff usable • Agriculture: 70% -> FOOOOOD• Industrial use: 20% -> POWER• Domestic: 10% -> HOME

Fred Pearce, author of When the Rivers Run Dry• Takes 450,000 liters or 2,400 bathtubs of water to

produce a car• 140 liters to produce a cup of coffee• 25 bathtubs to produce a T-shirt

Case Study: Freshwater Resources in the United States

More than enough renewable freshwater, unevenly distributed• Eastern states have more rain than western and

southwestern states• The three rainiest cities are:

• Mobile, AL• Pensacola, FL• New Orleans, LA

What are the most serious water problems in the US?• Floods• Pollution• Drought – when precipitation is at least 70% lower and

evaporation is higher than normal.

Average Annual Precipitation and Major Rivers, Water-Deficit Regions in U.S.

Fig. 13-4a, p. 317

Fig. 13-4b, p. 317

Long-Term Severe Drought Is Increasing

Causes• Extended period of below-normal rainfall• Diminished groundwater

Harmful environmental effects• Dries out soils• Reduces stream flows• Decreases tree growth and biomass• Lowers net primary productivity and crop yields• Shift in biomes

In Water-Short Areas Farmers and Cities Compete for Water Resources

2007: National Academy of Science study• Increased corn production in the U.S. to make

ethanol as an alternative fuel• Decreasing water supplies• Aquifer depletion• Increase in pollution of streams and aquifers

Who Should Own and Manage Freshwater Resources? (1)

Most water resources• Owned by governments• Managed as publicly owned resources

Veolia and Suez: French companies• Buy and manage water resources • Successful outcomes in many areas

Who Should Own and Manage Freshwater Resources? (2)

Bechtel Corporation• Poor water management in Bolivia

Potential problems with full privatization of water resources• Financial incentive to sell water; not conserve it• Poor will still be left out