Chapter 13 Water Resources

Supply of Water Resources Freshwater Readily accessible freshwater Biota % Biota % Rivers % Rivers % Atmospheric water vapor % Atmospheric water vapor % Lakes % Soil moisture % Groundwater 0.592% Groundwater 0.592% Ice caps and glaciers 1.984% 0.014%

Core Case Study: Water Conflicts in the Middle East - A Preview of the Future Many countries in the Middle East, which has one of the world’s highest population growth rates, face water shortages. Figure 14-1

Water Conflicts in the Middle East: A Preview of the Future Countries are in disagreement as to who has water rights. Currently, there are no cooperative agreements for use of 158 of the world’s 263 water basins that are shared by two or more countries.

Soil Properties  Infiltration  Porosity/permeability  Texture  Soil type here?  Texture  Soil type here? Water High permeabilityLow permeability Clay, granite Sand, gravel

Fig. 13-3, Unconfined Aquifer Recharge Area Precipitation Evaporation and transpirationEvaporation Confined Recharge Area Runoff Flowing artesian well Recharge Unconfined Aquifer Stream Well requiring a pump Infiltration Water table Lake Infiltration Unconfined aquifer Confined aquifer Confining impermeable rock layer Less permeable material such as clay Groundwater Zone of aeration Zone of saturation

Tapping Groundwater  Year-round use  No evaporation losses  Often less expensive

Other Effects of Groundwater Overpumping- Sea water intrusion Groundwater overpumping can cause land to sink, and contaminate freshwater aquifers near coastal areas with saltwater.

Other Effects of Groundwater Overpumping-subsidence Sinkholes Chemical contamination.

Use of Water Resources United States Industry 11% Public 10% Power cooling 38% Agriculture 41%

Case Study: The California Experience A massive transfer of water from water-rich northern California to water-poor southern California is controversial. Water rights –Prior appropriation –riparian Figure 13-17

Converting Salt Water to Fresh Water and Making it Rain  Distillation desalination  Reverse osmosis desalination  Desalination is very expensive  Cloud seeding

Fig Provides water for year-round irrigation of cropland Flooded land destroys forests or cropland and displaces people Large losses of water through evaporation Provides water for drinking Downstream cropland and estuaries are deprived of nutrient-rich silt Reservoir is useful for recreation and fishing Risk of failure and devastating downstream flooding Can produce cheap electricity (hydropower) Downstream flooding is reduced Migration and spawning of some fish are disrupted

Case Study: China’s Three Gorges Dam There is a debate –The electric output –It will facilitate ship travel reducing transportation costs. –Dam will displace 1.2 million people. –Dam is built over seismatic fault and already has small cracks.

Dam Removal Some dams are being removed for ecological reasons and because they have outlived their usefulness. –The Federal Energy Regulatory Commission has approved the removal of nearly 500 dams. –Removing dams can reestablish ecosystems, but can also re-release toxicants into the environment.

Using Water More Efficiently  Reduce losses due to leakage  Reform water laws  Improve irrigation efficiency  Improving manufacturing processes  Water efficient landscaping  Water efficient appliances

INCREASING WATER SUPPLIES BY WASTING LESS WATER Sixty percent of the world’s irrigation water Center-pivot, low pressure sprinklers sprays water directly onto crop. –It allows 80% of water to reach crop.

Fig Center pivot Drip irrigation Gravity flow (efficiency 60% and 80% with surge valves) Above- or below-ground pipes or tubes deliver water to individual plant roots. Water usually comes from an aqueduct system or a nearby river. (efficiency 90–95%) (efficiency 80%–95%) Water usually pumped from underground and sprayed from mobile boom with sprinklers.

Solutions: Getting More Water for Irrigation in Developing Countries – The Low-Tech Approach low-tech methods to pump groundwater Arsenic in India

Raising the Price of Water: A Key to Water Conservation We can reduce water use and waste by raising the price of water while providing low lifeline rates for the poor. –When Boulder, Colorado introduced water meters, water use per person dropped by 40%.

What Can You Do? Water Use and Waste Use water-saving toilets, showerheads, and faucet aerators. Shower instead of taking baths, and take short showers. Stop water leaks. Turn off sink faucets while brushing teeth, shaving, or washing. Flush toilets only when necessary. Wash only full loads of clothes or use the lowest water-level for smaller loads. Use recycled (gray) water for lawn, gardens, house plants, car washing. Wash a car from a bucket of soapy water, and use the hose for rinsing only. If you use a commercial car wash, try to find one that recycles its water. Replace your lawn with native plants that need little if any watering and decorative gravel or rocks. Water lawns and gardens in the early morning or evening. Sweep or blow off driveways instead of hosing off with water. Use drip irrigation and mulch for gardens and flowerbeds.

Too Much Water: Floods  Natural phenomena Floodplain Levee Flood wall Dam Reservoir  Renew and replenish  Aggravated by human activities Flood zone

TOO MUCH WATER Comparison of St. Louis, Missouri under normal conditions (1988) and after severe flooding (1993).

Water Conservation The average American uses 90 gallons of water each day. European-53 and Sub-Saharan Africa-5 Fix leaks, replace old toilets (trade ins), efficient washers (50% less water and energy). A switch to water efficient appliances family of 4- save 23,000 gallons a year. End chapter 13