Water and Water Pollution

All waterFresh waterReadily accessible fresh water Oceans and saline lakes 97.4% Fresh water 2.6% Groundwater 0.592% Ice caps and glaciers 1.984% Soil moisture 0.005% Biota % Rivers % Atmospheric water vapor 0.001% 0.014% Lakes 0.007% Earth’s Water Budget

Evaporation and transpiration Evaporation Stream Infiltration Water table Infiltration Unconfined aquifer Confined aquifer Lake Well requiring a pump Flowing artesian well Runoff Precipitation Confined Recharge Area Recharge Unconfined Aquifer Less permeable material such as clay Confining im permeable rock layer Unconfined Aquifer Recharge Area Hydrologic Cycle

Groundwater

Use of Water Resources Runoff use: about 54% Freshwater use US freshwater resources Domestic, agricultural, and industrial use

Annual Precipitation and Water-deficit Regions of the Continental US

Highly likely conflict potential Substantial conflict potential Moderate conflict potential Unmet rural water needs Wash. Oregon Idaho Nevada California Utah Montana Wyoming Colo. N.M. N.D. S.D. Neb. Kansas Oak. Texas Water Hot Spots in Western States

Freshwater Shortages Causes of water scarcity: dry climate and too many people Stresses on world’s major river systems 1 of 6 people have no regular access to clean water Poverty hinders access to water Hydrological poverty

HighNone Stress Stress on World’s River Basins North America Europe Asia Australia Africa South America

Politics and Ethics of Water Who should pay for the water? Public or private ownership

Increasing Freshwater Supplies Dams and reservoirs Extracting groundwater Desalination Reducing water waste Importing food Importing water Catching precipitation

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

Deliver nutrients to sea to help sustain coastal fisheries Deposit silt that maintains deltas Purify water Renew and renourish wetlands Provide habitats for wildlife N a t u r a l C a p i t a l Ecological Services of Rivers

North Bay Aqueduct South Bay Aqueduct California Aqueduct CALIFORNIA NEVADA UTAH MEXICO Central Arizona Project Colorado River Aqueduct Los Angeles Aqueduct Shasta Lake Oroville Dam and Reservoir Feather River Lake Tahoe Sacramento Fresno Hoover Dam and Reservoir (Lake Mead) Salton Sea Phoenix Tucson ARIZONA Colorado River Sacramento River San Francisco San Luis Dam and Reservoir Santa Barbara Los Angeles San Diego California Water Project and Central Arizona Project San Joaquin Valley

Aral Sea Disaster Large-scale water transfers in dry central Asia Salinity Wetland destruction and wildlife Fish extinctions and fishing Wind-blown salt Water pollution Climatic changes Restoration efforts

Shrinking Aral Sea

Trade-Offs Withdrawing Groundwater Advantages Disadvantages Good source of water for drinking and irrigation Available year-round Exists almost everywhere Renewable if not over- pumped or contaminated No evaporation losses Cheaper to extract than most surface waters Aquifier depletion from over- pumping Sinking of land (subsidence) when water removed Polluted aquifiers unusable for decades or centuries Saltwater intrusion into drinking water supplies near coastal areas Reduced water flows into streams, lakes, estuaries, and wetlands Increased cost, energy use, and contamination from deeper wells Tradeoffs of Withdrawing Groundwater

Groundwater Overdrafts: High Moderate Minor or none Aquifer Depletion

Major irrigation well Well contaminated with saltwater Saltwater Intrusion Normal Interface Fresh groundwater aquifer Interface Saltwater Sea Level Water table Seafloor Saltwater Intrusion into Coastal Water Wells Interface

Solutions Groundwater Depletion Prevention Control Waste less water Subsidize water conservation Ban new wells in aquifiers near surface waters Buy and retire ground- water withdrawal rights in critical areas Do not grow water- intensive crops in dry areas Reduce birth rates Raise price of water to discourage waste Tax water pumped from Wells near surface water Set and enforce minimum stream flow levels Groundwater Depletion

Desalination Removal of salts from ocean or brackish waters to produce useable water Distillation method Reverse osmosis method Used in 120 countries Major problems: high cost and a lot of brine wastes Research is needed

Reducing Water Waste Benefits of water conservation Reduce leakage and save water Water prices, government subsidies, and waste Improve irrigation Using less water in homes and businesses

Gravity Flow (efficiency 60% and 80% with surge valves) Water usually comes from an aqueduct system or a nearby river. Drip Irrigation (efficiency 90-95%) Above- or below-ground pipes or tubes deliver water to individual plant roots. Center Pivot (efficiency 80% with low-pressure sprinkler and 90–95% with LEPA sprinkler) Water usually pumped from underground and sprayed from mobile boom with sprinklers. Major Types of Irrigation Systems

Solutions Reducing Irrigation Water Waste Lining canals bring water to irrigation ditches Leveling fields with lasers Irrigating at night to reduce evaporation Using soil and satellite sensorsand computer systems to monitor soil moisture and add water only when necessary Polyculture Organic Farming Growing water-efficient crops using drought- resistant and salt tolerant crops varieties Irrigating with treated urban waste water Importing water-intensive crops and meat Reducing Irrigation Water Waste

Using Water More Sustainably Not depleting aquifers Preserving ecological health of aquatic systems Preserving water quality Integrated watershed management Agreements among regions and countries sharing surface water resources Outside party mediation of water disputes between nations Marketing of water rights Raising water prices Wasting less water Decreasing government subsides for supplying water Increasing government subsides for reducing water waste Slowing population growth Solutions Sustainable Water Use

Fig , p. 251 Use water-saving toilets, showerheads, and faucet aerators Shower instead of taking baths, and take short showers. Repair water leaks. Turn off sink faucets while brushing teeth, shaving, or washing. Wash only full loads of clothes or use the lowest possible water-level setting for smaller loads. 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. Water lawns and garden in the early morning or evening. Use drip irrigation and mulch for gardens and flowerbeds. Use recycled (gray) water for watering lawns and houseplants and for washing cars. What Can You Do? Water Use and Waste What Can We Do? Reducing Water Waste Solutions Redesign manufacturing processes Landscape yards with plants that require little water Use drip irrigation Fix water leaks Use water meters and charge for all municipal water use Use waterless composting toilets Require water conservation in water-short cities Use water-saving toilets, showerheads, and front-loading clothes washers Collect and reuse household water to irrigate lawns and nonedible plants Purify and reuse water for houses, apartments, and office buildings