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Water Resources
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Key Concepts The physical properties of water
Availability of fresh water Methods of increasing freshwater supplies Using water more efficiently Problems associated with flooding
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Water’s Unique Properties
Hydrogen bonding Liquid over wide temperature range Changes temperature slowly High heat of evaporation Great dissolving power Filters out ultraviolet radiation Adhesion and cohesion Expands when it freezes
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Hydrogen Bonding in Ice
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Hydrogen Bonding in Water
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Supply of Water Resources
All water Fresh water Readily accessible fresh water Groundwater 0.592% Biota 0.0001% Lakes 0.007% Rivers 0.0001% Lakes 0.007% Fresh water 2.6% 0.014% Oceans and saline lakes 97.4% Ice caps and glaciers 1.984% Oceans and saline lakes 97.4% Soil moisture 0.005% Ice caps and glaciers 1.984% Soil moisture 0.005% Atmospheric water vapor 0.001%
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Supply of Freshwater Resources
Readily accessible freshwater Biota 0.0001% Rivers Atmospheric water vapor Lakes 0.0007% Soil moisture 0.0005% Groundwater 0.592% Ice caps and glaciers 1.984% 0.014%
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Surface Water Surface runoff Watersheds Reliable runoff
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Evaporation and transpiration
Ground Water Evaporation and transpiration Evaporation Stream Infiltration Water table Unconfined aquifer Confined aquifer Lake Well requiring a pump Flowing artesian well Runoff Precipitation Confined Recharge Area Aquifer Less permeable material such as clay Confirming permeable rock layer
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Water Budget
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Use of Water Resources Humans use about 54% of reliable runoff
United States Industry 11% Public 10% Power cooling 38% Agriculture Agriculture Industry Domestic Power plants
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1 automobile 400,000 liters (106,000 gallons) 1 kilogram cotton 10,500 liters (2,400 gallons) 1 kilogram aluminum 9,000 liters (2,800 gallons) 1 kilogram grain-fed beef 7,000 liters (1,900 gallons) 1 kilogram rice 5,000 liters (1,300 gallons) 1 kilogram corn 1,500 liters (400 gallons) 1 kilogram paper 880 liters (230 gallons) 1 kilogram steel 220 liters (60 gallons)
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Too Little Water Dry climate Drought Desiccation Water stress
Acute shortage Adequate supply Shortage Metropolitan regions with population greater than 1 million Water stress
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Average annual precipitation (centimeters)
Less than 41 81-22 41-81 More than 122
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Acute shortage Shortage Adequate supply Metropolitan regions with population greater than 1 million
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Freshwater Stress
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Using Dams and Reservoirs to Supply More Water: The Trade-offs
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
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Pueblo Dam, Colorado
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Silt filled Reservoir behind a Dam
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Wash. N.D. Montana Oregon Idaho S.D. Wyoming Nevada Neb. Utah Colo. Kansas California Oak. N.M. Texas Highly likely conflict potential Substantial conflict potential Moderate conflict potential Unmet rural water needs
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Europe North America Asia Africa South America Australia Stress
High None
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Transferring Water from One Place to Another
Watershed transfer North Bay Aqueduct South Bay California Aqueduct CALIFORNIA NEVADA UTAH MEXICO Central Arizona Project Colorado River Los Angeles Shasta Lake Sacramento Fresno Phoenix Tucson ARIZONA Colorado River San Francisco San Diego California Water Project Central Arizona Project James Bay
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CALIFORNIA NEVADA Shasta Lake UTAH Sacramento River Oroville Dam and Reservoir Feather River Lake Tahoe North Bay Aqueduct Sacramento San Francisco Hoover Dam and Reservoir (Lake Mead) South Bay Aqueduct Fresno Colorado River Los Angeles Aqueduct San Luis Dam and Reservoir ARIZONA California Aqueduct Central Arizona Project Santa Barbara Colorado River Aqueduct Los Angeles Phoenix Salton Sea San Diego Tucson MEXICO
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CANADA II I II UNITED STATES
Hudson Bay Chisasibi NEWFOUNDLAND II James Bay I ONTARIO II QUEBEC New York City ATLANTIC OCEAN Chicago UNITED STATES
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IDAHO WYOMING Dam Aqueduct or canal Salt Lake City Upper Basin
Grand Junction Lower Basin Denver UPPER BASIN UTAH COLORADO Lake Powell Grand Canyon Glen Canyon Dam Las Vegas NEW MEXICO Boulder City ARIZONA CALIFORNIA Albuquerque Los Angeles LOWER BASIN Palm Springs Phoenix 100 mi. San Diego Yuma 150 km Mexicali Tucson All-American Canal Gulf of California MEXICO
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China’s Three Gorges Dam
Trade-Offs China’s Three Gorges Dam Advantages Disadvantages Will generate about 10% of China’s electricity Reduces dependence on coal Reduces air pollution Reduces CO2 emissions Reduces chances of downstream flooding for 15 million people Reduces river sitting below dam by eroded soil Increases irrigation water for cropland below dam Floods large areas of cropland and forests Displaces 1.9 million people Increases water pollution because of reduced water flow Reduces deposits of nutrient- rich sediments below dam Increases saltwater Introduced into drinking water near mouth of river because of decreased water flow Disrupts spawning and migration of some fish below dam High cost
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Tapping Groundwater Year-round use No evaporation losses
Often less expensive Potential Problems!
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Problems with Using Groundwater
Water table lowering Depletion Subsidence Saltwater intrusion Chemical contamination Reduced stream flows
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Water in the Ground (USGS)
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Withdrawing Groundwater
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 Aquifer depletion from over- pumping Sinking of land (subsidence) when water removed Polluted aquifers 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
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Groundwater Overdrafts: High Moderate Minor or none
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Wells
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Major irrigation well Well contaminated with saltwater Water table Sea Level Salt water Fresh groundwater aquifer Interface Interface Saltwater Intrusion Normal Interface
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Eastern US Aquifers Contaminated with Saltwater (USGS)
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Converting Salt Water to Fresh Water and Making it Rain
Distillation desalination Reverse osmosis desalination Desalination is very expensive Cloud seeding
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Distillation desalination
Reverse osmosis desalination
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Using Water More Efficiently
Reduce losses due to leakage Reform water laws Improve irrigation efficiency Improving manufacturing processes Water efficient landscaping (xeriscaping) Water efficient appliances
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Too Much Water: Floods Natural phenomena
Aggravated by human activities Reservoir Dam Levee Flood wall Floodplain
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Stages of Stream Development
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Ansel Adams: Snake River
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Flood Plains
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Groundwater Depletion
Solutions Groundwater Depletion Prevention Control Waste less water Subsidize water conservation Ban new wells in aquifers 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
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WYOMING SOUTH DAKOTA NEBRASKA KANSAS COLORADO OKLAHOMA NEW MEXICO
Less than 61 meters (200 ft) meters ( ft) More than 183 meters (600 ft) (as much as 370 meters or 1,200 ft. in places) NEBRASKA KANSAS COLORADO OKLAHOMA NEW MEXICO TEXAS Miles 100 160 Kilometers
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Solutions: Achieving a More Sustainable Water Future
Efficient irrigation Water-saving technologies Improving water management
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Center Pivot Drip Irrigation Gravity Flow
(efficiency 80% with low-pressure sprinkler and 90–95% with LEPA sprinkler) Water usually pumped from underground and sprayed from mobile boom with sprinklers. Drip Irrigation (efficiency 90-95%) Above- or below-ground pipes or tubes deliver water to individual plant roots. Gravity Flow (efficiency 60% and 80% with surge valves) Water usually comes from an aqueduct system or a nearby river.
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Colorado Center Pivot Irrigation
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Water Conserving Center Pivot Irrigation
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Flood Irrigation
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Furrow Irrigation
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Drip Irrigation
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Reducing Irrigation Water Waste
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 sensors and 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
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Solutions Reducing Water Waste
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 non-edible plants Purify and reuse water for houses, apartments, and office buildings
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Xeriscaping in Arizona
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Forested Hillside Oxygen released by vegetation Diverse ecological
habitat Evapotranspiration Trees reduce soil erosion from heavy rain and wind Agricultural land Steady river flow Leaf litter improves soil fertility Tree roots stabilize soil and aid water flow Vegetation releases water slowly and reduces flooding Forested Hillside
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Evapotranspiration decreases
Tree plantation Evapotranspiration decreases Roads destabilize hillsides Ranching accelerates soil erosion by water and wind Winds remove fragile topsoil Agriculture land is flooded and silted up Gullies and landslides Heavy rain leaches nutrients from soil and erodes topsoil Rapid runoff causes flooding Silt from erosion blocks rivers and reservoirs and causes flooding downstream After Deforestation
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Solutions Sustainable Water Use 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
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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. 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.
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