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Water and Water Pollution
Chapter 11
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Water Conflicts in the Middle East
Water shortages Nile River Jordan Basin Tigris and Euphrates rivers Peacefully solving the problems Fig. 11-1, p. 236
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Water Conflicts in the Middle East
Fig. 11-1, p. 236
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Importance and Availability of Water
Why is water so important? Earth as a watery world Water as a wasted resource Tiny fraction of Earth’ water is fresh Hydrologic cycle Water pollution Water haves and have-nots
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Readily accessible fresh water
Earth’s Water Budget All water Fresh water Readily accessible fresh water Groundwater 0.592% Biota 0.0001% Rivers 0.0001% Lakes 0.007% Fresh water 2.6% 0.014% Oceans and saline lakes 97.4% Atmospheric water vapor 0.001% Ice caps and glaciers 1.984% Soil moisture 0.005% Fig. 11-2, p. 238
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Groundwater Zone of saturation Water table Aquifers Natural recharge
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Evaporation and transpiration
Groundwater Systems Unconfined Aquifer Recharge Area Evaporation and transpiration Precipitation Evaporation Confined Recharge Area Runoff Flowing artesian well Recharge Unconfined Aquifer Stream Well requiring a pump Water table Infiltration Lake Infiltration Unconfined aquifer Less permeable material such as clay Confined aquifer Confining impermeable rock layer Fig. 11-3, p. 239
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Use of Water Resources Runoff use: about 54% Freshwater use
US freshwater resources Domestic, agricultural, and industrial use
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Annual Precipitation and Water-deficit Regions of the Continental US
Fig. 11-4a, p. 240
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Annual Precipitation and Water-deficit Regions of the Continental US
Average annual precipitation (centimeters) Less than 41 81-22 41-81 More than 122 Fig. 11-4a, p. 240
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Annual Precipitation and Water-deficit Regions of the Continental US
Acute shortage Shortage Adequate supply Metropolitan regions with population greater than 1 million Fig. 11-4b, p. 240
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Water Hot Spots in Western States
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 Fig. 11-5, p. 240
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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
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Stress on World’s River Basins
Europe North America Asia Africa South America Australia Stress High None Fig. 11-6, p. 241
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Hydrological Poverty Fig. 11-7, p. 241
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Politics and Ethics of Water
Who should pay for the water? Public or private ownership
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Increasing Freshwater Supplies
Dams and reservoirs Extracting groundwater Desalination Reducing water waste Importing food Importing water Catching precipitation
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Tradeoffs of Large Dams and Reservoirs
Large losses of water through evaporation Flooded land destroys forests or cropland and displaces people Migration and spawning of some fish are disrupted Downstream cropland and estuaries are deprived of nutrient-rich silt Provides water for year-round irrigation of cropland Reservoir is useful for recreation and fishing Can produce cheap electricity (hydropower) Downstream flooding is reduced Fig. 11-8, p. 243
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Ecological Services of Rivers
N a t u r a l C a p i t a l Ecological Services of Rivers • Deliver nutrients to sea to help sustain coastal fisheries • Deposit silt that maintains deltas • Purify water • Renew and renourish wetlands • Provide habitats for wildlife Fig. 11-9, p. 243
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California Water Project and Central Arizona Project
Shasta Lake NEVADA UTAH Oroville Dam and Reservoir Sacramento River Feather River Lake Tahoe North Bay Aqueduct Sacramento San Francisco Hoover Dam and Reservoir (Lake Mead) South Bay Aqueduct Fresno San Joaquin Valley San Luis Dam and Reservoir Colorado River Los Angeles Aqueduct California Aqueduct ARIZONA Colorado River Aqueduct Santa Barbara Central Arizona Project Los Angeles Phoenix Salton Sea San Diego Tucson MEXICO Fig , p. 244
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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
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Shrinking Aral Sea Fig , p. 245
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Stranded Ship at the Aral Sea
Fig , p. 245
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Tradeoffs of 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 Fig , p. 246
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Aquifer Depletion Fig. 11-14, p. 246 Groundwater Overdrafts: High
Moderate Minor or none Fig , p. 246
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Saltwater Intrusion into Coastal Water Wells
Well contaminated with saltwater Major irrigation well Water table Sea Level Saltwater Fresh groundwater aquifer Seafloor Interface Saltwater Intrusion Interface Normal Interface Fig , p. 247
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Groundwater Depletion
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 Fig , p. 247
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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
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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
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Major Types of Irrigation Systems
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. 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. Fig , p. 249
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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 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 Fig , p. 250
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Reducing Water Waste Fig. 11-19, p. 250 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 nonedible plants Purify and reuse water for houses, apartments, and office buildings Fig , p. 250
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Using Water More Sustainably
Blue revolution Cut waste Raise water prices Drier waste treatment Preserve forests Slow population growth
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Sustainable Water Use Solutions Fig. 11-20, p. 251
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 Fig , p. 251
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What Can We Do? What Can You Do? Fig. 11-21, p. 251
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. Fig , p. 251
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Benefits of Floodplains
Highly productive wetlands Provide natural flood and erosion control Maintain high water quality Recharge groundwater Fertile soils Nearby rivers for use and recreation Flatlands for urbanization and farming
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Dangers of Floodplains and Floods
Deadly and destructive Human activities worsen floods Failing dams and water diversion Bangladesh
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Before and During a Flood in St. Louis, Missouri
Fig , p. 252
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Flooding After Deforestation of a Hillside
Forested Hillside Oxygen released by vegetation Diverse ecological habitat Evapotranspiration Trees reduce soil erosion from heavy rain and wind Agricultural land Steady river flow Vegetation releases water slowly and reduces flooding Leaf litter improves soil fertility Tree roots stabilize soil and aid water flow Fig a, p. 253
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Flooding After Deforestation of a Hillside
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 Fig b, p. 253
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Table 11-1, p. 254
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Reducing Flood Risks Channelization Levees (floodwalls) Dams
Protect and restore wetlands Identify and manage flood-prone areas Precautionary approach
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Water Pollution: Types, Effects, and Sources
What is water pollution? Major types of pollutants, sources and effects (Table 11-1, p. 254) Point and nonpoint sources Is the water safe to drink?
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Polluted Streams Factors influencing stream recovery from pollution
Oxygen sag curve Importance of wastewater treatment plants Improvements in quality of US streams Cuyahoga River of Ohio Effect of regulations in US Pressures from US citizen groups Problems with nonpoint, accidental and illegal releases Problems in developing countries
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Pollution in Streams Fig. 11-24, p. 256 Normal clean water organisms
(trout, perch, bass, mayfly, stonefly) Trash fish (carp, gar, leeches) Fish absent, fungi, sludge worms, bacteria (anaerobic) Trash fish (carp, gar, leeches) Normal clean water organisms (trout, perch, bass, mayfly, stonefly) 8 ppm Types of organisms 8 ppm Dissolved oxygen (ppm) Biological oxygen demand Clean Zone Recovery Zone Septic Zone Decomposition Zone Clean Zone Fig , p. 256
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Lake Pollution Dilution less effective than with streams
Stratification in lakes and relatively little flow hinder rapid dilution of pollutants Lakes more vulnerable to pollutants than streams How pollutants enter lakes Eutrophication: causes and effects Oligotrophic and eutrophic lakes Cultural eutrophication Preventing or removing eutrophication
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Oligotrophic and Eutrophic Lakes
Fig , p. 257
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Groundwater Pollution: Causes and Persistence
Sources of groundwater pollution Slow flowing: slow dilution and dispersion Consequences of lower dissolved oxygen Fewer bacteria to decompose wastes Cooler temperatures: slow down chemical reactions “Degradable” and nondegradable wastes in groundwater
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Groundwater Pollution
Polluted air Hazardous waste injection well Pesticides and fertilizers De-icing road salt Coal strip mine runoff Buried gasoline and solvent tank Pumping well Gasoline station Water pumping well Cesspool septic tank Waste lagoon Sewer Landfill Leakage from faulty casing Accidental spills Discharge Unconfined freshwater aquifer Confined aquifer Confined freshwater aquifer Groundwater flow Fig , p. 258
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Extent of Groundwater Pollution
Not much is known about groundwater pollution Organic contaminants, including fuel leaks Arsenic Protecting groundwater: Prevention is best
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Preventing and Cleaning Up Pollution in Groundwater
Solutions Groundwater Pollution Prevention Cleanup Find substitutes for toxic chemicals Pump to surface, clean, and return to aquifer (very expensive) Keep toxic chemicals out of the environment Install monitoring wells near landfills and underground tanks Inject microorganisms to clean up contamination (less expensive but still costly) Require leak detectors on underground tanks Ban hazardous waste disposal in landfills and injection wells Pump nanoparticles of inorganic compounds to remove pollutants (may be the cheapest, easiest, and most effective method but is still being developed) Store harmful liquids in aboveground tanks with leak detection and collection systems Fig , p. 259
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Ocean Pollution How much pollution can oceans tolerate?
Some pollutants degrade and dilute in oceans Ocean dumping controversies
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Coastal Water Pollution
Industry Nitrogen oxides from autos and smokestacks; toxic chemicals, and heavy metals in effluents flow into bays and estuaries. Cities Toxic metals and oil from streets and parking lots pollute waters; sewage adds nitrogen and phosphorus. Urban sprawl Bacteria and viruses from sewers and septic tanks contaminate shellfish beds and close beaches; runoff of fertilization from lawns adds nitrogen and phosphorus. Construction sites Sediments are washed into waterways, choking fish and plants, clouding waters, and blocking sunlight. Farms Run off of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus. Red tides Excess nitrogen causes explosive growth of toxic microscopic algae, poisoning fish and marine mammals. Closed shellfish beds Closed beach Oxygen-depleted zone Toxic sediments Chemicals and toxic metals contaminate shellfish beds, kill spawning fish, and accumulate in the tissues of bottom feeders. Healthy zone Clear, oxygen-rich waters promote growth of plankton and sea grasses, and support fish. Oxygen-depleted zone Sedimentation and algae overgrowth reduce sunlight, kill beneficial sea grasses, use up oxygen, and degrade habitat. Fig , p. 260
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Oxygen-depleted Water in the Gulf of Mexico
Mississippi River Basin Ohio River Mississippi River Missouri River LOUISIANA Mississippi River Depleted Oxygen Gulf of Mexico Fig , p. 261
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Chesapeake Bay Largest US estuary Pollution “sink” Oxygen depletion
Chesapeake Bay Program Fig , p. 261
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Chesapeake Bay Fig. 11-30, p. 261 PENNSYLVANIA ATLANTIC OCEAN MARYLAND
NEW YORK Cooperstown PENNSYLVANIA ATLANTIC OCEAN Harrisburg NEW JERSEY MARYLAND WEST VIRGINIA Baltimore Washington DELAWARE Richmond VIRGINIA Chesapeake Bay Norfolk Drainage basin Low concentrations of oxygen No oxygen Fig , p. 261
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Effects of Oil on Ocean Life
Crude and refined petroleum Tanker accidents and blowouts Exxon Valdez Volatile hydrocarbons kill larvae Tar-like globs coat birds and marine mammals Oil destroys insulation and buoyancy Heavy oil sinks and kills bottom organisms Coral reefs die Slow recovery Oil slicks ruin beaches Limited effectiveness of clean up methods
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Preventing and Cleaning Up Pollution in Coastal Waters
Solutions Coastal Water Pollution Prevention Cleanup Reduce input of toxic pollutants Improve oil-spill cleanup capabilities Separate sewage and storm lines Ban dumping of wastes and sewage by maritime and cruise ships in coastal waters Sprinkle nanoparticles over an oil or sewage spill to dissolve the oil or sewage without creating harmful byproducts (still under development) Ban ocean dumping of sludge and hazardous dredged material Protect sensitive areas from development, oil drilling, and oil shipping Require at least secondary treatment of coastal sewage Regulate coastal development Use wetlands, solar-aquatic, or other methods to treat sewage Recycle used oil Require double hulls for oil tankers Fig , p. 263
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Preventing Nonpoint Source Pollution
Mostly agricultural wastes Use vegetation to reduce soil erosion Reduce fertilizer use Use plant buffer zones around fields Integrated pest management: Only use pesticides when necessary Use plant buffers around animal feedlots Keep feedlots away from slopes, surface water and flood zones
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Laws for Reducing Point Source Pollution
Clean Water Act Water Quality Act
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Sewage Treatment Systems
Sewage treatment in rural and suburban areas Septic tanks Primary (physical) sewage treatment Secondary (biological) sewage treatment Urban sewage treatment (Clean Water Act) Sewage treatment facilities in many cities fail to meet federal standards Bleaching and disinfection Disinfectants: chlorine, ozone, and ultraviolet radiation
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Typical Septic Tank System
Septic tank with manhole (for cleanout) Household wastewater Nonperforated pipe Distribution box (optional) Gravel or crushed stone Drain field Vent pipe Perforated pipe Fig , p. 264
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Primary and Secondary Sewage Treatment
Chlorine disinfection tank Bar screen Grit chamber Settling tank Aeration tank Settling tank To river, lake, or ocean Sludge Activated sludge (kills bacteria) Raw sewage from sewers Air pump Sludge digester Disposed of in landfill or ocean or applied to cropland, pasture, or rangeland Sludge drying bed Fig , p. 265
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Improving Sewage Treatment
Systems that exclude hazardous wastes Non-hazardous substitutes Composting toilet systems Working with nature to treat sewage Using wetlands to treat sewage
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Ecological Wastewater Treatment
Fig , p. 265
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Should the Clean Water Act be Strengthened?
Yes: environmentalists No: farmers, libertarians, manufacturers, and developers State and local officials want more discretion
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Drinking Water Quality
Purification of urban drinking water Purification of drinking water in developing countries Bottled water
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Reducing Water Pollution
Solutions Water Pollution Prevent groundwater contamination Greatly reduce nonpoint runoff Reuse treated wastewater for irrigation Find substitutes for toxic pollutants Work with nature to treat sewage Practice four R's of resource use (refuse, reduce, recycle, reuse) Reduce resource waste Reduce air pollution Reduce poverty Reduce birth rates Fig , p. 267
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What Can We Do? What Can You Do? Water Pollution Fig. 11-36, p. 268
Fertilize your garden and yard plants with manure or compost instead of commercial inorganic fertilizer. Minimize your use of pesticides. Never apply fertilizer or pesticides near a body of water. Grow or buy organic foods. Compost your food wastes. Do not use water fresheners in toilets. Do not flush unwanted medicines down the toilet. Do not pour pesticides, paints, solvents, oil, antifreeze, or other products containing harmful chemicals down the drain or onto the ground. Fig , p. 268
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