Transcript Chapter 13
Chapter 13 Water Conflicts in the Middle East: Water shortages in the Middle East: hydrological poverty Nile River – flows through 7 countries for irrigation and drinking water. Ethiopia, Sudan, Egypt. Jordan Basin – most water short, Tigris and Euphrates Rivers – Turkey Conflicts will increase among nations that share water resources Three Major River Basins in the Middle East Freshwater Is an Irreplaceable Resource Covers 71% of the earth’s surface Water sculpts the earth’s surface Moderates climate Removes, dilutes pollutants and wastes -------------------------------------------------------------- Poorly managed resource waste and pollute charge too little to make it available Water is an irreplaceable resource Global health issue : lack of safe drinking water and sanitation is the world’s single largest cause of illness 2007 – WHO – 1.6 million – 90% of them under 5 die from waterborne diseases – diarrhea, typhoid, hepatitis Economic Issue : vital for reducing poverty Developing countries – women and children’s issue National and global security issue : increasing tensions within and between nations over shared resources Environmental issue : excessive withdrawal of water from rivers and aquifers lowers water tables, lower river flows, shrinking lakes, reduce fish populations, species extinction, degradation of ecosystem services. Girl Carrying Well Water over Dried Out Earth during a Severe Drought Most of the Earth’s Freshwater Is Not Available to Us About 0.024% available as liquid water in groundwater deposits, lakes, rivers, and streams Rest in salty oceans, frozen in polar ice caps and glaciers, deep underground Hydrologic cycle Movement of water in the seas, land, and air Driven by solar energy and gravity People divided into Water haves Water have-nots We Get Freshwater from Groundwater and Surface Water Ground water – precipitation filters downwards through spaces in soil, gravel and rock until a layer of rock stops it Zone of saturation – spaces in soil and rock close to the earth’s surface are completely filled with water Water table – top of the ground water zone, falls in dry weather or when ground water removed too fast Aquifers – underground caverns and porous layers of sand, gravel or bedrock through which ground water flows, large elongated sponges, moves 1 meter/year Natural recharge –downward percolation through soil and rock Lateral recharge – from nearby rivers and streams We Get Freshwater from Groundwater and Surface Water Surface Water – freshwater from precipitation and snow melt flows across land surface into rivers, streams, lakes, wetlands Surface runoff - precipitation does not infiltrate into the ground or returns to atmosphere by evaporation Watershed (drainage) basin – land from which surface water drains into a specific body of water Reliable runoff – amount of surface run off that we can count on as a source of fresh water from year to year 1/3 of total Groundwater Unconfined and Confined Aquifer Unconfined Aquifer Recharge Area Evaporation and transpiration Evaporation Precipitation Confined Recharge Area Runoff Flowing artesian well Infiltration Water table Well requiring a pump Stream Lake Infiltration Less permeable material such as clay Fig. 13-3, p. 316 Large and Growing Portion of the World’s Reliable Runoff Used 2/3 of the surface runoff: lost by seasonal floods 1/3 runoff usable – 34% withdrawn now, 70% by 2025 to support increased population growth Domestic: 10% Agriculture: 70% Industrial use: 20% Fred Pearce – When Rivers Run Dry 450,000 liters(120 000 gallons) : produce small car 140 liters (37 gallons) : produce a cup of coffee 25 bath tubs full of water to produce ONE T-shirt Freshwater Resources in the US More than enough renewable freshwater, unevenly distributed Contaminated by agriculture, industry Effect of Floods Pollution Drought 2007: U.S. Geological Survey projection Water hotspots Water Hotspots in 17 Western U.S. States Fig. 13-4a, p. 317 water deficit regions Fig. 13-4b, p. 317 Water Shortages Will Grow…….. Dry climate Drought Too many people using a normal supply of water More than 30 countries in the Middle East and Africa Stress on the World’s Major River Basins Water Shortages Will Grow………. Wasteful use of water China and urbanization: 2/3rd of the country face water shortages Hydrological poverty- 1.1 billion people Stress on the World’s Major River Basins Long-Term Severe Drought Is Increasing Causes Extended period of below-normal rainfall Diminished groundwater due to falling water tables, climate change, severe drought Harmful environmental effects Dries out soils Reduces stream flows Decreases tree growth and biomass Lowers net primary productivity and crop yields Shift in biomes toward relatively dry conditions such savannas and deserts 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 Other crops – soybeans, oil palms, sugar cane Managing Freshwater Resources……. Most water resources Owned by governments Managed as publicly owned resources Veolia and Suez: French companies – water scarcity ,world’s most urgent environmental problem Buy and manage water resources – lucrative Veolia – water for 108 million in 57 countries Successful outcomes in many areas Managing Freshwater Resources……. Bechtel Corporation Poor water management in Bolivia -2002 A subsidiary of Bechtel Corporation - 2007 Poor water management in Ecuador Potential problems with full privatization of water resources Financial incentive to sell water; not conserve it Poor will still be left out Is Extracting Groundwater the Answer ? Groundwater that is used to supply cities and grow food is being pumped from aquifers in some areas faster than it is renewed by precipitation. Aquifers provide – drinking water, 37% of irrigation water Water Tables Fall When Groundwater Is Withdrawn Faster Than It Is Replenished India, China, and the United States Three largest grain producers Over pumping aquifers for irrigation of crops half a billion people India and China Small farmers drilling tube wells Effect on water table – falls Increasing demands for electricity-coal fired plants Saudi Arabia 70% of it’s drinking water at a high cost-salinization Deep Aquifer depletion and irrigation ( estimated to disappear within 1 to 2 decades) Irrigation in Saudi Arabia Using an Aquifer TRADE-OFFS Withdrawing Groundwater Advantages Disadvantages Useful for drinking and irrigation Aquifer depletion from overpumping Available year-round Sinking of land (subsidence) from overpumping Exists almost everywhere Renewable if not overpumped or contaminated No evaporation losses Cheaper to extract than most surface waters Aquifers polluted for decades or centuries Saltwater intrusion into drinking water supplies near coastal areas Reduced water flows into surface waters Increased cost and contamination from deeper wells Fig. 13-7, p. 321 Areas of Greatest Aquifer Depletion in the U.S. Aquifer Depletion in the United States Ogallala aquifer: largest known aquifer- lies under 8 mid western states from South Dakota to Texas Irrigates the Great Plains Water table lowered more than 30m Cost of high pumping makes it too expensive to irrigate in certain areas. Amount of farmland decreased by 11% Government subsidies to continue farming deplete the aquifer further by encouraging the growth of water thirsty crops Biodiversity threatened in some areas California Central Valley: serious water depletion WYOMING Ogallala World’s Largest Known Aquifer SOUTH DAKOTA NEBRASKA COLORADO KANSAS NEW MEXICO OKLAHOMA TEXAS Miles 0 100 160 0 Kilometers Saturated thickness of Ogallala Aquifer Less than 61 meters (200 ft.) 61–183 meters (200–600 ft.) More than 183 meters (600 ft.) (as much as 370 meters or 1,200 ft. in places) Fig. 13-10, p. 323 Groundwater Over pumping Has Other Harmful Effects Limits future food production Bigger gap between the rich and the poor – expensive to dig deeper wells, buy large pumps and use more electricity to drive the pumps. Poor farmers cannot afford to do this, give up farming and migrate to cities Land subsidence – with drawing large amounts of water causes the sand and rocks in aquifers to collapse Mexico City – sunk 10 meters, Beijing, Bangkok US – San Joaquin Valley, Baton Rouge, Phoenix Sinkholes – large craters that form when the roof of an underground cavern collapses when groundwater drained. Can appear suddenly SOLUTIONS Groundwater Depletion Prevention Control Waste less water Raise price of water to discourage waste Subsidize water conservation Tax water pumped from wells near surface waters Limit number of wells Set and enforce minimum stream flow levels Do not grow waterintensive crops in dry areas Divert surface water in wet years to recharge aquifers Fig. 13-11, p. 324 Harmful Effects of Groundwater Over pumping Groundwater overdrafts near coastal regions Salt Water Intrusion - Contamination of the groundwater with saltwater Undrinkable and unusable for irrigation Serious – coastal areas of Florida, California, South Carolina, Georgia, New Jersey , Texas Turkey, Manila, Philippines, Bangkok Rising sea levels from global warming will increase salt water intrusion and decrease the amount of ground water available Are Deep Aquifers the Answer? Locate the deep aquifers; determine if they contain freshwater or saline water. Drill a bore hole and measure the electrical resistance of layers of geological material at different depths. Freshwater aquifers has higher electrical resistance than saline Measurements of the natural radioactive emissions of gamma rays locates aquifers Major concerns Geological and ecological impact of pumping water from them Flow beneath more than one country Who has rights to it? Role of Large Dams and Reservoirs …….. Main goals of a dam and reservoir system Capture and store runoff Release runoff as needed to control: Floods Generate electricity Supply irrigation water Recreation (reservoirs) Advantages and Disadvantages of large dams and reservoirs Disadvantages 1.Displaces people 40-80 million people 2.Flooded regions 3.Impaired ecological services of rivers 4.Loss of plant and animal species 5.Fill up with sediment within 50 years Advantages 1.Increase available reliable run off 2. Reduce flooding 3. Grow crops in arid regions 4. Produce energy 800,000 dams world wide 45,000 large dams 22,000 in China The Ataturk Dam Project in Eastern Turkey on the River Euphrates 1976 1999 Some Rivers Are Running Dry and Some Lakes Are Shrinking Dams disrupt the hydrologic cycle reduce downtown flow to a trickle prevent river water from reaching the sea only 21 of the 177 rivers run freely to sea from source Major rivers running dry part of the year Colorado and Rio Grande, U.S. Yangtze and Yellow, China Indus, India Danube, Europe Nile River-Lake Victoria, Egypt Lake Chad, Africa: disappearing shrunk 96% since 1960 The Colorado River Basin— An Over tapped Resource 2,300 km through 7 U.S. states From snow melt in the Rocky Mountains 14 Dams and reservoirs Located in a desert area within the rain shadow of the Rocky Mountains The Colorado River Basin— An Over tapped Resource Supplies water and electricity for more than 25 million people Las Vegas ,San Diego, LA, California’s Imperial Valley Irrigation 15% of the nation’s crops and livestock Recreation The Colorado River Basin— An Over tapped Resource Four Major problems Colorado River basin has very dry lands Modest flow of water for its size Legal pacts allocated more water for human use than it can supply Amount of water flowing to the mouth of the river has dropped Aerial View of Glen Canyon Dam Across the Colorado River and Lake Powell Economic and ecological catastrophe Political and legal battle over who will get how much of the region’s diminished water supply Agricultural production would drop sharply China’s Three Gorges Dam World’s largest hydroelectric dam, built across the Yangtze 2 km long, built at a cost of $25 billion Produce enough power for 22 large coal-burning power plants. Reduce China’s dependence on coal and cut down greenhouse gas emissions Hold back the flood waters of the Yangtze which have killed more than 500,000 in the past 100 years Large cargo carrying ships to travel into China’s interior 600 km reservoir behind the dam China’s Three Gorges Dam Harmful effects Displaces about 5.4 million people Built over a seismic fault Significance? Rotting plant and animal matter producing CH4 Worse than CO2 emissions Will the Yangtze River become a sewer? Is Transferring Water from One Place to Another the Answer? Water transferred by Tunnels Aqueducts Underground pipes California Water Project from water rich North to south contention over water rights The Aral Sea Disaster Large-scale water transfers in dry central Asia 1960 on water diverted to 2 feeder rivers to create one of the world’s largest irrigation areas- cotton, rice Salinity risen 7 fold, average water dropped by 22 meters Lost 89% of water volume Wetland destruction (85%), wildlife(50%) gone Fish extinctions and fishing – 28 of 32 species gone The Aral Sea Disaster Wind-blown salt – up to 500 km away Aral sea dust settling on glaciers in the Himalayas, causing them to melt at faster rate Water pollution – salt spreads, kills fish Climatic changes – no thermal buffer, because sea has shrunk Restoration efforts Ship Stranded in Desert Formed by Shrinkage of the Aral Sea China Plans a Massive Transfer of Water South-North Water Transfer Project Water from three rivers to supply 0.5 billion people Completion in about 2050 Impact Economic Health Environmental Is Converting Salty Seawater to Freshwater the Answer? Desalination involves removing dissolved salts from ocean water/brackish water Converting salty ocean water to freshwater The cost is high, and the resulting salty brine must be disposed of without harming aquatic or terrestrial ecosystems. Removing Salt from Seawater Promising but Costly Desalination Distillation : heating saltwater until it evaporates, leaving behind salts in solid form and condenses as fresh water Reverse osmosis, microfiltration : high pressure forces salt water through a membrane filter with pores small enough to remove the salt 15,000 plants in 125 countries Saudi Arabia: highest number Removing Salt from Seawater Promising but Costly Problems High cost and energy footprint – desalination requires ten times more energy than reverse osmosis Pumping large volumes of sea water through pipes and using chemicals to sterilize the water keeps down algal growth and kills many marine organisms Large quantity of brine wastes that contain lots of salts and other minerals Dumping this brine into nearby coastal waters increases salinity -threatens aquatic life. Disposing on land – contaminates ground and surface water Future economics – water short, wealthy countries Improved Desalination Technology Desalination on offshore ships Solar or wind energy to desalinate water cheaply Energetech,H2AU (Australia) – energy from ocean waves drive reverse osmosis 2005 – GE developing technology Better membranes – more efficient separation , less pressure, less energy Develop molecular size nanofilters Better disposal options for the brine waste Reduce water needs, conserve water Use Water More Sustainably 65-70% water people use wasted through evaporation , leaks Main reason for water waste – low cost to users, government subsidies False message that water is abundant Use water more sustainably by cutting water waste to 15%, raising water prices, slowing population growth, and protecting aquifers, forests, and other ecosystems that store and release water. Life line rates – South Africa Lack of government subsidies Cut water waste in irrigation ……………. Flood irrigation method delivers far more water than is needed for crop growth and typically loses 40% of the water through evaporation, seepage, and run off. This wasteful method is used on 97% of China’s irrigated land More efficient and environmentally sound irrigation technologies can greatly reduce water waste on farms Irrigation Systems Flood irrigation Wasteful Center pivot, low pressure sprinkler Low-energy, precision application sprinklers Drip or trickle irrigation, micro irrigation Costly; less water waste Developing Countries Use Low-Tech Methods for Irrigation Human-powered treadle pumps to pump groundwater through irrigation ditches in Bangladesh Harvest and store rainwater – running pipes from roof tops, digging channels to catch rain water and stored – India Polyculture and agroforesstry to create a canopy over crops: reduces evaporation Plant deep rooted perennial crop varieties , control weeds, and mulch fields Fog-catcher nets developed in Chile are used to harvest water Cut Water Waste in Industry and Homes Recycle water in industry – 90% of water used by industry Raise water prices Fix leaks in the plumbing systems – stop 10-30% loss Use low flush toilets , low flow shower heads Use water-thrifty landscaping: xeriscaping Use gray water –irrigate lawns, non-edible plants Singapore – all sewage water is treated at reclamation plants for reuse by industry Pay-as-you-go water use Use Less Water to Remove Wastes…… Can we mimic how nature deals with waste? Return the nutrient rich sludge produced by conventional waste treatment plants to the soil as fertilizer, instead of dumping the plant nutrients extracted from waste water treatment plants into water systems Banning the discharge of industrial toxic chemicals into sewage treatment plants would help to make this feasible Waterless composting toilets that convert human fecal matter to a small amount of dry and odorless soil-like humus material that can be removed from a composting chamber every year or so Use Water More Sustainably ………….. “The frog does not drink up the pond in which it lives” Blue revolution – use less water and cut out water waste to reduce water footprint Reduce the Threat of flooding ………….. We can lessen the threat of flooding by protecting more wetlands and natural vegetation in watersheds and by not building in areas subject to frequent flooding. Some Areas Get Too Much Water from Flooding Flood plains – water in a stream overflows it’s normal channel and spills into an adjacent area Highly productive wetlands Provide natural flood and erosion control Maintain high water quality Recharge groundwater Benefits of floodplains Fertile soils Ample water for irrigation Nearby rivers for use and recreation Flatlands for urbanization and farming Some Areas Get Too Much Water from Flooding Floodplain - water in a stream overflows it’s normal channel and spills into an adjacent area Include highly productive wetlands, provide natural flood and erosion control, maintain high water quality Advantages : fertile soil, ample water for irrigation, flatland suitable for crops , rivers for transportation Disadvantages: floods kill people and damage property Removal of water-absorbing vegetation Draining and building on wetlands August 2005 – Hurricane Katrina – damage intensified because of removal of coastal wetlands, lost buffer Hillside Before and After Deforestation Living Dangerously on Floodplains in Bangladesh Dense population -147 million people (size of Wisconsin) Located on coastal floodplain - slightly above sea level Moderate floods maintain fertile soil – rice, thatched roofs Increased frequency of large floods –every 50 years, Effects of development in the Himalayan foothills monsoon rains now run more quickly carry vital topsoil with them Destruction of coastal wetlands for fuel wood, farming and aquaculture Result severe flooding from surges Reduce Flood Risks……….. Rely more on nature’s systems Wetlands Natural vegetation in watersheds Preserve wetlands and restore ones that have been damaged Rely less on engineering devices Dams Levees Increased possibility of flooding downstream SOLUTIONS Reducing Flood Damage Prevention Control Preserve forests on watersheds Straighten and deepen streams (channelization) Preserve and restore wetlands in floodplains Tax development on floodplains Use floodplains primarily for recharging aquifers, sustainable agriculture and forestry Build levees or floodwalls along streams Build dams Fig. 13-26, p. 340