Global Water Resources Unit 4

Core Case Study: Water Conflicts in the Middle East: A Preview of the Future Water shortages may be the biggest problem facing the Middle East Most freshwater comes from three river basins: Nile River Jordan River Tigris and Euphrates Rivers Peacefully solving the problems will require shared sacrifice among all the countries in the region.

Three Major River Basins in the Middle East

The Nile

Jordan River

Tigris and Euphrates Rivers

Egypt and the Nile The Nile provides Egypt with 97% of its water. The upstream countries of Ethiopia and Sudan plan to divert more water for their own use. Egypt will be forced to take action by….. Importing more food to reduce irrigation Cutting its population growth Working out water sharing agreements, OR Going to war with Ethopia and Sudan.

Will We Have Enough Usable Water? We are using available freshwater unsustainably by wasting it, polluting it, and charging too little for this irreplaceable natural resource. One of every six people in the world does not have sufficient access to clean water, and this situation will almost certainly get worse.

Why is water so important? The Earth is a watery world: 71% of the Earth’s surface is covered by water. But only 0.024% is available to us as liquid freshwater. With few exceptions, water is a poorly managed resource worldwide. The United States is the world’s largest user of water.

Access to water is… A global health issue: The world’s leading cause of illness is unsafe water An economic issue: Water is essential for the functioning of modern economies. A women’s and children’s issue: Women and children are the primary gatherers of water in the developing world A national and global security issue: Future wars may be fought over water.

Girl Carrying Well Water over Dried Out Earth during a Severe Drought in India

Most of the Earth’s Freshwater Is Not Available to Us People divided into Water haves Water have-nots The lack of sufficient water to meet the needs of the people in a country or region is called hydrological poverty Experts believe that developing water shortages around the world are one of the three primary problems the world faces during this century.

Groundwater Ground water is the water found underground in aquifers. Water table is the depth at which groundwater is found. The water table can rise or fall depending on climate and extraction rates. Aquifers are vast underground deposits of water that supply 50% of the world’s freshwater. Aquifers are a geologic layer consisting of underground caverns and porous layers of sand gravel and bedrock where groundwater flows.

Surface Water Surface runoff is the term used for the rain and groundwater that flows into streams and rivers Watershed (drainage) basin is defined as the total area of land that flows into a particular river. Only 1/3 of surface runoff is considered reliable runoff that can be used by humans. The other 2/3rds is lost to flooding or can’t be captured.

Flowing artesian well Well requiring a pump Water table Unconfined Aquifer Recharge Area Evaporation and transpiration Evaporation Precipitation Confined Recharge Area Runoff Flowing artesian well Well requiring a pump Stream Figure 13.3 Natural capital: groundwater system. An unconfined aquifer is an aquifer with a permeable water table. A confined aquifer is bounded above and below by less permeable beds of rock, and its water is confined under pressure. Some aquifers are replenished by precipitation; others are not. Water table Infiltration Lake Infiltration Unconfined aquifer Less permeable material such as clay Confined aquifer Confining impermeable rock layer Fig. 13-3, p. 316

Worldwide Usage of Surface Runoff Of the 1/3 of surface runoff that is usable. Throughout the world…. Cities and residences use 10% Agriculture uses 70%, mostly for irrigation. Industry uses 20%. For example, it takes 120,000 gallons of water to make one automobile!

Water shortages in the United States By 2012 at least 36 states are likely to face water shortages due to drought (exacerbated by global warming) population growth Urban sprawl (sprawling suburbs use much more water per capita than dense cities) Waste of water. Experts believe that low prices are the leading case of water waste.

Average annual precipitation (centimeters) Less than 41 81–122 41–81 More than 122 Figure 13.4 Average annual precipitation and major rivers (top) and water-deficit regions in the continental United States and their proximity to metropolitan areas having populations greater than 1 million (bottom). Question: Why do you think some areas with moderate precipitation still suffer from water shortages? (Data from U.S. Water Resources Council and U.S. Geological Survey) Fig. 13-4a, p. 317

Metropolitan regions with population greater than 1 million Figure 13.4 Average annual precipitation and major rivers (top) and water-deficit regions in the continental United States and their proximity to metropolitan areas having populations greater than 1 million (bottom). Question: Why do you think some areas with moderate precipitation still suffer from water shortages? (Data from U.S. Water Resources Council and U.S. Geological Survey) Acute shortage Shortage Adequate supply Metropolitan regions with population greater than 1 million Fig. 13-4b, p. 317

Water “hot spots” in 17 Western States Washington North Dakota Montana Oregon Idaho South Dakota Wyoming Nevada Nebraska Utah Colorado Kansas California Oklahoma New Mexico Arizona Figure 13.5 Water hotspots in 17 western states that, by 2025, could face intense conflicts over scarce water needed for urban growth, irrigation, recreation, and wildlife. Some analysts suggest that this is a map of places not to live during the next 25 years. Question: If you live in one of these hotspot areas, have you noticed any signs of conflict over water supplies? (Data from U.S. Department of the Interior) Texas Highly likely conflict potential Substantial conflict potential Moderate conflict potential Unmet rural water needs Fig. 13-5, p. 318

Long-Term Severe Drought Is Increasing Causes Extended period of below-normal rainfall Diminished groundwater Global warming? Harmful environmental effects of drought Dries out soils Reduces stream flows Decreases tree growth and biomass Lowers net primary productivity and crop yields Shift in biomes

Who Should Own and Manage Freshwater Resources? Most water resources are owned by governments And are managed as publicly owned resources Veolia and Suez: Two French companies. Actively buy and manage water resources around the world. They have achieved successful outcomes in many areas but controversy follows.

Who Should Own and Manage Freshwater Resources? Bechtel Corporation. Controversial water management in Bolivia led to riots that drove them from the country. Potential problems with full privatization of water resources Financial incentive to sell water; not conserve it Poor will still be left out

Water Tables Fall When Groundwater Is Withdrawn Faster Than It Is Replenished India, China, and the United States Three largest grain producers in the world All are over pumping aquifers for irrigation of crops The United State is withdrawing groundwater at a rate that is 4-times faster than it can be recharged.

TRADE-OFFS Withdrawing Groundwater Advantages Disadvantages Useful for drinking and irrigation Aquifer depletion from overpumping Sinking of land (subsidence) from overpumping Available year-round Aquifers polluted for decades or centuries Exists almost everywhere Saltwater intrusion into drinking water supplies near coastal areas Renewable if not overpumped or contaminated Figure 13.7 Advantages and disadvantages of withdrawing groundwater. Question: Which two advantages and which two disadvantages do you think are the most important? Why? Reduced water flows into surface waters No evaporation losses Increased cost and contamination from deeper wells Cheaper to extract than most surface waters Fig. 13-7, p. 321

Aquifer Depletion in the United States Ogallala aquifer: World’s largest known aquifer Irrigates the Great Plains Water table lowered more than 30 meters in many places. Cost of high pumping has eliminated some of the farmers Government subsidies to continue farming deplete the aquifer further Biodiversity threatened in some areas

Natural Capital Degradation: Areas of Greatest Aquifer Depletion in the U.S.

Natural Capital Degradation: The Ogallala is the World’s Largest Known Aquifer

Groundwater Overpumping in Coastal Areas can cause Catastrophic Problems Contamination of the groundwater with saltwater intrusion Groundwater becomes undrinkable and unusable for irrigation Growing problem in Florida and the Gulf Coast, including Texas.

Saltwater Intrusion

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 Figure 13.11 Ways to prevent or slow groundwater depletion by using water more sustainably. Question: Which two of these solutions do you think are the most important? Why? Set and enforce minimum stream flow levels Do not grow water-intensive crops in dry areas Divert surface water in wet years to recharge aquifers Fig. 13-11, p. 324

Active Figure: Threats to aquifers

Large Dams and Reservoirs Have Advantages and Disadvantages Main goals of a dam and reservoir system Capture and store runoff Release runoff as needed to control floods. Generate electricity Supply irrigation water Provide recreational opportunities (reservoirs). All the lakes in Texas are reservoirs except Caddo Lake

Advantages of Dams Increase the reliable runoff available Reduce flooding Grow crops in arid regions Reliable carbon-free supply of electricity

China’s Three Gorges Dam

Large Dams and Reservoirs Have Advantages and Disadvantages (3) Displaces people behind the dam Leads to devastating flooding if there is a failure. Impaired ecological services of rivers (disrupt migrations of fish) Loss of plant and animal species Fill up with sediment within 50 years Reduces downstream flow of nutrients and sediments.

The Ataturk Dam Project in Eastern Turkey

Case Study: The Colorado River Basin— An Overtapped Resource 2,300 km through 7 U.S. states 14 Dams and reservoirs Located in a desert area within the rain shadow of the Rocky Mountains Water supplied mostly from snowmelt of the Rocky Mountains

Case Study: The Colorado River Basin— An Overtapped 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

What will happen if some of the reservoirs empty out? Economic and ecological catastrophe. Cities like Las Vegas, Phoenix and Los Angeles will run out of water Political and legal battles over water will be intense.

The Colorado River Basin

Aerial View of Glen Canyon Dam Across the Colorado River and Lake Powell

The Flow of the Colorado River Measured at Its Mouth Has Dropped Sharply

The Aral Sea Disaster Large-scale water transfer project in dry central Asia removed the source of the Aral Sea. Surface level of the sea dropped by 22 meters Salt and sand from the dry sea bottom have spread by wind as far as 300 miles. Massive wetlands destruction. Populations of fish and wildlife have been driven to near extinction.

The Aral Sea Disaster– a Vanishing Freshwater Lake 1976 2006

Ship Stranded in Desert Formed by Shrinkage of the Aral Sea

Removing Salt from Seawater Seems Promising but Is Costly Two primary methods of Desalination Distillation turns water to vapor and condenses the vapor back to liquid (salt is left behind) Reverse osmosis uses high pressure to force saltwater through a membrane filter that excludes salt ions. Currently 15,000 plants in 125 countries. Saudi Arabia: highest number

Desalination plant in Saudi Arabia

Problems with desalination High cost and high energy footprint Keeps down algal growth and kills many marine organisms Large quantity of brine wastes (what do we do with all that salt?)

We Can Cut Water Waste in Irrigation Flood irrigation is the most wasteful form of irrigation. Center pivot, low pressure sprinkler are better Low-energy, precision application sprinklers better still. Drip or trickle irrigation offers the greatest conservation of water.

Major Irrigation Systems

(efficiency 60% and 80% with surge valves) Figure 13.20 Major irrigation systems. Because of high initial costs, center-pivot irrigation and drip irrigation are not widely used. The development of new, low-cost, drip-irrigation systems may change this situation. Center pivot (efficiency 80% with low-pressure sprinkler and 90–95% with LEPA sprinkler) Drip irrigation (efficiency 90–95%) Gravity flow (efficiency 60% and 80% with surge valves) Above- or below-ground pipes or tubes deliver water to individual plant roots. Water usually pumped from underground and sprayed from mobile boom with sprinklers. Water usually comes from an aqueduct system or a nearby river. Fig. 13-20, p. 335

(efficiency 60% and 80% with surge valves) 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. 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. Figure 13.20 Major irrigation systems. Because of high initial costs, center-pivot irrigation and drip irrigation are not widely used. The development of new, low-cost, drip-irrigation systems may change this situation. Stepped Art Fig. 13-20, p. 335

Solutions: Reducing Irrigation Water Waste

Flood Plains Highly productive wetlands Provide natural flood and erosion control Maintain high water quality Recharge groundwater Benefits of floodplains Fertile soils Nearby rivers for use and recreation Flatlands for urbanization and farming

Dangers of floodplains and Floods Floods are deadly and destructive Human activities worsen floods Failing dams and water diversion can be catastrophic (Johnstown Flood) Hurricane Katrina and the Gulf Coast Removal of coastal wetlands

Natural Capital Degradation: Hillside Before and After Deforestation

Forested Hillside Oxygen released by vegetation Diverse ecological habitat Evapotranspiration Trees reduce soil erosion from heavy rain and wind Agricultural land Figure 13.25 Natural capital degradation: hillside before and after deforestation. Once a hillside has been deforested for timber, fuelwood, livestock grazing, or unsustainable farming, water from precipitation rushes down the denuded slopes, erodes precious topsoil, and can increase flooding and pollution in local streams. Such deforestation can also increase landslides and mudflows. A 3,000-year-old Chinese proverb says, “To protect your rivers, protect your mountains.” See an animation based on this figure at CengageNOW. Question: How might a drought in this area make these effects even worse? Tree roots stabilize soil Vegetation releases water slowly and reduces flooding Forested Hillside Fig. 13-25a, p. 339

After Deforestation Tree plantation Evapotranspiration decreases Roads destabilize hillsides Overgrazing accelerates soil erosion by water and wind Winds remove fragile topsoil Agricultural land is flooded and silted up Gullies and landslides Figure 13.25 Natural capital degradation: hillside before and after deforestation. Once a hillside has been deforested for timber, fuelwood, livestock grazing, or unsustainable farming, water from precipitation rushes down the denuded slopes, erodes precious topsoil, and can increase flooding and pollution in local streams. Such deforestation can also increase landslides and mudflows. A 3,000-year-old Chinese proverb says, “To protect your rivers, protect your mountains.” See an animation based on this figure at CengageNOW. Question: How might a drought in this area make these effects even worse? Heavy rain erodes topsoil Silt from erosion fills rivers and reservoirs Rapid runoff causes flooding After Deforestation Fig. 13-25b, p. 339

Forested Hillside After Deforestation Oxygen released by vegetation Diverse ecological habitat Evapotranspiration Trees reduce soil erosion from heavy rain and wind Tree roots stabilize soil Vegetation releases water slowly and reduces flooding Forested Hillside Agricultural land Stepped Art Tree plantation Roads destabilize hillsides Overgrazing accelerates soil erosion by water and wind Winds remove fragile topsoil Agricultural land is flooded and silted up Gullies and landslides Heavy rain erodes topsoil Silt from erosion fills rivers and reservoirs Rapid runoff causes flooding After Deforestation Evapotranspiration decreases Figure 13.25 Natural capital degradation: hillside before and after deforestation. Once a hillside has been deforested for timber, fuelwood, livestock grazing, or unsustainable farming, water from precipitation rushes down the denuded slopes, erodes precious topsoil, and can increase flooding and pollution in local streams. Such deforestation can also increase landslides and mudflows. A 3,000-year-old Chinese proverb says, “To protect your rivers, protect your mountains.” See an animation based on this figure at CengageNOW. Question: How might a drought in this area make these effects even worse? Fig. 13-25a, p. 339

Solutions: Reducing Flood Damage