Water Resources Chapter 13
Core Case Study: Water Conflicts in the Middle East: A Preview of the Future • Water shortages in the Middle East: hydrological poverty • Nile River: flows through 7 countries, Ethopia @ the end is most desperate • Jordan Basin: • Tigris and Euphrates Rivers
Peacefully Solving the Problems • Negotiating agreements • Slow population growth • Cut water waste • Raise water prices (hopes to improve irrigation) • Increase Grain imports
13-1 Will We Have Enough Usable Water? • Concept 13-1A We are using available freshwater unsustainably by wasting it, polluting it, and charging too little for this irreplaceable natural resource. • Concept 13-1B One of every six people does not have sufficient access to clean water, and this situation will almost certainly get worse.
Freshwater Is an Irreplaceable Resource That We Are Managing Poorly (1) • Why is water so important? • Provides: food, shelter, 60% of human body, sculpts the earth, moderates climate, removes & dilutes wastes & pollutants • Earth as a watery world: 71% • Freshwater availability: 0.024%
Freshwater Is an Irreplaceable Resource That We Are Managing Poorly (2) • Poorly managed resource • Hydrologic cycle • Movement of water in the seas, land, and air • Driven by solar energy and gravity • Interfere with it by overloading water w/ wastes • Withdraw water from underground & surface supplies faster than it is replenished • Destroying wetlands • Cutting down forests • Climate Change
Freshwater Is an Irreplaceable Resource That We Are Managing Poorly (3) • Access to water is • A global health issue: lack of clean water for drinking and sanitation is the world’s largest cause of illness • An economic issue: vital for reducing poverty & producing food & energy • A women’s and children’s issue: poor women & children are responsible for finding & carrying daily supplies • A national and global security issue: increasing tensions within & between nations
Girl Carrying Well Water over Dried Out Earth during a Severe Drought in India
Freshwater Is an Irreplaceable Resource That We Are Managing Poorly (4) • Environmental Issue: • Withdrawal from rivers & aquifers lowers water tables • losses of wetlands • lowers water quality • declining fishing populations • shrinking lakes • species extinction • degredation of ecosystem services provided by aquatic systems
Most of the Earth’s Freshwater Is Not Available to Us • People divided into • Water haves • Ex.Canada 0.5% of world’s population has 20% of world’s water • Water have-nots • Ex. China 20% of world’s population has 7% of world’s water
We Get Freshwater from Groundwater and Surface Water (1) • Groundwater: precipitation that infiltrates the ground & percolates downward through spaces in soil, gravel, & rock until an impenetrable layer stops it • Zone of saturation: spaces that are completely filled in with water • Water table: top of the groundwater zone
We Get Freshwater from Groundwater and Surface Water (2) • Aquifers: underground caverns & porous layers of sand, gravel, or bedrock through which groundwater flows. • Natural recharge : recharged naturally by precipitation that percolates downward through soil & rock • Lateral recharge: recharged by nearby rivers & streams Most recharge very slowly due to urban landscape has been built on or paved
We Get Freshwater from Groundwater and Surface Water (3) • Surface Water:Freshwater from precipitation & snowmelt that flows across the earth’s land surface & into rivers, streams, lakes, wetlands, estuaries, & oceans • Surface runoff: Precipitation that does not infiltrate the ground or return to the atmosphere by evaporation • Watershed (drainage) basin: the land from which surface water drains into a particular river, lake, wetland, or other body of water • Reliable runoff: the amount of surface runoff that we can generally count on as a source of freshwater • 1/3 of total
We Use a Large and Growing Portion of the World’s Reliable Runoff • 2/3 of the surface runoff: lost by seasonal floods • 1/3 runoff usable • Domestic: 10% • Agriculture: 70% • Industrial use: 20% • Fred Pearce, author of When the Rivers Run Dry • 450,000 L to produce a small car • 140 L to produce a cup of coffee
Case Study: Freshwater Resources in the United States (1) • More than enough renewable freshwater, unevenly distributed • NE ample precipitation: most is used for energy production, power plant cooling, manufacturing • Western & SW have little: 85% used for irrigation • Effect of • Floods • Pollution • Drought: prolonged period in which precipitation is at least 70% lower & evaporation is higher than normal
Acute shortage Shortage Adequate supply Metropolitan regions with population greater than 1 million Fig. 13-4b, p. 317
Case Study: Freshwater Resources in the United States (2) • 2007: U.S. Geological Survey projection • Water hotspots: • Competition for scarce water • to support growing urban areas • Irrigation • recreation, & wildlife Could trigger intense political & legal conflicts between states & between rural and urban areas during the next 20 years
Water Shortages Will Grow (1) • Dry climate: climate change • Drought • Too many people using a normally reliable supply of water
Water Shortages Will Grow (2) • Wasteful use of water • China and urbanization • Hydrological poverty • In 2005 UN reported that: • 1.1 bil people lacked regular access to enough clean water for drinking, cooking, & washing • 2.6 bil people did not have access to even basic sanitation • In 2007 UN estimated that by 2025: • At least 3 bil people will lack access to safe water
Long-Term Severe Drought Is Increasing • Causes • Extended period of below-normal rainfall • Diminished groundwater • Harmful environmental effects • Dries out soils • Reduces stream flows • Decreases tree growth and biomass • Lowers net primary productivity and crop yields • Shift in biomes
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
Discussion Question 1 • Between farmers & city dwellers, which group should have greater access to water in water-short areas? Explain. • Can you think of a compromise for resolving this dilemma?
Who Should Own and Manage Freshwater Resources? (1) • Most water resources • Owned by governments • Managed as publicly owned resources • Currently 85% of Americans get water from publicly owned utilities Many governments still maintain ownership but hire private firms to manage, however some are selling the water resources to private companies
Who Should Own and Manage Freshwater Resources? (2) • Veolia and Suez: French companies • Buy and manage water resources • Especially in Europe, North America, & China • Ex. Veolia has 70,000 employees & provides water for 108 million people in 57 countries, including 17 Chinese cities • Successful outcomes in many areas • Chinese City Pudong: • Hooked up 300,000 new structures • Built water-treatment & sewage treatment • Hired 7,000 local workers • Established a 24 hour call center
Who Should Own and Manage Freshwater Resources? (3) • Bechtel Corporation (American owned) • Poor water management in Bolivia • Government couldn’t afford to fix leaky pipes that were losing 60% of their supply • They increase cost to the people • Started to seize & sell houses of those not paying their water bills • Strike ensued, violent clashes between protesters & government troops • Bechtel fled the city
Who Should Own and Manage Freshwater Resources? (4) • A subsidiary of Bechtel Corporation • Poor water management in Ecuador • Potential problems with full privatization of water resources • People believe that water is a public resource • Financial incentive to sell water; not conserve it • Poor will still be left out because they cannot pay their water bills
13-2 Is Extracting Groundwater the Answer? • Concept 13-2 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.
Water Tables Fall When Groundwater Is Withdrawn Faster Than It Is Replenished (1) • India, China, and the United States • Three largest grain producers • Overpumping aquifers for irrigation of crops • Water tables falling because pumping exceeds recharge • India and China • Small farmers drilling tubewells • Effect on water table • Keeps on lowering which makes it more & more expensive • Coal fire power plants for electrical demands
Water Tables Fall When Groundwater Is Withdrawn Faster Than It Is Replenished (2) • Saudi Arabia • Aquifer depletion and irrigation • 70% of water comes from desalinaziation
Trade-Offs: Withdrawing Groundwater, Advantages and Disadvantages
Natural Capital Degradation: Irrigation in Saudi Arabia Using an Aquifer
Case Study: Aquifer Depletion in the United States (1) • Ogallala aquifer: largest known aquifer 1/3 of all groundwater to the U.S. under 8 mid-western states • Irrigates the Great Plains • Water table lowered more than 30m-in TX & OK • Cost of high pumping has eliminated some of the farmers
Case Study: Aquifer Depletion in the United States (2) • Government subsidies to continue farming deplete the aquifer further: crop disaster payments tax breaks in form of groundwater depletion allowances • Biodiversity threatened in some areas • Ogallala creates wetlands • California Central Valley: serious water depletion
Discussion Question 2 • How is your lifestyle affected directly or indirectly by water withdrawn from the essentially nonrenewable Ogallala aquifer?
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 Has Other Harmful Effects (1) • Limits future food production • Bigger gap between the rich and the poor • As water tables drop farmers must drill deeper wells, buy larger pumps, use more electricity, this squeezes out the poor farmer • Land subsidence: Withdrawal of water causes sand & rock aquifers to collapse: impossible to recharge after this • Mexico City: built on an old lake bed-major subsidence problems • Sinkholes: large craters form when the roof of an underground cavern collapses
Groundwater Overpumping Has Other Harmful Effects (2) • Groundwater overdrafts near coastal regions • Contamination of the groundwater with saltwater • Undrinkable and unusable for irrigation
Science Focus: Are Deep Aquifers the Answer? • Locate the deep aquifers; determine if they contain freshwater or saline water: electrical resistance is an indication • Major concerns • Geological and ecological impact of pumping water from them • Flow beneath more than one country • Who has rights to it?
13-3 Is Building More Dams the Answer? • Concept 13-3 Building dam and reservoir systems has greatly increased water supplies in some areas, but it has disrupted ecosystems and displaced people.
Large Dams and Reservoirs Have Advantages and Disadvantages (1) • Main goals of a dam and reservoir system • Capture and store runoff • Release runoff as needed to control: • Floods • Generate electricity: ¼ of world’s dams produce ~20% of world’s energy • Supply irrigation water • Recreation (reservoirs)
Large Dams and Reservoirs Have Advantages and Disadvantages (2) • Advantages • Increase the reliable runoff available • Reduce flooding • Grow crops in arid regions
Large Dams and Reservoirs Have Advantages and Disadvantages (3) • Disadvantages • Displaces people • Flooded regions • Impaired ecological services of rivers • Loss of plant and animal species • Fill up with sediment within 50 years