Water Scarcity IWater is essential for life…Slide 3OverviewSlide 5Sources of waterHydrologic CycleWater and GlaciersScale of the problemWater shortagesSlide 11Population and water useWater use not uniformSlide 14Water and agricultureGroundwaterGroundwater in USOgallala AquiferSlide 19Example: China and GroundwaterGroundwater and subsidenceSlide 22Dams and RiversDams and displaced peopleThree Gorges DamWater and energySlide 27Rivers not running to the sea…Slide 29Water and ConflictExample: Colorado RiverColorado River DeltaLas VegasLake Mead and Las VegasSlide 35Water and UncertaintySlide 37Water Scarcity IWater Scarcity IES118 Spring 2008ES118 Spring 2008Water is essential for Water is essential for life…life…We all know water is essential forWe all know water is essential forDrinkingDrinkingProducing foodProducing foodWashingWashingIndustryIndustryEnergyEnergy……sustaining life on earth sustaining life on earthWe are in the midst of a global water crisis The 21st Century will be a century where one of humanity’s overriding problems will be water quality and management2005-2015: International Decade For Action 'Water for Life'OverviewOverviewFocus this week is on one aspect of Focus this week is on one aspect of the water problem, the water problem, water scarcitywater scarcityScale of the problemScale of the problemCausesCausesSolutions Solutions It is not until the well runs dry that we know the worth of water.- Benjamin FranklinLess than 0.01% of the planet's 1.4 billion cubic km is easily accessible freshwater in lakes and rivers. About a fifth of the water used worldwide comes from the 30% of the world's freshwater stored in groundwater.Sources of waterSources of waterPrecipitation is a primary source of Precipitation is a primary source of waterwaterSome precipitation taken up by plants and Some precipitation taken up by plants and returned to atmosphere through returned to atmosphere through transpirationtranspirationPrecipitation that does not infiltrate the Precipitation that does not infiltrate the ground or return to air by evaporation is ground or return to air by evaporation is surface runofsurface runof About 1/3 of surface runoff is potentially About 1/3 of surface runoff is potentially available for human useavailable for human useHydrologic CycleHydrologic CycleThe movement of water between the land, oceans, and the atmosphere.Water and GlaciersWater and GlaciersGlaciers are shrinking at Glaciers are shrinking at record rates and many record rates and many could disappear within could disappear within decades (UNEP 3-16-08)decades (UNEP 3-16-08)Data from 30 reference Data from 30 reference glaciers in 9 mountain ranges glaciers in 9 mountain ranges indicate between 2004-2005 indicate between 2004-2005 and 2005-2006 average rate and 2005-2006 average rate of melting and thinning more of melting and thinning more than doubledthan doubledOn average, shrank by 4.9 On average, shrank by 4.9 feet in 2006feet in 2006Glaciers lost an average of Glaciers lost an average of about a foot of ice a year about a foot of ice a year between 1980 and 1999; since between 1980 and 1999; since 2000 the average loss has 2000 the average loss has increased to about 20 inchesincreased to about 20 inchesScale of the problemScale of the problem54% of accessible runoff 54% of accessible runoff appropriated by humansappropriated by humansMay reach 70% - 90% of reliable surface May reach 70% - 90% of reliable surface runoff by 2025runoff by 2025Estimated that 6,000 people, mainly Estimated that 6,000 people, mainly children, have died every children, have died every dayday from from water-related problems for decadeswater-related problems for decadesWater shortagesWater shortagesPopulation and water Population and water useuseWorld's population has tripled in the last 100 years, but water use has increased sixfold.Water use not uniformWater use not uniformChild born in developed world consumes 30-50 times child born in Child born in developed world consumes 30-50 times child born in developing worlddeveloping worldWater and agricultureWater and agricultureAs Kabiri mentioned, agriculture and water As Kabiri mentioned, agriculture and water are closely linkedare closely linkedWorldwide, we use about 70% of water we Worldwide, we use about 70% of water we withdraw to irrigate 1/5 of world’s croplandwithdraw to irrigate 1/5 of world’s croplandProduces 40% of world’s foodProduces 40% of world’s foodGroundwatGroundwatererAquifers are water-bearing geologic Aquifers are water-bearing geologic formations that can store and yield waterformations that can store and yield waterrenewable if not withdrawn faster than renewable if not withdrawn faster than replacedreplacedGroundwater from aquifers provide water Groundwater from aquifers provide water for agriculture and drinking water for ¼ of for agriculture and drinking water for ¼ of world’s populationworld’s populationButBut water tables falling fast in many areas water tables falling fast in many areas as pumping exceeds rechargeas pumping exceeds rechargeGood example of “Tragedy of Commons”Good example of “Tragedy of Commons”Water is “free”, little incentive to conserve Water is “free”, little incentive to conserve despite abundant information about problemdespite abundant information about problemGroundwater in USGroundwater in USHouston TX: Pumping has led to Houston TX: Pumping has led to subsidence of 3m, groundwater lower subsidence of 3m, groundwater lower by 120 mby 120 mKansas: Groundwater accounts for Kansas: Groundwater accounts for 90% of total water supply; dropped 90% of total water supply; dropped by 200 ft in some areasby 200 ft in some areasOgallala AquiferOgallala AquiferLarger than Lake HuronLarger than Lake Huron170,000 sq. mi. area170,000 sq. mi. areaSupports over $50B in Supports over $50B in farmingfarming11% depleted since 193011% depleted since 193025% projected depletion 25% projected depletion by 2020by 2020India using groundwater so rapidly some areas have already run out In Rajasthan, a heavily agricultural state, up to 80% of groundwater areas in danger of running outIn a village in Rajasthan (above) the state sends in water by trainExample: China and Example: China and GroundwaterGroundwaterChina is heavily dependent on China is heavily