05_WaterSupplies

05_WaterSupplies - ESM 203 Water supplies and global change Water Supplies and Global Change ESM 203 1 Where is Earth's freshwater Oceans p Ice and

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ESM 203: Water supplies and global change 10/11/2007 1 Water Supplies and Global Change - ESM 203 - 1 Water for Life Decade - 2005 to 2015 N initiative • U.N. initiative motivated by the following: – 1 in 6 live w/o access to safe drinking water – 2.4 billion people lack access to adequate sanitation – water related diseases kill a child every 8 seconds *Open sewer in a Nairobi slum. Click on image for more on the Water for Life Decade. 2 Where is Earth’s freshwater? • Oceans 97.2% • Ice and snowpacks 2.0 p • Groundwater (750-4000m) 0.4 • Groundwater (<750m) 0.3 • Lakes 0.01 • Soil 0.005 tmosphere 001 Atmosphere 0.001 • Rivers 0.0001 • Biosphere 0.00004 Read: Black, P.E. On the critical nature of “useless” resources; Water Resources Bulletin (1995) 3 Region River Runoff Share of global R (%) Share of global global R / global Where is the renewable freshwater? (precipitation = runoff + ET) (km 3 /yr) population (%) pop. Europe 3,240 8 13 0.6 Asia 14,550 36 60 0.6 Africa 4,320 11 12 0.9 /C America 200 5 9 N/C America 6,200 15 8 1.9 S. America 10,420 26 6 4.3 Australia 1,970 5 0.5 10 Source: Postel et al., Science, 1996 4
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ESM 203: Water supplies and global change 10/11/2007 2 Gross use –- total volume required for Global Water Use some purpose. Usable many times if purified, naturally or technologically Consumptive use --- made unavailable by evaporation 5 Sector Gross use (km 3 /yr) Consumptive use (km 3 /yr) % Consumption Agriculture 2880 1870 65 Global Water Use Industry (incl. power) 975 90 9 Municipalities 300 50 17 Reservoir losses 275 275 100 Subtotal 4430 2285 stream flow 350 (?) Instream flow needs 2350 0 (?) Total as % of “available runoff” 54% 18% Projections for 2025 70% Source: Postel et al., Science, 1996 6 How is water used across the globe? Source: Vorosmarty et al., Science , 2000 7 • Moving freshwater from regions of surplus to regions of deficit. “In California, water doesn’t flow downhill; it flows Factors affecting runoff use toward money.” Great investment is needed to construct, operate, and maintain dams and pumps. – Regulation of flow by dams worldwide ~3500 km 3 /yr out of a total “available” runoff of ~ 12,500 km 3 /yr (Postel et al, 1996, Science ). China is considering a $7 billion investment to transfer water from the flood prone south to the drought stricken north. *Click on image for more from the BBC. "The only matter that could take Egypt to war again is water” (Anwar Sadat- 1979). *Click on image for more from the BBC. California’s water projects capture enough water to supply 8 cities the size of New York City. *More on the state’s water projects later. 8
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ESM 203: Water supplies and global change 10/11/2007 3 • Human society has become the equivalent of a geophysical [Earth-scale] process in affecting water availability through: Factors affecting runoff use – Climate change (variable but still uncertain degree) – Area of land occupied and vegetation cover altered – Size of populations and intensity of use by various technologies increasing – Expectations rising w.r.t. to lifestyle and health
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This note was uploaded on 08/06/2008 for the course ESM 203 taught by Professor Dozier,dunne during the Fall '07 term at UCSB.

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05_WaterSupplies - ESM 203 Water supplies and global change Water Supplies and Global Change ESM 203 1 Where is Earth's freshwater Oceans p Ice and

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