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Fresh Water Historically limiting factor in arid regions 1940-1990

Fresh Water Historically limiting factor in arid regions 1940-1990 World population more than doubled 2.3 billion  5.3 billion Per capita water use doubled 400 m 3 person -1 year -1  800 m 3 person -1 year -1 Global water use increased fourfold

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Fresh Water Historically limiting factor in arid regions 1940-1990

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  1. Fresh Water • Historically limiting factor in arid regions • 1940-1990 • World population more than doubled • 2.3 billion  5.3 billion • Per capita water use doubled • 400 m3 person-1 year-1 800 m3 person-1 year-1 • Global water use increased fourfold • 2000: USA ~2000 m3 person-1 year-1 (~1450 galday-1) • Current Status • In 1996, world human population using estimated 54% of all accessible fresh water in rivers, lakes, aquifers • Many people predict disastrous consequences for world’s fresh water supply in coming years • This potential disaster may have several causes

  2. Fresh Water • Current Status • Distribution • Uneven compared to population • 75% of annual rainfall in areas containing less than one-third of global population • Amazon River carries 20% of global runoff through area containing 10 million people • Congo River carries 30% of Africa’s runoff through area containing 10% of population • Uneven in space • North America contains 19,000 m3 per person per year vs. 4700 m3 per person per year in Asia • <10% of Mexico supplies >50% of annual runoff • Uneven in time • India gets 90% of annual rainfall during summer monsoon season (Jun-Sep); runs off too rapidly for efficient use

  3. Fresh Water • Current Status • Usage patterns • Agriculture – 69% • Industry/Energy – 23% • Domestic – 8% • Varies among regions and with development • Africa – 88% for agriculture (irrigation) • Europe – >50% for industry • Japan – Industrial but uses lots of water for growing rice • Spain/Portugal – Arid; water used heavily for agriculture • Personal use tracks standard of living • Africa – 17 m3 year-1 (47 l d-1) • Asia – 31 m3 year-1 (85 l d-1) • UK – 122 m3 year-1 (334 l d-1) • US – 211 m3 year-1 (578 l d-1) • By 2020, water shortages likely in Ethiopia, India, Kenya, Nigeria, China (parts of China already face problems) • Mexico City uses groundwater for 80% of municipal water supply • Depletion exceeds aquifer recharge rate by 50-80% • Sinking of land in some areas  Damage to buildings • City imports water to meet demand

  4. Fresh Water • Current Status • Contamination • Numerous examples worldwide • Biggest source = Agriculture • Europe – Over 90% of rivers have elevated nutrient levels from agrochemicals • Hungary – Nearly 40% of well fields contaminated • Developing countries – On average, 90% to 95% of all domestic sewage and 75% of all industrial waste discharged into surface waters without treatment • Impacts • Nile River – Diverting water + retention of sediment behind dams has caused fertile delta to shrink • Rhine River – Lost 8 of 44 fish species; 25 more endangered • Lake Chad – Diversion + drought has caused shrinkage from 25,000 to 2,000 km2 in 30 years Link • Aral Sea – Diversion for agriculture has caused severe shrinkage, with environmental & health problems L1L2

  5. Fresh Water • Consequence – Conflicts • World may have enough fresh water but uneven distribution  disputes, though few outright wars • Middle East – Most acute water conflicts • Jordan River Basin • River originates in Lebanon • Water shared by six nations (Wolf et al. 2005) • Israel – 467 m3 person-1 year-1 • Jordan – 224m3 person-1 year-1

  6. Fresh Water • Consequence – Conflicts • Jordan River Basin • 1951 • Jordan announces plans to irrigate Jordan Valley by tapping Yarmuk R. (major tributary) • Israel drains swamps between Israel & Syria • Military clash between Israel & Syria • 1953 • Israel begins construction of National Water Carrier to transfer water from Jordan basin to Negev Desert for irrigation • Syria responds with military action • Israel changes intake to Sea of Galilee • 1965 • Palestinian National Liberation Front attacks diversion pumps operated by Israeli NWC • 1960 • Arab leaders agree on plan to divert headwater via Yarmuk R. to East Ghor (King Abdullah) Canal (Jordan) • 1965-66 • Syria announces plans to divert headwaters • Military clash between Israel & Syria • 1967 • Israel destroys Arab diversion works on headwaters • Series of events  Six-Day War • 1969 • Israel destroys canal built by Jordan

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