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Fresh Water Historically limiting factor in arid regions 1940-1990 PowerPoint PPT Presentation


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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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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 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


Fresh water historically limiting factor in arid regions 1940 1990

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


Fresh water historically limiting factor in arid regions 1940 1990

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


Fresh water historically limiting factor in arid regions 1940 1990

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


Fresh water historically limiting factor in arid regions 1940 1990

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


Fresh water historically limiting factor in arid regions 1940 1990

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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