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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 - 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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Presentation Transcript
slide1
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
slide2
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
slide3
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
slide4
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
slide5
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
slide7
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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