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Fresh Water on Earth

Fresh Water on Earth. Episcopal Diocese of Virginia Stewardship of Creation Conference on Water Sustainability September 18, 2010 Dudley F. Rochester, M.D. The Big Picture. The total amount of water on earth is constant Its distribution varies with climate

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Fresh Water on Earth

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  1. Fresh Water on Earth Episcopal Diocese of Virginia Stewardship of Creation Conference on Water Sustainability September 18, 2010 Dudley F. Rochester, M.D.

  2. The Big Picture The total amount of water on earth is constant Its distribution varies with climate 97.5% of Earth’s water is in oceans

  3. Fresh Water Locations Frozen 69.6% Groundwater 30.1% Remainder 0.3%

  4. What’s in the Remainder? Lakes, rivers, wetlands 88% Atmosphere 11% In biological matter 1%

  5. Water Cycle Surface to atmosphere by evaporation, driven by solar energy Atmosphere to surface by precipitation Surface to underground by infiltration Underground discharge back to surface

  6. Sources of Fresh Water Surface water in lakes & rivers Shallow groundwater (renewable) Deep aquifers (non-renewable) Desalinated salt water (costly in energy and transportation)

  7. Sustainable Water Usage Annual accessible fresh water is 9200 cubic km; comes to 1350 cubic meters per capita Total world water withdrawal is 4400 cubic km per year, 48% of accessible Taking too much water causes environmental damage

  8. Water Supply in Jeopardy Pollution from sewage; runoff from agriculture & industry Depletion of deep aquifers Melting glaciers in Asia & South America Growing population & demand

  9. What Do We Use Water For? 7% for domestic uses (drink, cook, bathe, sanitation) 22% for industrial uses (manufacture & process materials) 70% for agriculture (grow food & other crops)

  10. Water Status & Per Capita Use Statusm3/year Water famine < 150 Need to import food < 1000 Adequate 1300-1500 Surplus, export food > 2000 USA average 2700

  11. Fresh Water Supply by Continent Asia 13,510 km3/year South America 12,030 “ North America 7,890 “ Africa 4,050 “ Europe 2,900 “ Oceania 2,360 “

  12. Fresh Water Supply Per Capita Asia 3,900 m3/person/yr Europe 4,200 “ Africa 5,700 “ North America 17,400 “ South America 38,200 “ Oceania 82,200 “

  13. Lack of Access to Fresh Water 1.1 billion people lack access to safe drinking water 2.2 billion do not have enough water for sanitation 3.1 billion have to carry water to their home (24 gallons, 200 lbs, for 3 miles)

  14. Ancient Conflicts over Water Lagash vs Umma in 2500 BC; Egypt, Persia, Babylon, Assyria in 612 BC; Athens vs Sparta in 430 BC; Goths vs Rome in 537 AD; China in 1642 AD. Tactics included diversion of streams, breaching dikes, cutting aqueducts and poisoning cisterns.

  15. Modern Conflicts over Water India, Pakistan& Kashmir Israel, Syria, Lebanon & Jordan Kenya, Sudan, Somalia, Yemen

  16. Cost versus Value of Water Water is too cheap; it is used unwisely Average fee for water is $2.30 per 1000 liters (range $0.40 to $5.20) “…colossal underpricing of water’s full economic and environmental worth” Steven Solomon, 2010

  17. Water Footprints CommodityAmountliters H2O Beef kg 15,000 Pork kg 4,800 Coffee liter 900 Tea liter 120 Blue jeans pair 11,000 Paper ream 5,000

  18. Conserve Water Irrigate parsimoniously Detect and fix leaks Save and recycle used or wasted water Scrimp on bottled water, lawns and meat

  19. Pricing, Fixing, Producing Price water realistically Repair aging infrastructure Increase production (desalination) Add storage & distribution facilities

  20. Summary: Problems Accessible water is unevenly distributed across the world Half the world population live in water-stressed areas Inadequate water supply engenders conflicts & wars

  21. Summary: Solutions Reset the price of water Conserve & reuse water Find new water sources Repair old & build new water infrastructure

  22. Domestic Water Requirement Activitym3/person/year Drink 1.8 Sanitation 7.3 Bathe 3.5 Prepare food 3.7 Grow food 986 Total 1004

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