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Water

Water. Importance and unique properties. Features. covers 71% of the Earth’s surface regulates Earth’s climate dilutes wastes sculpts earth’s surface, major habitat. Supply. 97% in oceans 3% fresh water 2.997% in ice caps glaciers .003% available to us. Watersheds - drainage basins.

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Water

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  1. Water • Importance and unique properties

  2. Features • covers 71% of the Earth’s surface • regulates Earth’s climate • dilutes wastes • sculpts earth’s surface, • major habitat

  3. Supply • 97% in oceans • 3% fresh water • 2.997% in ice caps glaciers • .003% available to us

  4. Watersheds - drainage basins • areas of land that drain into bodies of surface water • water flowing off land into these bodies is called surface runoff

  5. Hydrologic Cycle • natural recycling and purification process • plenty of fresh water, if not overloaded with degradable and non-degradable material • divide world into “haves” and “have nots”

  6. Solar powered hydrologic cycle • Evaporation • transpiration • condensation • precipitation • runoff • percolation • groundwater • water table

  7. Surface water • precipitation that does not soak into the ground or return to the atmosphere by evaporation • streams, lakes, wetlands, reservoirs

  8. Groundwater • precipitation infiltrates the ground and fills pores in soil and rocks • zone of saturation - all available soil and rock spaces filled by groundwater

  9. Water Table • upper surface of zone of saturation poorly demarcated between saturated soil and rock and unsaturated soil and rock • falls in dry weather and rises in wet weather

  10. Aquifers • groundwater which flows through water saturated layers of sand, gravel, bedrock • replenished naturally by precipitation(natural recharge) • slow moving underground lakes

  11. Diagram- aquifer • Major reservoirs of groundwater • consolidated forms • solid rock with groundwater in cracks • unconsolidated forms • sand,gravel,loose earth • amount of water depends on packing

  12. Cone of depression • withdrawal rate of aquifer exceed natural recharge rate , • water table around withdrawal well lowered • creates a waterless volume • any pollution discharged onto land above will be pulled directly into well

  13. Total Water Use

  14. Amounts - US examples • 100,000 = 1 car • 1000 gal = 1lb of aluminum • 800 gal = 1 LB of beef • 26 gal = 2.2 lbs. paper • All nuclear plants require more water than Lake Eerie

  15. Use of water • mostly to irrigate crops(69%) • energy production- 23% • industrial usage highest in Europe and N.America (US)

  16. Cause …freshwater shortages • dry climate • drought - • water stress • desiccation-overgrazing and deforestation • Africa,Middle East .S.Asia

  17. Drought • at least 80 countries (40%) of world population experience year long droughts • since 1970’s - more than 24,000 dead

  18. Water - political issue • 150 of world’s 214 river systems shared by 2 countries • another 50 • by 3-10 nations

  19. Water Resources in US - Case Study • East - energy production, cooling, manufacturing -flooding, occasional shortages, pollution • West - irrigation ,water tables dropping, groundwaterdepleted faster than recharging

  20. Increased water supply • build dams and reservoirs • withdraw groundwater • increase water efficiency

  21. Living….. • Developed -favorable climate ,bring in water from another watershed • Developing - must settle where water is available , borrow money to build dams and reservoirs

  22. Constructing dams/reservoirs • water stored in large reservoirs • used for hydroelectric power, irrigate land downstream, control flooding, recreation

  23. Examples - India • efficient irrigation let country become self sufficient in food, environmental problems with 1500 dam projects • still going ahead with 20 new dams in Gujerat - displace about 1 million people

  24. India

  25. Example -China • Three Gorges Project, world’s largest hydroelectric project, 370 mile reservoir ; power to 150 million Chinese,energy produced =18 nuclear power plants reduce dependence on coal, hold back Yangtze • flood 800 factories, displace 1.4 million people

  26. Peoples Republic of China

  27. Examples-Japan • inflatable small rubber dams, 1000 filled with air • can be deflected to allow accumulated silt to flow downstream

  28. Case Study : Aswan Dam • Advantages - supplies electricity, irrigation • Disadvantages- silt accumulates, schistosomiasis • $100 million spent - fertilizers • expensive barrier dams • fishing industry collapsed

  29. Case study : Watershed Transfer-California • maze of giant dams, pumps, aqueducts • transports water from N California to arid agricultural areas • irrigation for cotton, alfalfa uses as much water residential • needs of all 30 million Californians

  30. Aqueducts

  31. Case Study : James Bay Watershed Transfer • Quebec’s James and Hudson Bays • $60 billion, 50 year scheme to provide electricity • phase I completed, phase II indefinitely postponed

  32. Case Study : Aral Sea • regional ecological disaster • shrinking and increased salinity as a result of irrigation water being diverted • all fish dead • salt, dust ,pesticide residues carried by wind -salt rain

  33. Withdrawing groundwater - US • being withdrawn at 4 times replacement level • 1/2 of US drinking water and 40% of irrigation water from aquifers • Ogallala aquifer

  34. Aquifer depletion • Saudi Arabia, Northern China, Northern Africa • withdrawal 10 times the recharge

  35. Over use (fig 17- 18) • aquifer depletion aquifer subsidence • intrusion of salt water-water table lowered, normal interface between fresh and salt water moves inland

  36. How can we slow this • not plant water thirsty crops in dry areas • develop crop strains that require less water • waste less irrigation water

  37. Desalination • removal of dissolved salts from ocean or brackish water • 7500 plants in 120 countries- 0.1% fresh water • distillation = heating salt water until it evaporates,salt left as solid • reverse osmosis - salt water pumped through thin membrane,salt left behind

  38. Disadvantages • enormous amounts of electricity required • distribution from coastal plants expensive • dumping of concentrated brine, increases local salt concentration

  39. Cloud Seeding • injecting large rain cloud with chemicals - silver iodide • water droplets in cloud clump around the chemical particles • forms ice • drops to earth as precipitation

  40. Disadvantages • non availability of rain clouds • cloud seeding chemicals introduced into soil and water systems • ownership of water in clouds

  41. Solutions • using water efficiently

  42. Solutions • using water efficiently

  43. Why ? • Reduce usage of waste water plants and septic systems • decrease pollution of surface water • reduce number of dams that destroy wildlife, displace people • slows depletion of aquifers

  44. Curbing waste • evaporation, leaks, other losses

  45. Reason for waste • artificially low water prices • external costs not included in monthly bills

  46. Reducing irrigation losses • 69% of water usage is for irrigation, • 2/3 rd of this is wasted

  47. Irrigation • 3 different kinds

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