Water. Watersheds - drainage basins. Supply

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1 Water Importance and unique properties covers 71% of the Earth s surface regulates Earth s climate dilutes wastes sculpts Earth s surface major habitat Features 97% in oceans 3% fresh water 2.997% in ice caps glaciers.003% available to us Supply Watersheds - drainage basins areas of land that drain into bodies of surface water water flowing off land into these bodies is called surface runoff Hydrologic Cycle natural recycling and purification process (ecosystem services) plenty of fresh water, if not overloaded with degradable and non-degradable material divide world into haves and have nots Solar powered hydrologic cycle Evaporation transpiration condensation precipitation runoff percolation groundwater water table 1

2 Surface water precipitation that does not soak into the ground or return to the atmosphere by evaporation streams, lakes, wetlands, reservoirs Groundwater precipitation infiltrates the ground and fills pores in soil and rocks zone of saturation - all available soil and rock spaces filled by groundwater 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 Aquifers groundwater which flows through water saturated layers of sand, gravel, bedrock replenished naturally by precipitation(natural recharge) slow moving underground lakes Major reservoirs of groundwater consolidated forms solid rock with groundwater in cracks unconsolidated forms sand, gravel, loose earth Diagram- aquifer amount of water depends on packing 2

3 If withdrawal rate of aquifer exceeds 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 Cone of depression Total Water Use Amounts - US examples 100,000 gal = 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 mostly to irrigate crops(69%) energy production- 23% industrial usage highest in Europe and N.America (US) Use of water Causes of freshwater shortages dry climate drought - water stress desiccation-overgrazing and deforestation Africa, Middle East, S. Asia Drought at least 80 countries (40%) of world population experience year long droughts since 1970 s - more than 24,000 dead 3

4 150 of world s 214 river systems shared by 2 countries another 50 by 3-10 nations Water - political issue Water Resources in US - Case Study East - energy production, cooling, manufacturing - flooding, occasional shortages, pollution West - irrigation,water tables dropping, groundwater depleted faster than recharging Increased water supply build dams and reservoirs withdraw groundwater increase water efficiency Living.. Developed -favorable climate, bring in water from another watershed Developing - must settle where water is available, borrow money to build dams and reservoirs Constructing dams/reservoirs water stored in large reservoirs used for hydroelectric power, irrigate land downstream, control flooding, recreation 4

5 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 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 Examples-Japan inflatable small rubber dams, 1000 filled with air can be deflected to allow accumulated silt to flow downstream Case Study : Aswan Dam Advantages - supplies electricity, irrigation Disadvantages- silt accumulates, schistosomiasis $100 million spent - fertilizers expensive barrier dams fishing industry collapsed 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 Aqueducts 5

6 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 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 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 Aquifer depletion Saudi Arabia, Northern China, Northern Africa withdrawal 10 times the recharge Overuse aquifer depletion aquifer subsidence intrusion of salt water-water table lowered, normal interface between fresh and salt water moves inland How can we slow this? not plant water thirsty crops in dry areas develop crop strains that require less water waste less irrigation water 6

7 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 Disadvantages enormous amounts of electricity required distribution from coastal plants expensive dumping of concentrated brine, increases local salt concentration 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 Disadvantages non availability of rain clouds cloud seeding chemicals introduced into soil and water systems ownership of water in clouds Solutions using water efficiently 7

8 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 Curbing waste evaporation, leaks, other losses Reason for waste artificially low water prices external costs not included in monthly bills Reducing irrigation losses 69% of water usage is for irrigation 2 / 3 of this is wasted Irrigation 3 different kinds Gravity flow water from aqueduct or nearby river % efficiency leveling of fields, surge flooding, capture and reuse runoff 8

9 Center Pivot water pumped from underground and sprayed from mobile boom with sprinklers 70-80% efficiency Drip irrigation above or below ground pipes or tubes deliver water to individual plant roots 80-90% efficiency Less wastage - Industry use recycled water machines designed to save water Japan, Israel Most Wastage - Residences water - used to flush toilets, wash hands, baths green lawns in arid areas Xeriscaping vegetation adapted to dry climate 30-80% less water used Solutions water meter repair leaky pipes low flush toilets and showerheads gray water for irrigation 9

10 Sustainable Usage - Case study Columbia River Basin World s largest hydroelectric system more than 100 dams electricity prices - 40% lower interferes with salmon life cycles Salmon ranching artificial hatcheries genetic inbreeding world s largest program for ecosystem rehabilitation cost - $2 billion Time - 2 decades Florida Everglades restoration case study Everglades slow moving river 50 miles wide, 6 inches deep flows south through Everglades National Park into Estuary at Florida Bay World s largest marshland haven for 14 endangered or threatened species (American alligator, Florida panther) aquifer recharge, precipitation system Problems - development straightening Kissimmee river tremendous environmental impact 10

11 What can we do? Restore original path of Kissimmee reclaim areas of wetlands will cost $2 billion at the lower estimate 11