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APES Chapter 14
Transcript of APES Chapter 14
SFL 65”/yr Uses of water:
Irrigation 68% - can be reduced by xeriscaping (plant vegetation that requires a little water or use rocks in landscaping)
Municipal use 9% Types of Water
surface water (rivers, lakes, reservoirs)
Runoff from land
drainage basin (“watershed”- area of land drained by a river)
Aquifers ( deep storage caverns)
water table- upper surface of groundwater California- high amount of precipitation in North, high population in South Water Diversion Projects
India – 8,000 villages have no local water
China – water table falling 2-3 m / year
Pakistan – lack of water led to riots in 2001
Mexico – water table falling 3.5 m / year in Mexico City Population Growth and Water Problems High Plains- (N. Dakota south to Texas & west to California) draws water 40xs faster than it is re-charged.
Some areas require 100s-1000s of years for water to be recharged.
Ogallala Aquifer- world’s largest Groundwater/
Aquifer depletion Saltwater intrusion
When ground water drops, salt water can move inland to form brackish (somewhat salty) water.
Fresh water can have up to 1% salt conc. 9 states experienced flooding initially because of large rainfall
Wetlands had been drained for construction; now easily flooded
some levees failed The Mississippi Floods of 1993 (copy world’s top four largest watersheds) Hoover Dam, NV – 726 ft. high Aquifers Drip or trickle irrigation at roots 1. Reducing Agricultural Water Waste By Using: Water Conservation Water distribution globally is very inequitable (South America and Asia together receive more than 50% of the world’s precipitation)
In addition, stable runoff varies
Drinking Water Problems
1.4 billion lack safe water
2.9 billion lack proper wastewater disposal Global Water Problems The Colorado River Basin
Often becomes dry before it reaches Gulf of California. One of the most serious water supply problems in the U.S., servicing 6 states & Mexico with 49 dams. Downstream waters often have a high salt content. Most problems in the West and Southwest
Aqueducts (man-made rivers or pipes) transport water from distant sources Water Problems in the US 40% of world’s people live in arid or semiarid regions in Asia and Africa
Overdrawing Surface Waters for irrigation
Causes subsidence (sinking) of land
Can lead to saltwater intrusion
Salinization of Irrigated Soil (water evaporates and leaves salt behind) Too Little Water Too Much Water:
Flood Management (ex. Kissimmee River) Seawater:
mostly NaCl Our Supply of Fresh Water H Bonding Properties shapes continents
moderates our climate
is essential for all organisms
(Humans are composed of 70% water by weight)
“universal solvent” The Importance of Water All fish are gone
Salty dust storms have led to many human illnesses
Soviets buried 100s of tons of anthrax endospores on an island in the sea in 1988. 1997 1976 The Aral Sea- Kazakhstan, near Russia The Rhine River Basin The Rhine River Basin is shared among 5 countries. In 1986 Switzerland accidentally dumped 30 tons of toxins into Rhine, killing fish and ruining water supply. Sharing water among countries
Poor quality / contamination Water Problems : San Francisco Bay- largest Pacific estuary in U.S. Chapter 14 Water:
A Limited Resource Xeriscaping Recycling gray water 3. Reducing Municipal Water Waste- reduce & recycle
2.Reducing Water Waste in Industry- reuse Salt impermeable membrane Fresh water Pressure salt H2O Salt water 2) Reverse osmosis – make potable (drinking) water from salt water with salt impermeable membrane.
-Change filter often
-R.O. wastes a lot of water. Remove salt from seawater
1% of all treated drinking water has been
desalinized Desalinization Produces steam Water boiled Salt water Simplified process: Pure water is collected Condenses
1) Distillation Saltwater Intrusion