Water Use and Management

Water as a Resource Covers 71% of earth’s surface Important properties Polar Density 3 states of matter High heat capacity

Available Water Total = 326 million cubic miles 97% in oceans                                                                                                                                                                                                                                           Available Water Total = 326 million cubic miles 97% in oceans 2.997% is locked up in ice caps and glaciers 0.003% is easily accessible Soil moisture Groundwater Water vapor Lakes Streams

Surface Water Runoff flows into streams, lakes, wetlands and reservoirs watershed www.canaanvi.org/assistance/ watershed.asp

Groundwater Precipitation infiltrates and percolates Zone of aeration Pores, fractures, crevices, etc. Zone of aeration Zone of saturation Top of this zone is water table Falls and rises with weather

Water Compartments

Groundwater Aquifers - Porous layers of sand, gravel, or rock lying below the water table. Artesian - Pressurized aquifer intersects the surface. (Water flows without pumping) Recharge Zones Slow recharge rate

Groundwater

Use of Fresh Water United States China Agriculture Agriculture Power plant cooling Industry Public China Agriculture Industry Public

Water Use Globally 70% agriculture (irrigation) 23% Industry Domestic use (household, drinking water, sanitation) accounts for about 7%

Water Use According to the UN, the average person needs a minimum of: 1.3 gallons of water per day to survive in a moderate climate at an average activity level 13 gallons for drinking and cooking, bathing and sanitation Average person in the US uses 100 gallons per day

FRESHWATER SHORTAGES Estimated 1.5 billion people lack access to an adequate supply of drinking water. Nearly 3 billion lack acceptable sanitation. Globally, water supplies are abundant, but, along with capital resources, are unevenly distributed.

Freshwater Shortage Causes Dry climate Drought Desiccation deforestation & overgrazing Water stress

Global Precipitation Patterns Wright and Nebel, 2002. Michael D. Lee Ph.D. Geography and Environmental Studies

Rainfall Distribution Rain falls unevenly over the planet Three factors control rainfall Global atmospheric circulation-creates regions of high air pressure and low rainfall Prevailing Winds-bring moisture to land from ocean; areas far from oceans are usually dry Topography-mountains act as cloud formers and rain catchers

Rain Shadow Effect

Altering the Availability of Water Levees-enlarged bank built up on each side of a river Flood protection Problems?

Altering the Availability of Water Dikes Flood protection from oceans Dams and reservoirs Human consumption Electricity generation Flood control Recreation

Dams and Reservoirs Cons Environmental Costs Upsets natural balance of water systems Croplands downstream are deprived of nutrient rich silt Evaporation Ecosystem Losses Loss of wildlife habitat Migration and spawning of fish disrupted Flooded land destroys forests or cropland Displacement of People

Colorado River Basin Diversion of water from Colorado River Disputes between AZ, CA, Mexico Dams trap silt--- more fertilizer needed High levels of NaCl- salinization

Three Gorges Dams in China is forcing relocation of 1.2 million people Yangtze river

Tapping Groundwater Supplies About ½ of the drinking water in the US is pumped from aquifers Advantages Year-round use Renewable if not overpumped or contaminated No evaporation losses Often less expensive

Tapping Groundwater Supplies Disadvantages Water table lowering Overpumping Sinking of land (subsidence) when water removed Chemical contamination Saltwater intrusion

Cone of Depression and Saltwater Intrusion

Ogallala Aquifer Underlies 8 states from SD to TX Held more water than all freshwater on Earth Water shortages Largest in the US

Desalinization Removing salt from sea water Distillation-heat boils water; leaves salt behind Reverse osmosis-water forced through semi-permeable membrane at high pressure

Towing Icebergs Carry fresh water to places that need it How can it be done? Would it be economically sound?

Water Efficiency and Conservation Change in personal habits Fix leaky pipes Water–saving toilets, faucets, & shower heads Plant drought–tolerant vegetation in residential communities located in arid & semi–arid areas Increase efficiency of irrigation drip irrigation, computer monitoring, center-pivot Use recycled water treat gray water from showers, washing machines for reuse Education Eat less meat