Water Resources All water Fresh water Readily accessible

Water Resources All water Fresh water Readily accessible fresh water Groundwater 0. 592% Oceans and saline lakes 97. 4% Biota 0. 0001% Rivers 0. 0001% Lakes 0. 007% Fresh water 2. 6% 0. 014% Ice caps Ice and glaciers 1. 984% Soil moisture 0. 005% Atmospheric water vapor 0. 001% 77 trillion gallons/person 240, 000 gallons/person

Watershed, water table, aquifer Flowing artesian well Precipitation Well requiring a pump Evaporation and transpiration Evaporation Confined Recharge Area Runoff Stream Infiltration Water table Infiltration Lake Unconfined aquifer Less permeable material such as clay Confined aquifer Confirming permeable rock layer

Increasing Demand for Water use (cubic kilometers per year) 5, 500 5, 000 Total use 4, 500 4, 000 3, 500 3, 000 2, 500 Agricultural use 2, 000 Industrial use 1, 500 1, 000 Domestic use 500 1920 1940 1960 Year 1980 2000

Use of Water Resources Ø In U. S. , 2000 gallons/day/person Ø Agriculture - 700 gallons Ø Industry/commercial - 1200 gallons Ø Home - 100 gallons - 3 X world average - 20 X developing nations United States Power cooling 38% Agriculture 38% Industry 11% Public 10%

Problem: Too Little Water Ø Dry climate Ø Drought - 40% of people Acute shortage Adequate supply Shortage Metropolitan regions with population greater than 1 million

Problem: Too Much Water Ø Natural phenomena Ø Aggravated by human activities Ø Renew and replenish Reservoir Dam Levee Floodplain Flood wall

Maintaining Adequate Supplies Ø Increase current supply Ø Reduce pollution Ø Use water more efficiently

Tapping Groundwater Ø Year-round use Ø No evaporation losses Ø Often less expensive Ø Potential Problems!

Problems with Using Groundwater Ø Water table lowering Ø Depletion Ø Subsidence Ø Saltwater intrusion

Ogallala Aquifer SOUTH DAKOTA WYOMING NEBRASKA Less than 61 meters (200 ft) 61 -183 meters (200 -600 ft) COLORADO KANSAS More than 183 meters (600 ft) (as much as 370 meters or 1, 200 ft. in places) OKLAHOMA NEW MEXICO TEXAS 0 0 Miles 100 160 Kilometers

Lowering the Water Table Original water table Initial water table Cone of depression Lowered water table

Groundwater Overuse Groundwater Overdrafts: High Moderate Minor or none

Ground Subsidence: High Moderate Minor or none

Saltwater Intrusion Major irrigation well Well contaminated with saltwater Water table Sea Level Salt water Fresh groundwater aquifer Interface Saltwater Intrusion Interface Normal Interface

Using Dams and Reservoirs to Supply More Water Large losses of water through evaporation Flooded land destroys forests or cropland displaces people Downstream cropland estuaries are deprived of nutrient-rich silt Downstream flooding is reduced Reservoir is useful for recreation and fishing Can produce cheap electricity (hydropower) Migration and spawning of some fish are disrupted Provides water for year-round irrigation of cropland

Transferring Water from One Place to Another Ø Watershed transfer CALIFORNIA Sacramento River Ø California Water Project North Bay Aqueduct NEVADA Shasta Lake UTAH Sacramento San Francisco South Bay Aqueduct Ø Central Arizona Project California Aqueduct Fresno Los Angeles Aqueduct Los Angeles Colorado River ARIZONA Central Arizona Project Phoenix San Diego Colorado River Aqueduct Tucson MEXICO

Converting Salt Water to Fresh Water and Making it Rain Ø Distillation desalination Ø Reverse osmosis desalination Ø Desalination is very expensive Ø Cloud seeding

Using Water More Efficiently Ø Reduce losses due to leakage (e. g. , Boston) Ø Reform water laws (use it or lose it) Ø Improve irrigation efficiency Ø Improving manufacturing processes Ø Water efficient landscaping Ø Water efficient appliances

Solutions: Achieving a More Sustainable Water Future Ø Efficient irrigation Ø Water-saving technologies Ø Improving water management

Gravity Flow Drip or Trickle Irrigation (efficiency 60% and 80% with surge valves) Water usually comes from an aqueduct system or a nearby river. (efficiency 90 -95%) Above- or below-ground pipes or tubes deliver water to individual plant roots. Irrigation Methods Center Pivot (efficiency 80% with low-pressure sprinkler and 90– 95% with LEPA sprinkler) Water usually pumped from underground and sprayed from mobile boom with sprinklers.

Saving Water in the Bathroom

Gray Water and Dual Systems