Water resourse

Water as a resource : 

Water as a resource Water covers 70% of the planet How much of this is salt water? How much of this is fresh water? Why can’t we use all of this freshwater? ¾ of this is ice and inaccessible 90% of ice is in Antarctica Only 0.6% of earth’s water is fresh water that is readily available Most of this is groundwater only 0.014% is in freshwater lakes and rivers!

The Hydrologic Cycle : 

The Hydrologic Cycle “Pump” powered by? Circulates water through the major stores: Oceans (97.4%) Atmosphere (.001%) Land (2.6%) How long does it take for water to cycle? Atm = 9-10 days Rivers, streams = 2 weeks Lakes = 10s years Groundwater = 100s to 1000s yrs Ocean = 10,000s yrs Icecaps/glaciers =10,000s yrs

Global water budget : 

Global water budget Precipitation: Rain, snow, etc… Evapotranspiration: Transfers water into atmosphere by evaporation or transpiration ~2/3 of ppt is lost to evapotranspiration ~1/3 enters groundwater and surface water supplies

Surface waters : 

Surface waters River, streams, lakes Drainage basins and watersheds Area of land that forms the drainage of a stream or river Any drop of water falling within a watershed will drain out the same river or stream. Land along rivers highly populated… why? We get ½ of our drinking water from surface water supplies… http://www.movingwaters.org/images/upper_lower%20basin%20map%20copy.jpg

Groundwater : 

Groundwater Water infiltrates into soil and into rock pores until stopped by impermeable layer Water table = boundary between zone of saturation (aquifer) and zone of aeration Groundwater supplies drinking water for ½ of US

Groundwater depletion or overdraft : 

Groundwater depletion or overdraft Water from aquifer withdrawn faster than recharged Average aquifer takes 200 yrs to recharge Nonrenewable resource ? Aggravated by paving over recharge areas & destroying wetlands Ogallala Aquifer is ½ depleted

Water Use : 

Water Use Major water users: 48% thermoelectric (steam) 35% agriculture 10% public 5% industry Thermoelectric: Power plants withdraw the most water, but it’s a non-consumptive use (most returned to source) Agriculture 2nd largest water user Water used not returned (consumed) Very inefficient – only 37% of water absorbed by crops, most evaporates from ditches first Industry uses water in manufacturing Return not always clean Per capita water usage in the US since 1980 has _______?

Dams & Reservoirs : 

Dams & Reservoirs More than 36,000 major dams worldwide Reasons for building: Minimize floods Water source stored for nearby towns Move water via canals and aqueducts Hydroelectric power Recreation

Slide 9: 

1922 Colorado River compact 7 states and Mexico Entitlements exceed natural annual flow

“The most regulated river in the world” : 

“The most regulated river in the world”

Environmental impacts of dams : 

Environmental impacts of dams Sediment accumulation behind dam Will fill up in a few hundred years Scouring downstream doesn’t happen With low sediment water Submergence of shorelines Biological disturbance Blocking migration of fish, loss of habitat, disease, temperature changes, regeneration of native trees Water loss by evaporation In TX 3x lost vs. used by industry and cities Salinization Evaporation leaves salts behind http://nafbw.wsu.edu/Field-Trips.htm