1Water Resources in the Hydrosphere!• This unit:– Earth’s Water Reservoirs and the Hydrologic Cycle– Water As A Resource– Surface/Groundwater Systems– Water Quality/PollutionGeologyWater QualityPollutionEarth’s Water Reservoirs97.5%0.001%0.016%1.81% 0.63%Largest amount of fresh water is stored as ice.98.4% of all unfrozen fresh water is in the groundwater system.The Hydrologic CycleWater As A Resource• Historical View: Perpetual Resource• Surface Water - Renewable or “flow”resource on a global scale• Groundwater - Potentially renewable or non-renewable “stock” resource • Recoverable• No substitute resource for it!2Whiskey is for drinkin’, water is for fightin’… Mark Twain• Slightly less than 1% of all the water on Earth is fresh (potable) water.– 1250 km2stored at any one time– Continuous flow --> 40,000 km3/year• 6.3 billion people compete for it!US Water Budget – Billions of gallons per dayIs Ample Water Available everywhere?• No – it is unevenly distributed.• Demand exceeds availability in many areas.– Variability results from:• Climate Regions• Climate change (trend) • Changing patterns of precipitation•Seasonal• Random variabilityWater Distribution• Differences in supply related to:– Average annual precipitation– Evapotranspiration– Runoff• If precipitation > evapotranspiration:– Surface water fills channels, infiltrates soils, and replenishes groundwater3Average Annual Precipitation in U.S. Potential Evapotranspiration Annually in InchesEphemeral (flow only certain times per year) vs.Perennial Streams (flow continuously all year)How does U.S. use its water?• 400 billion gal/day46%42%12%U.S.69%23%8%WorldAgriculturalIndustrialDomestic4Water Consumption vs. Water Use• Use = water is returned to stream after use - recycled• Consumption = water lost to atmosphere• Agriculture is major consumer77%25,300Domestic24%137,000Irrigation85%27,800Industry98%195,000Electric Power% ReturnedMillion gal/yrIndustry38%Home19%Agriculture43%Water Use • A person needs approximately 1 gallon of water per day for fluid replenishment.• U.S., 1998, per capita use per day.– 250 gallons/day per person for domestic/personal use.– 1547 gallons/day per person for agriculture/ industry• In contrast: more than half the world’s people use less than 25 gallons per day for domestic purposes!How do you use water?The Growing Water Crisis5Summary• The Earth has a huge amount of water, but very little of it is fresh and fit for human consumption.• Water is not distributed evenly among the continental land masses, and there are areas that have water shortages.• The U.S. per capita use of water is much greater than the world average.• There is a difference between water use and water