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Hydrologic Cycle/Water Balances

Hydrologic Cycle/Water Balances

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Hydrologic Cycle/Water Balances

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  1. Hydrologic Cycle/Water Balances

  2. Earth’s Water • Covers approximately 75% of the surface • Volcanic emissions • Only known substance that naturally exists as a gas, liquid, and solid at surface temperatures and pressures http://earthobservatory.nasa.gov/Library/Water/

  3. One estimate of global water distribution http://earthobservatory.nasa.gov/Library/Water/

  4. Fresh Water

  5. Hydrologic Cycle • Powered by energy from the sun • Evaporation 90% of atmospheric water • Transpiration 10% • Evaporation exceeds precipitation over oceans • Precipitation exceeds evaporation over continents • All water stored in atmosphere would cover surface to a depth of 2.5 centimeters • 1 m average annual precipitation http://earthobservatory.nasa.gov/Library/Water/

  6. Hydrologic Cycle In the hydrologic cycle, individual water molecules travel between the oceans, water vapor in the atmosphere, water and ice on the land, and underground water. (Image by Hailey King, NASA GSFC.) http://earthobservatory.nasa.gov/Library/Water/

  7. Florida

  8. Florida

  9. U.S. total, surface-water, and ground-water withdrawals, 2000 http://water.usgs.gov/pubs/circ/ 2004/circ1268/htdocs/text-total.html

  10. U.S. total water withdrawals by category, 2000 http://water.usgs.gov/pubs/circ/2004/circ1268/htdocs/text-total.html

  11. Trends in population and freshwater withdrawals by source, 1950-2000 http://water.usgs.gov/pubs/circ/2004/circ1268/htdocs/text-total.html

  12. Water (Mass) Balance • In – Out = Change in Storage • Totally general • Usually for a particular time interval • Many ways to break up components • Different reservoirs can be considered

  13. Water (Mass) Balance • Principal components: • Precipitation • Evaporation • Transpiration • Runoff • P – E – T – Ro = Change in Storage • Units?

  14. Ground Water (Mass) Balance • Principal components: • Recharge • Inflow • Transpiration • Outflow • R + Qin – T – Qout = Change in Storage