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WATER USE & DISTRIBUTION PowerPoint Presentation
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  2. Key H20 Characteristics • Water is the prime constituent of all living organisms. • Water moves easily-from one physical state to another, and from one place to another. • Water slowly absorbs and releases large quantities of energy. • Creates habitable climate & moderates world temp. • Water is a superior solvent. • Michael D. Lee Ph.D. Geography and Environmental Studies (Source: Wright & Nebel 2002)

  3. The Hydrologic cycle • Driven by sun Gets into the air by… • Evaporation of surface water or sublimation of snow & ice • Transpiration from plants & animals • Evaporation + transpiration = evapotranspiration • Water enters atmosphere leaving behind salts & other contaminants • Amount of water in atmosphere is humidity • Warm air holds more water than cold • When air has all the water it can hold it has reached its saturation point. (Relative humidity is the amount of water vapor in the air expressed as a % of max amount (saturation point) that could be held at that particular temperature.) • When saturation point is exceeded the water molecules aggregate in process called condensation. • Condensation nuclei (particles that water adhere to) initiate the cloud forming process • When water droplets are too big for air currents to suspend, they fall to the ground as precipitation.

  4. Hydrologic Cycle When water reaches land… • Runoff- into lakes, rivers, streams • Infiltration- percolates thru soil • Temporary storage as snow and ice • Temporary storage in lakes • Temporary storage in plants (transpiration) and animals • Chemical reactions with rocks and minerals • Source of additional water? volcanism (steam)

  5. Hydrologic Cycle SW%20Management.htm

  6. Rainfall & Topography • Rainfall uneven over planet • Rainshadow Effect • Air sweeps up winward side of mtn, air cools, condenses, and rains. • As air falls down leeward side of mtn, air warms & rainfall decreases • EX: Mt. Waialeale in Hawaii, Himalayas in south Asia, Sierra Nevada of CA, Oregon & Washington State • Desert Belts • Located at Tropics of Cancer & Capricorn (around 20-40 latitude) • Evaporation & precipitation happen at equator and as air circulates toward poles it has less water and falls as hot dry air, creating deserts.

  7. Global Precipitation Patterns

  8. Available Water • Total = 326 million cubic miles • 97% of Earth’s water is in oceans • 2.997% is locked up in ice caps and glaciers • 0.003% is easily accessible • Soil moisture • Groundwater • Water vapor • Lakes • Streams

  9. Water Supply & Use

  10. Amount of water on planet From Water Exhibit @ Natural History Museum in New York Amount of USABLE water on planet

  11. Major Water Reservoirs

  12. Oceans • Regulates earth’s temp by absorbing and releasing heat • Too salty for human use- without expensive distillation process • 90% of earth’s living biomass is in the ocean • Warm & cold water occurs in layers • Sun warms surface, colder water is denser so sinks. Warm water sits on cold water • Average life of a water molecule in the ocean is 3000 years

  13. Glaciers, Ice & Snow • Glaciers- rivers of ice flowing downhill very slowly • Make up 2.4% of freshwater on earth • Made of freshwater- salt is excluded during freezing

  14. Groundwater • Water infiltrates thru soil and is stored underground • Zone of aeration • Upper soil layer where air & water mix • Contaminants may be removed here- but not all • Zone of saturation • Lower soil layer where all spaces are occupied by water • Top of this zone is the water table • Water table changes due to amnt of precip & infiltration rates • Aquifers- layers of porous sand, gravel or rock with underlying layer of solid bedrock that stores water • Confined Aquifer- if crust changes due to geologic processes, aquifer can be trapped btwn two layers of bedrock. Under pressure. Can gush out of ground as spring or artesian well. • Powder Springs use to be called Seven Springs because of the 7 mineral springs that bubbled up from ground. • Recharge zones- areas of land that allow seepage of water back into aquifer

  15. HOW RIVERS WORK: the role of groundwater outlines/groundwater.html

  16. Surface Water Surface runoff flows into rivers, streams, lakes, ponds, and wetlands Watershed- area of land that drains into a body of water • Moving water- rivers & streams • Standing water- lakes, ponds, wetlands

  17. Moving Waters(streams & rivers) • Originate as • Meltwater from snow or ice • Seepage from groundwater (spring) • Precipitation • Usually headwaters of stream are in mountainous areas • Cold (elevation), highly oxygenated (gravity pulls down over rocks), often small • As stream reaches level ground, deepens and slows & becomes a river • Small streams that empty into river are known as tributaries • EX: Sweetwater creek is a tributary to Chattahoochee River • EX: McEachern creek is a tributary to Noses Creek • Not all rivers carry same amount of water • This measured as discharge- amount of water that passes a fixed point in a given amount of time (cubic meters/second)

  18. Standing Water(lakes, ponds, and wetlands) • Ponds • Shallow enough to allow plants to root across bottom • Lakes • Inland depressions that hold standing freshwater all year • Both are relatively temporary- eventually fill in with sediment from rivers or are emptied by water diversion projects • More accessible than groundwater or glaciers • More plentiful than rivers & streams

  19. Chattahoochee River Lake Lanier West Point Lake Flint River Walter F. George Lake Apalachicola River Lake Seminole

  20. Standing Waters(lakes, ponds, and wetlands) • Wetlands • Bogs, swamps, marshes • Plant roots stabilize soil • Slow water for infiltration • Filter pollutants • In the US, 20% of the 1 billion hectares of land were wetlands. About ½ of this has been drained (for agriculture), filled or degraded • Results in • Reduced water holding capacity→ more flooding • Dry stream beds on other side of wetland • Reduction in biological diversity

  21. Atmosphere • Smallest major water reservoir • Water molecule lasts 10 days in atmosphere on average • Important in redistribution of water across planet