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Hydrologic Cycle

Hydrologic Cycle. Aquifer —a body of rock or sediment that stores, filters, and transmits water through pore spaces and openings in the rocks. Henri Darcy, Dijon, France, 1855 Defined the term “hydraulic conductivity” to mean the ease with which a material

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Hydrologic Cycle

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  1. Hydrologic Cycle

  2. Aquifer—a body of rock or sediment that stores, filters, and transmits water through pore spaces and openings in the rocks

  3. Henri Darcy, Dijon, France, 1855 Defined the term “hydraulic conductivity” to mean the ease with which a material transmits water.

  4. Darcy’s Law: Q K = AI K = hydraulic conductivity (m/day) I = hydraulic gradient (m/m) A = cross-sectional area (m2) Q = discharge (m3/day)

  5. Artesian system—confined aquifer

  6. Problems with groundwater withdrawal: • Overdraft—occurs when withdrawal from • wells + natural discharge > recharge

  7. High Plains (Ogallala) Aquifer

  8. 30 % of all groundwater withdrawn in US is taken from High Plains Aquifer, mostly for irrigation Center pivot irrigation

  9. Ogallala-- groundwater withdrawals for agriculture: 14 bgd 5.5% of 0.2% of total water withdrawals: 0.78 bgd groundwater withdrawals: 0.03 bgd Tennessee

  10. Changes in the water table level in the Ogallala (1890-1999): • 1900-1980—avg. water table • decline: 10 ft (max. 175 ft) • 1980-2000— water table decline has • slowed due to regulations • and more efficient irrigation • techniques MAP of Changes in Ogallala

  11. 2. Land subsidence • lowering of land surface due to • groundwater withdrawal

  12. Venice, Italy— land subsidence, coastal flooding

  13. Central Valley, Calif.— land subsidence

  14. Mexico City

  15. abaondoned well casing, Mexico City

  16. Special problems with groundwater: Karst—terrain having unique characteristics of relief and drainage due to dissolution of carbonate rocks (limestone, dolomite)

  17. landfill cave stream Karst aquifers are typically not good filters of groundwater pollutants

  18. Winterpark, FL “Oh no, my truck!”

  19. Collapse sinkhole in Cookeville

  20. TOTAL FRESHWATER WITHDRAWALS, 1995

  21. Groundwater withdrawals and uses in the US (2000) million gallons Use per day (bgd) % Irrigation 56.9 69 Public supply 16.0 19 Industry 3.6 4 Other 6.6 8 Total 83.1 100

  22. Fig. 4.2 California, Central Valley and western basin aquifers (10%) High plains aquifer (30%) Miss. R. aquifers (15%)

  23. Water resources of Tennessee % Tennesseans that rely on public water 1960……68% 1995….. 84% TN -- Total water withdrawals: Surface water (rivers, reservoirs): 96% Groundwater: 4%

  24. East TN: some high-producing aquifers in areas of fractured bedrock Middle TN: poor aquifers due to low-porosity, dense limestone bedrock West TN: very productive aquifers, sand and gravel deposits

  25. Note high withdrawals from TVA reservoirs. These supply major cities and provide water for steam plants.

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