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Ground Water Basics continued

Ground Water Basics continued. Soil Moisture Regimes. Aridic arid climate, usually dry, irrigation required for crop production. Ustic—semiarid climate, rainfall during a growing season. Xeric—semiarid climate, Mediterranean climate, cool, moist winters, dry summers,

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Ground Water Basics continued

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  1. Ground Water Basicscontinued

  2. Soil Moisture Regimes • Aridic arid climate, usually dry, irrigation required for crop production. • Ustic—semiarid climate, rainfall during a growing season. • Xeric—semiarid climate, Mediterranean climate, cool, moist winters, dry summers, • dryland crop possible from stored soil water. • Udic—humid climate, usually moist, generally irrigation not required for crop • production. • Perudic—precipitation exceeds evapotranspiration in all months, but soil is not • saturated for long periods. • Aquic—soil saturated long enough to cause anaerobic conditions

  3. Soil Moisture Regimes

  4. Types of Porous Media Isotropic Anisotropic Homogeneous Heterogeneous

  5. Hydraulic Conductivity Values Freeze and Cherry, 1979

  6. Layered media (horizontal conductivity) Q4 Q3 Q2 Q1 Q = Q1 + Q2 + Q3 + Q4 K2 b2 Flow K1 b1

  7. Layered media(vertical conductivity) R4 Q4 Flow R3 Q3 K2 b2 R2 K1 b1 Q2 Controls flow R1 Q1 Q = Q1 = Q2 = Q3 = Q4 The overall resistance is controlled by the largest resistance: The hydraulic resistance is b/K R = R1 + R2 + R3 + R4

  8. Aquifers • Lithologic unit or collection of units capable of yielding water to wells • Confined aquifer bounded by confining beds • Unconfined or water table aquifer bounded by water table • Perched aquifers

  9. Transmissivity • T = Kb gpd/ft, ft2/d, m2/d

  10. Schematic T2 (or K2) b2 (or h2) i = 2 k2 d2 T1 b1 i = 1 k1 d1

  11. T2 (or K2) k2 T1 k1 Pumped Aquifer Heads b2 (or h2) i = 2 d2 b1 i = 1 d1

  12. T2 (or K2) k2 T1 k1 Heads h2 - h1 b2 (or h2) h2 i = 2 d2 h1 b1 i = 1 d1

  13. LeakanceLeakage coefficient, resistance (inverse) • Leakance • From below: • From above:

  14. T2 (or K2) k2 T1 k1 Flows h2 h2 - h1 b2 (or h2) h1 i = 2 d2 qv b1 i = 1 d1

  15. Poisson Equation

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