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Flow in Aquifers

Flow in Aquifers. Groundwater Hydraulics Daene C. McKinney. Summary. Confined Aquifer Flow Continuity Equation Steady Horizontal Flow Transmissivity Unconfined Aquifer Flow Continuity Equation Steady Horizontal Flow Steady Horizontal Flow with Infiltration Drains.

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Flow in Aquifers

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  1. Flow in Aquifers Groundwater Hydraulics Daene C. McKinney

  2. Summary • Confined Aquifer Flow • Continuity Equation • Steady Horizontal Flow • Transmissivity • Unconfined Aquifer Flow • Continuity Equation • Steady Horizontal Flow • Steady Horizontal Flow with Infiltration • Drains

  3. Unconfined Aquifer Flow

  4. Flow in an Unconfined Aquifer • Dupuit approximations • Slope of the water table is small • Velocities are horizontal Ground surface Water table Unconfined aquifer h Qx K z y x Bedrock Dx

  5. Steady Flow in an Unconfined Aquifer • 1-D flow • Steady State • K = constant Ground Surface Water Table Flow hA h hB Bedrock L x

  6. Steady Flow in an Unconfined Aquifer With Infiltration Steady Flow Constant K N, Infiltration Ground Surface Water Table hMax h Flow hA hB Bedrock L x

  7. Steady Flow in an Unconfined Aquifer With Infiltration N, Infiltration Ground Surface Water Table hMax h Flow hA hB Bedrock L x

  8. Steady flow in an unconfined aquifer with infiltration N, Infiltration Ground Surface Water Table hMax h Flow hA hB Bedrock L x

  9. Example (Embankment) • Given L = 3000 m K = 20 m/day hA = 30 m hB = 20 m N = 500 mm/yr • Find: Flow to the streams and shape of water table N, Infiltration Ground Surface Water Table hMax h Flow hA hB Bedrock L x

  10. Example (Cont.) N, Infiltration Ground Surface Water Table hMax h Flow hA hB Bedrock L x

  11. Example (Drains) • Subsurface drains are often used to prevent the water table elevation from increasing to an elevation where it would waterlog the roots of crops or bring unwanted salts and other chemicals in to the root zone. • Steady, 1-D flow , homogeneous, isotropic aquifer, w/infiltration N, Infiltration Ground Surface Water Table hMax hd Lower Confining Layer L x

  12. Summary • Confined Aquifer Flow • Continuity Equation • Steady Horizontal Flow • Transmissivity • Unconfined Aquifer Flow • Continuity Equation • Steady Horizontal Flow • Steady Horizontal Flow with Infiltration • Drains

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