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Groundwater Fundamentals

Groundwater Fundamentals. Module 9.1. Groundwater. Source: Wisler & Brater, 1949, Hydrology. Groundwater Flow…. …Produces Baseflow. Groundwater as a “slow” reservoir. Groundwater Terminology. Confined and Unconfined Aquifers. Artesian Well. More on Aquifer Types…. Hydraulic Head.

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Groundwater Fundamentals

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  1. Groundwater Fundamentals Module 9.1

  2. Groundwater Source: Wisler & Brater, 1949, Hydrology

  3. Groundwater Flow… …Produces Baseflow

  4. Groundwater as a “slow” reservoir

  5. Groundwater Terminology

  6. Confined and Unconfined Aquifers

  7. Artesian Well

  8. More on Aquifer Types…

  9. Hydraulic Head Pressure: Where:r = density of water (kg m-3)g = gravitational acceleration (m s-2)hp = pressure head hp ht a Total hydraulic head (ht): z datum Where:z = elevationhp = pressure head

  10. Darcy’s Law Darcy’s Law defines groundwater flow: where:Q is discharge (L3 T-1)kv is the hydraulic conductivity (L T-1)A is area of flow (L2), anddht/dx is the gradient of pressure, or head

  11. Hydraulic Conductivity (kv) Hornberger, 1998

  12. Example 800 m 85 m 2 m kh=5 m day-1 Fine sand 25 m

  13. Groundwater Development

  14. Gaining Stream Groundwater/Surface Water Connections In systems with high degree of groundwater/surface water connectivity(highly transmissive sediments) Pumping Well Cone ofDepression Groundwater

  15. Subsidence Causes:Fluid withdrawal Sinkholes Drainage of Organic soils Mining From USGS Professional Paper 1401-A, "Ground water in the Central Valley, California- A summary report"Photo by Dick Ireland, USGS, 1977

  16. Recharge Zone Protection Example UnconfinedAquifer Recharge Zone Confined Aquifer landfill Municipal well field Piezometric surface Gravel flow Clay Clay

  17. Groundwater Development • Multiple pumping wells can cause interference between cones of depression • Extraction should not exceed recharge • Water mining • Extraction may cause subsidence • Recharge zones should be protected • Ensure adequate water flow • Ensure quality • Extraction may affect surface water • Many watershed management actions are taken to protect quality

  18. Gaining stream Effluent stream Losing stream Influent stream Perched losing stream Flow-through stream Gaining and Losing Streams Dingman

  19. Hyporheic Zone • Zone where water is exchanged between surface and groundwater • Controlled by geomorphology (upwelling and downwelling) • Biochemical processing: water quality & habitat issues • Temperature

  20. 2nd-Order / Unconstrained reach of WS03, HJA Scale (m) 0 25 50 Kasahara & Wondzell (2003) Water Resour. Res.

  21. Proposed C & D Landfill Example Creek Modeled contaminant plumes Zone exceedingMCL’s for drinking water Old Gravel Pit Constituents of ConcernSulfate Arsenic Chromium Iron 1,2-DCA Total Dissolved Solids Increased, butMCL’s for drinking Water not exceeded Glacial Outwash Domestic Wells Flow Direction Municipal Wells

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