Chapter 17 Groundwater. Figure 17.2 Variations in the Water Table Water tends to mimic the land...
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Transcript of Chapter 17 Groundwater. Figure 17.2 Variations in the Water Table Water tends to mimic the land...
Chapter 17 Groundwater
Figure 17.2
Variations in the Water Table
Water tends to mimic the land surface
Variations in rainfall & permeability
Gainingand
Losing StreamsFigure 17.4
Groundwater Storage
Porosity% of pore spacesFluid Storage
Table 17.2
Groundwater Movement
Permeabilityability to transmit a fluid
Aquifer
Yields significant quantities of water
High porosity & permeability
Aquifers
Confined/Closed
Unconfined/Open
Long Island Aquifers
Upper Glacial
Magothy
Lloyd
Aquiclude
Inhibits movement of groundwater Impermeable
Clay or Solid Bedrock
Groundwater Movement
Darcy’s Law
Q=K(dh/dl)A
Darcy’s Law
Q=Discharge
K=Hydraulic Conductivity
dh=Change in water table elevation
dl=Distance over which change occurs
A=Area in question
Spring Resulting from a Perched Water Table
Figure 17.8
Figure 17.13
Artesian Well
Figure 17.15
Artesian Pressure System
Excess Groundwater Withdrawal
Subsidence – land surface sinks
• California
• Venice
• Texas
Excess Groundwater Withdrawal
Saltwater Contamination• Excess groundwater withdrawal
• Saltwater is drawn into wells
• Coastal areas
• Ghyben-Herzberg Equation
Ghyben-Herzberg Equation
Total thickness of freshwater lens = x + 40x
Saltwater Contamination
Figure 17.19
Groundwater Contamination
Sewage
• Extremely permeable aquifers (gravel)
• Travels long distances without being filtered
Groundwater & Erosion
Caves
Caverns
Sinkholes
End of Chapter 17