Landform Geography

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Landform Geography
Groundwater and Karst Landscapes
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Movement Storage of Groundwater

• Precipitation sinks into soils soil-water belt
• In dry soil, water is held tight by sediment
  grains as hygroscopic water unavailable for
  plants
• When pore spaces within soil full of water, soil
  at Field Capacity additional water flows down
  into unsaturated zone
• Water collects above an impermeable aquiclude to
  form saturated zone
• Large saturated zone is aquifer

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Fate of Precipitation on Soil
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Soil-Water Conditions
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Saturated Zones Aquicludes
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High Plains (Ogallala) Aquifer

• Underlies much of Great Plains from TX to SD
• Water deposited in Ice Ages 1.6 M-10K yrs ago

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High Plains (Ogallala) Aquifer

• Heavy usage, esp. center-pivot irrigation
• Drawdown significant in parts of aquifer

Center-Pivot Irrigation
Drawdown
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Artesian Wells and Springs

• Natural pressure brings water to surface in
  artesian well

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Patterns of Groundwater Depletion

• Cone of Depression cone-shaped depression in
  water table that occurs around a well

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Subsidence

• Settling or sinking of a surface due to removal
  of water or sediment from below
• Worst around large cities such as Venice, Italy
  and agricultural regions such as the San Joaquin
  Valley of California

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Groundwater Contamination

• Dumped chemicals can be carried by moving
  groundwater to sources of drinking water
• Recent federal rules have reduced uncontrolled
  dumping and contamination

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Karst Landforms

• Caves, sinkholes and other soluble rock features
• Form in extensive, thick deposits of limestone
• Limestone 80 calcium carbonate dissolves
  easily through carbonation

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Caves and Caverns

• Caves underground voids in rock big enough for
  people to enter
• Cavern large cave system
• Form just below water table in limestone when
• water table falls, empty caverns are exposed

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Karst Topography - Sinkholes

• Most common surface feature of karst is sinkhole
• Sinkhole depression in regions of cavernous
  limestone forms from collapse of cave
• Often found with disappearing streams that enter
  underground channels
• Some sinkholes fill with water, forming ponds
• Sinkholes can be hazards, collapsing under homes
  or roads

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Sinkhole Landscape