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Note: Groundwater
Groundwater accounts for …
•The largest reservoir of usable freshwater on the planet
•Other functions:
•Water soaks & infiltrates through zone of … to the zone ...
Water Table =
Depth of water table can change
–Depends on amount of …
•Elevation of water table depends on …
–Water table elevation is higher …
–In many swamps & lakes, water table is …
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Factors affecting Groundwater
1.Porosity
–Water soaks into ground b/c rock, sediment & soil have pore spaces
–Porosity = …
–Sediment and sedimentary rock:
–Igneous Rock:
•Water can only exist in rock fractures/cracks
2.Permeability
–Pores in rock or sediment must be connected to allow water to flow through
–Permeability =
–Smaller pore spaces =
–Ex/ clay: high porosity but low permeability (prevents water from moving
through)
–Aquitard =
•Ex/ clay layers (small pore spaces)
–Aquifer =
•Ex/ sand or gravel (large pore spaces)
Movement of Groundwater
•Movement is slow (maximum 1 km/yr)
•Moves according to …
•Usually, it enters streams
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Springs
•Occur when a perched water table causes groundwater to flow and exit at
surface.
Hot Springs & Geysers
•Form as groundwater is heated by nearby …
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•Water heats, expands, and rises to surface
Wells
•Well =
•Heavy use of a well (irrigation) can cause water table to lower
–Other wells may dry up
Groundwater Erosion & Deposition
•Water may dissolve limestone beneath surface
–Produces …
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