Running Water (ch. 12, p. 244-
257)
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shapes landscape
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used for water, transportation, power, waste disposal
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hazard (floods)
Hydrologic Cycle: transfer of water between oceans, atmosphere,
and land
Current world water distribution:~ 97% oceans, 2% ice, 1% streams,
lakes, groundwater, atmosphere
When rain falls:
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Some evaporates
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Some infiltrates
depends on soil type, and amount of rainfall
Remaining water runs off. Starts as sheetflow.
becomes concentrated in channels (trough-like depressions)
erodes by:
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hydraulic action
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abrasion
Sediment Transport
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dissolved load: ions from chemical weathering
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suspended load: silt and clay..
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bed load: sand and gravel moves along bottom of channel
Velocity (distance/time) is controlled by:
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Gradient: change in elevation/distance
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Channel shape and roughness:
More friction in broad shallow channels
More friction in rocky channels
Discharge rate total volume moving past a point per unit
of time (velocity x depth x width)
often increases downstream due to:
1) groundwater inflow
2) merging with other streams
Drainage Basin: area from which a stream collects surface water
Drainage Divide: separate drainage basins