chapter12_post

Chapter12_post - Extra notes from Ch 11 A river can have high erosive or high depositional power Not both at the same time Relationship to sediment

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Extra notes from Ch. 11 • A river can have high erosive or high depositional power. Not both at the same time. Relationship to sediment load: •If sediment load in the river is high, it has high depositional power. •If sediment load in the river is low, it has high erosional power Relationship to velocity (and therefore discharge) •If velocity is high, erosive power is high •When sediment load or discharge is changed, a river will change its pattern or gradient to maintain a natural balance of erosion and deposition.
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Ch. 12-- Floods and Human Interactions Development Effects on Floodplains Urbanization Deforestation from fires, logging, overgrazing Mining Bridges Levees and their effects on flooding Flooding from dam failure Reducing flood damage
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Development Effects on Floodplains Early towns were established along rivers and waterfronts. Why? Though floodplains are created through natural processes, urban development and other human activities increase the size and damaging nature of floods Severe alterations of landscape through urbanization, logging, grazing, forest fires: adds sediment load to rivers; increased size and damaging nature of floods Increasing urbanization promotes increasing numbers of flash floods and higher flood levels wherever roads and buildings cover landscape, there is increased surface runoff
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Fires, Logging, and Overgrazing Forest soil and brush soaks up water Deforestation of watershed by fire, heavy logging or overgrazing cause increased sediment load Fire removes soil protection, decreases soil permeability Clear-cut logging methods remove brush, form logging roads that focus downslope drainage and add sediment to streams Grazing removes surface vegetation, increasing soil erosion Streams become choked with sediment, braided, steeper
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Streambed Mining Large amounts of sand and gravel for construction use come from streambed mining (It is easier to mine gravel from
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This note was uploaded on 02/02/2010 for the course GEO 107 taught by Professor Stidham during the Fall '08 term at SUNY Stony Brook.

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Chapter12_post - Extra notes from Ch 11 A river can have high erosive or high depositional power Not both at the same time Relationship to sediment

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