Periodic floods also deposit fresh alluvium

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Unformatted text preview: ands and associated wildlife. Periodic floods also deposit fresh alluvium replenishing soil nutrients and organic matter. Thus flooding, agriculture, and agricultural practices are closely connected. Present-day negative effects of deforestation swamp the normally positive effects of natural flooding. 9 3 The Hydrologic Cycle Processes involved: Evaporation Precipitation Infiltration Runoff Transpiration 10 Where does most of the precipitation fall? 11 12 4 Channel Morphology Drainage Basins A B Stream Gradient 13 - volume of water going past certain point over Longitudinal river profile time Head Waters: • high velocity • erosion Head Waters Plains - speed plus dimensions of channel Coastal Plains: • low velocity • _________ deposition Distance River Discharge : Q = W x D x V 14 - Tems River; central channel (meandering) Features of a Lowland River - flood plane = space that water will occupy Flood Plain Meander Oxbow lake Levees High f low Channels Back Swamps Deltas in case of flood, flattness records back and forth of channel, carve plato like feature - sendiment come out of water, decreses in speed no longer transport sediment 15 natural levees: high areas when water escapes banks flows out and forms these, helps prevent small flood 5 - places that are eroded, and deposition is the River Features - flood concentrated to outer bank, piles up - high pressure area on outer bank, wants to go Erosion & Deposition from high to low pressure, flows down to other side - now have area on inner bank where deposition occurs cause flow is slowest Deposition: Levees 16 - coarsest sediment, natural levees/guard against minor floods = breakwaters -flow fastest = erosion, slow is slowly =deposition -longitudial flow, vortical flow, add 2 together, flow is like a corkscrew, goes other way around other bank - oxbow lake when meander is working harder then needed, and it gets cut off River Features Deltas Oxbow Lake - deltas - lot of mud, not a lot of wave action - 17 - stream system curves down, terraces - point bar deposit, meander scar, backswamp, yazoo tributary, meandering, graded stream, oxbow lake Stream Processes and Floodplain Development 18 6 The worst flood of the centur...
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This document was uploaded on 02/25/2014.

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