8-1
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Alluvial Fan
8-7
Delta
8-8
Which stream is more likely to be “Seasonal”?
8-9
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8-16
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8-18
Insurance Companies & HomeownersStudy historical “Peak Discharge”
Discharge determines area to be floodedUse Recurrence Interval Equation
Allows you to “predict” floodingWhy is it getting worse?
8-19
Recurrence Interval (RI) = (N+1)/MN= number of years of dataM=magnitude of the event
This equation allows you to predict frequency of flooding events
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Type of Precipitation eventGround ConditionsVegetation Cover
8-24
Removal of VegetationDestruction of WetlandsConstruction ActivityUrbanization
8-25
Flash Floods (Upstream Floods)Smaller StreamsSteeper SlopesShorter “Lag Time”Little or No Warning
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8-27
Downstream FloodsWider valley and larger floodplainRegional water from higher in drainage basinSignificant “Lag Time”Time for WarningCovers larger area
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Build Dams
8-30
8-31Channelization
8-32
Retention Basins
8-33
Erosion Control
8-34Floodplain Management & Wetlands Restoration
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