EARTHSC 2GG3 Chapter Notes - Chapter 1: Silt, Flood, Hydrograph
15 Apr 2018
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Document Summary
Urbanization increases the magnitude and frequency of floods. Urban areas have impervious land cover and storm sewers that can quickly transport water to rivers. This decreases the lag time between a heavy rain event and flooding. Periodic deposits of nutrients by floods enriches the soil for agriculture. Floods flush out debris from channels thus having a positive effect on aquatic ecosystems. Floods keep the surface of river deltas above sea level and can sustain wetlands by adding sediment. These include both earthen and concrete levees, floodways, and storm-water retention basins. Breaks in levees can cause high energy flows of water that quickly inundate an area. The level the river surface must reach in order for it to cause property damage. A graph showing changes in discharge or changes in stage over time. The average time between floods of a certain size. Two or more channels that have intervening islands where sediment is temporarily stored.
