EARTHSS 17 Lecture Notes - Lecture 16: Refraction, 100-Year Flood, Overbank
2 Nov 2016
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A: courser sediments can only be transported in faster flowing water. Fine grained sediments drop out in slack water after a flood. During floods the capacity and competence of a river both increase. Natural levees form parallel to the stream channel by successive floods over many years. People try and build on the levees and increase height and regulate water levees, decrease overbank flow: they put these rocks and fine material called rip-raps on the side of rivers. People feel safe because there are levees and it prevents from water flood: water can be kept in but in times of flood. Levees will cause worse flooding upstream for others: also causes downstream flooding, water is going through a very narrow channel and speeds up, The super-fast flowing water goes through the town more sediment gets picked up. The channel gets deeper it then spills out farther down stream. Water ways were contaminated, just due to levy failure.
