EAS100 Lecture Notes - Lecture 19: Alluvial Fan, Downcutting, Alluvium
17 Oct 2018
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Eas 100 lecture 17 flooding and surface water disasters. In alberta, it is commonly because glaciers are melting faster, which feeds more water into rivers and streams. Downcutting can leave old floodplains as terraces, which appear as long broad steps along the length of the river. Flooding is when stream/river discharge is greater than the capacity of the banks. In edmonton, the valley is very built up and the river would have to rise 10s of metres to approach the structures at the top. In flooding, the peak discharge comes after the heavy rains that produced it: meaning water volume is greater well after the rain has stopped, result of surface run-off moving into stream channels, increasing discharge rapidly. Frequency of floods is plotted on a graph to calculate recurrence interval: predict how often it is likely to occur (every 100 years, 50 years, etc. , uses statistical data.
