ERS120H5 Lecture 21: LEC 21
Document Summary
Big floods: historic and from the geologic record. Late pleistocene: blockage of the clark"s fork river by the cordilleran ice sheet, up to 25 floods between 15 and 13,000 years ago, up to 17 million m^3/s, 2nd largest known flooding event. Katla jokulhlaup, iceland: katla eruption, 1918, 300,000 m^3/s, enough sediment in the flow to extend the coastline by 5km. Usoi landslide dam and lake sarez, tajikistan: 550m high landslide dam formed after earthquake in 1911, 5 million people live in the potentially affected downstream areas. Oroville dam, california: reservoir rise driven by high rainfall, 180,000 people evacuated downstream. Spillway not maintained properly: began to erode and exploit. Lagtime reflects the time it takes for water to flow into the river from all parts of the basin. Manitoba: 1997, 1950, 2009, 2011. , ground is often frozen so it can"t go through so it floats on the surface. Spring floods caused by snow melt and rain, with saturated or frozen ground.
