GEOS 1034 Lecture 10: Floods
18 Aug 2016
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Document Summary
8 inches of rain in 48 hours on estes park: 1800 homes destroyed, 16000 damaged, 9 deaths. 12 inches of rain in 4 hours: 400 homes destroyed, 143 deaths. A high-discharge event: level exceeds capacity of channel. Discharge levels predictable: given historical data. Volume of water per unit time: m3/sec, ft3/sec (cfs) Discharge from the drainage basin exits through a single outlet. Measure channel shape: fitting curve, intergrating manually. Give channel shape data, water level (stage) measured by gage: ruler type or stilling well. Low discharge results in sedimentation: high discharge results in erosion (scour, requires dynamic measurement. Geological survery monitors is about 7400 sites. Areas of low relief adjacent to river channel. Part of the river: stores excess water during high discharge, stores excess sediment during low discharge. River meanders back and forth: eventually reaches valley sides. When discharge overflows channel, sediment gets left behind: velocity highest in channel, lowest on floodplain.
