GEOG306 Lecture Notes - Lecture 7: Sediment Transport, Management System, Percolation Trench
8 May 2019
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Document Summary
More pollution-tolerant invertebrates in the river, more sensitive ones are lost: 2. Fish start spawning lay eggs in system, cover materials with gravel all fine sediment in gravel goes into water column: 3. Reservoirs in areas that are prone to considerable erosion, downstream the reservoirs have a shorter lifetime (3-10 instead of 10-50) bc they fill up with sediment. Soil erosion and land management: during past 12000 years, annual sediment loss worldwide has increased from 9 to 20 billion tons, ~ 4. 5 million square miles of land degraded due to farming, deforestation and grazing in. Type of soil erosion by water: when material enters the stream, it is transported down. Raindrop erosion: size (1 to 7 mm) Rill erosion: due to concentration of surface water (sheet erosion) into deeper, faster-flowing channels, velocity increases with flow depth detaching soil particles and scouring channels up to. 30cm deep: rills about 25-30 cm deep.
