SSC462 Soil Erosion1.notes

SSC462 Soil Erosion1.notes - SOIL EROSION Natural...

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S OIL E ROSION Natural (geologic) and accelerated (anthropogenic) erosion is the detachment, transport, and deposition of soil particles by erosive forces (gravity, water, wind). While soil erosion can be controlled, it is almost impossible to completely stop (exception is wind erosion). Erosion process:detachment transport deposition Mass Movement soil loss due to gravity (landslips, landslides) Water Erosion soil erosion types caused by water Wind Erosion soil erosion by wind Mass Movement (Landslides) downward movement of soil and rock under by gravity extensive mass movement can result in permanent loss of houses, roads and agricultural land Forms of mass movement include: Earthflow - slabs of soil become liquid and flow downhill Slumps and landslips - usually caused by rotational failure of subsoil layer Rock avalanches - collapse of rock structures Soil creep - slow downhill creeping and rolling of soil particles Terracetting - minor form of mass movement caused by livestock traversing hillsides Landslips, slides and earth flows occur on steep slopes with high clay content. Triggered by over-saturation of soils from excessive rainfall Rainfall increases soil weight, and lubricates layers within the soil Slips usually occur along a plane of weakness or highly lubricated soil layer Landslips, slides and earth flows may also be triggered by erosion at the base of the slope. Landslides occur when underlying soil layers are more saturated and erodible than outer layers. As water seeps through surface it acts as a lubricant and causes outer layers to detach. Then gravitational forces take over and cause mass to slide rapidly to foot of hill or bottom of gully. Prevention and Control requires combination of vegetation and engineering structures dense tree planting above susceptible areas surface drains within and above affected area sub-surface drains. In some cases engineering structures such as soil pins, retaining walls, rock filling and slope
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This note was uploaded on 08/01/2008 for the course SSC 462 taught by Professor Havlin during the Spring '08 term at N.C. State.

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SSC462 Soil Erosion1.notes - SOIL EROSION Natural...

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