![]() ![]() Gully erosion occurs when runoff water accumulates and rapidly flows in narrow channels during or immediately after heavy rains or melting snow, removing soil to a considerable depth. This means that rills exhibit hydraulic physics very different from water flowing through the deeper, wider channels of streams and rivers. Flow depths in rills are typically of the order of a few centimetres (about an inch) or less and along-channel slopes may be quite steep. Generally, where water erosion rates on disturbed upland areas are greatest, rills are active. Rill erosion refers to the development of small, ephemeral concentrated flow paths which function as both sediment source and sediment delivery systems for erosion on hillslopes. Ī spoil tip covered in rills and gullies due to erosion processes caused by rainfall: Rummu, Estonia ![]() Sheet erosion is the transport of loosened soil particles by overland flow. If the runoff has sufficient flow energy, it will transport loosened soil particles ( sediment) down the slope. If the soil is saturated, or if the rainfall rate is greater than the rate at which water can infiltrate into the soil, surface runoff occurs. The distance these soil particles travel can be as much as 0.6 m (2.0 ft) vertically and 1.5 m (4.9 ft) horizontally on level ground. In splash erosion, the impact of a falling raindrop creates a small crater in the soil, ejecting soil particles. Splash erosion is generally seen as the first and least severe stage in the soil erosion process, which is followed by sheet erosion, then rill erosion and finally gully erosion (the most severe of the four). Rainfall, and the surface runoff which may result from rainfall, produces four main types of soil erosion: splash erosion, sheet erosion, rill erosion, and gully erosion. Soil and water being splashed by the impact of a single raindrop However, there are many prevention and remediation practices that can curtail or limit erosion of vulnerable soils. Intensive agriculture, deforestation, roads, anthropogenic climate change and urban sprawl are amongst the most significant human activities in regard to their effect on stimulating erosion. Water and wind erosion are the two primary causes of land degradation combined, they are responsible for about 84% of the global extent of degraded land, making excessive erosion one of the most significant environmental problems worldwide. Off-site effects include sedimentation of waterways and eutrophication of water bodies, as well as sediment-related damage to roads and houses. In some cases, this leads to desertification. ![]() On-site impacts include decreases in agricultural productivity and (on natural landscapes) ecological collapse, both because of loss of the nutrient-rich upper soil layers. Excessive (or accelerated) erosion causes both "on-site" and "off-site" problems. At agriculture sites in the Appalachian Mountains, intensive farming practices have caused erosion at up to 100 times the natural rate of erosion in the region. While erosion is a natural process, human activities have increased by 10-40 times the rate at which soil erosion is occurring globally. The transport of eroded materials from their original location is followed by deposition, which is arrival and emplacement of material at a new location. Feedbacks are also possible between rates of erosion and the amount of eroded material that is already carried by, for example, a river or glacier. Typically, physical erosion proceeds the fastest on steeply sloping surfaces, and rates may also be sensitive to some climatically-controlled properties including amounts of water supplied (e.g., by rain), storminess, wind speed, wave fetch, or atmospheric temperature (especially for some ice-related processes). The rates at which such processes act control how fast a surface is eroded. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres.Īgents of erosion include rainfall bedrock wear in rivers coastal erosion by the sea and waves glacial plucking, abrasion, and scour areal flooding wind abrasion groundwater processes and mass movement processes in steep landscapes like landslides and debris flows. ![]() Removal of rock or soil as clastic sediment is referred to as physical or mechanical erosion this contrasts with chemical erosion, where soil or rock material is removed from an area by dissolution. Erosion is distinct from weathering which involves no movement. An actively eroding rill on an intensively-farmed field in eastern GermanyĮrosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust and then transports it to another location where it is deposited. ![]()
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