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Erosion
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Soils and Terrestrial Systems, 2020
A variety of soil conservation methods are available that can be applied on a landscape to minimize erosion problems caused by wind or water. Wind erosion can be controlled through the use of windbreaks, crop residues, and tillage to induce significant surface roughness. Control procedures for erosion by water need to be determined, based upon the types of active erosion processes. For example, if sheet and rill erosion is a major problem, then some type of conservation tillage practice that leaves large amounts of crop residues intact on the soil surface may be appropriate. However, if the water erosion problem is because of the large amounts of surface runoff concentrating in a field and forming an ephemeral gully, then crop residues may not be adequate; instead, permanent vegetative cover in a grass waterway may be necessary, along with appropriate engineering structures (e.g., drop-box). Erosion prediction models can be used to assist in selecting and designing appropriate conservation practices.
Basics of Soil Erosion
Published in Abrar Yousuf, Manmohanjit Singh, Watershed Hydrology, Management and Modeling, 2019
Manmohanjit Singh, Kerstin Hartsch
Rill Erosion is a function of the hydraulic shear T of the water flowing in the rill and two soil properties the rill erodibility Kr and the critical shear Tc, the shear below which soil detachment is negligible. Detachment rate Dr is the erosion rate occurring beneath the submerged area of the rill. Dr=Kr(T−Tc)(1−QsTc)
Water Resources Engineering
Published in P.K. Jayasree, K Balan, V Rani, Practical Civil Engineering, 2021
P.K. Jayasree, K Balan, V Rani
Sheet erosion is the uniform removal of soil without the development of visible water channels. It is the least apparent of the four erosion types. Rill erosion is soil removal through the cutting of many small, but conspicuous, channels. Gully erosion is the consequence of water that cuts down into the soil along the line of flow. Gullies develop more quickly in places like animal trails, plow furrows, and vehicle ruts. Tunnel erosion may occur in soils with sublayers that have a greater tendency to transport flowing water than does the surface layer.
Soil erosion estimation and risk assessment at watershed level: a case study of Neshe Dam Watershed in Blue Nile River basin, Ethiopia
Published in International Journal of River Basin Management, 2023
Israel Tessema, Belay Simane, Kenatu Angassa
RUSLE represents the combined effects of rill and inter-rill erosion. According to Pradhan et al. (2012), rill erosion is primarily caused by surface runoff and increases in a downward slope direction because the runoff increases in this direction and inter-rill erosion is mainly caused by raindrop impact on the soil surface and is considered uniform along a slope. The (L) parameter expresses the ratio of rill erosion (initiated by flow) to inter-rill erosion (raindrop impact) to find the loss of soil in relation to the standard plot length of 22.1 m. The slope steepness factor (S) reflects the influence of slope gradient on erosion. Both slope length and steepness substantially affect sheet and rill erosion estimated by RUSLE. In erosion prediction, the L and S factors are usually evaluated together. In this study, the flow length and slope gradient are generated from the DEM using ArcGIS 10.1 spatial analyst tools arc hydro extension. Then the combined LS factor was computed for the study watershed using a raster calculator following equation (3) in the ArcGIS environment, as proposed by Moore and Burch (1986a) and Moore and Burch (1986b). Finally, the resulting LS factor map of the watershed is calculated and its spatial distribution is presented in Figure 5 below.
Identification and quantification of erosion on a sand tailings dam
Published in Geosystem Engineering, 2020
N. Slingerland, A. Sommerville, D. O’Leary, N.A. Beier
Overland flow, subsurface flow, and subsurface discharge are the three main components of run-off: a predictor of erosion due to water movement (Dunne & Black, 1970). Overland flow is the most important component of run-off as it not only provides erosive forces but also dictates transport and deposition of eroded materials. Rill erosion occurs when overland flow down a slope is concentrated, generating thin but distinct channels, or ‘rills’. This concentration of flow generates greater flow velocity and energy in the rills than is created by sheet flow, thus the potential for soil erosion and transport is greater. Most erosion associated with rainfall occurs due to rill erosion (Schor & Gray, 2007). Gully erosion occurs when flow is concentrated and fast enough to remove soil to a depth and width that cannot be crossed by normal tillage equipment. This ambiguous definition comes from agriculture, and has been the standard for many years. More precisely, any fluvial erosion feature 0.3 m or deeper has been considered a gully by some (Dunne & Leopold, 1978; Queensland Government, 2013), while others have considered gullies to be any fluvial erosion greater than 75 mm in depth (Fifield, 2001; Government of Alberta Transportation, 2011; P4-2).
Water erosion assessment methods: a review
Published in ISH Journal of Hydraulic Engineering, 2021
Soil erosion is a process of the loss of topsoil particles by erosion agents such as wind and water. Soil erosion as a result of the natural causes exclusive of any interference of man is called geological erosion which occurs at low rates. When soil loss exceeds the annual soil formation, mainly on account of agriculture will generate accelerated soil erosion, which is very rapid and destructive than natural erosion (Hudson 1995). Water erosion is the removal of soil particles from the surface owing to runoff and raindrop impact. It is one of the most severe types of land degradation in the world (Bridges and Oldeman 1999). The soil erosion processes due to water are classified into inter rill (splash and sheet), rill, gully, and stream channel erosion. Splash and sheet erosions are the removal of soil by raindrop impact and shallow overland flow, respectively (Morgan 2005; Kothyari 2008). Rill erosion is the soil erosion as a result of runoff whereby several small but well-defined channels are formed. They are differentiated from gullies by the fact that they are small enough to be erased easily with normal tillage methods (Kothyari 2008; United States Departments of Agriculture [USDA] 2011). Among different types of water erosion, inter-rill and rill erosions are the major reason for the reduction of soil productivity. Gully erosion is a process of the wearing away of soil by large channels of not less than a 0.3 m width and 0.3 m depth, as a result of concentrated runoff, and stream bank erosion is the removal of stream bank soil by water either flowing over the sides of the stream or scouring from the stream bed. There are three complex processes in water erosion that acts in sequence, namely, detachment (the removal of individual soil particles from the soil mass), transport (the movement of soil particles), and deposition (the transfer of soil particles from the sediment load to the soil mass) (Lal and Humberto 2008; USDA 2011).