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Erosion by Water: Empirical Methods
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Soils and Terrestrial Systems, 2020
The USLE was the culmination of more than two decades of work in developing a national model of soil erosion by water.[4] As shown in Table 1, the form and factors were long identified before the USLE was developed. The defining scientific finding in the development of the USLE was that a single rainfall variable was selected that could be used over the United States to model soil erosion from rainstorms.[8] This allowed the application of factor values in one region to be used in another region. Climatic databases were developed for the entire United States, and tables and charts were published to allow use of the USLE for most U.S. conditions.[5,9,10] It is being replaced by the Revised Universal Soil Loss Equation (RUSLE)[11] in the United States.
Sediment Yield
Published in Kumkum Bhattacharyya, Vijay P. Singh, Reservoir Sedimentation, 2019
Kumkum Bhattacharyya, Vijay P. Singh
The Universal Soil Loss Equation (USLE), developed in the 1970s by the U.S. Department of Agriculture in cooperation with the Purdue University Agricultural Experiment Station, is an empirical soil loss prediction equation used for estimation of annual soil loss over the world, and widely used within the United States. The USLE calculates the average annual soil loss from: A= R K L S C P, where A = the approximate soil loss per unit area, R = the rainfall and runoff factor, K = the soil erodibility factor, L = the slope-length factor, S = the slope-steepness factor, C = the cover-management factor, and P = the conservation practice factor. The USLE model calculates longtime average soil losses from sheet and rill erosion under specified conditions. The model does not calculate sediment yields from gully, streambank, and streambed erosion (Wischmeier and Smith 1978). Generally, studies use USLE, RUSLE (Revised Universal Soil Loss Equation), and MUSLE (Modified Universal Soil Loss Equation) for erosion studies (Di Stefano et al. 2000; Gitas et al. 2009; Jain and Das 2009).
Soil erosion and desertification
Published in F.G. Bell, Geological Hazards, 1999
The soil erodibility factor, K, in the USLE is a quantitative description of the inherent erodibility of a particular soil. It reflects the fact that different types of soil are eroded at different rates. Many of these factors have been discussed above, such as infiltration capacity, saturation, permeability, dispersion, splash and transport of soil particles. Other factors of importance include the texture or crumb structure of the soil, the stability of the mineral aggregates, the strength of the soil, and its chemical and organic components. A nomogram can be used to derive the soil erodibility factor (Figure 9.9). Five soil parameters are needed to use the nomogram, namely, percentage of silt and fine sand; percentage of sand (0.1–2.0 mm); organic matter content; structure; and permeability. Some examples of the value of K are given in Table 9.4.
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
The rainfall erosivity (R-factor) is a measure of the erosivity of local average annual precipitation and runoff to cause soil erosion in a given circumstance. R factor is often calculated as an average of EI-values measured over 20–25 years to enclose cyclical rainfall patterns (Angima et al., 2003). EI is a statistical interaction term that reflects how total energy and peak intensity are combined in each particular storm (Renard et al., 1997). RUSLE (and its predecessor USLE) were designed to account for the effects of raindrop impact and subsequent overland flow on soil erosion (Cooley et al., 1988). Within the USLE, rainfall erosivity is estimated using the EI30 measurement (Renard et al., 1997). However, rainfall kinetic energy and intensity data are not available in our cases. Therefore, the erosivity factor R was calculated according to the equation given by Hurni (1985), derived from a spatial regression analysis of Hellden Hellden (1987) for Ethiopian conditions. The model adapted by Hurni (1985) for Ethiopian conditions is based on the available mean annual rainfall data. where P is the mean annual rainfall in mm.
Multiple geo-environmental hazards susceptibility assessment: a case study in Luoning County, Henan Province, China
Published in Geomatics, Natural Hazards and Risk, 2019
Linwei Sun, Chuanming Ma, Yonggang Li
The universal soil loss equation (USLE) is one of the most common techniques to assess the loss of soil due to water erosion. The average annual soil loss (A) is given by the product of six factors (Wischmeier and Smith 1978); see Eq. (3) for this expression. where A is the average annual soil loss per unit of area (t ha−1 yr−1), R is the rainfall-runoff erosivity factor (MJ mm ha−1 h−1 yr−1), K is the soil erodibility factor (t ha h MJ−1 ha−1 mm−1), L⋅S is the topographic factor (dimensionless), C is the cover-management factor (dimensionless), and P is the support practice factor (dimensionless).
Water erosion assessment methods: a review
Published in ISH Journal of Hydraulic Engineering, 2021
The USLE is the most commonly applied and widely recognized empirical water erosion model developed in the United States based on measured data on soil loss and its controlling factors from many field erosion plots. This model used by SWC planners and decision makers to predict the long-term average soil loss for possible alternative combinations of vegetative cover and land use in relationship with a specific slope gradient and length, soil, rainfall, and management systems (Wischmeier and Smith 1978). The equation assembled many interconnected physical and management parameters that affect soil loss under six major erosion controlling factors. Mathematically the equation is denoted as follows: