Slope Erosion Control, RUSLE - Design Calculator
Erosion is one of the major sources of damage to both natural and man-made slopes. Erosion on slopes can be caused by detachment and movement of soil particles due to raindrop impact and surface runoff. This calculator predicts the soil loss from a slope based on the Revised Universal Soil Loss Equation (RUSLE). Selection of a Geosynthetic Erosion Control Blanket (GECB) to limit erosion is achieved by submitting a proper cover factor into the calculation.
For more information on RUSLE, visit the USDA National Sedimentation Laboratory website at http://www.sedlab.olemiss.edu/rusle/current.html
Annual Soil Loss in tons/acre/year is calculated as follows, each factor will be explained in more detail below.
|Average Annual Soil Loss (ton/acre/year)|
|Regional Rainfall and Erosivity Index|
|Soil Erodibility Factor (tons/acre)|
|L||Slope Length Factor (ft)|
|S||Slope Angle Factor|
|C||Cover Management Factor|
|P||Crop Support Practice Factor|
R = Regional Rainfall and Erosivity index
The rainfall erosion index plus a factor for any significant runoff from snowmelt.
(use map below to determine your location, then follow the link to determine what your index would be)
K = Soil Erodibility factor
The soil-loss rate per erosion index unit for a specified soil as measured on a standard plot, which is defined as a 72.6 ft (22.1 m) length of uniform 9% slope in continuous clean-tilled fallow.
where Dg = geometric mean particle diameter
L= Slope Length Factor
The ratio of soil loss from the field slope length to soil loss from a 72.6-ft length under identical conditions.
where lh is the horizontal length and s is slope
S= Slope Steepness Factor
The ratio of soil loss from the field slope gradient to soil loss from a 9% slope under otherwise identical conditions.
If gradient < 0.09 then S = 10.8 * sin(s) + 0.03,
If lh <= 3 then S = 3(sin(s))0.8 + 0.56,
If lh < 15 then S = 16.8 * sin(s) - 0.50
C= Cover Management Factor
The ratio of soil loss from an area with specified cover and management to soil loss from an identical area in tilled continuous fallow.
P= Support Practice Factor
The ratio of soil loss with a support practice like contouring, stripcropping, or terracing to soil loss with straight-row farming up and down the slope.
K.G. Renard, G.R. Foster, G.A. Weesies, D.K. McCool, and D.C. Yoder. (1997), "Predicting Soil Erosion by Water: A Guide to Conservation Planning with the Revised Universal Soil Loss Equation (RUSLE)", U.S. Government Printing Office, ISBN 0-16-048938-5.
Copyright 2001 Advanced Geotech Systems. All rights reserved.