GIS based soil loss assessment using RUSLE model
A = R ∗ K ∗ LS ∗ C ∗ P equation(1)
Where,
A = annual soil loss (metric tons ha1yr1),
R = rainfall erosivity factor (MJ mm h1 ha1 yr1),
K = soil erodibility factor
(metric tons ha1 MJ–1 mm1),
LS = slope length and steepness factor (dimensionless)
C = land cover and management factor
(dimensionless) and
P = conservation practice factor (dimensionless).
SLOPE LENGTH AND STEEPNESS FACTORS (LS) The effect of topography on erosion in RUSLE is accounted for by the LSfactor. Erosion increases as slope length increases, and is considered by the slope length factor (L). Slope length is defined as the horizontal distance from the origin of overland flow to the point where either (1) the slope gradient decreases enough that deposition begins or (2) runoff becomes concentrated in a defined channel. Surface runoff will usually concentrate in less than 400 ft., which is a practical slopelength limit in many situations, although longer slope lengths of up to 1,000 ft. are occasionally found. For steep slopes, these lengths should be converted to horizontal distance for use in RUSLE.Both slope length and steepness substantially affect sheet and rill erosion
estimated by RUSE. The effects of these factors have been evaluated separately
in research using uniformgradient plots. However, in erosion prediction, the
factors L and S are usually evaluated together. Soil loss increases more rapidly
with slope steepness than it does with slope length.