The LS factor was limited to slopes ≤18% because data used
to develop RUSLE involved slopes up to 18% only (McCool et
al., 1987). However, the Taipingxi watershed has 68% of its
area having slope gradient in excess of 30%. Most of this
steeply sloping land is under forest cover or other nonagricultural
use. Under these slope gradients, much of the
sediment may move by gravity rather than shear force alone
and new LS factors should be developed. Using equations
proposed by McCool et al. (1987) for computing S in RUSLE,
Nearing (1997) proposed a logistic equation expressed as a
single continuous function of slope gradients for computing S: