Data for assessing the effects of slope gradient on soil erosion for t
he case of steep slopes are limited. Widely used relationships are bas
ed primarily on data that were collected on slopes up to approximately
25%. These relationships show a reasonable degree of uniformity in so
il loss estimates on slopes within that range, but are quite different
when extrapolated beyond the range of the measured data. In this stud
y, soil loss data from natural runoff plots at three locations on the
loess plateau in China were used to assess the effect of slope gradien
t on soil loss for slopes ranging from 9 to 55% steepness. Plot size a
t each location was 5 m wide by 20 m long, and the soils were silt loa
ms or silty-clay loam. The results indicated that for these plots, soi
l loss was linearly related to the sine of the slope angle according t
o the equation: S = 21.91 sine - 0.96, where theta is the slope angle
and S is the slope steepness factor normalized to 9%. This relationshi
p was assessed in terms of the limited existing experimental data for
rainfall erosion on steep gradients and found to be reasonable for dat
a collected on longer plots, but somewhat different than the data from
shorter plot studies. The results of this study would indicate a less
er soil loss at high slopes than does the relationship used in the Uni
versal Soil Loss Equation, but a greater soil loss than predicted by t
he Revised Universal Soil Loss Equation for steep slopes.