4. Conclusions
In this study, simulated rainfall was conducted above a series of
soil trays with nine different slopes. The specially designed runoff and
sediment collection system was used to partition total splash into four
directional components and interrill sediment transport into wash
and splash components. The results of this study demonstrated that
slope had a significant effect on these components. Specifically, the
downslope splash loss, total splash loss and net downslope splash loss
all increased with slope gradient and then decreased after amaximum
value was reached. Furthermore, the upslope splash loss and lateral
splash loss decreased as the slope steepness increased. A high error in
calculating the net downslope splash loss and total splash loss mayhave resulted from upslope splash loss which was not measured when
the slope is gentle and short whereas the error may be neglected
when slope steepness was greater than 36%.
When the slope gradient was less than or equal to 58%, the wash
loss increased with slope gradient. The slope factor equation of short
slopes in RUSLE matched the wash loss from the present study very
well. When the slope gradient was greater than 58%, the wash loss
decreased with slope gradient.
In the study case, total splash was greater than wash for all
experimental slopes. Slope had effects on the ratio of splash to wash.
The ratio of net downslope splash loss to wash loss increased with
slope gradient from 0.21 to 1.33. These findings indicate that splash
transport is a very important part of interrill sediment delivery which
is the sum of the wash loss and the net downslope transport splash
loss and rainfall splash detachment supplied enough loose soil
particles for runoff transport at short steep slopes.