Abstract
This study investigates the effect of rainfall temporal distribution pattern within a storm event on soil erosion rate and the possibility of using rain power type model for rainfall erosivity. Various rainfall distribution patterns, simulated by rainfall simulator, were used on 1.0 m2 plot of silica sand and loam soil with a minimum of three replications. The results show that the soil erosion rates spiked following every sharp increase in rainfall intensity followed by a gradual decline to a steady erosion rate. Transient effects resulted in the soil erosion rates for an oscillatory rainfall distribution to be more than two fold higher than those obtained for a steady-state rainfall intensity event with same duration and same average rainfall intensity. The 3-parameter and 4-parameter rain power models were developed for a process-based measure of rainfall erosivity. The 4 parameter model yielded better match with the observed data and predicted soil erosion rates more accurately for silica sand under all rainfall distributions, and good results for loam soil under low intensity rainfall. More research is necessary to improve the accuracy of soil erosion prediction models for a wider range of rainfall distributions.
Highlights
One of the key factors affecting temporal variation of soil erosion is rainfall intensity distribution during a storm event
The average soil erosion rate for the simulated storm that was applied to sand and loam (Figures 2 and 3) shows a distinct dependence on the rainfall intensity and rain power for silica sand
It was observed that the soil erosion rates spiked following every sharp increase in rainfall intensity followed by a gradual decline to a steady erosion rate
Summary
One of the key factors affecting temporal variation of soil erosion is rainfall intensity distribution during a storm event. A number of researchers have studied rainfall simulators and demonstrated the significance of various factors, including simulated raindrop size distribution, raindrop impact velocity, raindrop impact angle, and rainfall intensity and duration on rainfall erosivity [1, 3, 4]. Many rainfall simulators apply a temporally varied intensity of simulated rainfall to each small area of soil surface in a sweeping pattern [3, 5]. The power of natural rainfall has been found to be approximately linearly related to rainfall intensity [7, 8]. Meyer [4] has found that interrill detachment rates are related to the second power of intensity or more precisely as shown in
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