Impact of rainfall pattern on interrill erosion process

The impact of rainfall pattern on the interrill erosion process is not fully understood despite its importance. Systematic rainfall simulation experiments involving various rainfall intensities, stages, intensity sequences, and surface cover conditions were conducted in this study to investigate their effects on the interrill erosion process. Five rainfall patterns designed with the same total kinetic energy/precipitation (increasing, decreasing, rising–falling, falling–rising and constant patterns) were randomly delivered to a pre-wet clay loam soil surface at a 10° slope gradient. Significant differences in soil losses were observed among the different rainfall patterns and stages, but there was no obvious difference in runoff. Kinetic energy flux (KEr) was a governing factor for interrill erosion, and constant rainfall pattern (CST) produced nine times greater soil loss than runs with no KEr. Varied-intensity patterns had a profound effect on raindrop-induced sediment transport processes; path analysis results indicated that said effect was complex, interactive and intensity-dependent. Low hydraulic parameter thresholds further indicated that KEr was the dominant factor in detaching soil particles, while overland flow mainly contributed to transporting the pre-detached particles. This study not only sheds light on the mechanism of interrill sediment transport capacity and detachability, but also may provide a useful database for developing event-based interrill erosion prediction models. Copyright © 2017 John Wiley & Sons, Ltd.