Raindrop‐Induced Soil Detachment and Sediment Transport from Interrill Areas

Abstract

AbstractPhysically based soil erosion simulation models require input parameters of soil detachment and sediment transport due to the action and interactions of both raindrops and overland flow. In this study, we report on the soil detachability and transportability parameters for raindrop‐impact‐dominated interrill erosion processes. The detachability parameter is derived by integrating estimated soil detachment due to single raindrop impact over all the raindrops occurring in a storm. Using artificial rainfall characteristics and soil properties as inputs, we simulated raindrop‐induced soil detachment rates for 33 cropland soils used in the USDA‐ARS Water Erosion Prediction Project (WEPP) experiments in the USA. The magnitude of difference between the predicted detachment rates and the measured interrill sediment delivery rates decreased with clay content. This suggests that in coarse‐textured soils, most of the rain‐detached sediments are redistributed within the interrill area. Small differences between detachment rates and sediment delivery rates in clayey soils indicate that the interrill erosion is detachment limited. A raindrop‐induced interrill transportability parameter is derived by dividing the measured sediment delivery rates with the product of rainfall rate and unit effective kinetic energy. The derived transportability parameter increases linearly with an increase in clay content, thereby suggesting the predominant role of raindrop impact in the sediment delivery process, specifically on up‐slope areas with shallow overland flow. The raindrop‐induced soil detachment and sediment transport processes can be represented by incorporating intensity and effective kinetic energy of rainfall into the basic interrill erosion model.