Raindrop and flow interactions for interrill erosion with wind-driven rain

Wind-driven rain (WDR) experiments were conducted to evaluate the interrill component of the Water Erosion Prediction Project model with a two-dimensional experimental set-up in a wind tunnel. Synchronized wind and rain simulations were applied to soil surfaces on windward and leeward slopes of 7, 15 and 20%. Since WDR fall trajectory varied with horizontal wind velocities of 6, 10, and 14 m s-1, magnitude of raindrop normal and lateral stresses on flow at the impact-flow boundary also changed and differentially directed lateral jets of raindrop splashes with respect to downward flows occurred. To account for interactions between raindrop impact and interrill shallow flow, a vector approach with kinetic energy fluxes of both raindrop splashes and flow were used and this resulted in greater correlations in predicting sediment delivery rates