Effect of wind-driven rain on soil erosion processes under different soil surface roughness conditions

Abstract

Soil erosion is a critical issue that threatens agricultural productivity and long-term sustainability. While the effects of wind and rainfall on soil erosion are often studied separately, their combined effects on hydrological and erosion processes, under varying soil surface conditions, remain poorly explored. Understanding erosion dynamics requires evaluating the interactions between water, wind, and soil properties. Therefore, this study investigated the effect of windless rain (WLR) and wind-driven rain (WDR) at varying wind velocities on runoff, infiltration, and soil loss (through runoff and splash erosion) on both smooth and rough soil surfaces using a novel setup comprising rainfall and wind simulators. The study also quantified the effect of different rainfall events on soil surface roughness (SSR). Findings indicate that WDR significantly accelerated runoff generation and produced higher runoff volume and soil loss compared to WLR, due to increased rainfall kinetic energy caused by wind velocity. On smooth surfaces under the highest wind velocity, WDR increased runoff volume, sediment load, and sediment concentration by 74 %, 43 %, and 143 %, respectively, compared to WLR. Rough surfaces mitigated these effects at lower wind velocities but were less effective under higher wind speeds, resulting in soil and water losses comparable to or exceeding those measured under WLR. Moreover, WDR increased SSR on smooth surfaces by up to 172 % but reduced it on rough surfaces by up to 30 %. These results demonstrate that wind increases rainfall erosivity, affecting soil erosion processes. However, the magnitude of this effect was also influenced by wind velocity and initial SSR. Therefore, incorporating these factors is crucial for accurately assessing soil and water losses in erosion studies.