Quantifying wind-driven rain erosion: Splash distribution and transport rates in aggregated soils

Abstract

Wind-driven rain (WDR) is dominant agent of soil erosion in arid and semi-arid landscapes, yet the combined effects of wind velocity, rainfall intensity and soil aggregate size on splash and wash processes remain poorly quantified. This study investigated the spatial distribution and transport rates of splash and wash loads under controlled combinations of rainfall intensity (30, 50, and 75 mm h⁻¹) and wind velocity (6, 9, and 12 m s⁻¹) for three soil aggregate size classes (2, 4.75, and 8 mm) packed into a 35 × 100 cm soil pan. The results showed that wind significantly increased both the amount and travel distance of splashed particles, particularly at higher wind velocities. The splash load decreased exponentially with distance from the soil pan, from 234.65 to 0.4762 × 10⁻⁵ g m⁻¹ s⁻¹, with the rate of decline dependent on wind velocity. Similarly, the wash load increased with rising wind velocity and rainfall intensity, ranging from 2.329 to 23.52 × 10⁻² g m⁻¹ s⁻¹, with the highest erosion observed at wind speeds of 6–9 m s⁻¹. Overall, as wind velocity increased from 0 to 12 m s⁻¹, wash load rose by 266.47–436%, while splash load increased by 1,119–9,036.43%. demonstrating that splash load is substantially more sensitive to wind than wash load. These findings provide new quantitative insights into the synergistic effects of wind and rainfall on soil particle detachment and transport in aggregated soils of semi-arid regions. The results demonstrate that wind-driven rain markedly accelerates water erosion processes, highlighting the need for targeted soil conservation practices (such as residue retention and windbreaks) in landscapes where wind and rain frequently occur together.