The effect of rain, wind-driven rain and wind on particle transport under controlled laboratory conditions

Abstract

Transport of soil particles prior to the occurrence of overland flow is one of the big question marks in soil erosion studies. The exact measurement of short-distance transported soil particles is a challenge to soil erosion science due to the particular requirements of the experimental design and test procedure. To quantify amount and distance of each type of transport, we developed an experimental laboratory setup including a multiple-gutter system and the Trier Portable Wind and Rainfall Simulator (PWRS). Measured were amount and travel distance of soil particles detached and transported by raindrops (splash-creep and splash), wind-driven rain (splash-creep, splash-saltation and splash-drift) and wind (reptation and saltation). The test setup included three different agents of erosion (rain solely, wind-driven rain and wind solely), two substrates (sandy and loamy), three surface structures (smooth/ grain roughness, rills lengthwise and rills transversal) and three slope angles (0°/horizontal, 7° downslope and 7° upslope). The results give detailed transport patterns of the three erosion agents under the varying substrates and surface conditions up to a distance of 1.6m. Influence of the surface factors varies, whereas the factor “agent of erosion” seems to be the most crucial one. Under the applied rain intensity and wind velocity, wind-driven rain splash generates the highest erosion and a further travel distance of the particles due to the combined action of wind and rain. The impact of all three agents of erosion implicates considerable redistribution processes and is a crucial factor for investigation of source- and sink dynamics, field scale sediment budgets and connectivity.