The role of rainfall impact in soil detachment and transport

The relative importance of raindrop impact and flowing water to the erosion process was determined in a laboratory study using three soils, loam, silt loam, and sandy loam, prepared with preformed rills and subjected to simulated rainfall. The source and the mode of transport were determined for all soil detached and transported from the plot under conditions of both normal rainfall energy and greatly reduced rainfall energy. Decreasing rainfall impact energy by 89% without reducing rainfall intensity decreased soil losses by 90% or more, and it was thus indicated that the impact energy of raindrops is the major force initiating soil detachpent. For all three soils, 80–85% of the soil loss originating in the area between the rills was transported to a rill before leaving the plot, and it was thus indicated that the transport of detached particles from the plot was accomplished mainly by rill flow.