A grid type portable rainfall simulator, developed at Virginia Tech from support by the Office of Surface Mining, Department of Interior under Grant NO. G5114009, was used to apply 2.3 inch per hour “storms” to three replicated plots to determine surface mine soil erodibility factors for two distinctly different soils in southern West Virginia. Other variables included in the study were detailed soil descriptions for each site, initial and final soil moistures, plot rainfall distributions and the particle size distributions of the eroded materials.

The soil erodibility indexes for the silt silt-loam and sandy respectively. loam soils averaged 0.408 and 0.735. Erodibility indexes for the silt silt-loam decreased, while indexes for the sandy loam soil remained constant for repeated rainfall applications. Using statistical analysis, rainfall distributions were shown to be uniform across plots for most rainfall applications. From a particle size distribution analysis of the eroded soil material, the percentage of silt and clay decreased, while the percentage of sand increased at each site with repeated rainfall applications. A rock mulching effect was present at the end of each testing sequence.