How Surface Conditions Affect Sediment and Chemical Transport

Soil erosion process research produces knowledge and science used in the development of current process-based erosion prediction models. This paper highlights recent progresses at the USDA-ARS National Soil Erosion Research Laboratory (NSERL) on effects of soil surface conditions, i.e., roughness and moisture gradient, on sediment and chemical transport. We showed that surface depression caused a delay in runoff initiation. But once runoff was initiated, surfaces with depressions did not show any sediment reduction as compared those without depressions. On the surface hydrologic effects, saturation and seepage conditions greatly enhanced sediment and chemical transport. These findings showed the importance of understanding surface condition effects for better management strategies to minimize the sediment and chemical transport at the landscape. Also included in this paper are brief descriptions on experimental techniques using (1) a line-scan laser system to measure surface microtopography; and (2) a multiple-box system to quantify processes at a hillslope segment.