ARS | Publication request: Surface Roughness effects on Runoff and Soil Erosion Rates Under Simulated Rainfall

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: June 15, 2010
Publication Date: June 16, 2010
Citation: Vermang, J., Norton, L.D., Da Silva, A.M., Huang, C., Gabriels, D. 2010. Surface Roughness effects on Runoff and Soil Erosion Rates Under Simulated Rainfall [abstract]. United Nations Educational, Scientific and Cultural Organization Chair on Eremology Workshop 'Action of Rain and Wind in Soil Degredation Processes.' June 16, 2010, Ghent, Belgium. 2010 CDROM.

Technical Abstract: Soil surface roughness is identified as one of the controlling factors governing runoff and soil loss yet, most studies pay little attention to soil surface roughness. In this study, we analyzed the influence of random soil surface roughness on runoff and soil erosion rates. Bulk samples of a silt loam soil were collected and sieved to 4 aggregate sizes: 0.2-1.2, 1.2-2.0, 2.0-5.0, 5.0-10.0 cm. The aggregates were packed in a soil tray of 0.60 by 1.2 m, which was set at a slope of 5%. Rainfall simulations using an oscillating nozzle simulator were executed for 90 min at intensity of 50 mm h-1. The random soil surface roughness was analyzed before and after the rainfall application by an instantaneous profile laser scanner. From the laser scanner data, a digital elevation model was produced and a roughness factor extracted. The data revealed longer times to runoff with increasing soil surface roughness as surface depressions first had to be filled before runoff could take place. Once channels were interconnected, runoff velocity and runoff amount increased as aggregates were broken down and depressions were filled. Rough surfaces were smoothed throughout the rainfall event, diminishing the effect on runoff. Sediment concentrations were comparable for all different applications. The simulations reveal that the significance of soil surface roughness effect is the delay in runoff for rougher surfaces rather than the decrease of soil erosion amount.