Submitted to: Catena
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/5/2005
Publication Date: 4/20/2007
Citation: Moffet, C.A., Pierson Jr, F.B., Robichaud, P.R., Spaeth, K., and Hardegree, S.P. 2007. Modeling soil erosion on steep sagebrush rangeland before and after prescribed fire. Catena 71:218-228. Interpretive Summary: Runoff and erosion risks increase in steep sagebrush rangelands after fire. The Water Erosion Prediction Project (WEPP) is used to help managers assess these risks and identify areas where mitigation is needed. Previous work has shown that erosion due to flowing water is the dominant process after fire. This paper reports the effects of prescribed fire on runoff, soil erosion, and the erosivity of flowing water and compares measured erosion with WEPP estimated erosion for several modeling scenarios. Improvements in the way WEPP estimates factors related to the erosivity of the flowing water are suggested. These improvements can be used in WEPP and WEPP derivatives to improve erosion estimates due to flowing water after fire.
Technical Abstract: Fire in sagebrush rangelands significantly alters caopy cover, ground cover, and soil properties which influence runoff and erosion processes. Runoff can be geenrated more quicly and in larger volume following fire resulting in increased risk of severe erosion and downstream flooding. The Water Erosion Prediction Project (WEPP) model, was developed to predict erosion on cropland, forest, and rangeland. WEPP is a tool that has potential to model the effect of fire on hillslope hydrological processes and help managers address erosion and runoff risks following fire. Experimental results on a steep (35 to 50%) slope) sagebrush site suggest that rill erosion is the dominant erosion process following fire and the WEPP parameterization equations related to the rill erosion process need improvements. Rill detachment estimates could be improved by modifying regression-estimated values of rill erodibility. Also, the interactions of rill width and surface roughness on soil shear stress estimates may also need to be modified. In this paper, we report the effects of prescribed fire on runoff, soil erosion, and rill hydraulics and compare WEPP estimated erosion for several modeling options with measured erosion.