Submitted to: Journal of the American Water Resources Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2003
Publication Date: 4/1/2004
Citation: Laflen, J.M., Flanagan, D.C., Engel, B.A. 2004. Soil erosion and sediment yield prediction accuracy using wepp. Journal of the American Water Resources Association. (JAWRA). 40(2):289-297. Interpretive Summary: Soil erosion can cause many problems - both by removing fertile topsoil as well as producing sediment that can pollute water. People that are interested in controlling soil erosion need tools that allow them to estimate how much erosion might occur at a location and what land management can be used to try to control soil loss if necessary. Since it is very often impractical or impossible to directly measure soil loss on every piece of land, the tools used are usually mathematical equations and/or computer simulation models. This paper summarizes how well one erosion prediction computer model, WEPP, performed compared to measured soil loss data in a range of validation studies on erosion plots and small watersheds. Satisfactory WEPP performance indicates that the model can be applied for erosion prediction and conservation planning with confidence in the amount of soil loss it predicts.
Technical Abstract: There have been numerous comparisons of WEPP predicted soil loss and sediment delivery from cropland plots. In one study involving 1594 plot-years of data from runoff plots, WEPP performed similarly to the USLE technology, a major finding that indicates that WEPP has met the criteria of results being "at least as good with respect to observed data and known relationships as those from the USLE" (particularly since the USLE was developed using relationships and soil erodibility values derived from this data set). In many cases, WEPP performed as well as could be expected, based on comparisons with the variability in replicate data sets. One major finding has been that soil erodibility values calculated using the technology in WEPP for rainfall conditions may not be suitable for furrow irrigated conditions. WEPP was found to represent the major storms that account for high percentages of soil loss quite well, and WEPP has performed well for disturbed forests and forest roads. WEPP has been able to reflect the extremes of soil erosion, being quite responsive to the wide differences in cropping, tillage, and other managements. WEPP was also found to perform well on a wide range of small watersheds.