Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/1999
Publication Date: N/A
Interpretive Summary: Estimation of runoff and soil loss from small watersheds is becoming more and more important as concerns about surface water quality increase. New erosion prediction models, including the Water Erosion Prediction Project (WEPP) model, have been developed that improve the ability to estimate runoff and sediment leaving a watershed, but they are often difficult to apply due to the natural complexity and geometry of these areas. Geographic Information Systems (GIS) allow rapid development of input parameters (soil, slope, management data) for erosion prediction models, and can greatly assist in providing an automated and unbiased procedure for runoff and erosion simulation in small watersheds. This paper describes three different methods of using GIS data to apply the WEPP model to small watersheds. This research will benefit users of complex hydrologic and erosion models, applied at both the small watershed and hillslope profile scale. The ability to use automatic methods to configure hillslopes within small watersheds will help provide for much more rapid and more objective erosion predictions and management alternative evaluations.
Technical Abstract: Three different approaches for applying the Water Erosion Prediction Project (WEPP) model to small watersheds utilizing geographical information systems (GIS) and digital elevation models (DEMs) are described for assessing water erosion in small watersheds. The first approach describes the typical application of the watershed version of WEPP using GIS only as an aid for construction of required input files. The second approach represents an automated method for the application of WEPP through the extraction of hillslopes and channels from digital elevation models. The third approach uses WEPP model simulations on all possible flow-paths within a watershed. The three methods were applied to six research watersheds, one from Treynor, Iowa, two from Watkinsville, Georgia, and three from Holly Springs, Mississippi. An analysis from the application of each method was performed by comparing predicted against measured runoff and sediment yield from the outlet of each watershed on an event-by-event basis and on total runoff and sediment loss. The results indicate that the automatic hillslope method performs as well as the manual technique. The flow-path method could be valuable for estimating sediment erosion or deposition rates inside the watershed, but is dependent upon the accuracy of the DEMs used. The effectiveness and reliability of each method for assessing erosion in the short- and long-term are discussed.