Impact of Land-use Change on Soil Erosion and Hydrologic Response at Regional Scale: Application of a Coupled Erosion and Hydrologic Modeling Scheme

Large-scale land-use change will impact regional hydrologic responses, and seasonal soil frost adds its effect to the complexity. Increases in soil erosion potential related to cold season processes at scales larger than a hillslope or field is a concern for scientific decision support and resources management. Numerous watershed models capable of predicting soil erosion have been developed in the past, but they are often limited by their inappropriate representations of the hydrologic processes involved. The process-based Water Erosion Prediction Project (WEPP) model has the ability to predict spatial and temporal distribution of soil loss at the field scale, but its winter hydrology routines still need improvement. The recent development of a stand-alone version of the WEPP hillslope erosion code is coupled with the Variable Infiltration Capacity (VIC) large-scale hydrology model, which is capable of representing cold season processes for long-term, large-scale watersheds simulations. The coupled model system uses VIC model simulations of hydrologic variables as an input to the erosion model to develop predictions of soil erosion potential. Coupled model system point simulations produce very similar results to those from the full WEPP model for a series of sampled hillslopes. The coupled model system is then applied to watersheds in Minnesota, Wisconsin and Michigan to simulate the impact of land-use change from pre-settlement to modern conditions on hydrologic responses and soil erosion potential. The study thus demonstrates an improved ability to predict and analyze regional hydrologic responses and erosion potentials due to land-use change for large-scale applications.