Evaluation of the WEPP hillslope profile model for estimating runoff and soil loss for two sites in western Canada
The Water Erosion Prediction Project (WEPP) is a process based erosion prediction model based on the fundamentals of soil physics, hydrology and biomass prediction designed to replace empirically based soil loss estimators for use with action agencies involved with soil and water conservation and environmental planning and assessment. To better assess and predict soil erosion, the WEPP Hillslope Soil Erosion model (version 95.7) was evaluated with measured runoff and soil loss data from two
... esentative agricultural erosion monitoring sites located in distinctive climatic regions in Western Canada. The required climate, soil, slope and management data was carefully compiled to represent actual conditions. A sensitivity analysis was performed to assess model response to changes in parameters, and calibrations were performed to improve model efficiency. Original and calibrated model results were compared to annual and event based observations of runoff and soil loss. The WEPP model responded to changes in land use practices and it efficiently predicted annual runoff for a site with a temperate climate and soil loss for a fallow plot in a colder climate when adjustments to the soil detachment parameters were incorporated. Otherwise, the model did not comply with measured runoff and soil loss due to errors in estimation associated with weaknesses in the winter hydrology component, plant-growth and residue decomposition parameters, and the erosion component. If enhancements in the model components and a more comprehensive built-in database can improve soil loss predictions, the WEPP model can potentially be used as a powerful new tool for applications related to forestry, mine-reclamation, construction sites and rangelands in addition to agricultural situations to assess the impacts of on and off-site soil erosion and sedimentation.