Using soil erosion models for global change studies

Future changes in climate and atmospheric CO2 concentration will change the hydrologic cycle, affecting important soil-plant-water interactions, which in turn affect soil erosion rates. Climate and CO2 changes can be estimated with global circulation models (GCMs). Mathematical models are also available for simulating soil erosion as affected by weather and soil-plant-water interactions. Three major soil erosion models, including Environmental Policy Integrated Climate (EPIC) (formerly the Erosion-Productivity Impact Calculator); Water Erosion Prediction Project (WEPP); and Wind Erosion Prediction System (WEPS), are reviewed and briefly described here. The CLIGEN (Climate Generator) model, which has been refined to simulate changing climate, is also described here. Stockle et al. (1992) modified EPIC to simulate the effects of CO2 changes on plant growth and water-use efficiency. Recently, the Stockle relationships have been added to WEPP and to the basin scale model SWAT (Soil Water Assessment Tool) (Arnold et al. 1993). These relationships are also described in this paper. The EPIC model The Erosion-Productivity Impact Calculator (EPIC) (Williams et al. 1984) model was originally developed to assess the effect of soil erosion on soil productivity. It was used for that purpose as part …