Modeling soil erosion and its response to land-use change in hilly catchments of the Chinese Loess Plateau

Soil erosion is a major environmental problem threatening the sustainable development of the Chinese Loess Plateau. Distributed soil erosion models can be used for studying erosion patterns in relation to alternative land-use conditions, identifying sediment sources, and hence guiding soil and water conservation planning. In this study, we used the WATEM/SEDEM model to predict annual erosion patterns with respect to land-use change within a typical hilly catchment in the Loess Plateau. Soil erosion rates derived from 137Cs measurements in a nearby catchment were used to calibrate the model. The model's performance was assessed by comparing the simulated erosion pattern with the field observations, based on the model efficiency (ME), relative root mean square error (RRMSE) and kappa statistics. It was found that the WATEM/SEDEM model performs poorly in predicting erosion amounts for each raster cell used for the modeling, but is more reliable in predicting the spatial pattern of erosion. For the entire catchment, the land-use conversions between 1990 and 2005 reduced soil erosion, largely due to the Grain-for-Green project initiated by the Chinese central government. We also compared the contribution of specific land-use types to soil erosion reduction, and addressed the possible influences of land-use policy upon soil erosion.