Abstract: Currently, many different erosion and sediment transport models are available. They are important tools to predict soil erosion and sediment yield under different conditions. The most commonly used models include Universal Soil Loss Equation (USLE), Revised Universal Soil Loss Equation (RUSLE), Water Erosion Predict Project (WEPP), Soil and Water Assessment Tool (SWAT), and the Limburg Soil Erosion Model (LISEM), et al. The physical distributed soil models can be well used in other regions once they were built in a given region. Therefore, physical soil erosion model hasreceived more attentionover the decades. However, the structures of the physical erosion models are usually complex and a lot of parameters are required to run them, which to some extent limits their applications. The Water and Tillage Erosion Model and Sediment Delivery Model (WaTEM/SEDEM) developed at the Physical and Regional Geography Research Group, KU Leuven University, Belgium, is a spatially distributed soil erosion and sediment delivery model. Unlike other more sophisticated dynamic models, this model requires minimal basis data input and the model structure is simple, similar to RUSLE model. Although WaTEM/SEDEM has data requirement almost similar to RUSLE model, it can assess both water and tillage erosion simultaneously. Mostly importantly,WaTEM/SEDEM can spatially model soil erosion and sediment deposition rates as well as the soil redistribution patterns. This model also allows incorporation of landscape structure or the spatial organization of different land units and the connectivity, and can then be used to delineate sediment source areas in an agricultural landscape, and to simulate the impact of various scenarios of an integrated catchment management on the rates and patterns of soil loss and sediment delivery. Therefore, WaTEM/SEDEM can provide useful information for land managers to implement rational management to control soil loss. Up to date, the model has been successfully used in Europe and other regions around the world. However, few studieshave been conducted in China using this model. In this paper, the model structure, the algorithms used to calculate soil erosion and sediment transport, the model input and output, and its applications were systematically introduced. A case study in Shuangfengtan catchment, Hunan Province was also reported in this paper to verify its usefulness. Besides the advantages mentioned above, the disadvantages of this model were also pointed out. For example, WaTEM/SEDEM does not predict sediment transport within a river, bank erosion or floodplain sediment deposition. At the end of this paper, the prospect of the application of WaTEM/ SEDEM in the data-limited regions was discussed.

Key words: application prospect, soil erosion model, WaTEM/SEDEM