Several models have been developed to assess soil erosion caused by water, including the Universal Soil Loss Equation—USLE (Wischmeier and Smith, 1978), Revised Universal Soil Loss Equation—RUSLE (Renard et al., 1997), Erosion Productivity Impact Calculator—EPIC (Williams, 1985) and Water Erosion Prediction Project—WEPP (Flanagan and Laflen, 1997).
The USLE, or the lateral RUSLE model, is a universally accepted method that can be used as the best fitted model for monitoring soil erosion because its applicability has been proven over the last decades, and the reliability of the results are indisputable (Lee, 2004; Lu et al., 2004). Supported by GIS and remote sensing technologies, the RUSLE model has been used as a distributed model in estimating soil loss for its application not only in areas with relatively lower slope but also on topographically complex landscape units (Desmet and Govers, 1996).
In recent years, RUSLE has been applied in the study of soil erosion in the Chinese Loess Plateau. The model has been further developed to work with complex terrain and to permit the quantitative assessment of precipitation, vegetation cover and soil erosion. For example, Fu et al. (2011) predicted soil erosion on the Loess Plateau using the RUSLE model and assessed the possible influences of land-use policy on soil erosion. Similar applications reported for some areas on the Loess Plateau have indicated a good representation of soil erosion (Liu and Liu, 2010; Zhang et al., 2008).
Soil erosion by water is considered one of the most severe types of erosion and has attracted considerable attention in the past, mainly due to its destructive effects, including eutrophication, non-point pollution and, eventually, land degradation (Asselman et al., 2003; Jin et al., 2008; Singer and Shainberg, 2004).