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For over 40 years, the universal soil loss equation (USLE) and its revised version the revised universal soil loss equation (RUSLE) have been used all over the world for soil mean annual loss per area unit. Because of the watershed erosion models are under developing, many researchers applied the USLE and RUSLE to estimate soil loss in watershed estimations. However, a major limitation is the difficulty in extracting the LS factor. The geographic information system-based (GIS-based) methods which have been developed for estimating the slope length for USLE and RUSLE model also have limitations. A series of ARC/INFO AML program was created that can calculate LS factor for the USLE, however the program need a very long time to run in wide-ranging areas. The flowpath and cumulative cell length-based method (FCL) overcomes this disadvantage but does not consider the following questions: (1) Some original AML program functions are not achieved, so results are different. (2) Using USLE to calculate LS factor that do not adapt to the erosion environment of China. (3) There isnt a friendly graphic user interface. The purpose of this research was to overcome these limitations and extend the FCL method through Integrating CSLE equation. We developed a LS calculation tool (LS-TOOL) in Microsofts .NET environment using C# with a user-friendly interface. Comparing the LS factor calculated with the FCL method and AML method, LS factor values generated by using LS-TOOL method delivers improved results. The LS-TOOL algorithm can automatically calculate slope length, slope steepness, L factor, S factor, and LS factors, providing the results as ASCII files which can be easily used in some GIS software. This study is an important step forward in conducting fast large-scale erosion evaluation.

Poor vegetation cover as a result of irrational land use is generally considered to be the major factor of soil erosion in the Loess Plateau in China. However, there is lack of knowledge concerning the dynamics of land use and the complex role of socio-economic policy factors in inducing changes in land use, especially at detailed scale levels such as in individual small catchments. This study analyzes the process of human-induced landscape change in a small catchment in the northern part of the Chinese Loess Plateau from 1958 to 1999. During this period, a significant reduction of the area of farmland on steeper slopes and an increase in woodland took place. Household questionnaires among the local farmers, a review of the historic events and literature allowed the assessment of socio-economic and policy forces that caused these changes. The research showed that the changes of agricultural landscape pattern are mainly the result of the dissolution of People’s Communes in 1979 (established in 1956), the introduction of a Household Responsibility System (in 1978), the implementation of the Family Planning policy (in 1978), and the adoption of a market-directed economic system (in 1992), as well as the execution of an integrated soil erosion control project (begun in 1981). The changes of the agricultural landscape show the benefits in both ecological and economic respects.