Original Articles
JU Wenxue, LI Tianhong, NI Jinren
Abstract: Currently,a fast method for soil loss assessment that uses rapid water quality evaluation method as reference has been proposed The core thought of the method is that areas with similar environmental factors should suffer similar soil loss Compared with existing methods for soil loss assessment such as USLE, which needs too much factor calibration, the fast method can produce soil loss degrees in areas without enough data Some steps can be improved and concrete models should be constructed if it is used to estimate the soil loss module In this paper, the fast assessment method for soil erosion is improved based on probabilities of group membership supported by Geographical Information System,which is introduced in this paper The improved method can be implemented with 8 successive steps: 1)clustering standard referring regions using representative factor which can be indicated by soil erosion modulus, 2)constructing standard reference groups of soil erosion, 3)matching the environmental factors of reference regions to standard reference groups and calculating their probabilities of group membership, 4)getting the weight of each land use/cover category to soil loss by Analytical Hierarchical Process, getting the weights of topographical factors to soil loss by existing studies, and getting the weights of soil erodibility by experiences, 5)using standard referring groups, probabilities of group membership, and weights of environmental factors to construct fast assessment model, 6)testing the model in statistical theory, 7)analyzing and calibrating the environmental factors of unknown regions, and 8)predicting soil erosion modulus in unknown areas A case application of the method was also carried out in Zhifanggou catchment, Yanhe watershed in North part of Shaanxi Province The soil erosion map was produced and it revealed that the soil erosion degrees and their spatial distribution is in agreement with the actual situation The USLE method was also used in estimating the soil erosion module for unknown areas The module calculated by the proposed method is very similar to that obtained by USLE However, the method carries some advantages in factor calibration and easy operation Though the case study in this paper is for a small basin,the method does not limit itself to small basin level If some appropriate environmental factors are selected and proper spatial units are adopted in dividing the target region.
