Abstract:

With more and more studies focusing on the agricultural nonpoint source pollution (ANSP) in the Three Gorges Reservoir area(TGRA), promotion the applicability of these relevant research results is of great significant for the regional ecological environment protection. However, the key in this process is to make a comprehensive survey for the various typical areas of the ANSP in TGRA and their spatial distribution patterns. This can not only make full use of the related research resources, such as research data or results about the ANSP in the TGRA, but also can guide the control managements and policy orientations about ANSP in the TGRA. To these ends, we first screened out the key factors, namely soil type, land use type, and the soil erosion intensity, that can mainly affect the ANSP and prepared their corresponding spatial data in the TGRA. After then, 24 different types of regions of ANSP in TGRA, were mapped by using the GIS spatial analysis (i.e., overlay analysis) of the prepared data in the TGRA. In order to find out the type region of ANSP in TRGA, 8 types of region were selected from these 24 types under the hypothesis that the typical region generally has large area. Each of these 8 mapped typical regions was further fully analyzed from the spatial distribution pattern point of view, and it was found that these patterns are more decided by the soil type than the other two factors. Based on this fact, the 8 typical regions were then can be grouped in 3 categories, namely “purple soildrylandforestpaddy field” typical region, “yellow soildrylandforest” typical region, and “limestone soilforest” typical region.Finally, the typicality of the numerous study areas which have been selected and studied in the previous researches about the ANSP in the TGRA, were used to evaluate the research status of the typical regions. It was found that the “purple soildrylandforestpaddy field” typical region has been heavily considered, and the spatial distribution of these study areas in this region is reasonable. Moreover, although the “yellow soildrylandforest” typical region has been certainly concerned, it is still unable to meet the application requirements on the entire reservoir scale. Nevertheless, as there was seldom studies focused on the ANSP in the “limestone soilforest” typical region, it is suggested that more works should be put forward on this type region. Meanwhile, the maps of different classes of typical regions of ANSP in the TGRA can provide a basis for decision making in the study area selection in the future. Although this study is mainly focused on the typical region of ANSP in the TGRA, the method used in this paper can be further applied to other regions