基于GIS和USLE模型对滇池宝象河流域土壤侵蚀量的研究

The Amount of Soil Erosion in Baoxiang Watershed of Dianchi Lake Based on GIS and USLE

滇池已被列入国家“三河三湖”治理的重点,也是云南省9大高原湖泊治理的重中之重。非点源污染是滇池污染的主要原因,而水土流失则是非点源污染的主要来源,占非点源污染总量的80%。运用GIS栅格模块的空间分析功能,根据USLE模型的各个因子进行图形运算,估算了小流域土壤侵蚀量。结果表明,流域的年均土壤侵蚀模数为983.51 t/km2,侵蚀强度为轻度,占流域面积91.53%的区域土壤侵蚀强度在轻度以下,对流域土壤侵蚀量的贡献率为52.80%;而流域47.2%的土壤侵蚀来自于占流域面积8.5%的中度以上侵蚀区域。

Dianchi Lake has been listed as the focus of national river bodies harnessing, which attracts special attention in the conservation of the nine major plateau lakes in Yun＇nan Province. Non-point source pollution is regarded as the primary cause of pollution of Dianchi Lake, whereas soil erosion, which accounts to 80 % of the pollution amount, is the source of non-point source pollution. This paper introduced the integration of GIS with USLE, and usage of the spatial analysis of GIS and the algorithm of each factor of USLE to estimate the amount of soil erosion in the Baoxiang watershed. Results showed the annually averaged amount of soil erosion was 983.51 t/km^2, which was in the category of low-grade erosion. The none or slightly eroded area occupied 91.5 % of the watershed area, and contributed 52.80 % sediment in watershed. The middle and the upwards eroded area only occupied 8.5 % of the watershed area, but contributed 47.2 % sediment.