基于GIS和USLE的东圳库区土壤侵蚀量预测研究

运用GIS、遥感技术与USLE模型相结合预测东圳库区流域土壤侵蚀量,利用GIS平台建立东圳库区基础地理数据库,以10×10m为栅格单元对库区进行离散化,在GIS空间分析功能支持下,结合USLE土壤侵蚀预测模型,根据合适的USLE因子算法生成栅格图层,通过图层运算,预测了东圳库区土壤侵蚀量,进而标识库区土壤侵蚀严重区域,为库区非点源污染控制及水土流失治理提供定量依据,并通过建立实用的泥沙输移比模型结合水文监测数据,对预测结果进行验证。根据USLE方程,采用改进后的SDR方程,预测的渡里流域年输沙量与流域实际监测得到的年输沙量仅相差14.08%,说明本文采用USLE方程模拟流域土壤侵蚀结果可信,可定量评价、拟定水土保持措施方案。

Study on Predicting Soil Erosion in Dongzhen Watershed Based on GIS and USLE

Non-point source pollution is a major cause for water pollution.Sediment is a type of pollutants and the carrier of nutrient,so predicting soil erosion would provide exact information for making environmental planning and taking measures.The GIS software including Arc/Info,Mapinfo and the RS software PCI Geomatica made up the technology platform for the research,on which spatial database and non-spatial database were built,hydrological processes simulation and watershed subdividing were performed.Reasonable methods were adopted to obtain R,L,S,K,C and P factors values.Soil erosion was predicted and risk areas of soil erosion were identified in Dongzhen Watershed.According to the analysis on the affecting factors of SDR,founding on former equation,this paper added hydrological factor to SDR equation and built a SDR equation for Dongzhen reservoir watershed,which included underlying surface factor and hydrological factor.Finally,calculating results of soil erosion quantity were proved credibly by using SDR equation for Dongzhen Watershed and monitoring data of sediment.Results showed annual average soil erosion amount was 916.32 t/km2,falling in to the category of light-grade erosion.The gentle and light-grade erosion area amounted to 93.82%;other grades occupied only 6.18%,but contributed 45.21% of sediments to the watershed.