Abstract:

 Located in the Yangtze River，the Taihu Lake watershed is one of the most economically developed regions in China，but is also a region with frequent natural disasters Regional development and social progress make the patterns，depth and intensity of land use constantly change in watershed，as a result，humanland conflict is highlighted and the ecological environment is facing tremendous pressure，whats more，the ecosystem structure and function are strongly affected At present，study on the ecological risk of the Taihu Lake watershed is not plentitude，which only evaluates single risk sources such as heavy metal pollution，floods，etc，and is lacking of quantitative research Taking the main ecological risk sources of Taihu Lake Basin as the evaluation object，the article explored the mechanism of risk sources，and built a model of risk source assessment considering the differences of risk sources intensity in different grades and types Then according to the incidence，intensity and scope of ecological risk sources occurrence，this study established the hazard index system of ecological risk sources such as flood，drought，extreme weather，soil erosion and pollution emissions ArcGIS software was used to create the statistical database of risk source hazard including 1606 grids and 24 counties，and then to determine the weights of index by using AHP method At last，a quantitative assessment was conducted for single elements and comprehensive ecological risk by using the technology of overlay analysis，spatial analysis，and definite the leading ecological risk source Based on the hazard degree assessment of ecological risk source model，we used the probability analysis to assess the occurrence strength of floods，droughts，extreme weather，soil erosion，pollution and other natural disasters and human activities in the Taihu Lake watershed，and finally received the spatial distribution of comprehensive risk sourced Highrisk areas of risk source accounted for 1172% of the total area，mainly concentrated in the northern regions of the Taihu Lake watershed. Higher ecological risk areas appeared the “NorthwestNorthNortheastEast” semicircular distribution pattern，accounting for 2452% of the watershed，and lower risk source areas were concentrated in the Tiaoxi basin located in northwestern of Taihu watershed，accounting for 1566% of the watershed In different regions，the composition of ecological risk source and the dominant source was different In 599% of the region，the main risk source was pollution emission，mainly concentrated at the east of Zhenjiangyixingchangxinganji Over 25% of the region took drought as the main risk source，mainly concentrated at the west of Zhenjiangyixingchangxinganji For 1244% of the region,the main risk source was flood，concentrated at the huzhou，yixing The region taking the extreme weather and soil erosion as main risk source was relative dispersed and accounted for less percentage