Regional Ecological Risk Assessment By The Catastrophe Progression Method: A Case In The East Dongting Lake

The East Dongting Lake(EDL) is the largest one of Dongting Lake, which islocated at the south of the Jing River. EDL is considered as a key region for globalprotection of freshwater biodiversity in the world and the most important commoditygrain production base of Hunan Province. With rapid economic development, EDL issuffering many problems, such as frequent natural disasters, loss of biodiversity,eutrophication and degradation of ecological environmental, which had seriouslyconstrained the sustainable of socio-economic development in the region of EDL. Theregional ecological risk assessment (EPA) can reflect comprehensively and accuratelyecological environment status and its dynamic changes. Therefore, this paper takesEDL as the research area, by using remote sensing and GIS techniques，and using thecatastrophe progression method(CPM) to evaluate its ecological risk of2000-2006onthe base of the theoretical framework and method of EPA in the United States. In thestudy, the risk of five landscape types and multiple stressors were analyzed, while thetime and space variation of ecological risk also were analyzed. The research resultshowed that:(1) The ecological risk degree was in the highest condition at2000and2002; andmost region of the EDL, especially the core of the National East Dongting LakeReserve (NEDLR), was in low state at2001and2003; there was a great change withregional ecological risk after2004. All the regions were in high level, except thatNEDLR in low condition from2004to2006;(2) The unused land was in the highest condition from2000to2006; cultivatedfiled also in the highest condition from2000to2003, but the value of risk wasdecreased after2003because the improvement protection for cultivated filed due tothe Dongting Lake Ecological Resettlement Project and the Return Grain Filed to theLake(RETURNING) engineering; water bodies and grassland were in the highest stateby the drought in addition to2000and2002, the risk values for the other years were ata low level; and the land of construction was in low condition in the period of2004-2006;(3) The evaluation result by CPM indicated that Natural disasters directlyaffected the water environmental condition, there was a significant correlationbetween the sources of risk of natural disaster and water pollution; and the disastercontributes the most rate of the ecological risk in EDL, while the different landuse patterns was one of the key cause for spatial heterogeneity of ecological risk.