Dynamic Evaluation Of Ecological Vulnerability In The Three Gorges Reservoir Region In Chongqing Section, China

Global change and human activities have significantly influenced the eco-environments human-kind relies on, and increased their vulnerability. Nowadays, ecological vulnerability has been highlighted in the studies of global change and sustainability.The vulnerability of the eco-environment in the Three Gorges Reservoir Region has been a great concern in recent years. This region which plays an important role in the ecological function of the upper reaches of the Yangtze River, China, bears intensive human disturbance making it particularly vulnerable, especially the areas in Chongqing where the social economy is in a rapid development.In this study, the ecological vulnerability evaluation system of the Three Gorges Reservoir Region was built. The evaluation system contained18indicators including natural and anthropogenic factors. Based on remote sensing (RS) and geographical information system (GIS) techniques, the ecological vulnerability in the Three Gorges Reservoir Region in Chongqing section from2001to2010was evaluated quantitatively. Using Analytic Hierarchy Process (AHP) and Spatial Principal Component Analysis (SPCA), ecological vulnerability index (EVI) in different years in the study region was calculated. The standardized EVI value was classified into five levels (slight, light, medium, heavy and extreme level), according to the equal interval classification. On the basis of different ecological vulnerability levels over the past decade, the ecological vulnerability synthetic index (EVSI) in the area was calculated. The ecological vulnerability distribution and its dynamics over the decade were analyzed, by using centroid method and linear regression method. Meanwhile, Hurst index was applied to predict future trend of ecological vulnerability in the study area. The main results are as follows:(1) By comparison the ecological vulnerability evaluation results, the study showed that the result of SPCA is better able to reflect the real situation of ecological vulnerability in the Three Gorges Reservoir Region in Chongqing section from2001to2010. The SPCA has good application prospects in ecological and environmental evaluation.(2) The ecological vulnerability in the study region was caused by interactions between natural and anthropogenic factors, in which urban residential pollution, soil erosion, and vegetation condition were the most important factors.(3) The ecological vulnerability in the study area was at a medium level on the whole, and showed an apparent spatial distribution pattern. The heavily and extremely vulnerable areas were mainly distributed in the central and western part of the study region, while the slightly and lightly vulnerable areas were in the northeast and southeast. The ecological vulnerability changed significantly interannually, with the least vulnerable in2002and the most vulnerable in2008. The ecological vulnerability continuously increased after the impoundment of the Three Gorges Reservoir, followed by decline after2008.(4) During the study period, the centroid of ecological vulnerability migrated gradually from northeast to southwest. There was a spatial trend of polarization in the ecological vulnerability of the study region. In the seriously fragile regions, the eco-environment became worse, while the eco-environment in mildly fragile regions has improved gradually.(5) Future tendency of ecological vulnerability in study region, which keep consistence with the past10years. Most parts of the study region are in an important transition.