Comparison Study on Ways of Ecological Vulnerability Assessment ----- A Case Study in the Hengyang Basin

In the paper, Authors separately used analytical hierarchy process, expert scoring method, principal component and BP network to establish the weights of ecological vulnerability evaluation Index system in the Hengyang Basin as a case, and used hierarchical-comprehensive index -clustering model, principal component-comprehensive index- clustering analysis model, expert scoring-composite index-clustering analysis model, BP artificial neural network model to evaluate separately the reality vulnerability in 2000. The results shows that study area are moderate weak, and the results broadly similar. Authors think that Principal component and artificial neural network model can avoid subjective factors, and taking the way of the expert group judgment is to reduce the error of ecological vulnerability assessment.With the impact of global change and the strengthening of fragile ecosystems, China has carried out many researches and practices on vulnerability assessments [1,14].Although Vulnerability assessment in many ways, not yet formed a unified evaluation method, this paper draw on previous evaluation methods based on [1,11], using AHP, principal component analysis, BP neural network and expert scoring method on quantitative assessment and analysis, then clustering the results by comparison to determine which method to evaluate the most accurate.Authors analysis the Hengyang Basin reality vulnerability in 2000,attempting to explore a more suitable and easy erosion in hilly areas degraded fragile vulnerability assessment method.