基于RS和GIS的乌江流域生态安全度变化评价

乌江流岩溶地貌发育，水土流失、石漠化问题均较突出，生态环境极其脆弱，为了了解乌江流域生态安全状况及存在问题，文章基于RS和GIS技术，在分析流域土地利用/覆盖变化和景观格局时空变化特征基础上，从自然环境、社会经济、景观生态3方面构建生态安全度评价指标体系，将熵权法与属性识别模型相耦合，对流域41个地区进行生态安全度评价。结果显示:2000年贵州省乌江流域生态安全度属于差、较差、中等、较好的面积分别为745.8 km2、15 212.2km2、40 670.7km2、9 361.4km2，所占比重分别为1.13%、23.05%、61.63%、14.19%；2010年属于差、较差、中等、较好所占面积分别为4 330.5km2、12 254.1km2、42 804.0km2、6 591.4km2，所占比重分别为6.58%、18.57%、64.86%、9.99%；2000年和2010年乌江流域均缺少生态安全等级为好的地区，而2010年较2000年生态安全等级较差的地区面积增加，较好的面积却减少，表明流域生态环境整体呈恶化趋势；流域上游、中游地区较下游地区的生态安全状况偏差，生态本底脆弱、人地矛盾突出、水土流失、石漠化等是影响上游地区生态安全度的主要原因，中游地区受矿产资源开采及大城市人口聚集的影响，下游地区受水电资源过度开发影响。 

Evaluation of ecological security in the Wujiang river basin using remote sensing and GIS technologies

To understand the situation and existing environmental protection problems,and to promote coor-dinated development of the Wujiang river basin economy and ecological construction,the environmental eco-logical safety of the Wujiang river basin is evaluated in this paper.Applying the RS and GIS techniques,on basis of analyzing the changes of watershed land use and the space-time changes of landscape pattern,an as-sessment system for ecological security is builded by natural environment,economy and landscape ecology. And with this assessment system,integrating entropy method with attribute identification model,the ecologi-cal security of 41 regions of the watershed are assessed.The evaluation results are divided into five catego-ries：good,moderately-good,medium,moderately-bad and bad.The results indicate that：in 2000 the Wu-jiang river basin had 745.8 km2 （1.13%）of bad,15,212.2 km2 （23.05%）of moderately-bad,40,670.7 km2 （61.63%）of medium,and 9,361.4 km^2 （14.1 9%）of moderately-good conditions.It is noted that there are some differences between the results for 2000 and those for 2010.In 2010,the Wujiang river basin had 4,330.5km^2 （6.58%）of bad,12,254.1 km2 （18.57%）of moderately-bad,42,804.0 km^2 （64.86%）of medi-um and 6,591.4 km^2 （9.99%）of moderately-good conditions.No good conditions occurred in the Wujiang river basin in 2000 and 2010.However,compared with 2000,the moderately-bad area increased in 2010,and the moderately-good area decreased,indicating that ecological environment is facing a negative trend.The ecological security situation in the upper and the middle catchment is poorer than that in the lower catchment of the Wujiang river basin.In the lower catchment,the problem of hydropower resources over-exploitation is very serious,while in the middle catchment,mining of mineral resources and high population density in big cities play significant roles in ecological security.In the upper catchment,the main problems which affect ec-ological security include the fragility of t