香溪河流域水生态系统健康评价

Health Assessment of Aquatic Ecosystem in Xiangxi River Basin,China

随着人们环境保护意识的增强,河湖生态保护与修复成为社会关注的热点问题,科学的生态健康诊断则是有效进行河湖治理的前提.香溪河作为三峡水库典型支流,探究其水生态系统健康对于长江生态保护具有十分重要的意义.通过收集整理香溪河干支流的生物与生境数据,构建了涵盖水环境、水生生物、物理栖息地三方面共16项指标的水生态系统健康评价指标体系,综合运用专家判断法和熵权法确定评价因子权重,采用河流健康指数(RHI)表征香溪河流域水生态系统健康状况.结果表明:①2017年三峡水库蓄水期香溪河流域水生态系统整体健康水平为良好,优和良等级占比分别为12.5%和79.2%.②健康状况呈现出支流优于干流、非回水区优于回水区的空间分布特点,具体表现为支流南阳河>支流古夫河>支流高岚河>香溪河干流.干流水环境问题相对突出,而支流的河流连通性相对较差.③库湾健康状况的年内变化特征为冬季最好,春秋季次之,夏季最差.研究显示,该评价体系能准确地评估香溪河流域水生态健康状况,同时需重视三峡水库支流库湾的水环境治理.

As people′s awareness of environmental protection has increased,ecological protection and restoration of rivers and lakes have become hot issues,and scientific ecological health diagnosis is a prerequisite for effective governance.The Xiangxi River is a typical tributary of the Three Gorges Reservoir.Therefore,exploring its aquatic ecological health status is very important to the ecology of the Yangtze River.By collecting and organizing biotic and habitat data of the mainstream and tributaries of the Xiangxi River,a health evaluation index system for aquatic ecosystems was established.It consisted of a total of 16 indicators that are divided into three aspects:water environment,aquatic organisms,and physical habitats.Expert judgment method and entropy method were used to determine the weight of evaluation factors,and the River Health Index(RHI)was constructed to characterize the aquatic ecological status of the Xiangxi River Basin.The results showed that the overall health of the aquatic ecosystem in the Xiangxi River Basin during the impoundment period of the Three Gorges Reservoir in 2017 was good,with excellent and good samples accounting for 12.5%and 79.2%,respectively.The spatial distribution of the health level of the Xiangxi River Basin showed that the tributaries were healthier than the mainstream,and the non-backwater areas were healthier than the backwater areas.The specific performance was as follows:Nanyang River>Gufu River>Gaolan River>Xiangxi River.The water environment problems of the mainstream were relatively prominent,and the river connectivity of the tributaries was relatively poor.During the whole year,the health status of Xiangxi Bay changed,with the highest score in winter,followed by autumn,spring and summer.The research suggests that the evaluation system can be used to accurately assess the health status of the aquatic ecosystem in the Xiangxi River Basin,and it is necessary to keep focused on the water environment treatment of the bays of the Three Gorges Reservoir.