基于“碧水指数”的杭州市西湖区河道生态健康评价

Evaluation of River Ecological Health in Xihu District of Hangzhou Based on“Blue Water Index”

构建了针对杭州西湖区河道的“碧水指数”,包括5项一级指标、19项二级指标,一级指标包括水质特征、水文特征、河道形态特征、河岸带植被景观特征和河道管理,并采用层次分析法确定了指标权重。应用2021年8月的监测数据计算了西溪河、古荡湾河、益乐河9个河段的“碧水指数”,9个河段“碧水指数”综合评分在3.54~4.07分之间。各河道得分最低的指标均为“河道形态特征”,次低指标不尽相同,古荡湾河和益乐河为“水文特征”,西溪河为“河岸带植被景观特征”。二级指标中,得分较低的指标为透明度、河道宽深比、河道蜿蜒度、河道变化、流态多样性和河岸带景观。结合西湖区智慧治水平台汇集的数据,可以实现河道“碧水指数”自动评价,达到精细化评价、精准管理的目的,降低河道管理成本。

The“blue water index”is constructed for rivers in Xihu District of Hangzhou.The index includes 5 primary indicators and 19 secondary indicators,and the primary indicators include the characteristics of water quality,hydrology,channel morphology,riparian vegetation landscape and river management.The weight of each indicator is determined by analytic hierarchy process.Based on monitoring data in August,2021,the blue water index is calculated for 9 river subsections of Xixi River,Gudangwan River and Yile River.Our results show that the score of the blue water index of 9 river subsections is between 3.54 to 4.07.The indicator with the lowest score of all rivers are“channel morphology characteristics”,and the lower indicators are different:Gudangwan River and Yile River are“hydrological characteristics”,while Xixi River is“vegetation and landscape characteristics”.Among the secondary indicators,the indicators with generally low scores include transparency,river width-depth ratio,river meandering,riverway evolvement,flow pattern diversity and Riverbank Landscape.Combined with the data collected by the intelligent water control platform of Xihu District,the“blue water index”of each river can be evaluated automatically,so that refined evaluation and precise management can be achieved,and the cost of river management can be reduced.