Evaluation of river connectivity based on TOPSIS model: Taking the North District Expansion Zone of Zhangjiagang Economic Development Zone in Jiangsu Province as an Example

The river system connectivity has become an important indicator of current river health assessment. The proper connectivity of river systems has the functions of allocating resources, improving water and soil environment, and preventing floods and droughts. However, it will be affected by many factors. In this paper, take Zhangjiagang, Jiangsu Province as an example, the influence degree of the structural connectivity index (expressed as static indicators) and hydroconnectivity index (expressed as static and dynamic indicators) on the connectivity of river flow system is analyzed based on the TOPSIS model. The study finds that the order of influence of each index on the connectivity of water system in the study area is: The structure connectivity index (α、 γ) is greater than hydrological connectivity index (R b 、 W p 、 R d 、 E p 、 C EN ), and the Closeness T j =(0.546, 0.546, 0.471, 0.479, 0.506, 0.519, 0.463). when analyzing the regional scale, we should consider the local conditions and consider comprehensively from the perspectives of structural connectivity and hydrological connectivity. The results of the study hope to provide theoretical basis for water system planning and management.