Abstract: River network connectivity is an important parameter for consideration in the context of regional flood control, water supply and ecological security. Based on graph theory, the natural river network might be represented by a graph model. Taking into account the variability in delivery capacity of different channel types, the hydraulic conductivity (or the reciprocal of the hydraulic resistance) is used to describe the degree of patency within a river channel. Using the ArcGIS platform with the degree of patency as a weighted factor, the graph model can then be represented by a weighted adjacency matrix. Using MATLAB, the degree of patency within a river channel can be estimated, and the connectivity in river channel networks can also be calculated. The quantitative analysis of river network connectivity can thus be achieved. The proposed approach has been tested on a river network of the Jiaxing Plain in the Taihu Lake Basin. The result shows that the river network connectivity is improved significantly after dredging. The study provides a useful tool for evaluating the river network connectivity.