基于水流阻力与图论的河网连通性评价

Evaluation of river network connectivity based on hydraulic resistance and graph theory

河网连通是区域防洪、供水和生态安全的重要基础。基于图论将河网概化为图模型,考虑不同类型河道输水能力差异,以河道水流阻力倒数表征水流通畅度,并以河道水流通畅度为权值,借助ArcGIS平台建立河网图模型加权邻接矩阵,再利用MATLAB工具进行顶点水流通畅度计算和河网连通度分析,从而实现对河网连通性的定量化分析。以太湖流域嘉兴平原河网为例,进行河道疏浚前后的河网连通程度定量评价,结果表明河道疏浚后河网连通度明显增加。

River network connectivity is an important parameter for consideration in the context of regional flood con- trol, 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 conduc- tivity （ or the reciprocal of the hydraulic resistance） is used to describe the degree of pateney 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 connectivi- ty 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.