Study on Connotation and Analysis Modes of River System Connectivity

The river system connectivity is an important condition for keeping the river integrity and the river health and developing the river function normally. At present, the decline of the river system connectivity is very serious, which attracts much social concern. For the more thorough understanding of main characteristics and evaluation of the river system connectivity, based on the component units and main function, its connotation, types and analysis modes are systematically analyzed from the river boundary, water current, suspended matter (sediment) and so on. The river system connectivity mainly refers to the fluency and stability of the boundary, continuity and fluidity of the flow, transport and exchange of sediment load, and the biological multiplying and diversity. In addition, three aspects of the river system connectivity are summarized, namely, the river connectivity, the connectivity in the basin and the inter-basin connectivity, of which the river connectivity includes longitudinal connectivity and lateral connectivity between the main channel and floodplain, and the connectivity in the basin mainly includes the connectivity of trunk and branches, the connectivity of river and diversion channels, the connectivity between rivers and lakes, etc. Based on the analysis of the characteristics of various types of river system connectivity, its analysis modes are put forward such as the channel connectivity mode, the diversion-convergence connectivity mode and the floodplain-mainstream connectivity mode. Then the key problems and research ideas of each mode are discussed.