3.2 Judgment matrix and weight coefficient
The establishment of a connectivity judgment matrix is the key to the AHP model. In this paper, drawing on previous research results, we obtain the judgment matrix by comparing the connectivity indicators at different levels based on the river’s basic functions. The specific analysis is as follows.
The continuity and mobility of water flow are the basis of river health. On the one hand, water conveyance and sediment transport are the most important functions of rivers; on the other hand, sediment transport and channel evolution also require power or energy generated by the water flow. Therefore, water flow connectivity is more important than boundary connectivity and sediment connectivity. In addition, the balance of erosion and deposition will be disturbed if the sediment is not connected, which will change the boundary characteristics of the channel. In addition, there is no channel for water conveyance and sediment transport if the boundary is damaged, which would cause serious floods. Therefore, boundary connectivity is more important than sediment connectivity. According to the relative importance of each connectivity index, the constructed judgment matrix is shown in Table 2. The weights of boundary, flow and sediment connectivity indexes are 0.143, 0.571 and 0.286, respectively.