3 Method
The weighted sum index based on the Analytical Hierarchy Process (AHP) is useful in river connectivity, which is a systematic method that approaches decision-making problems using multiple criteria (Saaty, 1980, 2005). When using this approach, a hierarchical indicator system must be constructed. This system typically consists of three layers, from top layer to bottom layer: the objective layer, subsystem layer, and indicator layer. The weighted sum index is defined as the sum of the products of weights representing the level of importance of each subsystem to the objective layer and the normalized value of the node (Cinelli, Coles, & Kirwan, 2014). In this paper, we use the AHP to determine the weights of indicators with respect to the river’s natural function.