Evaluation of Channel Connectivity in the Lower Reaches of the Yellow River Based on Analytic Hierarchy Process

In recent decades, the connectivity of the lower reaches of the Yellow River has changed under the influence of human activities. By the means of analytical hierarchy process (AHP), this paper constructed the tomographic analysis model combined with connectivity index system, obtained the judgement matrixes of indexes by nine-demarcation method, calculated the weights of the indexes, and then constructed the formula of connectivity evaluation function. According to the data of runoff and sediment load of hydrological station, the channel connectivity was evaluated in the lower reaches Yellow River in 1960-2010. The results showed that the channel connectivity in the lower reaches of the Yellow River was better in the period from 1961 to 1965. Due to the rainfall decrease and excessive water diversion, the channel connectivity decreased significantly in 1985-1999. However, since the year 2000, the channel connectivity has been significantly improved owing to the impoundment of the Xiaolangdi reservoir.