Operation Safety Risk Assessment of Water Distribution Networks Based on the Combined Weighting Method (CWM)

This study proposes the risk assessment framework of water distribution networks with a focus on the determination of weights of various risk indices. First, the pipe risk list is built, in which pipe failure probability and consequence are considered. By integrating the analytic hierarchy process (AHP) and the entropy weighting method (EWM), the weights of these indices are obtained by the combined weighting method (CWM), by which both human experience and data distribution can be considered comprehensively. Taking a real WDN in an industrial zone in China as an example, the proposed method is demonstrated in detail and the risks of all pipes are determined. The accuracy of the CWM is validated from the perspective of risk levels of pipes with historical failure records. It is found that the AHP or EWM underestimates or overestimates pipe risks, respectively. Compared to them, the CWM provides reasonable results. In addition, the risks of plastic pipes, newly buried pipes less than five years old, and pipes over twenty years old are much higher.