ABSTRACT
The research presented in this chapter aims at alternative way of expressing network reliability index, which has been derived from a diagram named the hydraulic reliability diagram (HRD). This diagram shows the correlation between the pipe flows under regular supply conditions and the loss of demand caused by the pipe failure. The reliability index calculated from the position of all the dots on the graph, and also adding proportional weighting to the pipes carrying variable flows, has been named the network buffer index (NBI). In this way, the NBI quantifies the HRD that clearly shows the pipes that are major contributors to the loss of demand. Moreover, the HRD hints the network buffer for particular level of demand. The concept has been illustrated on the networks of different degree of complexity and the NBI has been compared with two other indices from the literature: the resilience index of Todini (2000) and the network resilience defined by Prasad and Park (2004). The results show clear correlation between all three indices, but the NBI evaluates network reliability more realistically being more sensitive towards the change of network configuration than the resilience indices that are predominantly influenced by energy balance in the network.
