RELIABILITY ANALYSIS OF WATER DISTRIBUTION NETWORK

Abstract

The hydraulic reliability of a water distribution system can be defined as the probability that the system can provide the demanded flow rate at the required pressure head. Due to random nature of future water demands and required pressure heads, the estimation of water distribution system reliability for the future is. subject to uncertainty. The reliability of water distribution system is concerned with two types of failure, namely mechanical failure and hydraulic failure. Since neither the mechanical measure nor the hydraulic measure alone are adequate to measure the system reliability, it seems reasonable to unify the hydraulic failure and mechanical failure definitions. This study proposes a heuristic method to assess the reliability of a least-cost water distribution network. The quantitative approach begins by obtaining an "optimal" layout design through linear programming. This approach addresses the probability of isolating a node through simultaneous failure of all links connected directly to that node. If after solving linear programming model, the node isolation probability is unacceptable, the maximum number of allowable failure per year is reduced and a new linear programming problem is solved. The process is continued until all the nodes have an acceptable node isolation probability.