Pipe and Isolation Valve Rehabilitation and Replacement Prioritization in an Urban Water Distribution System

A pipe and isolation valve failure in an urban water distribution system (WDS) causes service interruption to the water users at or downstream of the failure(s). The impact can be reduced by identifying and prioritizing the pipes and valves whose failure will affect the system's performance adversely. This study suggests a prioritization model for the pipe and valve rehabilitation and replacement in a WDS based on the analytic hierarchy process (AHP). The proposed model considers three parameters, namely, physical indices, system performance, and the socio-economic impacts. These parameters are further divided into the nine sub-parameters. The weightages of these parameters are assessed through the AHP technique which allows to prioritize individual water pipes and isolation valves. WaterGEMS and ArcGIS are used to simulate and model the WDS. A real WDS of Dire Dawa city in Ethiopia is considered as a case study to illustrate the methodology. It is noticed that the system supply shortfall are the most important parameters among the other system performance; age of the pipe and valves among the physical factors, and population among the socio-economic factors are the most important influencing sub-parameters in finalizing the rehabilitation scenario. It is felt that the proposed model can help the decision makers for ensuring efficient and effective operation and maintenance of an urban WDS resulting in the improved performance and hence the reliability.