Multiple-criteria Decision Analysis for the Selection of Water Hammer Protection Systems for Water Mains

If a water main is not well protected against hydraulic transients, devastating consequences can take place. However, there are often multiple viable alternatives for the protection of a water main. In this paper, with the application of multiple-criteria decision analysis (MCDA), it is done the selection, from alternatives, of the protection system for a case study water main against the hydraulic transient that comes from a pump trip. Four alternatives were developed, resulting in acceptable extreme pressures. These alternatives considered devices like hydropneumatic bladder tanks, air valves and flywheels. In order to decide which alternative to choose, the following criteria were selected: general costs, reliability of the system functioning without failures, reliability of the simulation model, avoidance of sub-atmospheric pressures and avoidance of high pressures. The MCDA methods used were the Analytic Hierarchy Process (AHP) and Cooperative Game Theory (CGT). Functions to translate how well the alternatives performed, regarding each criterion, were created.