Water distribution network analysis under fuzzy demands

Abstract

Looped pipe networks are analysed assuming that all the input variables have precise crisp values. If the hydraulic heads are to be determined, the water demands at the nodes, the diameters and the roughness coefficient of the pipes are considered known and crisp. The paper proposes a fuzzy set approach for addressing the uncertainty of the water demands at the nodes using the Newton–Raphson method for the analysis. In contrast with other studies which adopt the fuzzy approach for analysing the behaviour of the looped hydraulic networks, the proposed methodology exploits the monotony of the continuity equation at the nodes; therefore, the multicriteria optimisation procedure for handling fuzziness is not required. The application of the proposed methodology results in a range of hydraulic heads at the nodes of the network. This information is important for the designer and can be used to identify vulnerable areas of the network which may suffer from design pressure deviations. The proposed methodology is illustrated through a simple looped pipe network analysis exercise.