Effect of Parameter Uncertainty on Water Distribution Systems Modeling

Abstract

Analysis of awater distribution system requires input data from many sources. The value of these data are uncertain due to their spatial-temporal variability, measurement error and limited sampling. This uncertainty in estimating model input parameters generates through the governing equations an uncertainty in the predicted model output. Such uncertainty affects notions of risk, reliability and confidence associated with engineering decisions for planning, design and management of water distribution systems. This paper examines the impact of model output uncertainty as affected by uncertain input parameters. The effects of the uncertainties of pipe roughness, junction demand, and water tank's level on the pressure heads and chlorine residual at the junctions are investigated. The methodology, which is applied on real water distribution network, consists of using Monte Carlo Simulation (MCS) to generated input parameters for the hydraulic simulation model considering extended period simulation (EPS). Results indicate that nodal pressure is more sensitive to parameter uncertainty compared to chlorine residual and tank water level has higher influence on pressure compared to the uncertainties of nodal demand and pipe roughness.