Water distribution system design under uncertainties

ABSTRACT: A chance constrained model is presented for the minimum cost design of water distribution networks. This methodology attempts to account for the un-certainties in required demands, required pressure heads, and pipe roughness coef-ficients. The optimization problem is formulated as a nonlinear progmmmhg model which is solved using a generalized reduced gradient method. Details of the math-ematical model formulation are presented along with example applications. Results illustrate that uncertainties in future demands, pressure head requirements, and pipe roughness can have significant effects on the optimd network design and cost. There is currently no universally accepted definition or measure of the reliability of water distribution systems. In general, reliability is defined as the probability that a system performs its mission within specified limits for a given period of time in a specified environment. Over the past two de-cades, there have been many models developed for the analysis and the min-imum cost design of water distribution networks (e.g., Alperovit ~ and Shamir 1977; Quindry et al. 1981; Morgan and Goulter 1986; Lansey and May