Design of Optimal Reliable Multiquality Water-Supply Systems

A methodology which integrates the optimal design and reliability of a multiquality water-supply system is presented and demonstrated. The system designed is able to sustain prescribed failure scenarios, such as any single random component failure, and still maintain a desired level of service in terms of the quantities, qualities, and pressures supplied to the consumers. In formulating and solving the model, decomposition is used. The decomposition results in an “outer” nonsmooth problem in the domain of the circular flows, and an “inner” convex quadratic problem. The method of solution includes the use of a nonsmooth optimization technique for minimizing the outer problem, for which a member of the subgradient group is calculated in each iteration. The method allows reversal of flows in pipes, relative to the direction initially assigned. The methodology is applied to a system with 33 pipes, five pumps, and 16 nodes (two source nodes with treatment facilities and 14 consumer nodes) for a single loading condition and one quality parameter.