Optimal operation of multiquality water supply systems – III: The Q–C–H model

A new technique for optimal operation of multiquality water supply systems is proposed. The technique, which is known as a Q–C–H (flow–quality–head) model, combines previously developed flow–quality (Q–C) and flow–head (Q–H) models for optimal operation of water supply systems. The decision variables in the model are the operation of treatment plants, pumps and valves. The model minimizes the cost of water at sources, treatment, energy, and loss of agricultural yield when water quality is low. The model uses an iterative modified projected gradient method combined with the Complex method. As in the Q–C and Q–H models, the solution method is based on decomposition, disaggregation/aggregation approach, involving internal and external optimization. The decision variables of the external model are the flows in the loops of the network and the removal ratios at the treatment plants. The operation of the pumps and valves are the decision variables of the internal model. The method is demonstrated by application to an example problem.