A Proposed Flow Path Model for Scheduling Optimization of a Water Distribution System

A flow path model is developed for scheduling optimization of a water distribution system. The model simultaneously describes a water distribution system in two parts: (1) the water delivery relationships between suppliers and receivers and (2) the physical water delivery system. In the first part, the model considers waters from different suppliers as multiple commodities. This helps the model to clearly describe water deliveries by identifying the relationships between suppliers and receivers. The physical part characterizes a physical water distribution network by all possible flow paths. The advantages of the proposed model are that: (1) it is a general methodology to optimize water distribution, delivery scheduling, water trade, water transfer, and water exchange; (2) no simplifications are made for either the physical system or the delivery relationship; and (3) it can be used as a tool for real-time decision making for scheduling optimization. The model optimizes not only the suppliers to each receiver but also their associated flow paths for supplying water. This characteristic leads to the optimum solution that contains the optimal scheduling results and detailed information of water distribution in the physical system. That is, the water right owner, water quantity and its associated flow path of each delivery action are represented explicitly in the results rather than merely an optimized total flow quantity in each link. The proposed model is first tested on two hypothetical water distribution cases. The results show that the flow path model has the ability to optimize both the quantity of each water delivery as well as the flow path. The model is being applied to the water distribution system of the Metropolitan Water District of Southern California (MWD), which supplies water to 18 million people in Southern California.