Unit Penalty Setting for Linear Programming Based Priority Simulation Models

Most newer water supply simulations models employ optimization methods to allocate water and operations according to fixed operational priorities for each time-step. For extensive complex networks with return flows, loops arising from pumping, and proportional delivery reductions for equal-priority deliveries, the assignment of unit weights for operational priorities can be a matter of some art and controversy. A generalized method is developed and implemented to automate assignment of unit objective function weights to guarantee priority-preserving behavior for network flow and linear programming-based simulation models. The method is developed and applied to the CalSim II model of California's State and Federal water supply projects. The automated method should facilitate studies where major changes are made to the system. Examples illustrate some paradoxes of water management under prioritized deliveries and return flows, such as occasions when priority optimization implies that some lower priorities receive water when intermediate priorities do not.