Comparison of methods for yield assessment of multiple reservoir systems

This paper compares four different methods for estimating the yield of a multiple reservoir system. These include simulation, a combined simulation-optimization model (WATHNET), a full optimization model, and a simplified optimization model called the yield model. Simulation is used widely in practice and provides a good approximation of the behavior of the system but requires a set of operating rules to be specified, The optimization methods automatically determine operating rules and are therefore quite useful in estimating the yield of a new system that has not yet been operated. The four methods are used to estimate the safe historical yield of the Canberra water supply system (Australia). It was found that the full optimization model and the yield model provide high estimates of the system yield because they assume perfect knowledge of future inflows. WATHNET presents a reasonable compromise in estimating the system yield using implied operating rules that are achievable in practice.