UC Davis

This study couples the Muskingum routing method with multi-timestep optimization (MTO) to facilitate daily timestep mode in system operations planning models such as CalLite, CalSim II, and CalSim 3. The modeling framework used is the California Department of Water Resources’ (CA DWR) Water Resources Integrated Modeling Software (WRIMS) using Water Resources Simulation Language (WRESL). In the report, Muskingum routing is implemented in a simplified modeling domain representing California’s Sacramento Valley, North-of-Delta (NOD), based on the CalLite and HEC-FCLP schematics. The Muskingum method was chosen for its ease of implementation, relative accuracy, and parameter availability. Implementing channel routing involves introducing a storage node in between channel arcs to represent the accumulation and loss of storage as water travels from upstream to downstream. Models such as CalLite and CalSim mainly use single timestep optimization (STO). Unlike STO, MTO provides the capability to forecast and access future decision variables to optimize current timestep (e.g., one day) releases to meet future targets or objectives. Previous work demonstrated that using channel routing with STO where basin travel times (e.g., Shasta to the Delta) will exceed more than the timestep can generate unrealistic reservoir operations. As a result, a daily timestep model representing the NOD to Delta region requires both channel routing and MTO. Results during the simulation period of water year (WY) 1997 show reasonable reservoir releases at the major project reservoirs such as Shasta, Folsom, and Oroville. However, further work is needed in updating the weights and penalties to account for the MTO framework and to better represent the balancing of the NOD reservoirs. Overall, a daily timestep mode of the California Central Valley similar in scope with CalLite can be implemented using channel routing and MTO. One of the major areas of future work is performing a comprehensive recalibration and adjustment of weights, goal statements, and penalties to better represent real-time, daily-to-weekly coordinated operations among the major project reservoirs to meet obligations in the Delta and South-of-Delta.