By Dan Bunk (Bureau of Reclamation, Lower Colorado Region) & Katrina Grantz (Bureau of Reclamation, Upper Colorado Region)

Abstract: Several new operations models have been implemented or are in development in the Colorado River Basin. The Lower Colorado Region replaced an outdated spreadsheet application used for scheduling hourly releases out of Davis Dam and Parker Dam with an hourly RiverWare model which utilizes the new Unit Power method. The new model allows for easy storage and access of data in the Hydrologic Database (HDB) and better security of the short term operations system. Also, Reclamation’s mid-term operational model, the 24-Month Study, has been expanded so that all water use in the Lower Colorado basin is explicitly modeled in RiverWare. Previously, all data and functions that calculate the Parker Dam releases were in an external spreadsheet model. The RiverWare model expansion allows for easier access to water use data and more efficient accounting for water deliveries in the Lower Basin. Development of a probabilistic version of the 24-Month Study model is also currently underway. The model is based on the expanded 24-Month Study model but will utilize multiple inflow forecasts generated by the River Forecasting Center’s (RFC) Ensemble Streamflow Prediction model to produce probabilistic output of variables such as reservoir releases and diversions. Current work includes the development of rules for the Upper Basin reservoirs and a conversion for the model to use natural inflow forecasts rather than unregulated inflow forecast. The model will be a key tool for Reclamation and stakeholders to assess risk and uncertainty in the Colorado River Basin.