On the implementation of the dynamically zoned target release reservoir model in the GEM-Hydro streamflow forecasting system

Abstract

This study investigates the benefit of the dynamically zoned target release (DZTR) reservoir model to improve upon the natural lake model for storage and outflow simulations of regulated reservoirs. Simulations were performed with the GEM-Hydro hydrologic model over the Saskatchewan River Basin to study different implementation scenarios for DZTR, applicable for varying degrees of available observed data. Results show that DZTR brings significant improvements upon the natural lake model. Outflow simulations are always better with DZTR than with the natural lake model, while storage performances are sensitive to the implementation methodology considered. Even in the absence of observed lake level data, storage simulations with DZTR are more realistic than the natural lake model. Automatic calibration of the 76 DZTR model parameters did not significantly improve results upon the general implementation methodology. Given the performance variability across reservoirs and the subjective steps involved in the DZTR implementation, it seems risky to implement DZTR without any flow observations downstream of a reservoir.