Comparison of Generalized Non-Data-Driven Reservoir Routing Models for Global-Scale Hydrologic Modeling

Abstract. Large-scale hydrologic simulations should account for attenuation through lakes and reservoirs when flow regulation is present. Generalized methods for approximating outflow are required since reservoir operation is complex and specific real-time release information is typically unavailable at global scales. There is currently no consensus on the best approach for approximating reservoir release rates in large spatial scale hydrologic forecasting. This research compares two parsimonious reservoir routing methods previously implemented in large-scale hydrologic modeling applications, requiring minimal data so as not to limit their usage. The methods considered are those proposed by Doll et al. (2003) and Hanasaki et al. (2006). This paper compares the two methodologies across 60 reservoirs operated from 2006–2012 by the U.S. Army Corps of Engineers. The authors vary empirical coefficients for both reservoir routing methods as part of a sensitivity analysis. The Doll method generally outperformed the Hanasaki method at a daily time step, improving model skill in most cases beyond run-of-the-river conditions. The temporal resolution of the model influences performance. The optimal model coefficients varied across the reservoirs in this study and model performance fluctuates between wet years and dry years, and for different configurations such as dams in series. Overall, the Doll and Hanasaki Methods could enhance large scale hydrologic forecasting, but can be subject to instability under certain conditions.