This case study investigates the benefits of spatializing the calibration of the CEQUEAU hydrological model for two catchments located in the province of Quebec, Canada. The hydrological model is also used to correct the discharge curves of a spillway at the entrance of an artificial channel used to transfer water from one catchment to another. No real stream flow measurements are available for the catchments under study, and natural inflows are reconstituted through a water balance equation, which includes the water transferred from one catchment to the other. Although the application is specific to the Lake-St-Jean region in Quebec, Canada, this study could serve other users and water managers with similar issues regarding parameters and inflow uncertainty. The current calibration of the CEQUEAU hydrological model is based exclusively on stream flows recorded at the outlet of the downstream sub-catchments of each catchment. There exist, however, intermediate stream flow measurements at the outlet of the upstream sub-catchment for each catchment. It is demonstrated that using both stream flow records (upstream and downstream sub-catchments) to calibrate the hydrological model parameters leads to improved simulations. The recalculation of the discharge curves for the Bonnard channel through hydrological modelling also reveals that it is inexact for large stream flows and a simple but efficient correction method is proposed. Altogether, this case study shows that a careful revision of the modelling practices for those catchments can lead to more accurate estimation of inflows to reservoirs, which could reduce predictive uncertainty for future inflows.
