The Ontario hydrological modelling assessment project applies the Raven Hydrological modelling framework in multiple configurations to simulate the hydrologic behaviour across all of Ontario. This large-scale modelling effort is applied to the nine regions of Ontario and here we present comparative modelling results for the 35,500 km2 SE region, draining to the Ottawa River._x000D_ _x000D_ Our comparative results focus on streamflow and water level prediction. We benchmark our semi-distributed hydrologic models in Raven against a lumped Raven hydrologic model. We compare our semi-distributed hydrologic model against our vector-based routing-only Raven model and both models have 1) the same lake and river routing networks (1057 subbasins, 311 lakes) and 2) are ultimately forced with the same meteorological inputs (Canadian Surface Reanalysis or CaSR ver 2.1). In the case of our routing model, the surface runoff and baseflow forcings to Raven were taken as Environment and Climate Change Canada’s (ECCCs) calibrated GEM-Hydro model outputs produced by forcing GEM-Hydro with CaSR v2.1. _x000D_ _x000D_ Results show the value of distributed modelling with detailed treatment of lakes relative to lumped modelling and also show the improvements associated with a full hydrologic model versus a routing-only model constrained to utilize ECCC land surface hydrologic model fluxes. Furthermore, we show the differences between a regionally calibrated hydrologic model and watershed specific calibration of the same hydrologic model and then demonstrate how we combine these two models together, along with historical flows and lake levels, to create a high resolution 39-year streamflow and lake level reanalysis for the SE region.
