| Summary: | Hydrological models are simplified representations of the natural surface water dynamic system. This thesis focuses on improving these representations to make them more realistic and thus more appropriate tools to simulate past and future hydrological behaviors. The two specific hydrological model structural improvements in this thesis focus on the explicit representation of 1) lake representation in complex lake networks and 2) forest growth/disturbance representation in forest headwater catchments. The first and primary focus of this research is on lake (and reservoir) delineation and subsequent simulation in hydrological models. Lakes and reservoirs have critical impacts on hydrological, biogeochemical, and ecological processes, and they should be an essential component of hydrological and eco-hydrological watershed modelling. Past large-scale hydrological modelling efforts tend to either ignore the impacts of all lakes or explicitly simulate the behavior of only the largest lakes in a watershed. This is practically due to two reasons. First, the difficulties inherent in representing thousands of lakes in various hydrological models. Second, the model without representing lakes can typically provide reasonable streamflow simulation at the watershed outlet. However, the potential impacts of ignoring lakes on the simulated runoff components (i.e., quick runoff, baseflow, infiltration, eta) and streamflow at internal gauges have not been adequately studied. A suite of Pan-Canadian subwatershed-based lake and river routing GIS products at multiple spatial resolutions has been developed. These are the first routing networks available that explicitly and in a hydrologically consistent way represent lakes for the domain of Canada. The routing networks provide the necessary routing network topology and network attributes to enable vector-based hydrological routing anywhere in Canada. A case study using the Raven hydrological modelling framework to simulate routing from the Hudson Bay watershed shows that eliminating ...
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