The primary objectives of this dissertation research are to (1) improve the understanding of macro-scale hydrologic processes in cold climate regions, (2) improve macro-scale representation and modeling of depression-dominated areas, and (3) improve land use variations in macro-scale hydrologic models. To achieve the objectives, (1) a Macro-Scale Hydrologic Processes Simulator (Macro-HyProS) is developed and tested in the Red River of the North Basin (RRB), (2) the impacts of sub-daily temperature fluctuations around the freezing temperature on snowmelt simulations are evaluated by using a hybrid temperature index method (HTIM), and (3) the effects of two high-resolution gridded temperature datasets on magnitude and distribution of snowmelt are assessed in the Missouri River Basin (MRB). Macro-HyProS is a grid-based daily hydrologic model that uses a unique LEGO-fashion horizontal layout to account for the within-grid heterogeneity of land use. The model incorporates five vertical bands, each of which simulates different hydrologic processes. Eventually, a grid-to-grid routing method is used to estimate outlet discharge. The simulation results from the first study accentuated the significance of frozen ground condition on the generation of surface runoff in the RRB. It was found that the concurrent occurrence of frozen ground condition, snowmelt events, and early spring rainfalls in the RRB made the basin prone to frequent spring floods. In addition, it was demonstrated that the abundant surface depressions across the RRB regulate the release of surface runoff and streamflow discharge. Results from the second study revealed that the HTIM improved the representation of temperature variations in snow models. It was found that the daily snowmelt simulations were significantly affected by the sub-daily temperature fluctuations, while the monthly and annual snowmelt results were less prone to such changes. Lastly, results from the third study indicated that although different temperature datasets captured the spatial and temporal patterns of snowmelt in the MRB, the quantities of the simulated snowmelt were different on the western side of the basin with complex topographical features.