Snow Hydrology

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Snowmelt is the most significant contribution to water resources in most of Canada and so is not only vital to Canada's water security, but forms the basis for many impacts of climate change on Canadian ecosystems, communities and economies. The Alberta Flood of June 2013 was Canada's most expensive natural disaster, with costs >$5 billion, and was contributed to by mountain rain-on-snow processes. The Prairie floods of 2011 cost >$2 billion due to excess snowmelt runoff and the Great Drought of 2009-2013 cost >$3 billion due to lack of local snowmelt runoff and infiltration. Better understanding and prediction of snow processes will contribute to the development of improved flood and drought forecasting techniques, floodplain mapping and risk assessment using hydrological models.The objective of this research is to reduce uncertainty in hydrological prediction by improving the knowledge that underpins the application of physical principles to its simulation. The geographical focus of this research is the Canadian Rockies and Prairies. The goals are to 1) improve the understanding of vertical and horizontal snow mass and energy exchange processes, including rain-on-snow events, 2) better describe the role of grass, shrub and forest vegetation cover in modifying snow accumulation and the radiative and turbulent fluxes, 3) improve the understanding of internal snowpack energy and meltwater storage and release. * A combination of innovative field observation programmes in the Canadian Rockies and Prairies with advances in mathematical simulations of the fundamental hydrological processes deployed in hydrological simulations will be used to examine individual processes of great uncertainty such as rain-on-snow energetics and runoff, accumulation and ablation at edges of forest clearings and at treelines, advection during patchy snowmelt, and meltwater movement and runoff formation along hillslopes and how they affect snow hydrology from small to basin scales. The field programme and computer modelling will contribute to all three objectives through common field sites, a focus on hydrological processes and computational platforms addressing the processes at the field sites. * The study will use new and established research sites in the Canadian Rockies Hydrological Observatory (CRHO), AB and the Brightwater Creek Research Basin (BCRB), SK to supplement baseline measurements with detailed physical measurements. The CRHO is a transect of high-elevation heavily instrumented research basins in the headwaters of the Saskatchewan River Basin. The BCRB is an intensively-instrumented prairie agricultural watershed south of Saskatoon. Short intensive observation periods will be used to focus on process research; first on late-lying snowpacks at Fortress Mountain where the 2012 & 2013 Alberta rain-on-snow floods were centred. A second will focus on snow dynamics in forest clearings and at treelines. A third will examine advection to patchy snowpacks from dry and wet surfaces in prairies and mountains. The fourth will examine snowmelt runoff from deep snow sites. * To tie this together, computer simulations of cold regions hydrology will be used to study rain-on-snow, advection of melt energy, vegetation impacts and meltwater flow through snowpacks as part of the watershed hydrological system. Improved models will be implemented as modules in the flexible, modular Cold Regions Hydrological Modelling platform to determine the degree to which soil moisture and streamflow predictions in the mountains and prairies are improved by these new snow process descriptions. The results should improve Canada's flood and drought forecast capabilities and allow for better management of mountain headwater and prairie agricultural watersheds.