Climate change and the water towers of western Canada

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Mountains are often referred to as "water towers" as they receive a disproportionate amount of precipitation owing to topographic effects. They also store freshwater in the seasonal snowpack and in glaciers, with these reservoirs providing meltwater that becomes the source of many streams and rivers of western Canada. With growing demands for freshwater resources in a changing climate, there is an urgent need to better understand the role of these water towers in the hydrology of representative watersheds of western Canada such as the Quesnel River Basin (QRB). The long-term goal of this research program is to quantify the changing role of snow and ice in the water cycle of the QRB, located in the Cariboo Mountains of western Canada. Through this research program, we aim to expand our existing network of weather stations to monitor elevations above 2100 m in the Cariboo Mountains. This will provide some of the highest, long-term weather stations in western Canada and a database suitable for climatic studies to be undertaken by three graduate students. One project will examine the evolution of the region's seasonal snowpack and its role in the surface radiation balance. An accelerating retreat and melt of the snowpack may lead to amplified warming with elevation due to the positive snow-ice/albedo feedback. We will also explore the relationship between elevation and trends in the timing of the passage through the melting/ freezing point in both spring and fall. A second project will combine field data from our sites with those from other networks to develop an east-west profile of the climate across the spine of the Cariboo Mountains. This will provide a better understanding of windward versus leeward effects on climate and at what scales these processes operate. The final study will place this work in the larger context of the Fraser River by examining trends and variability at more than 50 gauges across this watershed. The study will also examine if the timing of the spring meltwater pulse and summer low flows is changing over time. Thus this work will give crucial information on the evolution of western Canada's "water towers" in a changing climate.