Environmental change, catchment hydrology and the stream environment

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Recent historical and projected future climatic warming has been associated with changes to the timing and magnitude of snow accumulation and melt, with a tendency for snowmelt to occur days to weeks earlier. Warming has also been associated with glacier mass loss and shrinkage. These changes to snow and glaciers result in changes to river flow patterns and water temperature, in particular by causing reduced flows and higher temperatures in late summer. Both of these changes can be harmful to valued cold-water fish species such as Pacific Salmon. Glacier shrinkage influences downstream river flows by reducing the amount of ice available for melt. In addition, glacier retreat often results in formation of lakes, and vegetation eventually establishes and develops on areas exposed by glacier retreat. Both of these changes can increase water loss by evaporation, which reduces the amount that becomes river flow; however, research on these changes is limited. While the general directions of change are understood, there is a need for more robust process-based tools to evaluate the magnitudes of these changes in specific situations. The overall objective of the proposed research is to increase our understanding of and ability to predict how changing snowmelt patterns and glacier retreat will cause late-summer river flows and temperature to change. The research will combine field measurements, data collection based on remote sensing from satellites, and the use of statistical analysis and computer simulation models. Research will focus on sites in the southern Coast Mountains of British Columbia, particularly on the Bridge and Lillooet Rivers, both of which contain significant glaciers. Research will also focus on Upper Penticton Creek, a long-term research site in the highlands of the Okanagan valley. The outcomes of the research will be improved tools for estimating river flows and temperatures under current conditions, which will support the assessment of current habitat suitability for fish species by fisheries managers. The tools can also be used to estimate how flows and temperature would change as a result of fututure climate change, which can help resource managers develop strategies for adaptation and mitigation to protect salmon and other cold-water fish species.