Publication Date:
2014-01-17
Description:
There have been widespread increases in winter streamflow across the circumpolar north since the mid to late 1900s. However, the physical processes that result in winter runoff generation are not well understood. The objective of this research was to determine the runoff generation processes and pathways of cold season streamflow, and to compare and contrast them with those of spring freshet in a subarctic Canadian Shield study catchment in which winter streamflow regime changes have been documented. Traditional hydrometric methods were used in conjunction with modelling and hydrochemistry to estimate runoff sources and pathways. Results suggest that while runoff generation processes do not necessarily differ between spring and winter runoff events, the timing at which pre-event and event water contributes does differ. Furthermore, the periods in which certain runoff pathways activate and deactivate are different. Runoff during the spring freshet is dominated by pre-event water that has not been exposed to the subsurface. In contrast, and most notably, isotopic chemistry reveals that 72% of high cold season streamflow is from new precipitation. In Precambrian Shield regions, or in other landscapes where there may be a large fraction of lakes, late autumn rainfall can increase lake levels, and in turn, storage, to ample volumes that can provide high amounts of winter runoff. Where autumn rainfall has been increasing, precipitation and surface water should be considered as a source of enhanced winter streamflow in these types of landscapes. These results have implications for how widespread environmental changes in the circumpolar north, especially those of aquatic chemistry and permafrost thaw, should be interpreted and predicted. © 2013 John Wiley & Sons, Ltd.
Print ISSN:
0885-6087
Electronic ISSN:
1099-1085
Topics:
Architecture, Civil Engineering, Surveying
,
Geography
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