Journal
HYDROLOGICAL PROCESSES
Volume 23, Issue 10, Pages 1514-1526Publisher
WILEY
DOI: 10.1002/hyp.7285
Keywords
Sediment yield; summer rainfall; soil moisture; High Arctic; antecedent conditions; precipitation event; polar desert
Categories
Funding
- Government of Canada International Polar Year Program
- ArcticNet NCE
- NSERC
- Northern Studies Training Program
- Polar Continental Shelf Project, Natural Resources Canada [03608]
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In cold regions, the response and related antecedent mechanisms that produce flood flows from rainfall events have received limited study. In 2007, a small watershed at Cape Bounty, Melville Island, Nunavut, was studied in detail during the melt season. Two rainfall events on June 30 and July 22, totalling 9.2 and 10.8 mm, respectively, represented significant contributions to seasonal discharge and sediment transport in a year with a low winter snowpack. The precipitation events elevated discharge and suspended sediment concentrations to twice the magnitude of the nival melt, and generated the only measurable downstream lacustrine turbidity current of the season. In two days, rainfall runoff transported 35% of the seasonal suspended sediment load, in contrast to 29% transported over the nival freshet. The magnitude and intensity of the rain events were not unusual in this setting, but the rainfall response was substantial in comparison with equivalent past events. Exceptional temperatures of July 2007 generated early, deep permafrost thaw, and ground ice melt. The resultant increase in soil moisture amplified the subsequent rainfall runoff and sediment transport response. These results demonstrate the importance of antecedent moisture conditions and the role of permafrost active layer development as an important factor in the rainfall runoff and sediment transport response to precipitation events. Copyright (C) 2009 John Wiley & Sons, Ltd.
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