Hydrology of Hillslope-Wetland Streams, Polar Bear Pass, Nunavut, Canada

Polar Bear Pass is a large High Arctic low-gradient wetland (100 km(2)) bordered by low-lying hills which are notched by a series of v-shaped valleys. The spring and summer hydrology of two High Arctic hillslope-wetland catchments, a first-order stream, 0.2 km(2) Landing Strip Creek (LSC) and a larger second-order basin, 4.2 km(2) Windy Creek (WC), is described here. A water balance framework was employed in 2008 to examine the movement of water from upland reaches into the low-lying wetland. Snowcover was low in both basins (<50 mm in water equivalent units), but they both exhibited nival-type regimes. After the main snowmelt season ended, runoff ceased in the smaller catchment (LSC), but not at the larger basin (WC) which continued to flow throughout the summer. Both basins responded to summer rains in different ways. At LSC, late-summer continuous streamflow occurred only when rainfall satisfied the large soil moisture deficit in the upper bowl-shaped zone of the basin. At WC, the presence of thinly thawed, ice-rich polygonal terrain within the stream channel and in the upper reaches of the catchment likely limited infiltration in these near-stream zones and enhanced runoff in response to both moderate and high rainfall. Subsequently, seasonal runoff ratios differed between the two sites (0.19 vs 0.68) as did the seasonal storage + residual (+16 vs -50 mm). This suggests that the post-snowmelt season runoff response to summer precipitation is very much modified by the unique basin characteristics (soil-type, vegetation, ground ice) and their location within each stream order type. Copyright. (C) 2010 John Wiley & Sons, Ltd.