Hydroclimatic and channel snowpack controls over suspended sediment and grain size transport in a High Arctic catchment

Abstract

Temporal variability in suspended sediment delivery processes was studied during three seasons in a 7·9 km 2 catchment at Cape Bounty, Melville Island, Nunavut in the Canadian High Arctic. Discharge was controlled primarily by the magnitude of snowmelt, with limited inputs from ground ice melt and precipitation. Years with greater snowpack non-linearly increased sediment yield and resulted in seasonal counter-clockwise hysteresis, while a year with low snowpack resulted in reduced sediment yield and clockwise hysteresis, and indicates that sediment was increasingly available after the onset of streamflow. In addition to the event-scale hysteresis observed during the nival discharge peak, diurnal clockwise hysteresis was observed during all three seasons and suggests daily exhaustion of sediment supplies. These results indicate that the channel snowpack plays a primary role over sediment accessibility during the nival discharge peak. Similarly, grain size analysis of suspended material in the river showed that the coarsest mean grain size was transported during the early phase of peak nival discharge and indicates that isolated sources of coarse material were being accessed by high velocity flow. Snowpack is present through the peak nival period and conditions sediment availability by isolating channel sediments from high-energy flow. These results indicate sediment delivery characteristics in small High Arctic catchments reflect complex interactions with channel snowpack and disproportionate responses to flow conditions that differ from glacial and temperate settings. Results HydrometeorologyThe three seasons studied exhibited substantially different hydrological and meteorological conditions. Both 2004 and 2006 were characterized as cool and wet melt periods, while 2005 was relatively warm and had substantially lower SWE prior to melt (Table I and Figure 3).During the winters prior to the 2004 and 2005 seasons, wind extensively redistributed snow and filled the channel with dense snowpack (depth σ = 27·4 and 29·1 cm, respectively).In 2006, snowpack was spread relatively evenly over the landscape (depth σ = 22·3 cm), and showed little evidence of Figure 2. An example of clockwise diurnal discharge-suspended-sediment-yield hysteresis on 27-28 July 2004 with k = 0·5. Q min , Q mid and Q max represent the discharge at the onset of the hysteresis event, the mid-event discharge and the maximum discharge, respectively. Q min , Q mid and Q max are used to calculate the hysteresis index detailed by Lawler et al. (2006).Figure 3. Daily mean air temperature and total precipitation from 2004 to 2006.Figure 5. Hourly (A) discharge, (B) suspended sediment concentration (SSC), (C) velocity and (D) peak mean daily grain size collected from the West River station in 2005. The dashed line represents the division between nival event and the recession-baseflow period. Error bars associated with the peak mean daily grain size represent one standard deviation from the mean. Gaps in the flow velocity resulted from stage falling below ...

1750 years of large rainfall events inferred from particle size at East Lake, Cape Bounty, Melville Island, Canada

“…1). As part of a long-term research program (the Cape Bounty Arctic Watershed Observatory), hydrological, limnological, and sedimentary processes have been investigated and monitored in two adjacent lakes and watershed systems since 2003 (Lamoureux et al 2006;Cockburn and Lamoureux 2008a, b;Dugan et al 2009;McDonald and Lamoureux 2009;Laurin 2010;Pautler et al 2010;Lewis et al 2011;Stewart and Lamoureux 2011). The East and West lakes (unofficial names) have similar morphologies: both are *1.5 km 2 , and maximum depths are 30 and 34 m, respectively.…”

Seasonal Accumulation and Depletion of Local Sediment Stores of Four Headwater Catchments

“…A few longer studies looking at multiple time scales have shown considerable temporal variation in sediment patterns. McDonald and Lamoureux [15] found significant temporal variation in suspended sediment transport in High Arctic catchments that was linked to snow melt. Rodriguez-Blanco et al [6] found for agricultural basins in Spain that at the event scale sediment peaked before discharge, at the seasonal time scale sediment yield decreased through the season, and at the annual scale yield was linked to the percentage of the year that large events occurred.…”

“…However, much of this work has been focused on individual discharge events [10][11][12], or has been in predominately agricultural areas [4,6,7,[11][12][13], in small hillslope plots [11] or in areas with drastically different physiographic and climatic regimes [7,14,15]. A few longer studies looking at multiple time scales have shown considerable temporal variation in sediment patterns.…”

Impact of permafrost thaw on the turbidity regime of a subarctic river: the Sheldrake River, Nunavik, Quebec

“…In spring, the rise in solar radiation and above-freezing air temperatures rapidly melt the snow cover and result in an increase in water flow and transport (Hudon et al 1996). However, during the freshet flood, a relatively low turbidity indicates that transport of TSS likely remains low because some channels stay armored with ice and snow and soils are still frozen, as observed in other catchments in the Arctic and Subarctic (McDonald and Lamoureux 2009). …”