Antecedent Controls on Rainfall Runoff Response and Sediment Transport in a High Arctic Catchment

Abstract

In the High Arctic, late summer rainfall events have the potential to increase discharge and transport substantial amounts of sediment. Past studies have not considered the role of antecedent soil moisture with respect to rainfall-runoff response, particularly in the context of changing climate. We investigate these processes through multiple major rainfall events and the associated discharge and suspended sediment response, measured in a small watershed at Cape Bounty, Melville Island, Nunavut. Fluvial and sedimentological responses to two major rainfall events on 9 Jul. and 23 Jul., 2012, totaling 35.4 and 10.6 mm, respectively, resulted in negligible responses in discharge and suspended sediment mobilization. The magnitude and intensity of these events were not unusual in this region, but the lack of response was substantial when compared with past events of similar magnitudes. The two-week antecedent period leading up to the 9 Jul. rainfall was characterized by exceptional temperatures and high solar radiation, decreasing soil moisture and increasing infiltration potential, all of which substantially diminished the runoff and resultant suspended sediment transport. These results demonstrate that antecedent catchment conditions may substantially attenuate suspended sediment transport responses to multiple major rainfall events and decrease runoff ratios and characterization of these conditions is necessary to accurately model catchment response.

Summer rainfall dissolved organic carbon, solute, and sediment fluxes in a small Arctic coastal catchment on Herschel Island (Yukon Territory, Canada)

“…This would mean that the 2014 rain event was the greatest of all monitored years. Favaro and Lamoureux (2014) find a high range of runoff ratios between 0.001 and 0.84 in a 8.0 km 2 watershed (West River) at Cape Bounty, Melville Island in the High Arctic depending on the soil moisture conditions in the catchment. Carey et al (2013) also find runoff ratios between 0.29 and 0.66 in a 7.6 km 2 alpine headwater stream (Granger Basin) in the discontinuous permafrost zone.…”

Active layer slope disturbances affect seasonality and composition of dissolved nitrogen export from High Arctic headwater catchments

“…The mean summer air temperature over the past 10 years (2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) (Lewis et al 2012;Favaro and Lamoureux 2014). The melt season runoff in the subcatchments at CBAWO generally lasts from early to mid-June until mid-July (Lafrenière and Lamoureux 2013).…”

“…Details of weather pre-and post-disturbance are presented in Favaro and Lamoureux (2014). The pre-disturbance year 2012 was the second warmest summer on record at CBAWO (after 2011), while the summer of 2007 was the third warmest.…”

Determining the terrain characteristics related to the surface expression of subsurface water pressurization in permafrost landscapes using susceptibility modelling

“…Precipitation primarily occurs as snow, which is extensively redistributed by wind and preferentially deposited on leeward slopes and in low-lying areas. Rainfall is infrequent but high-magnitude events do occur (Favaro and Lamoureux, 2014). Vegetation is composed of graminoid, prostrate dwarf shrub, and forb tundra.…”