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Slope disturbances are key sources of sediment, and the impact and recovery of disturbance on downslope erosion is poorly understood. We measured the erosional response of varying extents of slope disturbance in small permafrost catchments for 5 years following disturbance by active layer detachments. Initial erosion rates increased with the size of disturbance, but subsequent fluxes depended on specific morphological evolution of disturbances. Varying degrees of (i) channel density within the disturbances, (ii) downstream channel connectivity, and (iii) geomorphic evolution of disturbances lead to significant differences in catchment response to disturbance. Our results indicate that new equilibrium states of sediment erosion are achieved within the most disturbed and channelized catchments and contribute to greater heterogeneity of erosion on the landscape.

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.

Repeat, high-resolution orbital images and data from landers and rovers on the surface show that the sediment transport processes responsible for these aeolian features are currently active across much of the surface of Mars-a result of the interaction between surficial granular material and the thin Martian

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We report experimental results of near-surface winter temperatures along and adjacent to the channel bed of a High Arctic river on Melville Island, Canada. Temperature loggers 5 cm below the ground surface in areas where the terrain suggests varying snow accumulation patterns revealed that the maximum winter difference between air and near-surface temperatures ranged from 0 to +30°C during the winter of 2012-13, and that shallow near-surface freezing conditions were delayed for up to 21 days in some locations. Cooling to -10°C was delayed for up to 117 days. Modelled temperature at the top of permafrost indicates that permafrost at locations with thick snow can be up to 8°C warmer than those with thin snow. This thermal evidence for an ameliorated surface environment indicates the potential for substantial extended microbial and biogeochemical cycling during early winter. Rapid thaw of the bed during initiation of snowmelt in spring also indicates a high degree of hydrological connectivity. Therefore, snow-filled channels may contribute to biogeochemical and aquatic cycling in High Arctic rivers.

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