The impact of a shrinking cryosphere on the form of arctic alluvial channels

Abstract

Abstract:A shrinking cryosphere has important implications for the geomorphology of alluvial channels in arctic catchments because ice and permafrost alter the driving and resisting forces responsible for shaping local channel cross sections. For example, bedfast ice in shallow channels can suppress bedload transport during snowmelt events causing a reduction in the frequency of geomorphically effective flows, while cap ice in deeper channels can alter stream hydraulics. The impact of these local controls on catchment-scale geomorphic patterns, however, is less certain. A case study of one arctic river in northern Alaska, USA, reveals hydraulic geometry anomalies that can be reasonably explained by the influence of ice and permafrost on local channel form. However, there is a critical lack of data from rivers wholly contained in the continuous permafrost zone preventing comprehensive understanding of how arctic rivers might respond in a shrinking cryosphere.

Downstream patterns of suspended sediment transport in a High Arctic river influenced by permafrost disturbance and recent climate change

“…Sediment and discharge data from 2004 to 2012 provide insights into the changing pattern of sediment mobilization processes in this setting and also extends earlier work by McDonald andVeillette (2011) for portions of the longer record. With future climate change expected to be amplified in the Arctic (AMAP, 2011), predicting the responses of systems to increased sediment and discharge perturbations is a challenging problem (Woo and Winter, 1993;Woo and McCann, 1994;McNamara and Kane, 2009). Studies that document seasonal patterns of sediment dynamics are therefore important to undertake in order to improve our understanding of how rivers will respond to change (Bowden et al, 2008).…”

“…Snow in the channel acts as a systematic and potentially important barrier to sediment entrainment and erosion during early season flow when typically a substantial proportion of sediment transport occurs (McNamara and Kane, 2009). Progressive thermal erosion of the snowpack as the nival season progresses allows for flow to discontinuously access bed and bank materials (Clifford et al, 1995).…”

“…This reflects the influence of a number of mitigating factors to sediment transport, such as catchment connectivity, the volume and type of material stored, the distance of these materials from the channel, and the geomorphic response to disturbance events (Fryirs et al, 2007;Fryirs, 2013). In the Arctic, the dominant influence of snow represents a further factor, particularly as in-channel snow buffers and limits the downstream transport of sediment during the early nival melt, the most energetic time of the short hydrological season (Woo and Sauriol, 1980;McDonald and Lamoureux, 2009;McNamara and Kane, 2009;Woo, 2012). A number of approaches can be utilized to evaluate sediment processes in fluvial systems including sediment-discharge hysteresis and reach-level sediment budgets.…”

Drainage Network Structure and Hydrologic Behavior of Three Lake-Rich Watersheds on the Arctic Coastal Plain, Alaska

“…Research that identifies mechanisms of thermokarst lake expansion and drainage linked to historic climate reconstructions (Marsh et al, 2009;Arp et al, 2011;Jones et al, 2011) and future GCM predictions (Pohl et al, 2007) may provide an important basis for such understanding. Refining measurements and predictions of Arctic hydrologic intensification is a key aspect towards comprehending Arctic landscape responses to climate change (Rawlins et al, 2010), yet a more essential component maybe understanding land surface mechanisms that control drainage network structure and ultimately watershed function (Woo et al, 2008;McNamara and Kane, 2009). …”

“…Few hydrologic monitoring programs and watershed studies have been conducted on rivers systems with entirely ACP origins, however, with the main example being the Putuligayuk River where work by Bowling et al (2003) highlights the important role of lake and wetland storage and connectivity in runoff generation. Yet given the known heterogeneity of ACP landscapes with lake area extents ranging from Ͻ10 to Ͼ30% (Sellmann et al, 1975;Grosse et al, 2012) and the potential for future lake and channel evolution in ACP environments (Smith et al, 2005;Jorgenson and Shur, 2007;McNamara and Kane, 2009), few systematic studies have analyzed how this variation in watershed structure relates to aquatic habitat and hydrological processes.…”