Effects of permafrost on stream channel behavior in Arctic Alaska

Scott, Kevin M.

doi:10.3133/pp1068

Cited by 44 publications

(58 citation statements)

References 16 publications

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“…Alluvial channels on the ACP are considered highly dynamic and often with very high rates of bank erosion due to interactions with permafrost such that major changes in channel course can occur over short time periods (Scott, 1978). Our observations of a stable course along Crea Creek over 64 a, along with an apparent lack of beaded channels that appear abandoned on the ACP, suggest long-term behavior more similar to bedrock channels (Wohl, 2000).…”

Section: Channel Change and Formationmentioning

confidence: 58%

Distribution and biophysical processes of beaded streams in Arctic permafrost landscapes

et al. 2015

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Abstract. Beaded streams are widespread in permafrost regions and are considered a common thermokarst landform. However, little is known about their distribution, how and under what conditions they form, and how their intriguing morphology translates to ecosystem functions and habitat. Here we report on a circum-Arctic survey of beaded streams and a watershed-scale analysis in northern Alaska using remote sensing and field studies. We mapped over 400 channel networks with beaded morphology throughout the continuous permafrost zone of northern Alaska, Canada, and Russia and found the highest abundance associated with medium to high ground-ice content permafrost in moderately sloping terrain. In one Arctic coastal plain watershed, beaded streams accounted for half of the drainage density, occurring primarily as low-order channels initiating from lakes and drained lake basins. Beaded streams predictably transition to alluvial channels with increasing drainage area and decreasing channel slope, although this transition is modified by local controls on water and sediment delivery. The comparisons of one beaded channel using repeat photography between 1948 and 2013 indicate a relatively stable landform, and 14 C dating of basal sediments suggest channel formation may be as early as the Pleistocene-Holocene transition. Contemporary processes, such as deep snow accumulation in riparian zones, effectively insulate channel ice and allows for perennial liquid water below most beaded stream pools. Because of this, mean annual temperatures in pool beds are greater than 2 • C, leading to the development of perennial thaw bulbs or taliks underlying these thermokarst features that range from 0.7 to 1.6 m. In the summer, some pools thermally stratify, which reduces permafrost thaw and maintains cold-water habitats. Snowmelt-generated peak flows decrease rapidly by two or more orders of magnitude to summer low flows with slow reach-scale velocity distributions ranging from 0.01 to 0.1 m s −1 , yet channel runs still move water rapidly between pools. The repeating spatial pattern associated with beaded stream morphology and hydrological dynamics may provide abundant and optimal foraging habitat for fish. Beaded streams may create important ecosystem functions and habitat in many permafrost landscapes and their distribution and dynamics are only beginning to be recognized in Arctic research.

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Section: Channel Change and Formationmentioning

confidence: 58%

Distribution and biophysical processes of beaded streams in Arctic permafrost landscapes

et al. 2015

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“…This is also true for the beds of smaller streams where bottom-fast ice and frozen sediments armor channels during snowmelt (Scott, 1978). Where channels impinge onto higher terrain, a large part of lateral channel migration is due to thermal erosion of ice-rich permafrost .…”

Section: Study Areamentioning

confidence: 97%

Responses of an arctic landscape to Lateglacial and early Holocene climatic changes: the importance of moisture

Mann

Peteet

Reanier³

et al. 2002

Quaternary Science Reviews

117

132

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Many of the physical and biological processes that characterize arctic ecosystems are unique to high latitudes, and their sensitivities to climate change are poorly understood. Stratigraphic records of land-surface processes and vegetation change in the Arctic Foothills of northern Alaska reveal how tundra landscapes responded to climatic changes between 13,000 and 8000 14 C yr BP. Peat deposition began and shrub vegetation became widespread ca. 12,500 14 C yr BP, probably in response to the advent of warmer and wetter climate. Increased slope erosion caused rapid alluviation in valleys, and Populus trees spread northward along braided floodplains before 11,000 14 C yr BP. Lake levels fell and streams incised their floodplains during the Younger Dryas (YD) (11,000-10,000 14 C yr BP). A hiatus in records of Populus suggest that its geographic range contracted, and pollen records of other species suggest a cooler and drier climate during this interval. Basal peats dating to the YD are rare, suggesting that rates of paludification slowed. Immediately after 10,000 14 C yr BP, lake levels rose, streams aggraded rapidly again, intense solifluction occurred, and Populus re-invaded the area. Moist acidic tundra vegetation was widespread by 8500 14 C yr BP along with wet, organic-rich soils. Most of these landscape-scale effects of climatic change involved changes in moisture. Although low temperature is the most conspicuous feature of arctic climate, shifts in effective moisture may be the proximate cause for many of the impacts that climate change has in arctic regions. r

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“…The base of the cliff section in our study is not made of ice-rich and highly erodible sediments but is composed of a sand unit that buffers the thermo-erosional activity of the Lena River also during spring flood. This prevents the development of thermo-erosional niches and consequently the rapid erosion by block collapse that is an important component at other Arctic riverbank and coastal cliff systems [11,14,17]. Given that the cliff top is decoupled from the thermo-erosional processes of the Lena River, its erosion likely results from atmospheric forcing and depends on the local sediment and ground ice properties [55], as well as regional climatic conditions [4].…”

Section: Intra-annual Dynamics Of Cliff-top Erosionmentioning

confidence: 99%

“…Thermo-erosional niching is the undercutting of cohesive, ice-rich banks by water and is a prominent process of riverbank erosion [17] leading to rates of up to 19 m per year [11]. Different stages of erosion are observed over long time periods with riverbanks eventually stabilizing, a process that can occur in as little as three years [11].…”

Section: Introductionmentioning

confidence: 99%

Monitoring Inter- and Intra-Seasonal Dynamics of Rapidly Degrading Ice-Rich Permafrost Riverbanks in the Lena Delta with TerraSAR-X Time Series

et al. 2017

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Arctic warming is leading to substantial changes to permafrost including rapid degradation of ice and ice-rich coasts and riverbanks. In this study, we present and evaluate a high spatiotemporal resolution three-year time series of X-Band microwave satellite data from the TerraSAR-X (TSX) satellite to quantify cliff-top erosion (CTE) of an ice-rich permafrost riverbank in the central Lena Delta. We apply a threshold on TSX backscatter images and automatically extract cliff-top lines to derive intra-and inter-annual CTE. In order to examine the drivers of erosion we statistically compare CTE with climatic baseline data using linear mixed models and analysis of variance (ANOVA). Our evaluation of TSX-derived CTE against annual optical-derived CTE and seasonal in situ measurements showed good agreement between all three datasets. We observed continuous erosion from June to September in 2014 and 2015 with no significant seasonality across the thawing season. We found the highest net annual cliff-top erosion of 6.9 m in 2014, in accordance with above-average mean temperatures and thawing degree days as well as low precipitation. We found high net annual erosion and erosion variability in 2015 associated with moderate mean temperatures but above average precipitation. According to linear mixed models, climate parameters alone could not explain intra-seasonal erosional patterns and additional factors such as ground ice content likely drive the observed erosion. Finally, mean backscatter intensity on the cliff surface decreased from −5.29 to −6.69 dB from 2013 to 2015, respectively, likely resulting from changes in surface geometry and properties that could be connected to partial slope stabilization. Overall, we conclude that X-Band backscatter time series can successfully be used to complement optical remote sensing and in situ monitoring of rapid tundra permafrost erosion at riverbanks and coasts by reliably providing information about intra-seasonal dynamics.

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Effects of permafrost on stream channel behavior in Arctic Alaska

Cited by 44 publications

References 16 publications

Distribution and biophysical processes of beaded streams in Arctic permafrost landscapes

Distribution and biophysical processes of beaded streams in Arctic permafrost landscapes

Responses of an arctic landscape to Lateglacial and early Holocene climatic changes: the importance of moisture

Monitoring Inter- and Intra-Seasonal Dynamics of Rapidly Degrading Ice-Rich Permafrost Riverbanks in the Lena Delta with TerraSAR-X Time Series

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