M.M. Darrow | Search USGS

USGS2023

Vulnerability and resilience of ice-rich permafrost to thermal erosion gullying in the Arctic Foothills infrastructure corridor, Alaska

The Arctic and its permafrost terrains are inherently dynamic, complex, and sensitive environments. Understanding the past and current changes occurring in these systems is key in predicting future variations, including the response of permafrost to climate change and to surface disturbances resulting from natural processes or anthropogenic activities. Here, we focus on advancing our understanding of the drivers controlling terrain vulnerability and resilience to thermal erosion gullying proximal to linear infrastructure in the lowlands of the Arctic Foothills (Alaska). This builds upon our previous work (Stephani et al. 2023) in the infrastructure corridor that includes the Dalton Highway and Trans Alaska Pipeline System (TAPS). To identify locations affected by thermal erosion gullying and recognize changes in the ~80-km long corridor section that travels through the Arctic Foothills, we compared time series of high-resolution satellite imagery from 2001 to 2023. When we captured the timing of gullying onset and/or growth, we examined prevailing climatic conditions (Sagwon Station) prior to these terrain changes. We integrated our findings with our field-based data (e.g., drilling) described in Stephani et al. (2023).

Alaska↗

USGS2012

Rapid movement of frozen debris-lobes: implications for permafrost degradation and slope instability in the south-central Brooks Range, Alaska

We present the results of a reconnaissance investigation of unusual debris mass-movement features on permafrost slopes that pose a potential infrastructure hazard in the south-central Brooks Range, Alaska. For the purpose of this paper, we describe these features as frozen debris-lobes. We focus on the characterisation of frozen debris-lobes as indicators of various movement processes using ground-based surveys, remote sensing, field and laboratory measurements, and time-lapse observations of frozen debris-lobe systems along the Dalton Highway. Currently, some frozen debris-lobes exceed 100 m in width, 20 m in height and 1000 m in length. Our results indicate that frozen debris-lobes have responded to climate change by becoming increasingly active during the last decades, resulting in rapid downslope movement. Movement indicators observed in the field include toppling trees, slumps and scarps, detachment slides, striation marks on frozen sediment slabs, recently buried trees and other vegetation, mudflows, and large cracks in the lobe surface. The type and diversity of observed indicators suggest that the lobes likely consist of a frozen debris core, are subject to creep, and seasonally unfrozen surface sediment is transported in warm seasons by creep, slumping, viscous flow, blockfall and leaching of fines, and in cold seasons by creep and sliding of frozen sediment slabs. Ground-based measurements on one frozen debris-lobe over three years (2008–2010) revealed average movement rates of approximately 1 cm day −1 , which is substantially larger than rates measured in historic aerial photography from the 1950s to 1980s. We discuss how climate change may further influence frozen debris-lobe dynamics, potentially accelerating their movement. We highlight the potential direct hazard that one of the studied frozen debris-lobes may pose in the coming years and decades to the nearby Trans Alaska Pipeline System and the Dalton Highway, the main artery for transportation between Interior Alaska and the North Slope.

Alaska↗