Permafrost Monthly Alerts (PMAs)

2021070871 Angelopoulos, Michael (Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Permafrost Research Section, Potsdam, Germany); Overduin, Pier P.; Jenrich, Maren; Nitze, Ingmar; Günther, Frank; Strauss, Jens; Westermann, Sebastian; Schirrmeister, Lutz; Kholodov, Alexander; Krautblatter, Michael; Grigoriev, Mikhail N. and Grosse, Guido. Onshore thermokarst primes subsea permafrost degradation: Geophysical Research Letters, 48(20), Article e2021GL093881_, illus. incl. sketch map, 70 ref., October 2021. Part of a special issue entitled The Artic; an AGU joint special collection.

The response of permafrost to marine submergence can vary between ice-rich late Pleistocene deposits and the thermokarst basins that thawed out during the Holocene. We hypothesize that inundated Alases offshore thaw faster than submerged Yedoma. To test this hypothesis, we estimated depths to the top of ice-bearing permafrost offshore of the Bykovsky Peninsula in northeastern Siberia using electrical resistivity surveys. The surveys traversed submerged lagoon deposits, drained and refrozen Alas deposits, and undisturbed Yedoma from the coastline to 373 m offshore. While the permafrost degradation rates of the submerged Yedoma were in the range of similar sites, the submerged Alas permafrost degradation rates were up to 170% faster. Remote sensing analyses suggest that 54% of lagoons wider than 500 m along northeast Siberian and northwest American coasts originated in thermokarst basins. Given the abundance of thermokarst basins and lakes along parts of the Arctic coastline, their effect on subsea permafrost degradation must be similarly prevalent. Abstract Copyright (2021), . The Authors.

DOI: 10.1029/2021GL093881

2021070847 Guimond, Julia A. (Dalhousie University, Department of Civil and Resource Engineering and Centre for Water Resources Studies, Halifax, NS, Canada); Mohammed, Aaron A.; Walvoord, Michelle A.; Bense, Victor F. and Kurylyk, Barret L. Saltwater intrusion intensifies coastal permafrost thaw: Geophysical Research Letters, 48(19), Article e2021GL094776, illus., 58 ref., October 2021.

Surface effects of sea-level rise (SLR) in permafrost regions are obvious where increasingly iceless seas erode and inundate coastlines. SLR also drives saltwater intrusion, but subsurface impacts on permafrost-bound coastlines are unseen and unclear due to limited field data and the absence of models that include salinity-dependent groundwater flow with solute exclusion and freeze-thaw dynamics. Here, we develop a numerical model with the aforementioned processes to investigate climate change impacts on coastal permafrost. We find that SLR drives lateral permafrost thaw due to depressed freezing temperatures from saltwater intrusion, whereas warming drives top-down thaw. Under high SLR and low warming scenarios, thaw driven by SLR exceeds warming-driven thaw when normalized to the influenced surface area. Results highlight an overlooked feedback mechanism between SLR and permafrost thaw with potential implications for coastal infrastructure, ocean-aquifer interactions, and carbon mobilization. Abstract Copyright (2021). The Authors.

DOI: 10.1029/2021GL094776

2021075909 Li, Dongfeng (National University of Singapore, Department of Geography, Singapore, Singapore); Lu, Xixi; Overeem, Irina; Walling, Desmond E.; Syvitski, Jaia; Kettner, Albert J.; Bookhagen, Bodo; Zhou Yinjun and Zhang, Ting. Exceptional increases in fluvial sediment fluxes in a warmer and wetter high mountain Asia: Science, 374(6567), p. 599-603, illus. incl. sketch map, 71 ref., October 29, 2021.

Rivers originating in High Mountain Asia are crucial lifelines for one-third of the world's population. These fragile headwaters are now experiencing amplified climate change, glacier melt, and permafrost thaw. Observational data from 28 headwater basins demonstrate substantial increases in both annual runoff and annual sediment fluxes across the past six decades. The increases are accelerating from the mid-1990s in response to a warmer and wetter climate. The total sediment flux from High Mountain Asia is projected to more than double by 2050 under an extreme climate change scenario. These findings have far-reaching implications for the region's hydropower, food, and environmental security.

DOI: 10.1126/science.abi9649

2021072002 Song Chunlin (Sichuan University, College of Water Resource and Hydropower, State Key Laboratory of Hydraulics and Mountain River Engineering, Chengdu, China); Wang Genxu; Sun Xiangyang and Hu Zhaoyong. River runoff components change variably and respond differently to climate change in the Eurasian Arctic and Qinghai-Tibet Plateau permafrost regions: Journal of Hydrology, 601, Article no. 126653, illus. incl. 1 table, sketch map, 80 ref., October 2021.

Cryohydrological processes in the Eurasian Arctic and Qinghai-Tibet Plateau (QTP) permafrost regions have been changing rapidly, yet the details of the river runoff changes are still obscure. Here we use multidecadal natural daily discharge data to compute annual flow duration curves (FDCs) and percentile flows for 20 Eurasian Arctic and QTP river basins with permafrost underlain. We provide detailed trends of various percentile flows that almost all runoff components change variably, either with the distinct magnitude or opposite direction or both. We demonstrate that the lower flows increase monotonically faster than higher flows. Most low flows increase while the high flows show spatial heterogeneity with both increased and decreased trends observed. The portion of deep and total groundwater flow in total discharge increases, with the deep groundwater flow increases faster. Interestingly, the river runoff components respond differently to climatic change factors. The low flows, mainly sustained by groundwater, are more sensitive to warming than high flows, while the high flows are more sensitive to precipitation than low flows. Our results may suggest an increased subsurface hydrological connectivity under the warming climate and thawing permafrost. We show that FDCs have the potential to reveal the long-term runoff components change. Future climatic change may alter the shapes and distributions of FDCs since the asynchronous changes of runoff components, which have important implications for cold region river management and mitigation under climatic change.

DOI: 10.1016/j.jhydrol.2021.126653

2021075126 Steiner, Matthias (Technische Universität Wien, Department of Geodesy and Geoinformation, Research Unit Geophysics, Vienna, Austria); Wagner, Florian M.; Maierhofer, Theresa; Schöner, Wolfgang and Flores Orozco, Adrian. Improved estimation of ice and water contents in alpine permafrost through constrained petrophysical joint inversion; the Hoher Sonnblick case study: Geophysics, 86(5), p. WB61-WB75, illus. incl. 2 tables, sketch map, 85 ref., October 2021.

Quantitative estimation of subsurface water and ice content values is critical for the understanding and modeling of permafrost evolution in alpine regions. Geophysical methods permit the assessment of subsurface conditions in a noninvasive and quasicontinuous manner; in particular, the combination of seismic refraction tomography (SRT) and electrical resistivity tomography (ERT) through a petrophysical model can quantitatively estimate ground water and ice content values. For the Hoher Sonnblick study area (3106 m.a.s.l., Austrian Alps), we have investigated the improved estimation of water and ice content values based on SRT, ERT, and ground-penetrating radar data collected in June and October 2019. We solve for the water and ice content values following different approaches, namely, (1) the independent inversion and subsequent transformation of the imaging results to the target parameters through a petrophysical model and (2) the petrophysical joint inversion (PJI) of the data sets. Supported by a synthetic study, we determine that the incorporation of structural and porosity constraints in the PJI allows for an improved quantitative characterization of subsurface conditions. For our measurements at Hoher Sonnblick, the constrained PJI resolves a shallow debris layer characterized by high air content and porosity, on top of a layer with lower porosity corresponding to fractured gneiss, and the bedrock layer with the lowest porosity. For both time steps, we find high water content at the lower end of the investigated area. Substantial variations in the subsurface ice content resolved between June and October 2019 indicate a correlation between the high water content and the meltwater discharge within the debris layer. Our results demonstrate that the constrained PJI permits an improved characterization of subsurface hydrologic parameters in alpine permafrost environments.

DOI: 10.1190/geo2020-0592.1

2021070884 Vulis, Lawrence (University of California Irvine, Department of Civil and Environmental Engineering, Irvine, CA); Tejedor, Alejandro; Zaliapin, Ilya; Rowland, Joel C. and Foufoula-Georgiou, Efi. Climate signatures on lake and wetland size distributions in arctic deltas: Geophysical Research Letters, 48(20), Article e2021GL094437, illus. incl. sketch maps, 65 ref., October 2021.

Understanding how thermokarst lakes on arctic river deltas will respond to rapid warming is critical for projecting how carbon storage and fluxes will change in those vulnerable environments. Yet, this understanding is currently limited partly due to the complexity of disentangling significant interannual variability from the longer-term surface water signatures on the landscape, using the short summertime window of optical spaceborne observations. Here, we rigorously separate perennial lakes from ephemeral wetlands on 12 arctic deltas and report distinct size distributions and climate trends for the two waterbodies. Namely, we find a lognormal distribution for lakes and a power-law distribution for wetlands, consistent with a simple proportionate growth model and inundated topography, respectively. Furthermore, while no trend with temperature is found for wetlands, a statistically significant decreasing trend of mean lake size with warmer temperatures is found, attributed to colder deltas having deeper and thicker permafrost preserving larger lakes. Abstract Copyright (2021), . The Authors.

DOI: 10.1029/2021GL094437

2021072008 Xu Zhicheng (Wuhan University, State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan, China); Cheng Lei; Liu Pan; Makarieva, Olga and Chen Menghan. Detecting and quantifying the impact of long-term terrestrial water storage changes on the runoff ratio in the head regions of the two largest rivers in China: Journal of Hydrology, 601, Article no. 126668, illus. incl. 3 tables, sketch map, 90 ref., October 2021.

The Yangtze River and the Huang River are the two largest rivers in China. Annual runoff ratios (runoff/precipitation, denoted as RR) of the head regions of these two basins (HYR and HHR, respectively) have significantly decreased over the past several decades, closely related to changes in water storage capacity (WSC) and terrestrial water storage (TWS). However, such effects have rarely been quantified due to limitations associated with complicated arctic hydrological processes and the absence of long-term reliable TWS data. In this study, a TWS reconstruction dataset (TWS_rec) was validated, and demonstrated good performance in capturing TWS variations derived from the Gravity Recovery and Climate Experiment (GRACE) and in the terrestrial water budget for these two head regions. Long-term (1980-2015) changes in TWS and WSC were then detected and their effects on RR were quantified through trend detection, change point analysis, and path analysis. Results showed that TWS increased significantly with a rate of 27.6 mm/10 yr and 19.8 mm/10 yr at HYR and HHR, respectively. These increases were mainly caused by wetting (increases in precipitation) or soil moisture increases from the TWS component perspective. WSC (represented as the ratio of TWS to precipitation) gradually enlarged in response to continuous climate warming. RR decreased significantly with rates of 2.0%/10 yr at HYR and 3.6%/10 yr at HHR, attributed to the increased evaporation ratio (»80%) and increased WSC (»20%) in both head regions. Further analysis suggested that permafrost degradation under climate warming could increase WSC. These results demonstrate that climate change has resulted in unstable terrestrial water storage at HYR and HHR, and that increases in WSC due to permafrost degradation play an important role in accurately simulating runoff in the Tibetan Plateau and other permafrost-degradation regions.

DOI: 10.1016/j.jhydrol.2021.126668

2021074978 Steiner, Matthias (University of Wien, Department of Geodesy and Geoinformation, Research Unit Geophysics, Vienna, Austria); Wagner, Florian M.; Maierhofer, Theresa; Schoner, Wolfgang and Flores Orozco, Adrian. Improved estimation of ice and water contents in Alpine permafrost through constrained petrophysical joint inversion; the Hoher Sonnblick case study: Geophysics, 86(5), p. WB61-WB75, illus. incl. 2 tables, sketch map, 85 ref., September 2021.

Quantitative estimation of subsurface water and ice content values is critical for the understanding and modeling of permafrost evolution in alpine regions. Geophysical methods permit the assessment of subsurface conditions in a noninvasive and quasicontinuous manner; in particular, the combination of seismic refraction tomography (SRT) and electrical resistivity tomography (ERT) through a petrophysical model can quantitatively estimate ground water and ice content values. For the Hoher Sonnblick study area (3106 m.a.s.l., Austrian Alps), we have investigated the improved estimation of water and ice content values based on SRT, ERT, and ground-penetrating radar data collected in June and October 2019. We solve for the water and ice content values following different approaches, namely, (1) the independent inversion and subsequent transformation of the imaging results to the target parameters through a petrophysical model and (2) the petrophysical joint inversion (PJI) of the data sets. Supported by a synthetic study, we determine that the incorporation of structural and porosity constraints in the PJI allows for an improved quantitative characterization of subsurface conditions. For our measurements at Hoher Sonnblick, the constrained PJI resolves a shallow debris layer characterized by high air content and porosity, on top of a layer with lower porosity corresponding to fractured gneiss, and the bedrock layer with the lowest porosity. For both time steps, we find high water content at the lower end of the investigated area. Substantial variations in the subsurface ice content resolved between June and October 2019 indicate a correlation between the high water content and the meltwater discharge within the debris layer. Our results demonstrate that the constrained PJI permits an improved characterization of subsurface hydrologic parameters in alpine permafrost environments.

DOI: 10.1190/geo2020-0592.1

2021075072 Zhu Xiaofan (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources, Cryosphere Research Station on the Qinghai-Tibet Plateau, Lanzhou, China); Wu Tonghua; Hu Guojie; Ni Jie; Zou Defu; Chen Jie; Li Xiangfei; Wu Xiaodong and Li Ren. Non-negligible contribution to seasonally thawing depth of active layer from extreme warming events in the Tanggula permafrost region of Qinghai-Tibet Plateau: Journal of Geophysical Research: Atmospheres, 126(17), Article e2021JD035088, illus. incl. geol. sketch maps, 2 tables, sects., 54 ref., September 16, 2021.

Despite rising interest in the impacts of long-term gradual climate warming on permafrost changes, little is known about the changes in active-layer thermal conditions after transient and abrupt extreme warming events. Here, we investigated the Tanggula permafrost region of the Qinghai-Tibet Plateau using in situ meteorological and active-layer hydrothermal data. The results showed that the magnitude of variation in the thermal condition of the active layer was positively correlated with the duration and intensity of extreme warming events. The average contribution rate of extreme warming events to seasonally thawing depth was 13.5% ± 4.9% from April to October, and higher rates occurred in the initial and final stages of the thawing process. The thawing process of the active layer was the main factor controlling the thermal responses of this layer to extreme warming events. Moreover, the interannual differences in active-layer thermal conditions during the thawing period were likely related to the interannual differences in the frequency and intensity of extreme warming events. Abstract Copyright (2021), . American Geophysical Union. All Rights Reserved.

DOI: 10.1029/2021JD035088

2021075050 de Bruin, Jelte G. H. (Wageningen University, Department of Environmental Sciences, Hydrology and Quantitative Water Management Group, Wageningen, Netherlands); Bense, Victor F. and van der Ploeg, Martine J. Inferring permafrost active layer thermal properties from numerical model optimization: Geophysical Research Letters, 48(16), Article e2021GL093306, illus. incl. 1 table, 94 ref., August 28, 2021.

Permafrost has become increasingly unstable as a result of surface warming; therefore it is crucial to improve our understanding of permafrost spatiotemporal dynamics to assess the impact of active layer thickening on future hydrogeological processes. However, direct determinations of permafrost active-layer thermal properties are few, resulting in large uncertainty in forecasts of active layer thickness. To assess how to reduce the uncertainty without expanding monitoring efforts, a total of 1,728 numerical 1D models were compared using three error measures against observed active layer temperature data from the Qinghai-Tibetan Plateau. Resulting optimized parameter values varied depending on the error measure used, but agree with reported ones: bulk volumetric heat capacity is 1.82-1.94 ´ 10⁶ j/m³ K, bulk thermal conductivity 1.0-1.2 W/m K and porosity 0.25-0.45 (--) The active layer thickening rate varied significantly for the three error measures, as demonstrated by a ~15 year thawing time-lag between the error measures over a 100 years modeling period. Abstract Copyright (2021), . The Authors.

DOI: 10.1029/2021GL093306

2021070798 Kim, Ji-Hoon (Korea Institute of Geoscience and Mineral Resources, Petroleum & Marine Division, Daejeon, South Korea); Hong, Wei-Li; Torres, Marta E.; Ryu, Jong-Sik; Kang, Moo-Hee; Han, Dukki; Nam, Seung-Il; Hur, Jin; Koh, Dong-Chan; Niessen, Frank; Lee, Dong-Hun; Jang, Kwangchul; Rae, James William Buchanan and Chen Meilian. A pulse of meteoric subsurface fluid discharging into the Chukchi Sea during the early Holocene Thermal Maximum (EHTM): Geochemistry, Geophysics, Geosystems - G³, 22(8), Article e2021GC009750, illus. incl. 1 table, sketch map, 70 ref., August 2021.

The response of Arctic Ocean biogeochemistry to subsurface flow driven by permafrost thaw is poorly understood. We present dissolved chloride and water isotopic data from the Chukchi Sea Shelf sediments that reveal the presence of a meteoric subsurface flow enriched in cations with a radiogenic Sr fingerprint. This subsurface fluid is also enriched in dissolved inorganic carbon and methane that bear isotopic compositions indicative of a carbon reservoir modified by reactions in a closed system. Such fluid characteristics are in stark contrast with those from other sites in the Chukchi Sea where the pore water composition shows no sign of meteoric input, but reflect typical biogeochemical reactions associated with early diagenetic sequences in marine sediment. The most likely source of the observed subsurface flow at the Chukchi Sea Shelf is from the degradation of permafrost that had extended to the shelf region during the Last Glacial Maximum. Our data suggest that the permafrost-driven subsurface flow most likely took place during the 2-3°C warming in the Early Holocene Thermal Maximum. This time scale is supported by numerical simulation of pore water profiles, which indicate that a minimum of several thousand years must have passed since the cessation of the subsurface methane-bearing fluid flow. Abstract Copyright (2021), . American Geophysical Union. All Rights Reserved.

DOI: 10.1029/2021GC009750

2021075045 Patton, A. I. (Colorado State University, Fort Collins, CO); Rathburn, S. L.; Capps, D. M.; McGrath, D. and Brown, R. A. Ongoing landslide deformation in thawing permafrost: Geophysical Research Letters, 48(16), Article e2021GL092959, illus. incl. 1 table, sketch maps, 61 ref., August 28, 2021.

Thawing permafrost influences landslide initiation, but observation of landslide development in thawing permafrost is limited. To evaluate the impact of landslide age, morphology, and permafrost conditions, we quantified topographic deformation of three shallow-angle, thaw-initiated landslides in discontinuous permafrost in Alaska. Two of the landslides initiated <3 years ago and the third initiated 20-50 years ago. The two recent landslides are still mobile, with maximum elevation loss of 0.8 ± 0.04 and 1.0 ± 0.08 m over the study period. At one site, shallow permafrost (<2.3 m) is present at 0.4-1.9 m depth adjacent to the landslide but not within the landslide. The lack of shallow permafrost within the slide indicates that permafrost has thawed faster within the landslide because ground surface disturbance increased heat flux to the subsurface. We propose that a positive feedback between permafrost thaw and landslide development exists. Climate warming will accelerate loss of permafrost in recent landslides. Abstract Copyright (2021), . American Geophysical Union. All Rights Reserved.

DOI: 10.1029/2021GL092959

2021075782 Ruebsam, Wolfgang (University of Kiel, Department of Organic and Isotope Geochemistry, Kiel, Germany) and Schwark, Lorenz. Impact of a northern-hemispherical cryosphere on late Pliensbachian-early Toarcian climate and environment evolution: in Carbon cycle and ecosystem response to the Jenkyns event in the early Toarcian (Jurassic) (Reolid, M., editor; et al.), Special Publication - Geological Society of London, 514, p. 359-385, illus., 219 ref., June 11, 2021.

The historical view of an equable Jurassic greenhouse world has been challenged by recent studies documenting recurrent alternation between contrasting climate modes. Cooling of high-latitudinal areas may have been caused by orogenic processes at the northern margin of the Tethys Ocean that reduced heat transport towards the polar regions. Warm phases correlate to periods of intensified volcanism. The Jenkyns Event occurred during the transition from a late Pliensbachian icehouse into an early Toarcian greenhouse. Parallel evolution of different environmental processes, including sea level, climate and carbon cycle, indicate a causal mechanism tied to astronomical forcing. Insolation-controlled variations in the extent of the cryosphere (ice caps and permafrost) facilitated orbitally paced sea-level cycles via waxing and waning of the polar ice caps, and negative carbon isotope excursions via the release of cryosphere-bound ¹²C-enriched carbon. This review and synthesis of sedimentological, geochemical and palaeontological palaeoenvironment indicators, and of simulations from climate models, aims to reconstruction, in particular, the high-latitudinal environmental conditions of late Pliensbachian-early Toarcian times. Focus is laid on the extent of the regions that were potentially suitable for hosting a cryosphere. An environmental response to cryosphere dynamics is considered to have been a key component of the Jenkyns Event.

DOI: 10.1144/SP514-2021-11

2021071880 Yao Yuan (Xi'an Jiaotong University, Institute of Global Environmental Change, Xi'an, China); Huang Yongsong; Zhao Jiaju; Wang Li; Ran Youhua; Liu Weiguo and Cheng Hai. Permafrost thaw induced abrupt changes in hydrology and carbon cycling in Lake Wudalianchi, northeastern China: Geology (Boulder), Pre-Issue Publication, p. 1117-1121, illus. incl. block diag., geol. sketch map, 32 ref., June 3, 2021. NSF grants EAR-1122749, PLR-1503846, EAR-1502455, and EAR-1762431.

Lakes in the permafrost zone have been proposed to serve as key outlets for methane and carbon dioxide emissions. However, there has been no geological record of the hydrological and biogeochemical responses of lakes throughout the thawing of surrounding permafrost. We use multiple biomarker and isotopic proxies to reconstruct hydrological and biogeochemical changes in Lake Wudalianchi in northeastern China during regional thawing of the permafrost. We show permafrost thawing, as indicated by lignin degradation, initiated rapid lake water freshening as a result of the opening of groundwater conduits, and negative organic d¹³C excursion due to increased inorganic and organic carbon fluxes. These hydrological changes were followed, with an ~5-7 yr delay, by abrupt and persistent increases in microbial lake methanotrophy and methanogenesis, indicating enhanced anaerobic organic decomposition and methane emissions from lakes as permafrost thaws. Our data provide a detailed assessment of the processes involved during permafrost thaw, and highlight the importance of lakes in ventilating greenhouse gases to the atmosphere.

DOI: 10.1130/G48891.1

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2021075971 Zufelt, Jon, editor (HDR Alaska, Anchorage, AK). Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering: Proceedings of the International Symposium on Cold Regions Engineering, 19, 373 p., illus., 2021. ISBN: 978-0-7844-8358-9. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web. Published by the American Society of Civil Engineers. Individual papers are cited separately.

These Proceedings contain 34 peer-reviewed papers prepared and published as part of the Technical Program for the 2021 Regional Conference on Permafrost and 19th International Conference on Cold Regions Engineering. The U.S. Permafrost Association under the auspices of the International Permafrost Association co-organized the Conference with the American Society of Civil Engineers. The goal of the Conference organizers was to provide a venue for permafrost science and frozen ground engineering topics to be meaningfully merged together for the first time. Increasingly, basic research and applied engineering efforts must incorporate a broad variety of information to ensure project results. From carbon itemization to bridge design, project deliverables must have meaningful and broad impact. Many of the difficult challenges facing permafrost researchers and engineers are the result of ongoing and projected future climate warming in Earth’s cold regions. To adequately address this challenge, we must find ways to cross disciplines and share best practices and lessons learned. These Proceedings include papers dealing with Permafrost Detection, Monitoring, and Change; Mountain Permafrost and Rock Glaciers; Cold Regions Transportation Infrastructure; Impacts of Permafrost on Engineered Structures; and Permafrost Issues Experienced by the Trans Alaska Pipeline System (TAPS).

DOI: 10.1061/9780784483589

2021075972 Andersen, Trevor S. (Carleton University, Department of Geography and Environmental Studies, Ottawa, ON, Canada); Jardine, Patrick A. and Burn, Christopher R. Long-term (2000-2017) response of lake-bottom temperatures and talik configuration to changes in climate at two adjacent tundra lakes, western Arctic coast, Canada: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 1-13, illus. incl. 5 tables, sketch maps, 18 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Lakes, commonly underlain by taliks, are principal agents of disturbance to permafrost. We have measured lake-bottom temperatures with submerged loggers on near-shore terraces and in deep central pools at two tundra lakes on Richards Island, NT, to determine inter-annual lake thermal responses to climate variation. We have modelled associated potential adjustments in talik geometry. In 2000-17, annual mean temperatures varied between -5.7 and 2.8°C for terraces and 1.1 and 4.5°C for pools. Permafrost in the terraces is warmer than surrounding the lakes: talik configuration varies with horizontal terrace extent and terrace and pool temperatures. The talik break-through depth declines as terrace size increases. Using the four warmest and coldest years as an analogue for climate change-an adjustment that may occur this century-the increase in talik depth may be up to 100 m, but it may take millennia for talik geometry to reach equilibrium.

DOI: 10.1061/9780784483589.001

2021075981 Badilo-Rivera, Edwin (National University of Callao, Faculty of Environmental Engineering and Natural Resources, Bellavista, Peru); Loarte, Edwin; Medina, Katy; Bodin, Xavier; Azócar, Guillermo and Cusicanqui, Diego. An estimation of past and present air temperature conditions, water equivalent, and surface velocity of rock glaciers in Cordillera Volcanica, Peru: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 105-116, illus. incl. sketch map, 21 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Rock glaciers (RG) are one of the most important geomorphological features in the Peruvian Andes. However, the local characteristics of RG have barely been studied or remain unknown. The aim of this research was to characterize past and present conditions of the RG located in Cordillera Volcanica in the southern of Peru. For this purpose, an inventory of RG was carried out and modern and past regional mean air annual temperatures (MAATs) were calculated. We estimate the water equivalent of RG to assess their importance as possible storage of frozen water for past and present conditions using an empirical rule. In addition, the local surface velocity of RG was obtained from Landsat 8 imagery. Within the study area, 187 RG were identified (surface area of 8.3 km2 ). Of these, 63 were classified as inactive, 39 as active and 85 as relict forms. The altitudinal distribution of RG ranges between 4616 to 5551 m a.s.l. (meter above sea level) where modern MAAT is 0.9°C. In the current conditions, relict RG are located in positive MAAT levels around 1.4°C, however, for the past conditions, relict RG were located in negative MAAT levels around -5°C. The amount of water stored in intact RG range between 28 and 64 million m3. Meanwhile, for past conditions (paleo-WVE), we estimated that volume stored within rock relict RG was between 16 and 35 million m3 (we assume an ice-rich layer of RG permafrost has between 20-45%). On the other hand, the average surface velocities of the active RG have been estimated between 1 to 10 cm/month. The finding of this research contributes to increasing knowledge about RG in the Peruvian Andes, however, further research is needed to understand the importance of RG as stores of frozen water during the past and present conditions.

DOI: 10.1061/9780784483589.010

2021075994 Bjella, Kevin (U. S. Army Cold Regions Research and Engineering Laboratory, Fairbanks, AK); Affleck, Rosa T.; Barna, Lynette; Vandevort, Daniel and Margules, Andrew. Arctic expeditionary infrastructrue research: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 245-252, illus. incl. 2 tables, 8 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

The warming of high latitude regions is causing geopolitical concerns and spurring increased human presence across the Arctic. Potentially these situations require only a short-term occupation facilitating the need for tested and developed expedient infrastructure. Operating requirements for high latitude conditions are vastly divergent from temperate locations and parameters have been established for habitable conditions to -60?F, withstand 100 mph wind speed, and support 25 lb/ft2 snow load. Although great advances have been made in providing efficient and comfortable Arctic infrastructure since the onset of the Cold War, significant work remains to further increase efficiencies, and adapt to changing climate parameters. To address infrastructure technology gaps, the U.S. Army Corps of Engineers-Engineering Research and Development Center (USACE-ERDC) has established an Arctic Infrastructure Research Group (AIRG). Current members comprise U.S. Department of Defense (DoD) and federal agency researchers, program managers, and shelter end users. The purpose of the AIRG is to provide a forum to synchronize research activities and pursue needs, ideas, and technical projects. Current ERDC efforts include the development of an external insulation wrap for rigid wall shelters, mobile insulation system for energy reduction (MISER), to include ground cover for permafrost protection. Additionally, a parallel effort is initiated to fully characterize the effects of the extreme environments on several expeditionary structures at the Cold Regions Research and Engineering Laboratory (ERDC-CRREL) Farmers Loop Permafrost Experiment Station (FLPES), in Fairbanks, Alaska. This initiative has created a research centric facility to test new technologies and innovative materials while validating and verifying the requirements of Arctic hardened infrastructure, both vertical and horizontal, particularly for the DoD.

DOI: 10.1061/9780784483589.023

2021075993 Bjella, Kevin (U. S. Army Cold Regions Research and Engineering Laboratory, Fort Wainwright, AK); Brooks, Heather; Yang, Zhaohui and Yarmak, Edward. Synopsis; permafrost engineering in a warming climate; current state and future strategy: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 233-244, 11 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

The permafrost engineering profession is challenged with the next stage of evolution, as the last few decades have seen a steady rise in permafrost temperature. The changing environment is generating uncertainty regarding safe engineering, and longevity, and the result is often overly conservative designs that greatly increase development costs. The ASCE Cold Regions Engineering Division (CRED) committees agreed a review of the current state of the profession and an outline of a future strategy were needed. The International Permafrost Association (IPA) sanctioned an action group to perform a workshop and look at the permafrost engineering discipline, determine knowledge gaps, and suggest a path forward. This paper presents a synopsis of the more important findings such as: the need for programmatic work in developing 'living' permafrost temperature forecast tools, technical advances in methods to design for increasing thaw sensitivity, designing and planning with threats from altered hydrology (thermo-erosion) and slope instabilities, and techniques to mitigate thaw-affected vertical and horizontal infrastructure, to name a few. Most importantly, the engineering profession, with the help of universities, must promote the backfill of the retiring frozen ground engineering workforce.

DOI: 10.1061/9780784483589.022

2021075986 Boekweg, Enoch T. (Brigham Young University, Department of Electrical and Computer Engineering, Provo, UT); Guthrie, W. Spencer and Mazzeo, Brian A. Nondestructive evaluation of a new concrete bridge deck subject to excessive rainfall during construction; implications for durability in a cold region: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 163-171, illus. incl. 2 tables, 14 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

This study demonstrated the application of nondestructive evaluation techniques for quality assurance of a newly constructed bridge deck in northern Utah that was subjected to an unexpected rainstorm during concrete placement. Because excess water can lead to lower concrete durability, evaluating the ability of water and chloride ions to penetrate the concrete and quantifying the overall protection of the reinforcing steel were important objectives. Several deck properties were measured, including concrete cover depth, deck surface temperature, resistivity, vertical electrical impedance (VEI), and Schmidt rebound number. Statistical analyses performed on the collected data indicated that the section most affected by the rain exhibited a lower Schmidt rebound number but was not different from the other sections in terms of resistivity or VEI; therefore, the results of the testing suggest that the effect of the rain was limited to a shallow depth of concrete, which was corroborated by petrographic analysis performed on several cores removed from the bridge deck. The upper approximately 0.13 in. was then milled from the deck surface before a polyester polymer concrete overlay was applied to seal the deck.

DOI: 10.1061/9780784483589.015

2021075996 Chesnokova, Irina V. (Russian Academy of Sciences, Water Problems Institute, Russian Federation); Popova, Alexandra A.; Sergeev, Dmitrii O. and Tipenko, Gennadii S. Infrastructure's adaptation to climate change at the Russian cold region's territories: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 260-265, illus., 3 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

The apparent trends in average annual ground temperatures are different at different depths. This is due to the multidirectional influence of climatic factors and territorial differences in the vertical distribution of temperatures in rocks. Temperature trends at different depths are used in conjunction with the time indicators of the onset of geocryological events to draft the climate adaptation programs. Adaptation is planned at three main levels. At the national level, zoning of the Arctic is carried out according to the predicted timing of the permanent transformation of geocryological conditions. At the regional level the facilities and responsible companies must be determined. At the local level the engineering protection programs must be developed for each facility under construction or in operation. This makes it possible to take into account the background influence of climatic changes and separate these changes from the influence of the engineering structures.

DOI: 10.1061/9780784483589.025

2021075988 Clark, Rob (Geokon, Lebanon, NH) and Burghart, Doug. Early warning frost detection system: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 184-191, illus., 2 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Occurrence of freeze and thaw conditions in rural roadway subgrades throughout the years resulted in significant labor efforts from Whatcom County Public Works engineers to monitor and evaluate conditions for implementing road restrictions. Extended periods of frost conditions followed by warmer temperatures can result in extensive damage to the road system if restrictions are not applied. Previously, subsurface temperatures were measured manually at various locations throughout the county to assist with evaluation of roadway conditions. Recently, a network of automated measurement and remote communication systems were designed and implemented to facilitate improved monitoring and response for the County engineers. Sixteen remote monitoring locations were selected throughout the county and at each site a 1-meter long tube with 18 thermistors at 50 mm spacing was installed into the roadway subgrade. Additional instrumentation at each site included ambient air temperature sensors and moisture sensors for the datalogger enclosures. Data is collected and transmitted to a web-based data management system for County personnel to access, and to provide alarm notifications to County personnel with indications as to when temperature thresholds are exceeded. Having the automated system allows the County to monitor the thaw process more accurately and be more confident with respect to when road restrictions are applied and their duration. The current monitoring system has increased the effectiveness and efficiency of the County's rural roadway management process during freeze/thaw cycles, resulting in significant savings in operating and maintenance costs.

DOI: 10.1061/9780784483589.017

2021076004 Croft, Peppi (Consultant, Fairbanks, AK); Hoopes, Oliver; Wuttig, Frank and Mathieson, Wendy. Embankment fill slope movement on thaw sensitive permafrost; movement mechanisms and thermal conditions at Lost Creek along the Trans-Alaska Pipeline system; Lost Creek; Part 1: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 351-359, illus. incl. sketch map, 5 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

The Trans-Alaska Pipeline System was constructed in the 1970s to transport oil through a 48- inch diameter pipeline (mainline) 800 miles from Prudhoe Bay to Valdez, Alaska. The system traverses continuous and discontinuous permafrost and is supported above-ground or buried, depending on permafrost and ground conditions. The Lost Creek site is in discontinuous, warm permafrost on a northwest-facing cut and fill slope. On the lower portion of the slope, fill was placed over frozen colluvium and ice-rich peat. The mainline at this site is supported aboveground on H-type bents, which consists of two piles supporting a crossbeam on which the pipe is supported. Since 1990, Alyeska Pipeline Service Company has observed signs of ground and pile movement. This paper presents our interpretation of geotechnical site conditions based on instrumentation monitoring and field observations. We developed mitigation options to control ground movement and present our approach in a separate paper within these proceedings.

DOI: 10.1061/9780784483589.033

2021076003 Croft, Peppi (Shannon & Wilson, Fairbanks, AK); Hoopes, Oliver T.; Wuttig, Frank J.; Schulz, Charles and Mathieson, Wendy L. Slope stabilization along a buried crude-oil pipeline in ice-rich permafrost: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 339-350, illus. incl. sketch map, 8 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

The Trans-Alaska Pipeline System (TAPS) transports warm oil through a 48-inch diameter pipeline (mainline) 800 miles from Prudhoe Bay to Valdez, in Alaska. The system traverses continuous and discontinuous permafrost terrain and is supported aboveground or belowground, depending on subsurface conditions. The stabilization site is in discontinuous warm permafrost in the Copper River Basin in Alaska's interior. The mainline at the site is buried in thaw-unstable, ice-rich permafrost and actively refrigerated to allow for animal crossings. Alyeska Pipeline Service Company (APSC) initially observed evidence of ground movement at the study site in 2012, threatening to expose the mainline. APSC developed and implemented stability mitigation measures to protect the mainline. This paper demonstrates how geotechnical hazards due to changing environment and permafrost conditions are being managed along TAPS and evaluates mitigation design by comparing predicted and observed subsurface conditions at the study site 3 years after mitigation.

DOI: 10.1061/9780784483589.032

2021075989 Dagvadorj, Otgonjargal (Kitami Institute of Technology, Kitami, Japan); Nakamura, Dai; Kawaguchi, Takayuki and Kawajiri, Shunzo. Deformation caused by frost heave on a rock slope a mudstone: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 192-202, illus. incl. 1 table, 8 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

In this study, we measured freezing depth, amount of frost heave, and weathering depth of a mudstone slope where damage had occurred. In addition, rocks collected from the survey field were subjected to a frost heave test and a slaking test. The results of the laboratory tests show that the rocks collected at the survey field were easy to slake and had high frost susceptibility. The field survey showed that the rock slope frost heaves significantly in winter and that the surface layer of the slope thaws in spring and becomes extremely weak. Furthermore, the weathering depth of the rock slope was found to be in good agreement with the freezing depth. On the other hand, the weathering depth of the rock slope did not change during the summer, and no slaking was observed due to repeated wetting and drying.

DOI: 10.1061/9780784483589.018

2021075974 Debolskaya, Elena (Russian Academy of Sciences, Water Problems Institute, Moscow, Russian Federation); Debolskiy, Vladimir; Maslikova, Oksana; Gritsuk, Ilya and Ivanov, Alexander. The influence of thermal erosion at river bed deformation in permafrost areas: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 14-26, 35 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

The study is focused on the deformations caused by the impact of water flow in a river channel composed of meltable permafrost bed materials. It is based on the results of laboratory and mathematical simulation. The results of numerical calculations are compared with data of laboratory and field observations. The study shows that a comprehensive and adequate model of river channel deformations should take into account not only ablation, but also other factors, including heat transfer in the soil, sediment transport, and bank slope collapses. Experiments in a hydraulic flume were good enough to reproduce the effect of delayed collapse, consisting in nonsimultaneous impacts of channel-forming rock melting and a freshet. The major factors that have an effect on channel transformations in permafrost-zone rivers are identified.

DOI: 10.1061/9780784483589.002

2021075975 Deslauriers, Catherine (Université Laval, Department of Geography, Quebec City, QC, Canada); Allard, Michel and Roy-Léveillée, Pascale. Ground temperature responses to climatic trends in a range of surficial deposits near Kangiqsualujjuaq, Nunavik: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 27-37, illus. incl. geol. sketch map, 37 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

This paper discusses ground temperature responses to climate variations in a range of surficial geology units near Kangiqsualujjuaq, Nunavik. Sixteen thermistor cables, extending to depths from 2.9 to 20 m, were installed in various settings near the community over 35 years. Here we examine ground temperature at three contrasting sites: a lithalsa in ice-rich marine clays near the shoreline, a glaciofluvial delta (sand and gravel), and bedrock (massive gneiss), to compare thermal regimes and responses to climatic variations over the last 20 to 30 years. With climate warming, the site in marine deposits has become isothermal near 0°C and the release of latent heat now impedes ground temperature responses to climate. In sand and gravel, freeze-back is delayed until late in winter with clear development of a zero curtain due to formation of a perched water table in the deepened active layer. Short-term air temperature variations and regional climatic trends are effectively transmitted at depth into highly conductive dry bedrock, where active layer depth also readily responds to air temperature variations.

DOI: 10.1061/9780784483589.003

2021075980 Fritz, Stacey A. (National Renewable Energy Laboratory, Cold Climate Housing Research Center, Fairbanks, AK) and Romero-Lankao, Patricia. Engage the public in science and embrace future change with human-centric stories, art, and imaginings: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 94-104, 33 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Human-centric stories that weave in real scientific data may be able to engage the public in environmental issues that do not yet directly affect them. Science fiction and artistically rendered futuristic scenarios can unleash the imagination and act as a lens to envision technological, social, and cultural aspects of transitioning to clean energy. Cultures with strong oral traditions use stories to record history, develop a shared identity, pass on environmental lessons, and prepare for future change. Through the lenses of our non-physical science disciplines (cultural anthropology and environmental sociology), we discuss challenges to communicating science, the use of narratives to illustrate ecosystem processes, and we report on a collaborative, interdisciplinary workshop and book project that is creating narratives of hope and visions for the future through inspiring art, short stories, and essays. We explore the surprising potential of 'cli-fi', humor, games, and the research behind emotion and imagination-driven engagement. We describe methods that help people visualize their future well-being and we explore opportunities to spread those methods.

DOI: 10.1061/9780784483589.009

2021075987 Fuentes, Anthony J. (U. S. Army Cold Regions Research and Engineering Laboratory, Hanover, NH); Vecherin, Sergey N.; Bodie, Mark O. and Parker, Michael W. Quantification of rut detection and height mapping in winter terrains for off-road mobility: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 172-183, illus. incl. 3 tables, 14 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Off-road autonomous vehicle navigation in winter environments requires reliable identification and quantification of potential obstacles, such as deep vehicle rutting or buried objects. The advent of consumer-grade light detection and ranging (LiDAR) sensors and unmanned aerial system (UAS) based photogrammetry present new avenues for the implementation of change detection algorithms for the purpose of obstacle identification. Few studies have provided a quantifiable statistical method for determining the input parameters of these change detection algorithms based upon user-defined confidence metrics. Previous detection methods also fail to derive the degree of assurance associated with the identification of a perceived obstacle. Here, we present an automated method for identification of snow-covered obstacles and vehicle ruts within LiDAR-derived digital elevation models based on false-alarm and detection probabilities. Detection maps and accurate height maps are generated for snow-covered objects by the algorithm to demonstrate the reliability of this method to assist with obstacle avoidance in snowy off-road conditions. The algorithm described here is a reliable and fast method for the identification and measurement of snow-covered obstacles. While this study is concerned with snow-covered terrain, the methods described here may be leveraged to monitor route deformation features as a result of vehicle traffic across a variety of terrain types.

DOI: 10.1061/9780784483589.016

2021076005 Hoopes, Oliver (Shannon & Wilson, Seattle, WA); Croft, Peppi; Wuttig, Frank; Schulz, Chuck and Mathieson, Wendy. Embankment fill slope movement on thaw sensitive permafrost; combining creep testing and thermal simulations to develop mitigation options at Lost Creek along the Trans-Alaska Pipeline system; Lost Creek; Part 2: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 360-373, illus., 13 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

The Trans-Alaska Pipeline System was constructed in the 1970s to transport warm oil through a 48-inch-diameter pipeline (mainline) 800 miles from Prudhoe Bay to Valdez, Alaska. The system traverses continuous and discontinuous permafrost terrain and is supported aboveground or buried, depending on subsurface conditions. The Lost Creek site is a northwest-facing cut and fill slope in discontinuous, warm permafrost. The mainline is supported aboveground by vertical support members (VSMs). Since 1990, Alyeska Pipeline Service Company has observed signs of ground and VSM movement. Movement mechanisms at the site include longitudinal creep movement along a shear zone in ice-rich permafrost and transverse shoulder rotation due to thaw settlement. The movement causes lateral pile loading, VSM displacement, and embankment shoulder failure. This paper presents the methods we used to develop options to mitigate slope movement at the site. We present our interpretation of site conditions in a separate paper within these proceedings.

DOI: 10.1061/9780784483589.034

2021075976 Kirkwood, Adam H. (Laurentian University, Department of Biology, Sudbury, ON, Canada); Roy-Léveillée, Pascale; Branfireun, Brian A. and Basiliko, Nathan. Mercury, methylmercury, and microbial communities in a degrading palsa of the Hudson Bay Lowlands, far north Ontario: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 49-59, illus. incl. 1 table, sketch map, 42 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

The Hudson Bay Lowlands (HBL) may be one of the largest mercury (Hg) pools in the permafrost zone according to recent estimates. However, little is known about the abundance and distribution of organic methylmercury (MeHg), and it is unclear how permafrost degradation relates to the release and potential methylation of Hg. This research characterized total Hg and MeHg distributions in a degrading palsa of the HBL and investigated relations between thawing permafrost, MeHg concentrations, and microbial community structure. Near the study site, palsas lost ~1.0% of their area per year to thermokarst encroachment between 1955 and 2019. The abundance of microbes in families with taxa capable of Hg methylation was not related to MeHg concentrations, which were low (0.13-0.49 ng/g), and strongly related to THg concentrations. Hg concentrations in the top 100 cm of the peat profile were lower in this study than previously estimated for the area, with a storage of approximately 9 mg THg m-2.

DOI: 10.1061/9780784483589.005

2021075982 León, Hairo (Santiago Antúnez de Maylo National University, Faculty of Environmental Sciences, Huaraz, Peru); Medina, Katy; Loarte, Edwin; Azócar, Guillermo; Iribarren, Pablo and Huggel, Christian. Mountain permafrost in the tropical Andes of Peru; the O°C isotherm as a potential indicator: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 117-129, illus. incl. 1 table, sketch map, 49 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

In the tropical Andes of Peru very little is known about the occurrence and extent of mountain permafrost. Only recently systematic studies have been carried out on the high elevation sites of the mountain ranges (cordilleras). In the framework of the first pioneering studies, and with the objective to improve the understanding of characteristics of mountain permafrost and rock glaciers, we analyze how mountain permafrost in the Peruvian Andes is correlated with the altitude of the 0°C isotherm (ZIA). Climate change has generated an increase in air temperature and in the ZIA in the past decades. These temperature changes could lead to impact the state of the mountain permafrost. In this research, we focus on two mountain regions: The Cordillera Central (CC) and the Cordillera Volcanica (CV), the first located in the central zone and the second in the south zone of Peru. The study used air temperature data from 20 weather stations (2002-2016) to calculate the mean annual air temperature (MAAT), interpolated using a multiple linear regression model (MLRM) and digital elevation model (MERIT DEM). Occurrence and extent of 46 intact rock glaciers (IRG) and the global model of permafrost (Permafrost Zonation Index) were used to validate the results. The MAAT of CC has a minimum value around -4.1°C (R²=0.8) and a ZIA average of ~5152 m a.s.l. None of the IRGs are located above the ZIA. The MAAT of CV has a minimum value around of -5.5°C (R²=0.8), a ZIA average of ~4861 m a.s.l., and 60% of the IRGs are located above of the ZIA. The results show a greater variation of the position of the ZIA in CC in comparison to CV, which could indicate a possible degradation of mountain permafrost in these mountain ranges.

DOI: 10.1061/9780784483589.011

2021076000 Mattos, Kaitlin J. (University of Colorado, Department of Civil, Environmental, and Architectural Engineering, Boulder, CO); Warren, John; Heavener, Mia and Linden, Karl. Rethinking water and sanitation in challenging environments; lessons learned from installing portable, adaptable, mid-tech household systems: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 302-316, illus. incl. 2 tables, 27 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Permanent water and sanitation infrastructure faces major technical and economic challenges in cold region communities because of the threats of freeze-thaw cycles, permafrost instability, and a changing climate. As a result, thousands of households suffer health and wellbeing consequences because they live without basic access to clean water, safely managed sanitation, and appropriate hygiene. In response, the Alaska Native Tribal Health Consortium has spent five years developing, piloting, and deploying portable, adaptable, mid-tech household water and sanitation systems in rural Alaskan communities that lack piped infrastructure. These portable alternative sanitation systems (PASS) work with natural freeze-thaw cycles to help households manage potable water and human waste. They can be adapted to various modes of operation based on end-user preferences and environmental conditions. These systems require little training and technical expertise to operate and maintain and can be easily moved to new locations if households have to relocate. End users have demonstrated that PASS units can be successful at providing incremental improvements in water and sanitation services to households if they are appropriately designed, installed, and supported. We evaluated function, use, and adoption of PASS units over the first year after their installation. We discuss lessons learned from deploying these innovative mid-tech systems in houses, such as the need to develop basic technical installation and operation guidance and socially appropriate trainings to ensure success of the technology. These lessons can be used to support the development of new types of adaptive and resilient infrastructure with low environmental impacts for underserved communities.

DOI: 10.1061/9780784483589.029

2021075992 McCallum, Adrian B. (University of the Sunshine Coast, School of Science, Technology and Engineering, Sippy Downs, Queensl., Australia). Estimating sub-surface snow density using GPR and the surface reflection method: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 227-232, illus. incl. 1 table, 6 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

The surface reflection method is a popular method of determining layer dielectrics in road pavements. Previous research has also applied this technique to snow to estimate surface snow density. Here, this method is extended to estimate sub-surface snow density and layer thicknesses. An air-coupled 800 MHz ground penetrating radar (GPR) antenna was used to image alpine snow, and comparison was made with an ideal reflector, a metal plate. Quantitative analysis of the GPR trace and application of the surface reflection technique allowed sub-surface snow density and surface layer thickness to be resolved. Although discrimination of second layer thickness was poor, this technique introduces a simple method by which surface and sub-surface snow layer density and thickness could be rapidly estimated over large spatial areas.

DOI: 10.1061/9780784483589.021

2021075990 Menke, Amelia (U. S. Army Cold Regions Research and Engineering Laboratory, Hanover, NH); Shoop, Sally and Elder, Bruce. Use of a portable friction tester on snow and ice pavement: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 203-213, illus. incl. 3 tables, 6 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

The objective of this project was to determine if portable friction testers could be used for friction measurements on compacted snow and ice surfaces. First, the effect of cold temperatures on the operation, consistency, and accuracy of commercially available portable pavement friction measuring tools was evaluated. Tests entailed a series of experiments in a controlled cold room environment. Two portable fixed slip continuous measurement devices and one deceleration spot measurement device were evaluated. The controlled temperature testing determined how ambient temperature and duration of exposure can affect results, but that with care, the devices could be operated in conditions as cold as -25°C. This was followed by using one of the devices on outdoor testing on snow, ice, and asphalt surfaces and compared the portable tester to the well-known SAAB vehicle runway friction tester. Results showed good agreement between the portable tester and the SAAB Friction tester, providing validation for the operational use of a portable tester on frozen surfaces.

DOI: 10.1061/9780784483589.019

2021076002 Mosley, Larry (Alyeska Pipeline Service Company, Fairbanks, AK); Zarling, John; Wuttig, Frank and Schulz, Charles. Alyeska's 40-plus years of experience with heat pipes on the Trans-Alaska Pipeline system: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 327-338, illus., 23 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Heat pipes (thermosyphons) were installed in the vertical support members (VSMs) of the Trans-Alaska Pipeline System where the pipeline is elevated in warm non-thaw-stable permafrost areas. More than 124,000 heat pipes with pure anhydrous ammonia, NH3, as the working fluid were installed during pipeline construction in the mid-1970s to thermally stabilize the permafrost surrounding the VSMs. Shortly after pipeline construction, non-condensable-gas, NCG, began to occur in some of the heat pipes, affecting their performance. Alyeska conducted an extensive research effort to identify the root cause for the occurrence of NCG and performed a test program on the degradation in heat pipe performance with the build-up of NCG. Two procedures have been used to repair underperforming heat pipes due to NCG issues: (1) Using "getter devices" and (2) recharging the heat pipes with carbon dioxide, CO₂. Using getter devices was not a permanent solution to the NCG problem, and experience has shown CO₂ recharging to be a successful repair option. This paper describes 40-plus years of heat pipe experience for an aboveground pipeline system in permafrost, several heat pipe options Alyeska considered prior to construction, and the choice and development of the heat pipes that were used on the pipeline. This paper also describes how Alyeska has managed NGC issues that developed after construction to ensure integrity of the aboveground system and the innovative use of heat pipes as thermometers to monitor end-of-thaw-season ground temperatures at the base of thermal VSMs as an additional integrity management tool.

DOI: 10.1061/9780784483589.031

2021075985 Rahman, Jesika (Lakehead University, Department of Civil Engineering, Thunder Bay, ON, Canada); Muntasir Billah, A. H. M. and Iqbal, Asif. Performance of bridges in cold regions with sliding seismic isolation bearings: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 151-162, illus. incl. 4 tables, 30 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Effects of extreme temperature on highway bridges in cold regions seismically isolated with sliding type bearings are investigated. The critical factor in consideration is the change in the performance of isolation bearings with significant variation in temperature between seasons. The sliding bearing behavior is characterized by the friction coefficient of the sliding surfaces. The friction coefficient during a seismic motion varies with the sliding velocity and temperature at the sliding surface. Tests associated with past applications have indicated a marked increase in the value of friction coefficient resulting in higher stiffness of bearings at very cold temperatures. The effects of change in bearing stiffness on the seismic performance of the bridge in general and the substructure in particular are demonstrated here. This study aims to capture the change in bearing response and subsequently the overall structural response considering a temperature variation between -40°C and +40°C. Response parameters considered for this study are the base shear in the piers, the acceleration of the bridge deck, maximum and residual displacement of the isolation bearings, as well as the energy dissipation capacity. The response parameters are compared for individual ground motions as well as the mean and coefficient of variation (COV). It is observed that the higher bearing stiffness at extreme cold temperature leads to additional forces on the substructure which reduces the margin of safety and hence should be considered carefully in design.

DOI: 10.1061/9780784483589.014

2021075977 Robinson, Chantae (Laurentian University, Department of Biology, Sudbury, ON, Canada); Roy-Léveillée, Pascale; Turner, Kevin and Basiliko, Nathan. Impacts of shrubification on ground temperatures and carbon cycling in a sub-arctic fen near Churchill, MB: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 60-70, illus. incl. 1 table, sketch map, 44 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

This paper examines the extent and impact of shrubification on near surface ground temperatures and microbial greenhouse gas production (GHG) in fen environments of the Hudson Bay Lowlands near Churchill, MB. Greening during 1984-2018 was analyzed using Google Earth Engine, temperature sensors were installed just below the ground surface, and active layer samples were incubated to determine potential GHG production. Greening was extensive in the area and, at the site, mean annual ground surface temperature was more than 3°C warmer under shrubs, with twice as many thawing degree-days and half as many freezing degree-days than in sedge dominated fen sites. Methane production was lower in soils from shrub-dominated sites. These preliminary results suggest it is unlikely that permafrost is sustainable where shrubs encroach, yet the effects of permafrost thaw on carbon cycling could be in part offset by lower microbial methane production associated with shrubs in near surface soils.

DOI: 10.1061/9780784483589.006

2021075995 Rooney, James W. and Riddle, Charles H. A second foundation review of Ahtna Corporation Glennallen facility, Alaska, USA: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 253-259, illus., 3 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

In the spring of 1975 a geotechnical investigation was accomplished at the proposed building site and included six test holes drilled to a depth of 10.7 meters into warm permafrost. Ground temperature measurements were taken in January 1976 at each test hole. Based on this investigation the decision was made to support the elevated structure on modified H-piles driven to a depth of 9.1 meters. Details of the installation of the foundation piles and a subsequent limited monitoring effort are presented in a prior 2004 technical report by the authors. The primary interest in monitoring the foundation ground temperatures has been to again observe temperature change below the relatively undisturbed ground surface. On July 23, 2020, some 45 years later, the authors had the opportunity to again revisit the site and obtain current ground temperatures at limited accessible pile locations. Although some ground cooling was observed in 2004, it appears that (while still frozen) some slight warming is now occurring. Ideally, evaluation of conditions should be made in the fall in order to better assess full summer warming impacts. Unfortunately, access to most pile locations was limited by "hoar frost" accumulation or other obstructions in the pile angle openings that equipment was not available to allow us to penetrate. Also, the observed past desiccation of the undisturbed thin surface organic mat must have had some influence on reducing ground warming at this site. An assessment of long ago design concerns, as related to current climate warming impacts, are also reviewed.

DOI: 10.1061/9780784483589.024

2021076001 Rooney, James W. Permafrost test sites; a summary of Alaskan pipeline industry efforts in addressing frozen ground and related technical issues: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 317-326, illus., 4 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

This paper is an attempt to identify and provide a brief summary of some industry efforts that occurred during the late 1960s on through the mid-1980s, that I was involved with or aware of. All of the test sites were focused on evaluating terrain conditions and assessing potential pipeline impacts that would be involved while dealing with frozen ground conditions. Efforts included various organizations and participation by government agencies that occurred during both the Alyeska Pipeline Service Company (APSC), Arctic gas pipeline, and Alaska northwest natural gas transmission system early project activities. There were at least 11 test sites having locations in various parts of Alaska. These included Barrow, Prudhoe Bay, Prospect Creek, Hess Creek, the Fairbanks area, and Glennallen. They addressed concerns relating to thermal modeling of a hot oil 48-inch pipe buried in frozen ground, thaw settlement/frost heave effects, trench excavation methods, and testing vertical support solutions for the designated above ground pipeline segments.

DOI: 10.1061/9780784483589.030

2021075984 Schwarber, Jaimy A. (University of Alaska, Department of Civil, Geological and Environmental Engineering, Fairbanks, AK); Darrow, Margaret M.; Daanen, Ronald P. and Stevens, De Anne S. P. Preliminary interpretations from a landslide inventory in interior Alaska: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 142-150, illus. incl. 1 table, sketch map, 20 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Landslides are geologic hazards that threaten human life, infrastructure, and property. To mitigate these threats, a landslide inventory map must first be developed. We present preliminary interpretations of the first comprehensive landslide inventory in the Fairbanks North Star Borough (FNSB), Interior Alaska. The inventory was developed using light detection and ranging (LiDAR) digital elevation models (DEMs), and validated with field checks of landslides accessible on public lands along the road system. The inventory provides a landslide spatial distribution that can be correlated to types of soil and/or bedrock, slope, aspect, and permafrost distribution. We can determine relative age of landslides using morphology, vegetation, and cross-cutting relationships with infrastructure. We provide landslide examples of: 1) different ages, 2) mechanisms of movement, and 3) morphology; and explore potential triggers of the prehistoric landslides.

DOI: 10.1061/9780784483589.013

2021075997 Simon, Doug P. (HDL Engineering Consultants, Anchorage, AK); Dvorak, Jeremy R. and Jordt, Erik J. Improving construction and performance of a runway in Nuiqsut, Alaska: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 266-276, illus. incl. 3 tables, sketch map, 4 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Airports provide the only means of reliable access to many arctic communities in Alaska and are essential for goods, transportation, and medical care. Despite being surfaced with gravel, the runways must provide reliable access year-round. Many of the runways in the North Slope region were constructed in the 1980s, when conventional engineering design indicated 1.3-meter to 2-meter embankments were adequate to protect the runways from settlement of the underlying permafrost. Global climate change has resulted in thaw instability of many runways. Short, wet, cold construction seasons make construction of arctic runways challenging. In addition, gravel surfacing can be difficult to produce locally and is generally of poor quality. This paper presents the solutions used to address the challenges for rehabilitating the gravel runway in Nuiqsut, Alaska. Insulation was installed in the runway embankment to limit the potential for future global warming to thaw the underlying permafrost. Geotextiles accelerated drainage during reconstruction of the embankment fill over the insulation. Dust control additives were blended into the gravel surfacing to increase strength and performance. This paper also presents lessons learned through design and construction. Recommendations are provided for design of future runways, and the value of the insulation, wicking geotextile, and dust control blending is discussed.

DOI: 10.1061/9780784483589.026

2021075991 Trisch, Holly P. (University of Alaska at Anchorage, Anchorage, AK) and Abaza, Osama A. Developing pavement performance prediction models using rutting criteria for a cold region environment: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 214-226, illus. incl. 1 table, 13 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Maintenance and rehabilitation of roadway pavements in Alaska's south central and south coast regions are triggered by rutting based on the FHWA threshold of 0.5 in. (12.7 mm) used by Alaska DOT&PF. This leads to short pavement life due to a relatively high rut rate caused by studded tire use during wintertime. Research into the overall rut in these regions shows insignificant rutting from truck traffic. Average pavement resurfacing life in these regions, when considering the effects of rutting, is seven to nine years for freeways and higher for other road classes. This represents about half of the expected design life for principle arterials. Establishing a prediction models that considers the overall rutting will allow agencies to incorporate these models in their pavement management system (PMS). Using rutting and age as the dependent and independent variables, respectively, two models were developed, one for interstate pavements and another for other principal arterial pavements.

DOI: 10.1061/9780784483589.020

2021075978 Tutton, Rosamond (Queen's University, Department of Geography and Planning, Kingston, ON, Canada); Way, Robert G.; Beddoe, Ryley; Zhang, Yu and Trant, Andrew. Modelled soil temperature sensitivity to variable snow and vegetation conditions in low-relief coastal mountains, Nunatsiavut and NunatuKavut, Labrador: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 71-81, illus. incl. sketch map, 35 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Understanding permafrost vulnerability and resilience to climate warming is critical for predicting impacts on northern communities and ecosystems. The thermal characteristics of near-surface permafrost are influenced by effects from overlying vegetation and snow cover, both of which are changing in northern environments. The association between vegetation and snow is important in the coastal mountains of Labrador, northeast Canada, because of high annual snowfall totals and greening tundra biomes. In this study, we present a series of one-dimensional simulations using the Northern Ecosystem Soil Temperature (NEST) model to characterize ground thermal conditions at two field sites (Nain, Nunatsiavut and Pinware, NunatuKavut) along the Labrador coast. NEST simulations covering 1979-2019 were run using ERA5 atmospheric reanalysis for three ecotypes (tundra, shrub, treed) with three different snow accumulation regimes (snow drifting away from site, no snow drift, snow drifting to site). At Nain, perennially frozen ground was present for all three ecotypes when snow cover was kept thin (drifting away) but was largely absent for the ecotypes when snow accumulation was higher. At Pinware, frozen ground was mostly absent except where snow cover was shallow (wind drifting away). For low-snow simulations, frozen bodies (<20 m) persisted in all ecotypes during cold periods but only remained intact following warmer years for treed ecotypes. These results highlight the importance of spatial and temporal variability in snow cover on ground thermal regimes in coastal Labrador.

DOI: 10.1061/9780784483589.007

2021075979 Wang, Yifeng (University of Ottawa, Deprtment of Geography, Environmental and Geomatics, Ottawa, ON, Canada); Lewkowicz, Antoni G.; Holloway, Jean E. and Way, Robert G. Thermal modelling of past-fire permafrost change under a warming coastal subarctic climate, Eastern Canada: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 82-93, illus. incl. 2 tables, sketch map, 37 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Forest fires are known to have lasting thermal impacts on permafrost, but there are no previous studies of such effects along the eastern Canadian coastline. One-dimensional thermal modelling was used to examine the ground thermal regime at a coastal forest fire site in the discontinuous permafrost zone near Nain (56.5°N), Nunatsiavut, eastern Canada. Simulations were undertaken for both the unburned forest and adjacent fire-disturbed area, which were modelled to have an initial permafrost thickness of 15.6 m in 1965. Future scenarios incorporated changes to regional air temperature following Representative Concentration Pathway (RCP) 4.5 and 8.5, as well as variations in surface organic material regeneration. Results varied from permafrost thinning but persisting beyond 2099 under RCP4.5 (unburned) to thawing entirely by 2060 under RCP8.5 (high severity burn, no organic material regeneration). In all burned scenarios, a supra-permafrost talik developed immediately following disturbance, but in most cases, frozen ground re-aggraded after several decades. Our findings are broadly consistent with those from western North America and demonstrate that the main impact of fire is to accelerate permafrost thaw due to climate warming.

DOI: 10.1061/9780784483589.008

2021075973 Way, Robert G. (Queen's University, Department of Geography and Planning, Kingston, ON, Canada); Lewkowicz, Antoni; Wang, Yifeng and McCarney, Paul. Permafrost investigations below the marine limit at Nunatsiavut, Canada: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 38-48, illus. incl. 1 table, sketch map, 29 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Discontinuous permafrost is a challenge for development in the coastal communities of Nunatsiavut, Labrador, northeast Canada, where local high relief limits suitable terrain for construction. These issues are particularly pronounced in Nain, the largest and northernmost community in Nunatsiavut, which is undergoing rapid population growth and expansion. In this study, DC electrical resistivity tomography was combined with geotechnical borehole records and in situ field data to evaluate the distribution of permafrost at four sites in the lowest parts of the community. Permafrost was identified in at least six of the seven geophysical transects, including beneath culturally critical community infrastructure. A supra-permafrost talik was imaged beneath a convenience store that has experienced extreme differential subsidence, demonstrating that excess ice exists in some of the region's frozen sediments. The presence of permafrost near the shoreline likely reflects ground cooling due to wind-scouring of snow at the exposed sites and the thermal impact of frost-susceptible sediments. Despite uncertainties in geophysical interpretation due to local site disturbance and coarse near-surface fill at some sites, these results have important implications for future development in this northern coastal community.

DOI: 10.1061/9780784483589.004

2021075983 Way, Robert G. (Queen's University, Department of Geography and Planning, Kingston, ON, Canada); Wang Yifeng; Bevington, Alexandre R.; Bonnaventure, Philip P.; Burton, Jake R.; Davis, Emma; Garibaldi, Madeleine C.; Lapalme, Caitlin M.; Tutton, Rosamond and Wehbe, Mishélle A. E. Consensus-based rock glacier inventorying in the Torngat Mountains, northern Labrador: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 130-141, illus. incl. sketch map, 40 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

The Torngat Mountains of northern Labrador are an Arctic cordilleran mountain range located at the southern limit of the Canadian Arctic. Sparse observations of periglacial landforms including rock glaciers and ice-cored moraines imply that permafrost may be widespread but limited in situ information is available for the region. In this study, we provide the first comprehensive feature inventory of intact rock glaciers in the Torngat Mountains of northeast Canada. Prospective features were identified by a team of eight independent mappers using high-resolution satellite imagery. The initial inventory was re-assessed via consensus-building and review stages, resulting in a final inventory of 608 rock glaciers. Rock glaciers were distributed from ~58°N to ~60°N and were primarily concentrated in the northern end of the Torngat Mountains National Park with southern clusters located in high relief coastal mountains near 59°N. The use of a large mapping team and the multistage consensus-based approach maximized feature inclusion and reduced misinterpretation of other features (e.g., debris-covered glaciers, ice-cored moraines, and talus couloirs) for rock glaciers. Our results show the efficacy of consensus-based landform identification for geomorphological mapping in the heterogeneous environment of the Torngat Mountains.

DOI: 10.1061/9780784483589.012

2021075998 Zhang Xiyin (Lanzhou Jiaotong University, School of Civil Engineering, Lanzhou, China); Chen Xingchong and Guan Jiada. Permafrost degradation effect on seismic response of bridge pile foundation along Qinghai-Tibet Railway: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 277-289, illus., 29 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

With climate warming, widespread permafrost degradation is found worldwide in recent years. For permafrost regions located in earthquake belts, i.e., the Qinghai-Tibet Plateau permafrost region in China, permafrost degradation effect on seismic performance of the bridge pile foundation is worthy of research. In this study, a pile-soil interaction model considering thermal-mechanical effect is presented and applied to a case study of the bridge pile foundation along Qinghai-Tibet Railway. Seismic responses of the bridge pile foundation are analyzed with consideration of the thawed permafrost. Numerical results show that thawed permafrost can influence the lateral displacement, shear force, and bending moment of the bridge pile foundation under seismic actions. The freeze-thaw state of the active layer should be considered when analyzing the permafrost degradation effect on seismic responses of bridge piles. The seismic safety of the existing bridge pile foundations along Qinghai-Tibet Railway is evaluated. It is recommended that seismic design of bridge with pile foundation in permafrost region should consider the thermal-mechanical effect of pile-soil system and the permafrost degradation effect.

DOI: 10.1061/9780784483589.027

2021075999 Zhao, Yue (University of Alaska Anchorage, Anchorage, AK); Yang, Zhaohui; Liu, Haibo and Dai Changlei. Prediction of climate change impact on a highway in warm permafrost: in Permafrost 2021: Merging Permafrost Science and Cold Regions Engineering (Zufelt, Jon, editor), Proceedings of the International Symposium on Cold Regions Engineering, 19, p. 290-301, illus. incl. 4 tables, sketch map, 16 ref., 2021. Meeting: Regional conference on Permafrost 2021 and the 19th international conference on Cold regions engineering, Oct. 24-29, 2021, World Wide Web.

Climate warming is causing a widespread impact on the built infrastructure, such as roads, airports, and pipelines, and threaten their safe operation in the broad cold regions. Such problems are particularly severe in areas where ice-rich and thaw-unstable warm permafrost exists extensively. This paper presents the preliminary results of a case study on a highway in Bethel, Alaska, located in deep, warm permafrost in western Alaska. The climate change influence on the thermal state of warm permafrost and its potential impact on the built infrastructure are assessed. We first analyzes the characteristics of the near-surface air temperature predictions from 31 climate models in the fifth phase of the Coupled Model Intercomparison Project (CMIP5) for the next century. The air freezing and thawing indices are evaluated from the climate modeling results and compared with historical data. A thermal model of a selected ice-rich soil profile is built and used to assess the ground temperature variation and permafrost degradation during the next century. Subsequently, permafrost thaw settlement is predicted, and their potential impact on the built transportation infrastructure is discussed.

DOI: 10.1061/9780784483589.028

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