Bridging Arctic pathways: integrating hydrology, geomorphology and remote sensing in the North

Dissertation (Ph.D.) University of Alaska Fairbanks, 2015This work presents improved approaches for integrating patterns and processes within hydrology, geomorphology, ecology and permafrost on Arctic landscapes. Emphasis was placed on addressing fundamental interdisciplinary questions using robust, repeatable methods. Water tracks were examined in the foothills of the Brooks Range to ascertain their role within the range of features that transport water in Arctic regions. Classes of water tracks were developed using multiple factor analysis based on their geomorphic, soil and vegetation characteristics. These classes were validated to verify that they were repeatable. Water tracks represented a broad spectrum of patterns and processes primarily driven by surficial geology. This research demonstrated a new approach to better understanding regional hydrological patterns. The locations of the water track classes were mapped using a combination method where intermediate processing of spectral classifications, texture and topography were fed into random forests to identify the water track classes. Overall, the water track classes were best visualized where they were the most discrete from the background landscape in terms of both shape and content. Issues with overlapping and imbalances between water track classes were the biggest challenges. Resolving the spatial locations of different water tracks represents a significant step forward for understanding periglacial landscape dynamics. Leaf area index (LAI) calculations using the gap-method were optimized using normalized difference vegetation index (NDVI) as input for both WorldView-2 and Landsat-7 imagery. The study design used groups to separate the effects of surficial drainage networks and the relative magnitude of change in NDVI over time. LAI values were higher for the WorldView-2 data and for each sensor and group combination the distribution of LAI values was unique. This study indicated that there are tradeoffs between increased spatial resolution and the ability to differentiate landscape features versus the increase in variability when using NDVI for LAI calculations. The application of geophysical methods for permafrost characterization in Arctic road design and engineering was explored for a range of conditions including gravel river bars, burned tussock tundra and ice-wedge polygons. Interpretations were based on a combination of Directcurrent resistivity - electrical resistivity tomography (DCR-ERT), cryostratigraphic information via boreholes and geospatial (aerial photographs & digital elevation models) data. The resistivity data indicated the presence/absence of permafrost; location and depth of massive ground ice; and in some conditions changes in ice content. The placement of the boreholes strongly influenced how geophysical data can be interpreted for permafrost conditions and should be carefully considered during data collection strategies

Modeling discharge using HBV in the Imnavait Basin, North Slope, Alaska

Thesis (M.S.) University of Alaska Fairbanks, 2009"The Arctic fresh water hydrological cycle is dominated by the melting of the seasonal snow cover and scattered precipitation events during the summer months. Predicting and characterizing potential hydrological response is an important component for engineering infrastructure for the appropriate climatic conditions. A semi-distributed Swedish conceptual model, HBV, has been applied to the Imnavait basin, located in the headwaters of the Kuparuk River on the North Slope of Alaska, to examine runoff during spring and summer months. The methodology began by analyzing the long-term climatic records of the Imnavait basin from 1986 to present. Initial calibration work was completed in both spring and summer periods using the Monte Carlo technique; one set from each period was selected and used in the complete version of HBV. The model was recalibrated from 1988 to 2002 and then validated against the 2003 to 2008 time frame. The overall model performance was adequate for engineering purposes, with the best results when the input precipitation was accurate in terms of timing and magnitude. Differences between observed and modeled results included the impact of snow-damming and evaporation during the spring, while convective storms and melting of basal ice in the active layer distorted the summer period"--Leaf iiiAlaska Department of Transportation and Public Facilities, Alaskan Department of Natural Resources, National Science Foundation, Office of Polar Programs (OPP-0335941

Geophysical Applications for Arctic/Subarctic Transportation Planning

This report describes a series of geophysical surveys conducted in conjunction with geotechnical investigations carried out by the Alaska Department of Transportation and Public Facilities. The purpose of the study was to evaluate the value of and potential uses for data collected via geophysical techniques with respect to ongoing investigations related to linear infrastructure. One or more techniques, including direct-current resistivity, capacitive-coupled resistivity, and ground-penetrating radar, were evaluated at sites in continuous and discontinuous permafrost zones. Results revealed that resistivity techniques adequately differentiate between frozen and unfrozen ground, and in some instances, were able to identify individual ice wedges in a frozen heterogeneous matrix. Capacitive-coupled resistivity was found to be extremely promising due to its relative mobility as compared with direct-current resistivity. Ground-penetrating radar was shown to be useful for evaluating the factors leading to subsidence in an existing road. Taken as a whole, the study results indicate that supplemental geophysical surveys may add to the quality of a geotechnical investigation by helping to optimize the placement of boreholes. Moreover, such surveys may reduce the overall investigation costs by reducing the number of boreholes required to characterize the subsurface

ROADS AND AIRFIELDS CONSTRUCTED ON PERMAFROST: A Synthesis of Practice

This synthesis provides the practicing engineer with the basic knowledge required to build roadway and airports over permafrost terrain. Topic covered include an overview of permafrost, geotechnical investigations, slope stability, impacts of climate, and adaptation strategies during the design, construction and maintenance phases. The purpose of the synthesis is not to provide a comprehensive body of knowledge or to provide a complete how‐to manual. Rather the synthesis provides a working knowledge for those working in permafrost regions such that the practicing engineer will be able to work with subject matter experts to obtain the desired project outcomes

Risk Evaluation for Permafrost-Related Threats:Methods of Risk Estimation and Sources of Information

In our evaluation of permafrost-related threats that affect Alaska communities, we have focused on threats associated with permafrost degradation and thawing ground ice, which can result in significant thaw settlement and cause unacceptable damage to engineered structures. Our evaluation system for permafrost-related threats includes risks of general permafrost degradation and thaw settlement (general and differential). We have evaluated permafrost-related threats for 187 Alaska villages based on available information including scientific publications, maps, satellite imagery and aerial photographs, geotechnical reports, personal communication, community plans and reports, and other sources. Evaluation was based on five criteria: permafrost (PF) occurrence; PF temperature; thaw susceptibility of frozen soils (expected thaw settlement in case of permafrost degradation); massive ice occurrence; and existing PF-related problems. For each of these categories, four risk levels (ranks) were considered. The total (cumulative) risk level was based on the rating score (sum of individual ranks for all five categories). Based on the rating score, each village was assigned one of four risk levels: 0 – no permafrost; 5–8 – low risk level; 9–11 – medium risk level; 12–15 – high risk level. A vulnerability score was developed for each community allowing the identification of communities with the highest risk of damage due to thawing permafrost. Most of communities with the high-risk level (22 villages of 34) are underlain by continuous permafrost, while the low risk level is typical mainly of communities underlain by predominantly unfrozen soils/bedrocks (33 villages of 46), and no high risk levels were detected for this group of villages. Medium risk level is typical mainly of communities underlain by discontinuous and sporadic permafrost (35 villages of 47); some villages of this group are characterized by high and low risk levels (12 and 9, correspondingly). Occurrence of massive-ice bodies (mostly ice wedges) is typical exclusively of communities underlain by continuous and discontinuous permafrost (23 and 20 villages, correspondingly). We presume that at least 20 communities may have extremely ice-rich yedoma deposits with large ice wedges either within villages or in their vicinity. Permafrost conditions in Alaskan communities are very diverse, and in many cases they are extremely variable even within the same community. Detailed studies are required for more precise evaluation of potential permafrost-related threats associated with permafrost degradation and/or thawing of ground ice.The Denali Commissio

Consequences of permafrost degradation for Arctic infrastructure - Bridging the model gap between regional and engineering scales

Infrastructure built on perennially frozen ice-rich ground relies heavily on thermally stable subsurface conditions. Climate-warming-induced deepening of ground thaw puts such infrastructure at risk of failure. For better assessing the risk of large-scale future damage to Arctic infrastructure, improved strategies for model-based approaches are urgently needed. We used the laterally coupled 1D heat conduction model CryoGrid3 to simulate permafrost degradation affected by linear infrastructure. We present a case study of a gravel road built on continuous permafrost (Dalton highway, Alaska) and forced our model under historical and strong future warming conditions (following the RCP8.5 scenario). As expected, the presence of a gravel road in the model leads to higher net heat flux entering the ground compared to a reference run without infrastructure and thus a higher rate of thaw. Further, our results suggest that road failure is likely a consequence of lateral destabilisation due to talik formation in the ground beside the road rather than a direct consequence of a top-down thawing and deepening of the active layer below the road centre. In line with previous studies, we identify enhanced snow accumulation and ponding (both a consequence of infrastructure presence) as key factors for increased soil temperatures and road degradation. Using differing horizontal model resolutions we show that it is possible to capture these key factors and their impact on thawing dynamics with a low number of lateral model units, underlining the potential of our model approach for use in pan-Arctic risk assessments. Our results suggest a general two-phase behaviour of permafrost degradation: an initial phase of slow and gradual thaw, followed by a strong increase in thawing rates after the exceedance of a critical ground warming. The timing of this transition and the magnitude of thaw rate acceleration differ strongly between undisturbed tundra and infrastructure-affected permafrost ground. Our model results suggest that current model-based approaches which do not explicitly take into account infrastructure in their designs are likely to strongly underestimate the timing of future Arctic infrastructure failure. By using a laterally coupled 1D model to simulate linear infrastructure, we infer results in line with outcomes from more complex 2D and 3D models, but our model's computational efficiency allows us to account for long-term climate change impacts on infrastructure from permafrost degradation. Our model simulations underline that it is crucial to consider climate warming when planning and constructing infrastructure on permafrost as a transition from a stable to a highly unstable state can well occur within the service lifetime (about 30 years) of such a construction. Such a transition can even be triggered in the coming decade by climate change for infrastructure built on high northern latitude continuous permafrost that displays cold and relatively stable conditions today.publishedVersio

Modelling consequences of permafrost degradation for Arctic infrastructure and related risks to the environment and society

The fate of infrastructure in the Arctic is heavily depending on the stability of frozen ground which it is built on. Climate change and consequent degradation of permafrost will negatively affect various infrastructure types and can cause ultimate failure. Comprehensive pan-Arctic assessments are urgently needed to better quantify environmental, economic and societal risks and to help adaptation planning. The use of physical models can be a powerful tool for risk evaluation, but modelling challenges remain with respect to resolving construction details at infrastructure scales together with decadal-scale climate change impacts. Here we used the dynamic permafrost land-surface model CryoGrid3 to capture both - the effects from the interaction of small-scale infrastructure with permafrost and large-scale climate change effects evolving in the 21century under an extensive warming scenario. We discuss how infrastructure can affect ground temperatures, and how climate change increases the risk of future infrastructure failure. We modelled two exemplary cases of permafrost-affected infrastructure: a gravel road on continuous permafrost at Prudhoe Bay (Alaska), and the case of a diesel tank facility at Norilsk (Siberia) placed on permafrost already subject to degradation under present day climate. We use the latter example to discuss environmental risks from contamination of hazardous legacy waste stored on and in permafrostand discuss the urgency for near-term policy strategies

Modelling consequences of permafrost degradation for Arctic infrastructure – a case study of the Dalton highway

The fate of infrastructure in the Arctic and in high altitude regions is heavily depending on the stability of frozen ground which it is built on. Climate change and consequent degradation of permafrost will negatively affect various infrastructure types and can cause ultimate failure. Comprehensive pan-Arctic assessments are urgently needed to better quantify environmental, economic and societal risks and to help adaptation planning. The use of physical models can be a powerful tool for risk evaluation, but modelling challenges remain with respect to resolving construction details at infrastructure scales together with decadal-scale climate change impacts. Here we used the dynamic permafrost land-surface model CryoGrid3 (including a soil subsidence module) to capture both - the effects from the interaction of small-scale infrastructure with permafrost and large-scale climate change effects evolving in the 21st century under an extensive climate warming scenario. We discuss how infrastructure can affect ground temperatures, and how climate change increases the risk of future infrastructure failure. As an exemplary case of permafrost-affected infrastructure failure, we modelled a gravel road on continuous permafrost at Prudhoe Bay (Alaska). We investigate the timing of infrastructure failure from soil subsidence in dependence of assumed embankment thickness and depth of excess ice in the ground

Consequences of permafrost degradation for Arctic infrastructure - Bridging the model gap between regional and engineering scales

Infrastructure built on perennially frozen ice-rich ground relies heavily on thermally stable subsurface conditions. Climate-warming-induced deepening of ground thaw puts such infrastructure at risk of failure. For better assessing the risk of large-scale future damage to Arctic infrastructure, improved strategies for model-based approaches are urgently needed. We used the laterally coupled 1D heat conduction model CryoGrid3 to simulate permafrost degradation affected by linear infrastructure. We present a case study of a gravel road built on continuous permafrost (Dalton highway, Alaska) and forced our model under historical and strong future warming conditions (following the RCP8.5 scenario). As expected, the presence of a gravel road in the model leads to higher net heat flux entering the ground compared to a reference run without infrastructure and thus a higher rate of thaw. Further, our results suggest that road failure is likely a consequence of lateral destabilisation due to talik formation in the ground beside the road rather than a direct consequence of a top-down thawing and deepening of the active layer below the road centre. In line with previous studies, we identify enhanced snow accumulation and ponding (both a consequence of infrastructure presence) as key factors for increased soil temperatures and road degradation. Using differing horizontal model resolutions we show that it is possible to capture these key factors and their impact on thawing dynamics with a low number of lateral model units, underlining the potential of our model approach for use in pan-Arctic risk assessments. Our results suggest a general two-phase behaviour of permafrost degradation: an initial phase of slow and gradual thaw, followed by a strong increase in thawing rates after the exceedance of a critical ground warming. The timing of this transition and the magnitude of thaw rate acceleration differ strongly between undisturbed tundra and infrastructure-affected permafrost ground. Our model results suggest that current model-based approaches which do not explicitly take into account infrastructure in their designs are likely to strongly underestimate the timing of future Arctic infrastructure failure. By using a laterally coupled 1D model to simulate linear infrastructure, we infer results in line with outcomes from more complex 2D and 3D models, but our model's computational efficiency allows us to account for long-term climate change impacts on infrastructure from permafrost degradation. Our model simulations underline that it is crucial to consider climate warming when planning and constructing infrastructure on permafrost as a transition from a stable to a highly unstable state can well occur within the service lifetime (about 30 years) of such a construction. Such a transition can even be triggered in the coming decade by climate change for infrastructure built on high northern latitude continuous permafrost that displays cold and relatively stable conditions today

The Expanding Footprint of Rapid Arctic Change

Arctic land ice is melting, sea ice is decreasing, and permafrost is thawing. Changes in these Arctic elements are interconnected, and most interactions accelerate the rate of change. The changes affect infrastructure, economics, and cultures of people inside and outside of the Arctic, including in temperate and tropical regions, through sea level rise, worsening storm and hurricane impacts, and enhanced warming. Coastal communities worldwide are already experiencing more regular flooding, drinking water contamination, and coastal erosion. We describe and summarize the nature of change for Arctic permafrost, land ice, and sea ice, and its influences on lower latitudes, particularly the United States. We emphasize that impacts will worsen in the future unless individuals, businesses, communities, and policy makers proactively engage in mitigation and adaptation activities to reduce the effects of Arctic changes and safeguard people and society.Key PointsRapid changes in the Arctic physical environment have substantial impacts in low and midlatitudesLoss of sea ice, land ice, and permafrost is accelerating, and these losses are further exacerbating climate changeEffects of Arctic change include rising sea level, increased coastal erosion, greater storm impacts, and ocean and atmospheric warmingPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149352/1/eft2525.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149352/2/eft2525_am.pd