Permafrost hazard mapping in the discontinuous permafrost zone of Alaska

Abstract:

Permafrost degradation is expected to cause extensive damage to infrastructure across the Arctic and sub-Arctic in coming decades. This poses a significant hazard to communities and industry and is expected to result in significant economic impacts. Permafrost degradation can lead to ground collapse where excess ground ice is present and can lower the bearing capacity of soils leading to the failure of building foundations. Hazard maps for both the present and future can potentially assist communities in hazard mitigation and adaptation. Here we present two hazard maps for the Fairbanks North Star Borough (FNSB) for the present and for the year 2050. The FNSB has a population of ~ 100,000 people and is home to both state University, two major military bases, and supports the function of the trans Alaskan Pipeline. To establish a current hazard map for the FNSB we combined a suite of data sets to characterize both the distribution and cryolithological characteristics of permafrost across the Borough. Data sources included existing non-digitized permafrost maps, Department of Natural Resources well logs, Department of Transportation boring logs for road alignments, and an array of ground temperature station measurements from several entities including the U.S. Army Cold Regions Research and Engineering Laboratory, and numerous research groups from the University of Alaska Fairbanks. For the 2050 hazard mapping we employed a high-resolution ecotype-based numerical model of the temperature dynamics. Model parameters, such as thermal properties, were estimated using collected temperature measurements and were upscaled using 30-m resolution vegetation maps derived with the scope of the NASA Arctic Boreal Vulnerability Experiment (ABoVE) initiative. Temperature dynamics, talik development and the potential for thermokarst degradation is estimated for IPCC Representative Concentration Pathway scenarios 4.5 and 8.5.

Warming permafrost, ground subsidence, and development of taliks will have serious implications for ecosystems, human activities, and potential feedbacks to climate change. The developed permafrost characteristics maps are sought to provide guidance to homeowners and borough planners about the present and future permafrost conditions.