Physics-based Simulation Can Facilitate Hypothesis Testing for
Increasingly Dynamic Coastal Permafrost Systems
Abstract
Declining sea ice in the Arctic Ocean is exposing its coasts to more
frequent and intense forms of wave energy and storm surge. As a result,
erosion rates along some stretches of coastline in the Alaskan Arctic
have doubled since the middle of the 20th century and
now rank among the highest in the world. People concentrated near the
coast are being heavily impacted by erosion, with some facing
relocation. Coastal erosion is projected to increase the cost of
maintaining infrastructure by billions of dollars in the coming decades.
The financial impact of enhanced erosion will likely be further
exacerbated by emerging geopolitical pressures, including the discovery
of natural resources, opening of new shipping routes, and construction
of support facilities in the Arctic. Scientific knowledge and
engineering tools for predicting coastal erosion and guiding land-use
decision are not well-suited for the ice-bonded bluffs of the Alaskan
Arctic. Investigation of the oceanographic, thermal, and mechanical
processes that are relevant to permafrost bluff failure along Arctic
coastlines is thus needed. We introduce a geomechanical simulation
framework, informed by field observation and laboratory testing, that
focuses on the impact of bluff geometry and material variability on
permafrost bluff stress states associated with a 9-km stretch of Alaskan
Arctic coastline fronting the Beaufort Sea that is prone to
toppling-mode block failure. Our approach is advantageous in that it is
based on measurable physical properties (e.g., the bluff geometry,
permafrost bulk density, Young’s Modulus, and Poisson’s Ratio) and does
not require the potential failure to be defined a priori, but rather,
the failure area can be interpreted from the multidimensional patterns
of stress produced by the model. Our findings highlight how (1) block
failure characteristics could be tied to variations in the intensity and
duration of the storm energy that intersects the coastline and (2) how
deformation processes that create non-uniform patterns of displacement
may play a role in localizing block failure. We propose that this kind
of physics-based simulation approach can facilitate hypothesis testing
regarding the prediction of decadal-scale erosion rates for increasingly
dynamic coastal permafrost systems.