A Process-Based Model for Arctic Coastal Erosion Driven by Thermodenudation and Thermoabrasion Combined and including Nearshore Morphodynamics

Abstract

Various models have recently been developed to describe Arctic coastal erosion. Current process-based models simulate multiple physical processes and combine them interactively to resemble the unique mechanism of Arctic coastal erosion. One limitation of such models is the difficulty of including hydrodynamic forces. The available coastal erosion models developed for warmer climates cannot be applied to Arctic coastal erosion, where permafrost is a significant environmental parameter. This paper explains a methodology that allows us to use the models designed for warmer climates to simulate Arctic coastal erosion. The open-source software XBeach is employed to simulate the waves, sediment transport and morphological changes. We developed different submodules for the processes unique to Arctic coasts, such as thawing–freezing, slumping, wave-cut niche, bluff failure, etc. The submodules are coupled with XBeach to enable concurrent simulation of the two mechanisms of Arctic coastal erosion, namely thermodenudation and thermoabrasion. Some of the model’s input parameters are calibrated using field measurements from the Arctic coast of Kara Sea, Russia. The model is then validated by another set of mutually exclusive field measurements under different morphological conditions from the study area. The sensitivity analysis of the model indicates that nearshore waves are an important driver of erosion, and the inclusion of nearshore hydrodynamics and sediment transport are essential for accurately modelling the erosion mechanism.