Arctic-capable coastal geomorphic change modeling with application to Barter Island, Alaska

An Arctic-capable coastal geomorphic change model was developed based on the open-source coastal geomorphic change model, Xbeach. In this paper, we describe an approach to make the 2D version of the Xbeach model Artic-capable by adding a heat transfer module which computes the temperature and the phase of the sediment and water (frozen or unfrozen). During execution of the overall model, the conventional Xbeach model and the heat transfer module alternate, according to a predetermined schedule. First, assuming the water is unfrozen, the conventional Xbeach model executes the hydrodynamic and sediment transport routines determining the potential sediment and geomorphic change. Then, the heat transfer module is executed taking into account output from the hydrodynamic calculations and accounting for heat energy flows across the boundaries. If the sediment is deemed frozen in a given time step during the model execution, the sediment is treated as a non-erodible surface - a feature already built into the conventional Xbeach model. The Arctic-capable Xbeach model is used to simulate geomorphic change on Barter Island, Alaska, where bluff retreat and coastal erosion typically results from thawing and slumping of bluff-face material onto the beach face followed by offshore transport of deposited materials during storms.