Simulation of ice wedge polygon geomorphic transition, Prudhoe Bay, Alaska
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A numerical model is presented to simulate the changes in topography associated with ice wedge polygon transition from low-centered to high-centered form. The model applies a hillslope diffusion equation to an eroding polygon using a finite-difference approach. It is calibrated using a LiDAR dataset from a site where low-centered polygons exist within meters of high-centered polygons, whose formation appears to have been triggered by construction of the Dalton Highway. The loss of hydrologic storage and the transport of soil from the polygon center into polygon troughs during transition are estimated from model simulations. Optimized values of the hillslope diffusion coefficient suggest that multiple physical processes, including frost heave and continuous soil creep, may drive lateral soil transport at the site. The optimized parameters, furthermore, capture the decreasing influence of anthropogenic disturbances (in this case, the Dalton Highway) on polygon form at distances greater than 35 meters. Overall, a match between the topography of simulated and observed high-centered polygons confirms that the hillslope diffusion paradigm approximates much of the complexity of polygon transition. Future refinements to the model should include more process-based treatment of the mechanisms that drive soil transport and control rates of polygon erosion.