Ice and Permafrost Effects on Delta Morphology and Channel Dynamics

Arctic regions are changing rapidly as permafrost thaws and sea ice retreats. These changes directly affect Arctic river deltas, but how permafrost and ice alter delta hydrology and sediment transport are not well researched. This knowledge gap limits our ability to forecast how these systems will respond to continued warming. We adapt the reduced complexity model of delta morphodynamics DeltaRCM to investigate the influences of permafrost and landfast ice on delta morphology and channel dynamics. We find that ice cover and permafrost decrease channel mobility, increase shoreline roughness, and route and deposit more sediment offshore. Ice cover also enhances overbank deposition, increasing subaerial delta elevations. Our modeling suggests that permafrost and ice loss in a warming climate could lead to less overbank and offshore deposition and more dynamic and spatially distributed fluxes of water and sediment across Arctic river deltas.