Sediment Entrainment and Slump Blocks Limit Permafrost Riverbank Erosion

Climatic warming and permafrost thaw are predicted to increase Arctic riverbank erosion, threatening communities accelerating sediment, carbon nutrient cycling between rivers floodplains. Existing theory assumes that pore-ice sets erosion rates, but overpredicts observed rates by orders of magnitude. Here, we developed a simple model predicts more modest due sediment-entrainment limitation armoring slump blocks. Results show during times thaw-limited the river rapidly erodes undercuts its banks, consistent with previous work. However, overhanging banks generate blocks must erode sediment entrainment. Sediment entrainment can limit bank block producing seasonally averaged observations. Importantly, entrainment-limited does not depend on water temperature, indicating decadal may be less sensitive than previously.