QUANTIFYING THE EFFECTS OF RIVER SINUOSITY ON ICE-BANK INTERACTIONS AND EROSION

Rivers that freeze for part of the winter erode and transport significant portions of their annual load during the spring thaw, yet the erosive effect of mobile river ice’s interactions with river banks is not well understood. During the spring thaw, ice blocks impacting and dragging along river banks may contribute to bank erosion, destabilize river restoration, or cause damage to infrastructure. This research supports the understanding of how processes pertaining to ice flowing through rivers of varying sinuosities contributes to erosion using a lab-scale stream table, GIS, and Structure from Motion (SfM). To compare the relative locations of ice-bank interactions and bank erosion, a series of lab-scale, river erosion experiments were performed using paraffin wax to simulate river ice, recording locations where the wax hit or dragged on the banks. Erosional and depositional volumes were determined by differencing elevation models from before and after ice/wax addition during the final time-step of experiments. Results show that (1) more sinuous channels have a greater frequency of ice-bank interactions per channel length, (2) river ice more frequently interacts with the outer bends of meanders in comparison to inner bends and straights, (3) in unstable channels the locations of the most frequent ice-bank interactions don’t always correlate with the most erosive banks, and (4) in stable channels, erosional areas are mostly located in the areas with the most ice-bank interactions. These results suggest that mobile river ice is capable of contributing to river meandering and sediment entrainment through the mechanical abrasion of sediment from the outer banks of meander bends.