128-6 Arctic River Morphodynamics in a Changing Environment

Abstract:

Arctic rivers are increasingly attracting global attention as rapid changes in climate, ecosystems, and land cover reshape these high-latitude environments. Through the delivery of significant water, sediment, and nutrients, Arctic rivers both respond to and influence regional and global environmental change. However, their remote locations and the lack of sufficient gauge station constrain our ability to predict how rivers evolve under intensified permafrost thaw, extreme weather, and direct human modifications. To address this, this work characterizes the morphological characteristics and dynamics of major rivers in Alaska, the Canadian Arctic, and Siberia over multi-decadal timescales. Specifically, we processed sequential satellite imagery to quantify channel migration, bank erosion and accretion, and assess spatial variability of channel morphodynamics. We demonstrate that all rivers showed stable, dominant vegetated multi-channel patterns, with considerable width variability among individual channel threads. The observed channel change reflects two competing processes: increased permafrost thaw promotes bank erosion, while eroded sediments redeposit along downstream river sections, causing deposition and island formation and/or expansion. These rivers showed positive correlations between anabranching intensity and channel change, along with a relationship between anabranching intensity and channel stability. As remote-sensing missions such as SWOT continue to improve spatial coverage and data accuracy for hydrologic monitoring of Arctic rivers, our work provides a geomorphic foundation for data integration and systematic understanding of these high-latitude environments.

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