Implications of climate variability and changing seasonal hydrology for subarctic riverbank erosion

Warmer climatic conditions have been associated with numerous hydrologic changes that may impact riverbank erosion in cold regions, but the net effect is not well understood. We used regression and correlation analyses to examine the relationships among subarctic riverbank erosion and seasonal hydrology, the impact of climate change and variability, and the societal implications. Geomorphic change (loss and gain of vegetated land) was mapped along several river reaches in the Yukon River Basin, Alaska, throughout 1984 and 2017 using Landsat satellite imagery. Annual erosion rates were estimated from these spatial data. At most study sites, erosion rates (km²/year) were either positively correlated (r = 0.68–0.84, p = 0.0085–0.061) with monthly mean discharge within the cold season or inversely correlated (r = − 0.74 – −0.62, p < 0.10) with river ice breakup date in the spring. These proximate controls on erosion, in turn, were influenced both by climate variability and long-term climatic change. We conclude that increased cold season discharge and earlier freshet that occurs under warmer conditions enhance riverbank erosion in most areas. Climate-related changes to fluvial dynamics may impact communities through effects on infrastructure, travel safety, channel navigability, fish and wildlife habitat, and access to subsistence resources.