Arctic regions are responding rapidly to modern climate change, as high latitudes have warmed more than twice as fast as the global average. Among the changes in recent decades are thawing and degradation of permafrost, and hydrologic shifts that include earlier snowmelt and higher river discharge.
Zheng et al.  developed a heat-exchange model to investigate how changes in river flow affect permafrost within floodplains, and applied their model to the Kuparuk River, Alaska, where mean annual flow has increased by 35% since the 1970s and snowmelt floods now arrive earlier. Their results indicate that the changes to inundation extent and timing of river discharge cause floodplain permafrost to thaw more rapidly, as heat is transferred from the warmer floodwater down into the cooler subsurface. The model shows that the earlier arrival of spring flooding impacts permafrost warming more than a prolonged warm season would.
Accelerated degradation of permafrost due to more sustained floodwater inundation could enhance the release of old carbon, large quantities of which are currently stored in Arctic floodplains.
Citation: Zheng, L., Overeem, I., Wang, K., & Clow, G. D. . Changing Arctic river dynamics cause localized permafrost thaw. Journal of Geophysical Research: Earth Surface, 124. https://doi.org/10.1029/2019JF005060
—Amy East, Editor in Chief, JGR: Earth Surface