Taliks, cryopegs, and permafrost dynamics related to channel migration, Colville River Delta, Alaska

Abstract

Talik and cryopeg development related to channel migration has been observed in arctic deltas, but our knowledge on the configuration, properties, and rate of freezeback has remained limited. Along a main channel of the Colville River Delta (Alaska), we integrated subsurface data from 79 boreholes with a remote sensing analysis to measure channel changes in 1948-2013. We found that closed taliks occurred under the active channel and extended into intrapermafrost cryopeg layers under the riverbed/riverbar and active floodplain. Cryopegs as isolated small pockets were also identified at depths in older terrain units. In the study corridor, we estimated that the likelihood of talik and cryopeg occurrence was predominantly (42.2% of area) low, yet a high likelihood was also identified (27.0% of area). Permafrost growth occurred at a rapid rate in the land exposed following channel migration, likely due to the low and delayed release of latent heat as the freezing front progresses downward in the coarse-grained soils of increasing salinity but decreasing temperatures. As the deposits keep cooling, ground ice will continue forming therefore increasing furthermore the salinity of the remaining unfrozen soil pore-water and likely prevent the complete freezeback of the cryopegs developed in relation to channel migration. K E Y W O R D Scryopeg, epigenetic permafrost, landscape, salinity, talik

A conceptual model for talik dynamics and icing formation in a river floodplain in the continuous permafrost zone at Salluit, Nunavik (Quebec), Canada

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Serpentine (Floating) Ice Channels and their Interaction with Riverbed Permafrost in the Lena River Delta, Russia

“…The longterm stability (longer than centennial) of a deep channel's position determines the location and size of a sub-river talik. Migrating or meandering river channels can expose preexisting taliks to the atmosphere, causing their refreezing and formation of new permafrost, and in the case of saline sediment, even cryopegs (Stephani et al, 2020). Thermal conditions beneath Arctic river channels, sandbars, intermittent channels and delta deposits and their impact on subsurface water flow have rarely been mapped.…”

Arctic riparian shrub expansion indicates a shift from streams gaining water to those that lose flow

“…Permafrost temperatures are warming 17 and cold, ice-rich near-surface permafrost is degrading 18,19 . Large rivers draining to the Arctic Ocean, which are underlain by taliks in the continuous permafrost zone 20 , have shown an increased winter discharge 21,22 , indicating an increased groundwater contribution. Nutrient export from Arctic waterways of all sizes has also increased 23,24 .…”