![]() Energetic high-water stands during ice break up encounter a delta whose channels are still frozen, which can result in ice jams and occasional flooding ( Rokaya et al., 2018b Rokaya et al., 2018a). The land- and bedfast ice influence channel morphology by protecting river bars from erosion and hindering sediment transport in winter ( McNamara and Kane, 2009) but also by intensifying erosion and sediment transport during the ice break-up in spring ( Walker and Hudson, 2003 Piliouras and Rowland, 2020). Secondly, river ice covers channels within Arctic deltas for most of the year, slowing down or even stopping the water flow within the channels. ![]() For catchments draining northward to the Arctic Ocean, meltwater begins to flow in the south and accumulates from the entire river watershed northward toward the river mouth as warming moves northward in spring (e.g., Woo, 1986 Walker, 1998). Understanding Arctic delta systems and their response to climate warming requires more detailed knowledge of the interactions between deltaic processes and the three components of the cryosphere: snow, river ice and permafrost.įirstly, Arctic rivers are subject to a nival discharge regime, in which most of the annual discharge volume derives from snow melt during the spring freshet. The observed increase of solid precipitation ( Prowse et al., 2011), earlier river ice break up and later freeze up ( Cooley and Pavelsky, 2016 Park et al., 2016 Brown et al., 2018), thinning of the river ice ( Prowse et al., 2011 Shiklomanov and Lammers, 2014 Arp et al., 2020 Yang et al., 2021), degradation of the permafrost within the river catchments ( Biskaborn et al., 2019), as well as the increase of water and heat energy discharge ( Ahmed et al., 2020 Park et al., 2020) in most of the Arctic rivers induce a multitude of interacting processes controlling the physical and ecological state of these regions and the adjacent coastal and offshore waters of the Arctic Ocean. In addition to the complex interactions between hydrological, sedimentological, and biological processes that occur in most river deltas, Arctic deltas are characterized over a long period by the cryosphere, which is strongly affected by amplified Arctic climate warming and subject to profound changes. Furthermore, our results provide viable information for the summer navigation for shallow-draught vessels. channels, presumably disconnected for winter water flow. Besides insight into sub-river thermal properties, our study shows the potential of remote sensing for identifying river channels with active sub-ice flow during winter vs. Our results show that the serpentine ice identified with both types of remote sensing spatially coincides with the location of thawed riverbed sediment observed with in situ geoelectrical measurements and as simulated with the thermal model. We use numerical modeling and geophysical field surveys to investigate the temperature field and sediment properties beneath the riverbed. The optical data is used to differentiate elevated floating ice from bedfast ice, which is flooded ice during the spring melt, while radar data is used to differentiate floating from bedfast ice during the winter months. ice, resting on top of the unfrozen water layer (floating or so-called serpentine ice) within the Arctic’s largest delta, the Lena River Delta. In this study, we use optical and radar remote sensing to map ice frozen to the riverbed (bedfast ice) vs. Thinning river ice and rising river water temperatures may affect the thermal state of permafrost beneath the riverbed, with consequences for delta hydrology, erosion, and sediment transport. 4Geography Department, Humboldt Universität zu Berlin, Berlin, GermanyĪrctic deltas and their river channels are characterized by three components of the cryosphere: snow, river ice, and permafrost, making them especially sensitive to ongoing climate change.3Melnikov Permafrost Institute, Siberian Branch of the Russian Academy of Sciences, Yakutsk, Russia.2Department of Geophysics, Institute of Earth Sciences, Saint-Petersburg State University, Saint-Petersburg, Russia.1Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI), Potsdam, Germany. ![]() Bennet Juhls 1*, Sofia Antonova 1, Michael Angelopoulos 1, Nikita Bobrov 2, Mikhail Grigoriev 3, Moritz Langer 1,4, Georgii Maksimov 3, Frederieke Miesner 1 and Pier Paul Overduin 1
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