Geomorphology and InSAR-Tracked Surface Displacements in an Ice-Rich Yedoma Landscape

Abstract

Ice-ridge Yedoma terrain is susceptible to vertical surface displacements by thaw and refreeze of ground ice, and geomorphological processes of mass wasting, erosion and sedimentation. Here we explore the relation between a 3 year data set of InSAR measurements of vertical surface displacements during the thaw season, and geomorphological features in an area in the Indigirka Lowlands, Northeast Siberia. The geomorphology is presented in a geomorphological map, based on interpretation of high resolution visible spectrum satellite imagery, field surveys and available data from paleo-environmental research. The main landforms comprise overlapping drained thaw lake basins and lakes, erosion remnants of Late Pleistocene Yedoma deposits, and a floodplain of a high-sinuosity anastomosing river with ancient river terrace remnants. The spatial distribution of drained thaw lake basins and Yedoma erosion remnants in the study area and its surroundings is influenced by neotectonic movements. The 3 years of InSAR measurement include 2 years of high snowfall and extreme river flooding (2017–2018) and 1 year of modest snowfall, early spring and warm summer (2019). The magnitude of surface displacements varies among the years, and show considerable spatial variation. Distinct spatial clusters of displacement trajectories can be discerned, which relate to geomorphological processes and ground ice conditions. Strong subsidence occurred in particular in 2019. In the wet year of 2017, marked heave occurred at Yedoma plateau surfaces, likely by ice accumulation at the top of the permafrost driven by excess precipitation. The spatial variability of surface displacements is high. This is explored by statistical analysis, and is attributed to the interaction of various processes. Next to ground ice volume change, also sedimentation (peat, colluvial deposition) and shrinkage or swelling of soils with changing water content may have contributed. Tussock tundra areas covered by the extreme 2017 and 2018 spring floods show high subsidence rates and an increase of midsummer thaw depths. We hypothesize that increased flood heights along Siberian lowland rivers potentially induce deeper thaw and subsidence on floodplain margins, and also lowers the drainage thresholds of thaw lakes. Both mechanisms tend to increase floodplain area. This may increase CH4 emission from floodplains, but also may enhance carbon storage in floodplain sedimentary environments.

Towards a Monitoring Approach for Understanding Permafrost Degradation and Linked Subsidence in Arctic Peatlands

“…However, several years of data were needed to build a sufficient database in line with findings from temperate peatlands [48,49]. The surface motion across the peatlands were in the same range as those reported for degrading permafrost areas in Siberia, also using InSAR methods [35,37]. This suggests that the relatively low levels of ground motions reported from the InSAR at our sites are not site specific and that InSAR can detect ground motion resulting from permafrost degradation.…”

“…Repeated passes of airborne light detection and ranging (LiDAR) have been used to measure top-down permafrost thaw [33,34], but this approach, though highly detailed, is operationally limited to small spatial extents. The monitoring of larger spatial extents for the surface motion of permafrost thaw could be possible through the use of satellite Interferometric SAR (InSAR) methods [35][36][37][38][39][40], which have the added advantage of overcoming cloud cover that hampers optical satellite systems. SAR data from the Sentinel-1 satellite system, which has the advantage of providing open data, with a return rate of 6 to 12 days, can be processed into surface deformation products to a resolution of tens of metres [41] and thus has the potential for detecting surface motion resulting from permafrost degradation.…”

Tundra Browning in the Indigirka Lowlands (North‐Eastern Siberia) Explained by Drought, Floods and Small‐Scale Vegetation Shifts

“…High snow accumulation led to extensive floods throughout the Indigirka Lowlands in 2016–2018 and strong browning surrounding the Khroma and Indigirka rivers (Magnússon et al., 2021; Tei et al., 2020). Floods in 2017 and 2018 inundated the entire floodplain and parts of surrounding drained thaw lake basins (Van Huissteden et al., 2021; Magnússon & Heijmans, pers. obs.).…”

“…obs.). Potential mechanisms could be delayed onset of the growing season or erosional processes (Van Huissteden et al, 2021). Years with record high snowfall generally also showed lower than average rainfall in summer and higher than average winter temperatures (Figure S2 in Supporting Information S1), which may have additionally contributed to low NDVI.…”

Greening, browning, or drowning? : permafrost – vegetation – climate interactions in the Siberian lowland tundra

“…With anticipated increases in winter precipitation Selten 2014, IPCC 2021) and flood events (Shkolnik et al 2018), such periodic browning events will likely occur more frequently. Apart from floodplains, severe floods may reach low lying areas in surrounding drained thaw lake basins, which may be less adapted to periodic waterlogging and may potentially show more lasting impacts on permafrost (van Huissteden et al 2021), shrub growth and NDVI. Interestingly, negative impacts of extreme snowfall were not limited to flooded areas, as Landsat maxNDVI and shrub radial growth on high elevation landscape positions both showed negative responses to recent extreme snow accumulation (fig.…”