Lena Delta hydrology and geochemistry: long-term hydrological data and recent field observations

Fedorova, Irina; Chetverova, Antonina; Bolshiyanov, Dimitry Yu; Макаров, А. А.; Boike, Julia; Heim, Birgit; Morgenstern, Anne; Overduin, Paul; Wegner, Carolyn; Kashina, V.; Eulenburg, Antje; Dobrotina, E.; Сидорина, Инесса Евгеньевна

doi:10.5194/bg-12-345-2015

Cited by 81 publications

(74 citation statements)

References 27 publications

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“…Much of the Chukchi and Beaufort seas' coastlines are similarly ice-rich and can be expected to be subject to the same mechanisms of geomorphologic change in response to shifts in environmental drivers of coastal dynamics (Ping et al, 2011). Regionally, relevant shifts in the energy and water balances at the land-atmosphere interface (Boike et al, 2013), increases in Lena River discharge (Fedorova et al, 2015) and increases in the duration of open water and coastal erosion (Günther et al, 2015) have recently been observed, matching similar circumpolar observations (Barnhart et al, 2014).…”

Section: Study Areasupporting

confidence: 64%

Coastal dynamics and submarine permafrost in shallow water of the central Laptev Sea, East Siberia

et al. 2016

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Abstract. Coastal erosion and flooding transform terrestrial landscapes into marine environments. In the Arctic, these processes inundate terrestrial permafrost with seawater and create submarine permafrost. Permafrost begins to warm under marine conditions, which can destabilize the sea floor and may release greenhouse gases. We report on the transition of terrestrial to submarine permafrost at a site where the timing of inundation can be inferred from the rate of coastline retreat. On Muostakh Island in the central Laptev Sea, East Siberia, changes in annual coastline position have been measured for decades and vary highly spatially. We hypothesize that these rates are inversely related to the inclination of the upper surface of submarine ice-bonded permafrost (IBP) based on the consequent duration of inundation with increasing distance from the shoreline. We compared rapidly eroding and stable coastal sections of Muostakh Island and find permafrost-table inclinations, determined using direct current resistivity, of 1 and 5 %, respectively. Determinations of submarine IBP depth from a drilling transect in the early 1980s were compared to resistivity profiles from 2011. Based on borehole observations, the thickness of unfrozen sediment overlying the IBP increased from 0 to 14 m below sea level with increasing distance from the shoreline. The geoelectrical profiles showed thickening of the unfrozen sediment overlying ice-bonded permafrost over the 28 years since drilling took place. We use geoelectrical estimates of IBP depth to estimate permafrost degradation rates since inundation. Degradation rates decreased from over 0.4 m a −1 following inundation to around 0.1 m a −1 at the latest after 60 to 110 years and remained constant at this level as the duration of inundation increased to 250 years. We suggest that long-term rates are lower than these values, as the depth to the IBP increases and thermal and porewater solute concentration gradients over depth decrease. For the study region, recent increases in coastal erosion rate and changes in benthic temperature and salinity regimes are expected to affect the depth to submarine permafrost, leading to coastal regions with shallower IBP.

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Section: Study Areasupporting

confidence: 64%

Coastal dynamics and submarine permafrost in shallow water of the central Laptev Sea, East Siberia

et al. 2016

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“…The study site is located in a riverine environment without marine wave activity, about 10 km inland from the outer delta margins. The annual average water discharge of the Olenekskaya channel shows strong annual variations ranging from 700 to 1.500 m 3 /s [43] and open water conditions exist from June to October. The water levels during spring river ice break-up in late May to early June can reach up to 12 m above normal at this location but does not exceed the upper limit of the sand unit (Figure 1c).…”

Section: Study Areamentioning

confidence: 99%

Monitoring Inter- and Intra-Seasonal Dynamics of Rapidly Degrading Ice-Rich Permafrost Riverbanks in the Lena Delta with TerraSAR-X Time Series

et al. 2017

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Arctic warming is leading to substantial changes to permafrost including rapid degradation of ice and ice-rich coasts and riverbanks. In this study, we present and evaluate a high spatiotemporal resolution three-year time series of X-Band microwave satellite data from the TerraSAR-X (TSX) satellite to quantify cliff-top erosion (CTE) of an ice-rich permafrost riverbank in the central Lena Delta. We apply a threshold on TSX backscatter images and automatically extract cliff-top lines to derive intra-and inter-annual CTE. In order to examine the drivers of erosion we statistically compare CTE with climatic baseline data using linear mixed models and analysis of variance (ANOVA). Our evaluation of TSX-derived CTE against annual optical-derived CTE and seasonal in situ measurements showed good agreement between all three datasets. We observed continuous erosion from June to September in 2014 and 2015 with no significant seasonality across the thawing season. We found the highest net annual cliff-top erosion of 6.9 m in 2014, in accordance with above-average mean temperatures and thawing degree days as well as low precipitation. We found high net annual erosion and erosion variability in 2015 associated with moderate mean temperatures but above average precipitation. According to linear mixed models, climate parameters alone could not explain intra-seasonal erosional patterns and additional factors such as ground ice content likely drive the observed erosion. Finally, mean backscatter intensity on the cliff surface decreased from −5.29 to −6.69 dB from 2013 to 2015, respectively, likely resulting from changes in surface geometry and properties that could be connected to partial slope stabilization. Overall, we conclude that X-Band backscatter time series can successfully be used to complement optical remote sensing and in situ monitoring of rapid tundra permafrost erosion at riverbanks and coasts by reliably providing information about intra-seasonal dynamics.

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“…Despite such small-scale variability, the LRD can be classified in three main geomorphological units (Fig. 1), which have distinctly different characteristics regarding their surface and subsurface properties, such as ground ice contents, thermokarst features and vegetation cover (Morgenstern et al, 2013;Fedorova et al, 2015).…”

Section: The Lena River Deltamentioning

confidence: 99%

Transient modeling of the ground thermal conditions using satellite data in the Lena River delta, Siberia

et al. 2017

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Abstract. Permafrost is a sensitive element of the cryosphere, but operational monitoring of the ground thermal conditions on large spatial scales is still lacking. Here, we demonstrate a remote-sensing-based scheme that is capable of estimating the transient evolution of ground temperatures and active layer thickness by means of the ground thermal model CryoGrid 2. The scheme is applied to an area of approximately 16 000 km 2 in the Lena River delta (LRD) in NE Siberia for a period of 14 years. The forcing data sets at 1 km spatial and weekly temporal resolution are synthesized from satellite products and fields of meteorological variables from the ERA-Interim reanalysis. To assign spatially distributed ground thermal properties, a stratigraphic classification based on geomorphological observations and mapping is constructed, which accounts for the large-scale patterns of sediment types, ground ice and surface properties in the Lena River delta.A comparison of the model forcing to in situ measurements on Samoylov Island in the southern part of the study area yields an acceptable agreement for the purpose of ground thermal modeling, for surface temperature, snow depth, and timing of the onset and termination of the winter snow cover. The model results are compared to observations of ground temperatures and thaw depths at nine sites in the Lena River delta, suggesting that thaw depths are in most cases reproduced to within 0.1 m or less and multi-year averages of ground temperatures within 1-2 • C. Comparison of monthly average temperatures at depths of 2-3 m in five boreholes yielded an RMSE of 1

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Lena Delta hydrology and geochemistry: long-term hydrological data and recent field observations

Cited by 81 publications

References 27 publications

Coastal dynamics and submarine permafrost in shallow water of the central Laptev Sea, East Siberia

Coastal dynamics and submarine permafrost in shallow water of the central Laptev Sea, East Siberia

Monitoring Inter- and Intra-Seasonal Dynamics of Rapidly Degrading Ice-Rich Permafrost Riverbanks in the Lena Delta with TerraSAR-X Time Series

Transient modeling of the ground thermal conditions using satellite data in the Lena River delta, Siberia

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