The study presents a semi-authomated model of bathymetry derivation from various satellite imageries (Pleiades, PlanetScope, and Sentinel 2-A) with different spatial resolutions, for two islands of the south-eastern Crete coast (Chrisi and Koufonisi) whose marine cultural heritage attributes remain undocumented.The workflow of the model is based on the empirical, band ratio approach and carried out within ESRI's ArcMap application.The highest accuracy that was achieved was an RMSE of 1.1 m for the bathymetry model from the PlanetScope image for Chrisi island.A low level of turbidity (low NDTI), high amount and reliability of depth training points, specific spectral characteristic (such as narrower bandwidths) and high spatial resolution provide a more precise bathymetry model for the studied islands.The resultsdemonstrate a time-efficient and geographically broad investigatory technique having the potential to form an initial step in the identification and hazard management of coastal cultural heritage sites.

The retreat rates of Arctic coasts have increased in recent decades at many sites, and an essential part of coasts considered accumulative before have turned erosional due to global climate changes and construction in the coastal zone. In this paper, we study a 7 km long coastal section of the western Gydan Peninsula in a new construction area. Based on the interpretation of multi-temporal satellite imagery, we assessed coastal dynamics in distinct periods from 1972 to 2020. We analyzed the geological structure of the coast as well as changes in hydrometeorological parameters with time, and considering the human impact, we proposed the main drivers of spatial and temporal variations of coastal dynamics. The studied low-lying sandy accumulative marine terrace was more or less stable in the period before construction (1972–2014). However, with the area’s development, the coast dynamics changed drastically: in 2014–2017, three-quarters of the studied area experienced retreat, and the average retreat rate amounted to 5.8 m/yr, up to 28.5 m/yr near the construction sites. We relate this coastal erosion intensification to human impact combined with the growth of hydrometeorological forcing. Although coastal erosion slowed down after 2017, the retreat trend remained. In the coming years, with Arctic climate warming, erosion of the studied coast will continue.

In recent decades, acceleration of coastal erosion has been observed at many key sites of the Arctic region. Coastal dynamics of both erosional and accretional stretches at Kharasavey, Kara Sea, was studied using multi-temporal remote sensing data covering the period from 1964 to 2022. Cross-proxy analyses of the interplay between coastal dynamics and regional (wave and thermal action) and local (geomorphic and lithological features; technogenic impact) drivers were supported by cluster analysis and wind–wave modelling via the Popov–Sovershaev method and WaveWatch III. Ice-rich permafrost bluffs and accretional sandy beaches exhibited a tendency towards persistent erosion (−1.03 m/yr and −0.42 m/yr, respectively). Shoreline progradation occurred locally near Cape Burunniy (6% of the accretional stretch) and may be due to sediment flux reversals responding to sea-ice decline. Although the mean rates of erosion were decreasing at a decadal scale, cluster analysis captured a slight increase in the retreat for 71% of the erosional stretch, which is apparently related to the forcing of wind–wave and thermal energy. Erosional hotspots (up to −7.9 m/yr) occurred mainly in the alignment of Cape Kharasavey and were predominantly caused by direct human impact. The presented study highlights the non-linear interaction of the Arctic coastal change and environmental drivers that require further upscaling of the applied models and remote sensing data.

About half of the Russian Arctic coastline consists of ice-rich permafrost deposits. The dynamic response of this coastal type is forced mainly by the change of natural environment caused by the development of global warming. Rising temperatures are altering the arctic coastline and much larger changes are projected to occur during this century as a result of reduced sea ice, thawing permafrost. Less extensive sea ice creates more open water, allowing stronger wave generation by winds, thus increasing wave-induced erosion along Arctic coast. Technogenic impact can also influence the rates of their erosion, causing rapid retreat. For key areas on the coasts of the Russian Arctic Seas, connections between climate change, human activity and coastal erosion have been analyzed.

Studies of Arctic coasts are of great importance given their active dynamics with the tendency to retreat, especially in the last decades under the conditions of global climate warming and enhanced human impact.Here, we present the results of the first surveys of the Kara Sea coasts with use of such new technique as unmanned aerial vehicles (UAVs).Land surveys using DJI Phantom 4 PRO drone were conducted at two key sites: the Yamal coast of Baydaratskaya Bay in the area of the Bovanenkovo-Ukhta gas pipeline crossing (western Kara Sea) in 2018, and the western coast of Taymyr peninsula in the area of Dikson settlement, Lemberova Bay (eastern Kara Sea) in 2019.The imagery and DEMs built based on the UAV survey data were compared to earlier satellite imagery and ArcticDEMs that allowed estimation of coastal dynamics for several periods.Since the 1960s, coasts of the key areas had relatively slow retreat (0.4 m/yr for the Yamal area and 0.1 m/yr for the Taymyr area) compared to other sites of the Kara Sea and the Arctic in general.At the same time, there were high erosion rates at separate segments in certain periods: they reached 2 m/yr at erosional coastal segments with ice wedge outcrops, and up to 10 m/yr at low accumulative coasts in the area of gas facilities in the period of their construction.

Coastal erosion in the Arctic has numerous internal and external environmental drivers. Internal drivers include sediment composition, permafrost properties and exposure which contribute to its spatial variability, while changing hydrometeorological conditions act as external drivers and determine the temporal evolution of shoreline retreat. To reveal the relative role of these factors, we investigated patterns of coastal dynamics in an enclosed bay in the southwestern Kara Sea, Russia, namely the Gulf of Kruzenstern, which is protected from open-sea waves by the Sharapovy Koshki Islands. Using multitemporal satellite imagery, we calculated decadal-scale retreat rates for erosional segments of the coastal plain from 1964 to 2019. In the field, we studied and described Quaternary sediments and massive ground-ice beds outcropping in the coastal bluffs. Using data from regional hydrometeorological stations and climate reanalysis (ERA), we estimated changes in the air thawing index, sea ice-free period duration, wind-wave energy and total hydrometeorological stress for the Gulf of Kruzenstern, and compared it to Kharasavey and Marre-Sale open-sea segments north and south of the gulf to understand how the hydrometeorological forcing changes in an enclosed bay. The calculated average shoreline retreat rates along the Gulf in 1964–2010 were 0.5 ± 0.2 m yr−1; the highest erosion of up to 1.7 ± 0.2 m yr−1 was typical for segments containing outcrops of massive ground-ice beds and facing to the northwest. These retreat rates, driven by intensive thermal denudation, are comparable to long-term rates measured along open-sea sites known from literature. As a result of recent air temperature and sea ice-free period increases, average erosion rates rose to 0.9 ± 0.7 m yr−1 in 2010–2019, with extremes of up to 2.4 ± 0.7 m yr−1. The increased mean decadal-scale erosion rates were also associated with higher spatial variability in erosion patterns. Analysis of the air thawing index, wave energy potential and their total effect showed that inside the Gulf of Kruzenstern, 85% of coastal erosion is attributable to thermal denudation associated with the air thawing index, if we suppose that at open-sea locations, the input of wave energy and air thawing index is equal. Our findings highlight the importance of permafrost degradation and thermal denudation on increases in ice-rich permafrost bluff erosion in the Arctic.

Электронный атлас «абразионной и ледово-экзарационной опасности прибрежно-шельфовой зоны Российской Арктики», созданный при поддержке Российского научного фонда, размещен в открытом доступе на платформе arcticcoast.ru. Атлас включает в себя серию обзорных и региональных карт, аналитических и фотоматериалов, наглядно иллюстрирующих распространение в Российской Арктике процессов, которые наибольшую опасность при строительстве инженерных сооружений в прибрежно-шельфовой зоне замерзающего моря: абразии и ледовой экзарации. Атлас может быть полезен широкому кругу специалистов, ученых и студентов, занимающихся вопросами освоения побережья и шельфа арктических морей России.

ABSTRACT Belova, N.G.; Novikova, A.V.; Günther, F., and Shabanova, N.N., 2020. Spatiotemporal variability of coastal retreat rates at Western Yamal Peninsula, Russia, based on remotely sensed data. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 367–371. Coconut Creek (Florida), ISSN 0749-0208. The work aims at estimating coastal retreat at Western Yamal from 1972 to 2016, when significant climate change occurred in the Arctic. One fourth of the Kara Sea coasts are collapsing cliffs composed of permafrost, i.e. thermoabrasional coasts. Although these coasts are bounded by sea ice for most of the year, they retreat with rates comparable to those of temperate latitudes, but only during the short ice-free period. Permafrost cliffs are not only eroded by waves; they also get destroyed by melting of the ground ice bounding the sediments (thermo-denudation). Arctic coasts are sensitive to climate change, as rising summer air temperatures lead to deeper thawing of frozen sediments, and longer ice-free periods extend the time of the wave impact on the coast. At Western Yamal, in the area of Kharasavey gas condensate field, the average long-term coastal retreat rate is 1.3 m/yr (1972-2016) for 5.9 km of the coastline, reaching mean annual rates of 3 m/yr in some areas. The greatest retreat rates are typical for coastal segments composed of permafrost with high ice content. Based on the analysis of multitemporal aerial and space images, the coastal retreat rates for four time periods between 1972 and 2016 were estimated. The retreat rates were brought into context with data on sediment composition and type (grain size, ice content, presence of massive ice), reconstructed evolution of hydrometeorological parameters and the history of economic development of Kharasavey area. Unlike other Kara Sea sites of coastal dynamics' monitoring, the strongest coastal retreat rates at Kharasavey were observed earlier in 1977-1988, when the hydrometeorological stress was low, implying vulnerability of the coasts to significant anthropogenic impact at the beginning of the gas field development.

Permafrost coasts make up roughly one third of all coasts worldwide. Their erosion leads to the release of previously locked organic carbon, changes in ecosystems and the destruction of cultural heritage, infrastructure and whole communities. Since rapid environmental changes lead to an intensification of Arctic coastal dynamics, it is of great importance to adequately quantify current and future coastal changes. However, the remoteness of the Arctic and scarcity of data limit our understanding of coastal dynamics at a pan-Arctic scale and prohibit us from getting a complete picture of the diversity of impacts on the human and natural environment. In a joint effort of the EU project NUNATARYUK and the NSF project PerCS-Net, we seek to close this knowledge gap by collecting and analyzing all accessible high-resolution shoreline position data for the Arctic coastline. These datasets include geographical coordinates combined with coastal positions derived from archived data, surveying data, air and space born remote sensing products, or LiDAR products. The compilation of this unique dataset will enable us to reach unprecedented data coverage and will allow us a first insight into the magnitude and trends of shoreline changes on a pan-Arctic scale with locally highly resolved temporal and spatial changes in shoreline dynamics. By comparing consistently derived shoreline change data from all over the Arctic we expect that the trajectory of coastal change in the Arctic becomes evident. A synthesis of some initial results will be presented in the 2020 Arctic Report Card on Arctic Coastal Dynamics. This initiative is an ongoing effort – new data contributions are welcome!

Earth and Space Science Open Archive PosterOpen AccessYou are viewing the latest version by default [v1]Hydrometeorological forcing of coastal dynamics in the Russian Arctic: link to erosion rates in the last decadesAuthorsAlisaBaranskayaiDStanislavOgorodovNatalyaShabanovaAnnaNovikovaBenjaminJonesSee all authors Alisa BaranskayaiDCorresponding Author• Submitting AuthorLomonosov Moscow State UniversityiDhttps://orcid.org/0000-0001-8392-1638view email addressThe email was not providedcopy email addressStanislav OgorodovLomonosov Moscow State Universityview email addressThe email was not providedcopy email addressNatalya ShabanovaLomonosov Moscow State Universityview email addressThe email was not providedcopy email addressAnna NovikovaMoscow State Universityview email addressThe email was not providedcopy email addressBenjamin JonesUniversity of Alaska Fairbanksview email addressThe email was not providedcopy email address

ABSTRACTThe generation of reliable age models for palaeoenvironmental and archaeological records in the Eurasian Arctic is often problematic when using conventional dating techniques. Tephrochronology can potentially improve the chronologies of such records and synchronise disparate sedimentary archives. However, to date, systematic tephra studies are lacking for this region. This paper presents the first cryptotephra data from the White Sea region (northwestern Russia) based on a peat core spanning the past ~1800 years. We identify seven geochemical glass populations that derive from six Icelandic volcanoes and correlate four of them to north European tephra isochrons; these include Askja ad 1875, the basaltic component of the ad 877 Landnám tephra, and tephras BTD‐15 (c. ad 1750–1650) and SL‐2/SB‐2 (ad 803–767) from unknown eruptions of Katla and Snæfellsjökull, respectively. The remaining three populations originate from Grímsvötn, Hekla and Katla; however, their attribution to individual eruptions remains ambiguous. These findings highlight the potential to extend the Late Holocene tephrochronological framework of northern Europe to the west Eurasian Arctic. The detection of at least three basaltic tephras in the core suggests that basaltic shards can be transported over larger distances than previously known and that peatlands are well suited to preserve such components.

The low coasts of Beliy Island, Kara Sea, composed of perennially frozen sands and silts with peat are extremely vulnerable to all changes in sea level and climate conditions in the Arctic. The complex Holocene history of the island is reflected in sediments outcropping in its coastal bluffs. Modern erosion leads to destruction of these bluffs, continuing to change the topography of the island. To reconstruct Late Quaternary history, coastal exposures were investigated. They generally consist of three units: the lower clays and sands with plant debris, parallel and rippled lamination formed in shallow marine conditions in MIS 3. The middle sandy unit with allochtonuous peat lenses was deposited in the mid-Holocene (5 to 8 ka BP) in coastal conditions. The upper peats, sandy loams and silts accumulated in continental conditions after 5 ka. To estimate modern coastal erosion rates, multitemporal satellite imagery (1969-2016) was used. The western coast retreated at higher average rates than the eastern coast (1.9 +/- 0.2 m/y and 1.2 +/- 0.2 m/y, respectively). Extreme rates during 47 years were higher from the eastern side (4.6 m/y compared to 3.1 m/y in the west). Both mean and extreme erosion rates are higher than the known erosion intensity of the Kara Sea coastal dynamics monitoring sites, evidencing considerable vulnerability of the low coasts to erosion in the changing climate. Evolution of the hydrometeorological parameters affecting coastal erosion in the XX-XXI century was estimated. High average retreat rates must have happened in the 2000s-2010s as a result of both temperature and wave energy increase providing unprecedent environmental forcing of coastal dynamics.