remote sensing Article Dynamics of Permafrost Coasts of Baydaratskaya Bay (Kara Sea) Based on Multi-Temporal Remote Sensing Data Anna Novikova 1,*, Nataliya Belova 1, Alisa Baranskaya 1 , Daria Aleksyutina 1, Alexey Maslakov 1, Egor Zelenin 2, Natalia Shabanova 1 and Stanislav Ogorodov 1 1 Laboratory of Geoecology of the North, Faculty of Geography, Lomonosov Moscow State University, GSP-1, Leninskie Gory, 119991 Moscow, Russia; [email protected] (N.B.); [email protected] (A.B.); [email protected] (D.A.); [email protected] (A.M.); [email protected] (N.S.); [email protected] (S.O.) 2 Laboratory of Neotectonics and Modern Geodynamics, Geological Institute, Russian Academy of Sciences, Pyzhevsky lane, 7, 119017 Moscow, Russia; [email protected] * Correspondence: [email protected]; Tel.: +7-495-939-2526 Received: 8 August 2018; Accepted: 11 September 2018; Published: 16 September 2018 Abstract: Arctic coasts composed of frozen deposits are extremely sensitive to climate change and human impact. They retreat with average rates of 1–2 m per year, depending on climatic and permafrost conditions. In recent decades, retreat rates have shown a tendency to increase. In this paper, we studied the coastal dynamics of two key sites (Ural and Yamal coasts) of Baydaratskaya Bay, Kara Sea, where a gas pipeline had been constructed. Based on multi-temporal aerial and satellite imagery, we identified coastal erosion rates at several time lapses, in natural conditions and under human impact, and discussed their temporal variability. In addition to planimetric (m/yr), we calculated volumetric (m3/m/yr) retreat rates of erosional coasts using ArcticDEM. We also estimated the influence of geomorphology, lithology, and permafrost structure of the coasts on spatial variations of their dynamics. Erosional coasts of the Ural key site retreat with higher mean rates (1.2 m/yr and 8.7 m3/m/yr) as compared to the Yamal key site (0.3 m/yr and 3.7 m3/m/yr) due to their exposure to higher open sea waves, more complex lithology, higher ice content and lower coastal bluffs. Since the 1960s, coastal retreat rates have been growing on both coasts of Baydaratskaya Bay; we relate this effect with Arctic climate warming. From the 1960s to 2005, such growth was moderate, while in 2005–2016 it became rapid, which may be explained by the enhanced wave and thermal action or by the onset of industrial development. The adjacent coastal segments, originally accumulative, remained relatively stable from the 1960s to 2005. After 2005, a considerable part of them began to retreat as a result of changing weather conditions and/or increasing human impact. Keywords: permafrost; coastal erosion; Baydaratskaya Bay; remote sensing 1. Introduction Permafrost coasts make up to 34% of the world’s coastlines and retreat with an average rate of 0.5 m/yr [1]. Dynamics of Arctic coasts composed of frozen unlithified sediments have a strong influence on terrestrial [2,3], marine [4,5], and atmospheric [6] systems. In recent decades, coastal erosion accelerated in most of the polar regions due to rapid climate change, with its impact on the Arctic two times larger than on the rest of the world [7,8]. The decline of sea ice extent [9,10], storm frequency increase [11,12], thermal and wave action growth [13], and sea-level rise [14] have a dramatic impact on the arctic coastal dynamics [15–20]. Remote Sens. 2018, 10, 1481; doi:10.3390/rs10091481 www.mdpi.com/journal/remotesensing Remote Sens. 2018, 10, 1481 2 of 30 NumerousRemote Sens. 2018 studies, 10, x FOR provide PEER REVIEW detailed data on contemporary coastal dynamics at local2 of[ 3021 –23] and regional [24,25] scales. Studies on the Beaufort Sea coast [26,27] and the Chukchi Sea coast of Numerous studies provide detailed data on contemporary coastal dynamics at local [21–23] and Alaska [28] showed an increase in retreat rates at the beginning of the 21st century. At the same time, regional [24,25] scales. Studies on the Beaufort Sea coast [26,27] and the Chukchi Sea coast of Alaska little[28] of the showed Arctic an coast increase is covered in retreat by rates multi-temporal at the beginning studies. of the Remoteness21st century. At and the vastness same time, of little the polar regionsof the make Arctic it coast difficult is covered to conduct by multi-temporal comprehensive studies. field Remoteness studies and on coastalvastness erosion,of the polar and regions therefore, estimatemake reliable it difficult circum-Arctic to conduct comprehensive trends. Application field studies of remote on coastal sensing erosion, techniques, and therefore, such estimate as satellite and aerialreliable imagery circum-Arctic [29–31 trends.], unmanned Application aerial of remote vehicles sensing (UAVs) techniques, [32–34], such light as detection satellite and and aerial ranging (LiDAR)imagery [35] [29–31], surveys, unmanned etc., provides aerial reliable vehicles data (UAVs) for observing,[32–34], aerial quantifying, imagery [35], modeling light detection and monitoring and coastalranging dynamics (LiDAR) over [35] vaster surveys, regions etc., and provides larger reliable time periods data for compared observing, toquantifying, instrumental modeling measurements. and Aboutmonitoring 20% coastal of the dynamics Kara Sea over coasts vaster are regions thermoerosional and larger time [25 ]periods (Figure compared1). They to retreat instrumental especially intensivelymeasurements. due to their composition of ice-rich permafrost and the presence of ice wedges and massive ice About 20% of the Kara Sea coasts are thermoerosional [25] (Figure 1). They retreat especially bodies, their thawing is resulting in formation of retrogressive thaw slumps [15,36], thermoerosional niches intensively as they are composed of ice-rich permafrost and the presence of ice wedges and massive and gulliesice bodies, [37,38 their]. Surveys thawing of coastalis resulting dynamics in formation in the Kara of Searetrogressive region at Yugorskythaw slumps Peninsula [15,36], [21 ,39], Baydaratskayathermoerosional Bay[ 40niches–42], and and gullies Western [37,38]. Yamal Surveys [25,43 of,44 coastal] revealed dynamics mean in annual the Kara coastal Sea region erosion at rates rangingYugorsky from 0.5Peninsula to 2.5 m/yr,[21,39], what Baydaratskaya is significant Bay [40–42], in comparison and Western to other Yamal Arctic [25,43,44] regions. revealed Most mean of these worksannual were coastal based onerosion the results rates ranging of field from monitoring 0.5 to 2.5 along m/yr, separatewhat is significant profiles, conductedin comparison for to two other or three decades.Arctic The regions. profiles Most were of typically these works set everywere 100–500based on m. the Such results low of spatial field monitoring resolution madealong itseparate challenging to estimateprofiles, the conducted relative inputfor two of or different three decades. drivers The into profiles the resulting were typically retreat set rates. every To 100–500 reliably m. assess Such rates of coastallow spatial erosion resolution and to made determine it challenging the contribution to estimate of the various relative factors, input of data different with drivers higher into spatial the and temporalresulting resolution retreat arerates. required. To reliably Obtaining assess rates such of data coastal has erosion become and much to determine easier in the recent contribution decades of thanks various factors, data with higher spatial and temporal resolution are required. Obtaining such data to high-resolution aerospace imagery. has become much easier in recent decades thanks to high-resolution aerospace imagery. (a) (b) FigureFigure 1. Typical 1. Typical thermoerosional thermoerosional coast coast ofof thethe Kara Sea: Sea: (a ()a )field field view view and and (b) (QuickBird-2b) QuickBird-2 (2005) (2005) satellitesatellite imagery imagery (natural (natural color color composite), composite), the the UralUral coast of of Baydaratskaya Baydaratskaya Bay. Bay. Remote Sens. 2018, 10, 1481 3 of 30 In the present study we consider the coast as the zone of modern wave action, including foreshores withRemote beach Sens. ridges, 2018, 10 beaches,, x FOR PEER coastal REVIEW bluffs, and low-lying laidas (inundated during the highest3 of 30 tides and storm surges), as well as adjacent areas indirectly influenced by sea wave action (such as thermal gullying,In khasyrei the present formation study onwe theconsider surface the of coast terraces, as the etc.). zone We of focused modern on wave coastline action, (top including of thebluffs on theforeshores erosional with coasts beach or ridges, dense beaches, vegetation coastal boundary bluffs, and on low-lying the accumulation laidas (inundated coasts) during as indicator the of shiftinghighest of the tides entire and coastalstorm surges), zone. as well as adjacent areas indirectly influenced by sea wave action (suchThe present as thermal study gullying, aims khasyrei at estimating formation rates on of the the surface coastal ofchanges terraces, ofetc.). Baydaratskaya We focused on Bay coastline (Kara Sea) (top of the bluffs on the erosional coasts or dense vegetation boundary on the accumulation coasts) from the 1960s to 2016 using remote sensing accompanied by long-term field monitoring data. The Ural as indicator of shifting of the entire coastal zone. and the YamalThe present coasts study of Baydaratskaya aims at estimating Bay rates were of chosen the coastal as key changes sites of because Baydaratskaya (1) they Bay have (Kara different geomorphicSea) from and the 1960s geographic to 2016 conditions,using remote whichsensing allows accompanied to estimate by long-term their impact field monitoring on coastal data. erosion, and (2)The the Ural underwater and the Yamal part coasts of the of gas Baydaratskaya pipeline Bovanenkovo-Ukhta Bay were chosen as key crossing sites because Baydaratskaya (1) they have Bay was builtdifferent at these geomorphic two sites in and 2009–2012, geographic making conditions, it possible which to allows compare to estimate natural their conditions impact withon coastal the period of humanerosion, impact.