Erodibility of permafrost exposures in the coasts of Eastern Chukotka Alexey Maslakov a, * , Gleb Kraev b a Faculty of Geography, Lomonosov Moscow State University, GSP-1, Leninskie Gory,1, Moscow,119991, Russia b Center of Forest Ecology and Productivity, Russian Academy of Sciences,14 Leninskii Avenue, Moscow,119991, Russia article info Article history: Received 12 November 2015 Received in revised form 11 April 2016 Accepted 13 April 2016 Available online xxx Keywords: Permafrost Coastal erosion Erodibility Chukotka Lorino abstract Coastal retreat caused by coastal erosion decreases the territory of Russia by 50 km 2 annually. Erosion of the Arctic coasts composed by fine-grained permafrost turns coastlines into badlands dozens of meters wide and is harmful to the coastal infrastructure. Regional-level variations in the coastal retreat rate in the Arctic tend to follow the climate change dynamics and its consequences, mainly the shrinkage of the perennial sea ice area. This study considers the lower level local-scale variability linked to permafrost features, lithology, and morphology of the coasts in the remote region on the western shore of the Bering Sea within Lorino settlement (Chukotka, Russia). The coastal dynamics was tracked by means of geodesy and remote sensing in 2012e14, and the archival engineering surveydata available since 1967. We have derived the erodibility of sediments from the conventional soil properties measured by engineers, and linked the coastal retreat rates to erodibility of the sediments, so that it could be extrapolated to other coastal areas of Eastern Chukotka with similar sediment structure. © 2016 Elsevier B.V. and NIPR. All rights reserved. 1. Introduction The shrinkage of the Arctic sea ice cover (ACIA, 2005; Comiso et al., 2008), and higher frequency of storms (Atkinson, 2005) occur synchronously with permafrost warming and rise of the active layer. These marine and terrestrial feedbacks to Arctic warming (IPCC, 2014) meet and work together in the coastal zone as factors emphasizing the coastal erosion in many locations in the Arctic (Solomon, 2001; Vasiliev et al., 2001; Streletskaya et al., 2004; Grigoriev et al., 2006; Lantuit and Pollard, 2008; SAC, 2011). Russia's land shrinks by up to 50 km 2 every year due to the coastal retreat (Luk'yanova et al., 2002) at the average rate of 2.2 m$a 1 . The average rate is even higher on the Eastern Arctic sea shores, composed with the fine-grained sediments enriched with ground ice, ranging from 2 to 3.8 m a 1 depending on lithology (Grigoriev et al., 2006). Field-based monitoring of the Arctic coastline is challenged by its remoteness and accessibility. Therefore, no more than 1% of its length is covered with field monitoring (Lantuit et al., 2013). At the same time, remote monitoring of the Arctic coasts covers less than 25%, or 100,000 km of the Arctic coastline (Lantuit et al., 2012). Remote sensing methods have intrinsic limitations in use for extrapolation of the data from ground monitoring sites to regional scales. Despite the fact that the coastal retreat is sufficient for correlation with weather patterns and hydrological time series, it is disconnected from the physical processes of coastal destruction: coastal erosion and transport of sediments (Are, 2012). Highly variable geology and morphology of the coasts contribute greatly to the variations in coastal dynamics, which should be studied in or- der to raise the reliability of extrapolations and forecasts. In this study we consider the erosional coefficient e the volume of soil eroded by the unit of water flow (or wave) energy, m 3 J 1 . It is one of the indicators of erodibility, the ability of soils to disaggre- gate under thermal and mechanical impact of water flow, as defined in Russian engineering geology literature (Pashkin et al., 2011). However, the data on erodibility of permafrost is sparse in Russian literature (Shur Yu et al., 1984; Zhestkova et al., 1985; Sovershaev and Kamalov, 1992; Aksyonov, 2008) and engineering survey materials. Maximal erodibility is typical for fine-grained ice rich soils (Are, 2012). This is a reason for the highest rates of coastal retreat typical for the Eastern Arctic coasts reported above, where the total gravimetrical ice content could exceed 60% (Romanovskii et al., 2004). The water heat energy adds on to mechanical energy when eroding such soil. Not only the ice content, but also the grain size of soils controls the erodibility (Hequette and Barnes, 1990). The higher the sand content in silty and clayey soils, the lower is the erodibility (Are, 1980). The rate and the character of coastal destruction could also be related to the width of the beach and the * Corresponding author. E-mail address: alekseymaslakov@yandex.ru (A. Maslakov). Contents lists available at ScienceDirect Polar Science journal homepage: http://ees.elsevier.com/polar/ http://dx.doi.org/10.1016/j.polar.2016.04.009 1873-9652/© 2016 Elsevier B.V. and NIPR. All rights reserved. Polar Science xxx (2016) 1e8 Please cite this article in press as: Maslakov, A., Kraev, G., Erodibility of permafrost exposures in the coasts of Eastern Chukotka, Polar Science (2016), http://dx.doi.org/10.1016/j.polar.2016.04.009