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Abstract

ABSTRACTWe reconstruct the behaviour of a High Arctic gravel-dominated beach complex that has developed in centralSpitsbergen, Svalbard, since the end of the Little Ice Age (LIA). The studied coastal environment in northernBillefjorden (Petuniabukta) is characterised by limited wave action and ephemeral sediment delivery from non-glaciated, mainly snow-fed fans and talus slopes. Aerial photographic evidence and morpho-sedimentologicalobservations of a beach-ridge plain and spit complex in northern Billefjorden reveal a dynamic coastal system.During the post-LIA period, a prominent coastal barrier at the mouth of the Ebbaelva migrated seawards severaltens of metres and prograded northwards to form new spit systems, each>150 m in length. The post-LIA coastalevolution occurred in two main phases. In thefirst half of the 20thcentury, increased paraglacial sediment releasedby retreating land-based glaciers led to the development of a subaqueous spit platform and the progradation of anebb-tide delta into the mouth of the Ebbaelva, diverting its mouth to the northwest. In the second half of the 20thcentury, the barrier prograded onto this platform, promoting the development of three massive spits. Sedimentolog-ical data suggest that changes in beach-ridge composition that occurred during the 20thcentury are linked toepisodic sediment delivery from an adjacent permafrost and snow-fed alluvial fan and delta system. Our work pro-vides a basis for a new model of paraglacial barrier development that recognises the fundamental role of climateand sediment supply as two intimately connected processes that control coastal development in the High Arcticover decadal to centennial timescales.

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... Coastal erosion, including cliff retreat, occurred along the coastlines exposed to prevailing winds (Sessford et al., 2015a;Guégan and Christiansen, 2017;Nicu et al., 2020). Wave-built morphologies such as spits and gravel beaches attest to the significance of waves in sediment transport and the availability of sediment sources (Strzelecki et al., 2017). The wave-built morphologies appear to register temporal changes in wave intensity modulated by climate change over the last 100 years (Strzelecki et al., 2017). ...
... Wave-built morphologies such as spits and gravel beaches attest to the significance of waves in sediment transport and the availability of sediment sources (Strzelecki et al., 2017). The wave-built morphologies appear to register temporal changes in wave intensity modulated by climate change over the last 100 years (Strzelecki et al., 2017). Despite the recently growing number of case studies focusing on coastal geomorphic changes in Svalbard, most of the coastal areas in Svalbard remain unexplored. ...
... Spit 5 has remained the most active in sediment transport among the spit complexes during the study period. early 1900s after the termination of the LIA ( Fig. 16A; Strzelecki et al., 2017), however, the inner Dicksonfjorden would have vast and prolonged ice cover than the present, and wave intensity was unlikely to exceed the present-day condition. The higher crest elevations of the breached spits may result from the isostatic rebound (e.g., Forman et al., 2004). ...
Article
Recent global warming triggered pronounced geomorphic changes such as coastal retreat and delta progradation along the coastlines of the Arctic regions. Coastal morphodynamics and associated sediment transport at the Arctic fjord head remain relatively unexplored due to the logistically limited accessibility to the field area, especially at short-term temporal scales. A repeat survey using an unmanned aerial vehicle (UAV)-assisted photogrammetry was conducted to quantify the annual morphodynamics of gravel spit complexes developed on the tidal delta plain of the deglaciated Dicksonfjorden, Svalbard of Arctic. Results show that the spit morphodynamics varies in time and space with an overall downfjord increase in the growth and migration rate of the spits. The youngest spits elongated 22 m yr⁻¹ and migrated landward 4.3 m yr⁻¹ between 2015 and 2019, marking the most pronounced spit morphodynamics documented to date in the Svalbard fjord systems. The spit morphodynamics is driven primarily by longshore drift and to a lesser degree by overwash processes. Gravels constituting the spits originate from the unconsolidated debris-flow deposits of old alluvial fans, which locally retreat 0.5 m yr⁻¹. The growth of the spit complexes is also fed by snow meltwater discharge on the alluvial fans, accounting for a downfjord imbrication of angular gravel layers that are intercalated with interlaminated sands and muds on the landward sides of the spits. The breached spits at the most upfjord location have remained stationary during the study period and presumably since the 1930s. Rapid delta progradation combined with an isostatic rebound after the Little Ice Age (LIA) has decreased spit morphodynamics on the tidal delta plain upfjord in Dicksonfjorden with infrequent and insignificant wave influence. Sparse distribution of the isolated spits signifies the intermittent spit development, which is constrained by the proximity to the protruded alluvial fans. The spit complexes in Dicksonfjorden highlight that climate change accelerates coastal geomorphic changes at the fjord head by enhancing wave intensity and regulating episodic sediment delivery that led to the downfjord shift in the locus of wave shoaling.
... Research on paraglacial and periglacial coasts has been conducted in the Gulf of Maine (Hein et al. 2012;Hein et al. 2014), Alaska (Brown et al. 2003), New England (FitzGerald andvan Heteren 1999), Canada (Irrgang et al. 2018), Greenland Bendixen and Kroon 2017;Fenger-Nielsen et al. 2020), and Russia (Lantuit et al. 2011;Ogorodov et al. 2020) and extensively in Svalbard (Mercier and Laffly 2005;Wangensteen et al. 2007;Sessford, Baeverford, and Hormes 2015;Zag orski et al. 2015;Bourriquen et al. 2016;Strzelecki 2016;Strzelecki, Long, and Lloyd 2017;Bourriquen et al. 2018;Grabiec et al. 2018;Jask olski, Pawłowski, and Strzelecki 2018;Strzelecki et al. 2018;Lim et al. 2020;Strzelecki et al. 2020). Despite including different types of classifications of coasts to address specific research problems and applications (Lantuit et al. 2012;Sessford, Baeverford, and Hormes 2015;Zag orski et al. 2015;Jask olski, Pawłowski, and Strzelecki 2018;Kavan 2019;Zag orski, Jarosz, and Superson 2020), no standardized classification of paraglacial coasts has been developed so far. ...
... Their development (G6b/16,17,18) can also occur during the transformation of coasts G5/11, 12, 13, 14, particularly where material supply to the aligned coast with beach increases (Figures 8 and 9). Coastal landforms such as spits have also been reported from the Billefjorden (Strzelecki, Long, and Lloyd 2017;Strzelecki et al. 2018;Kavan 2019) or the Brepollen region . Research in northern Billefjorden (Petuniabukta) showed that the oldest spit developed in the early twentieth century and the youngest began developing in the 1990s. ...
... Research in northern Billefjorden (Petuniabukta) showed that the oldest spit developed in the early twentieth century and the youngest began developing in the 1990s. The rate of development of spits in the period from 1990 to 2009 was 0.4 m a À1 , a reduction from the preceding period ; 1 m a À1 ; Strzelecki, Long, and Lloyd 2017;Strzelecki et al. 2018). Where there is a considerable supply of sediment from melting glaciers (e.g., at Brepollen; Strzelecki et al. 2020), lagoons are likely to develop. ...
Article
Progressing climate changes and declining ice cover (glacial) are accompanied by an increase in the length of paraglacial coasts. Therefore, issues related to the development and transformation of such areas attract increasing interest. No complex classification of paraglacial coasts has been presented so far. The main aim of this study was the determination of the mutual relations and evolution of paraglacial coasts in a systemic approach (paraglacial, proglacial, periglacial) based on the example of Recherchefjorden (Svalbard). Classification of coasts based on geomorphological mapping of the coasts of Recherchefjorden has been developed in terms of the lithology of sediments, genetic origins of hinterland, morphology, and morphodynamics. Analyses of field data and archival materials permitted the preparation of a model of the evolution of six main groups of coasts. Three groups were designated, characteristic of each of the glacial and paraglacial, and periglacial landscape and conditions causing transitions between particular types of coasts were determined. Due to the comprehensive and universal characteristics used in the development of the scheme and the representative landscapes of the Recherchefjorden region, the classification of High Arctic rock coasts presented here is readily transferable to other regions, potentially facilitating future research, management, and modeling of paraglacial areas.
... In comparison with the rest of the region, due to its location in a relatively warm sector of the Arctic Ocean, the glaciers in Svalbard are retreating relatively quickly in response to rising summer temperatures (Błaszczyk et al. 2013;Aas et al. 2016;Østby et al. 2017). Continued retreat of glaciers over the last century has exposed new proglacial zones and valley systems from where newly-developed river networks transport glacial sediments to the coast, leading to the development of paraglacial barriers and prograding deltas and tidal flat systems (Szczuciński et al. 2009;Zagórski et al. 2015;Strzelecki et al. 2017Strzelecki et al. , 2018 (Fig. 2). ...
... Relationships between accommodation space and sediment supply determine resulting coastal response (Simms and Rodriguez 2014;Zecchin et al. 2015), and this is the same with paraglacial coasts where variations in geological contexts along the coastline control the extent to which accommodation space is available, even with regionally-consistent amounts of sediment availability or sea-level change (Dickson et al. 2007). In Svalbard, several studies have examined evidence for contemporary and recent coastal dynamics, linked specifically to paraglacial changes in sediment supply and sea-level (Strzelecki et al. 2017). Knight and Harrison (2018a) proposed an evolutionary model of paraglacial landscape evolution in Ireland, focusing on how sediment transfer from mountains is largely captured within mountain river systems which have narrow valleys and thus limited accommodation space. ...
Article
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A challenge for coastal conservation over the next decades is to predict and then effectively manage the outcomes of ongoing climate change in the context of the Anthropocene. Paraglacial coasts are those on or adjacent to present or formerly glaciated terrain and which are still influenced by glacigenic processes. Ongoing response of paraglacial coasts to the influences of glaciation can give rise to diverse regional-scale coastal responses that may variously amplify or suppress any effects caused by global climate change. Here we provide insight into the richness of landforms and coastal system responses from two contrasting paraglacial environments, in Svalbard where glaciers are still present but are actively retreating, and in Ireland where late Pleistocene glaciers melted away around 14,000 years ago. Svalbard and Ireland exhibit different paraglacial coastal responses which reflect long-term variations in sediment supply from inland source areas to the coast, and variations in sediment residence times and storage areas within the coastal zone. The conservation of paraglacial coasts in the context of Anthropocene global warming requires an understanding of regional glacial history and longer term coastal responses to paraglacial relaxation.
... Detailed local scale field studies show that the coastlines of the Svalbard archipelago are highly dynamic. Key processes that control local and regional changes in shoreline morphology include changes in sediment supply (from terrigenous and marine sources), variations in nearshore wave climate caused by storms, temperature changes that influence sea-ice extent, as well as local changes in relative sea-level (e.g., Niewiarowski and Myzyk 1983;Laffly and Mercier 2002;Mercier and Laffly 2005;Kowalska and Sroka 2008;Sessford, Baeverford, and Hormes 2015;Sessford, Strzelecki, and Hormes 2015;Strzelecki, Małecki, and Zag orski 2015;Zag orski et al. 2015;Bourriquen et al. 2016Bourriquen et al. , 2018Strzelecki 2017, 2018;Strzelecki, Long, and Lloyd 2017;Strzelecki et al. 2018;Kavan 2019). ...
... Further research in the same area showed a rate of increase of deltas and their submarine extensions locally up to 5 m/yr in the years , and up to 4 m/yr in the period 2011-2014 (Bourriquen et al. 2016). In Kongsfjorden it was determined that it is the only described place in Svalbard where accumulation on the beach is higher than erosion (mean increase is 20,000 m 2 per 10 years), resulting in the development of prodeltas on the shore (Strzelecki, Long, and Lloyd 2017). Research on the tidal plane in northern Petuniabukta in the years 1990-2009 showed an almost identical amount of sediment deposited on the plane area and eroded from the neighbouring area (Strzelecki, Małecki, and Zag orski 2015). ...
Article
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Arctic coasts are sensitive indicators of polar environment change. Here we present the results of a study that examines the coastal morphodynamics of the Calypsostranda coastline in Svalbard (High Arctic) between 2007 to 2017 and compare these short-term changes to previous studies for the period 1936–2007. During the 2007-2017 study period, the study area lost ca. 10 710 m2, at a mean Net Shoreline Movement (NSM) of -1.86 m and End Point Rate (EPR) -0.19 m/yr. Erosion also dominated between 1936–2007, -28800 m2, at a mean NSM of -4.99 m and EPR -0.07 m/yr. Using EPR and Linear Regression Rate (LRR) parameters, we divide the Calypsostranda coastline into eroding and aggrading zones. The overall pattern of coastline change during the two study periods is similar, but the rate of erosion is higher in the recent interval, reflecting stronger climate-driven processes. Recent climate warming in the study area has been accompanied by an intensification of extreme events such as storms (e.g. ocean swell). The situation is becoming more pronounced due to the progressively reduced period of winter shore ice. Depending on the anemometric conditions, the Calypsostranda coast is modified by wind waves, and consequently longshore currents and associated sediment movement.
... The most distinct feature of eastern coast of Petuniabukta is a spit platform that developed in the mouth of Ebbaelva throughout the 20th century. It evolved in response to pulses of sediment supplied from a snow-fed alluvial fan delta (Strzelecki, Long, & Lloyd, 2017). In contrast to the straight coast formed in the eastern part of (2017). ...
... It is important to note that 1960s were the coolest period since the termination of the LIA and were characterised by cold conditions in all seasons and particularly strong cooling in winters and stable sea ice conditions (e.g., Macias Fauria et al., 2010;Mahoney, Barry, Smolyanitsky, & Fetterer, 2008). In our previous work we have shown that during climate cooling (1960s-1970s) the sediment supply to Petuniabukta was limited to high magnitude/low frequency pulses associated with snow melt and summer discharge (Strzelecki, Long, & Lloyd, 2017). The Ferdinand Spits were also very sensitive to shifts in nearshore water depths which in turn impact on wave energy at the coast. ...
Article
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In Svalbard, the rapid glacier retreat observed since the end of the Little Ice Age (LIA) has transformed the geomorphology and sediment budgets of glacial forelands, river valleys and slope systems. To date, relatively little information exists regarding the impact of such a profound glacial landscape degradation on the evolution of coastal environment. This paper addresses this deficiency by detailing the post-LIA sediment fluxes to the coastal zone in Billefjorden, central Spitsbergen (Svalbard). We analysed the response of the gravel-dominated barrier coast to the decay of Ferdinandbreen, one of the fastest retreating glaciers in the region. Glacier retreat resulted in the development of paraglacial sediment cascade where eroded and reworked glacigenic sediments progressed through alluvial fans to the coast, thus feeding gravel-dominated spit systems in Petuniabukta. We demonstrated the that coastal systems in central Spitsbergen responded abruptly to post-LIA climatic changes. The acceleration of coastal erosion and associated spit development was coincident with rapid climate warming that dates from the 1980's and has been associated with longer ice-free periods and activation of multiple sediment supply sources from the deglaciated landscape. In colder phases of post-LIA period, coastal zone development was subdued and strongly dependent on the efficiency of sediment transport via in a longshore drift. Finally, we discuss the differences in the post-LIA coastal responses between central Spitsbergen and western Spitsbergen highlighting the efficiency of paraglacial sediment delivery from land to the coast controlled by the state of glacial systems, bedrock topography and development of river channels.
... The changes taking place on the Arctic coasts were presented by many authors (John and Sugden 1975;Forbes et al. 2011;Overduin et al. 2014). The research was mostly carried out on the shores of Alaska (Jones et al. 2009;Wobus et al. 2011;Gibbs and Richmond 2015), Canada (McCann and Owens 1969;Solomon 2005;St-Hilaire-Gravel et al. 2010Atkinson et al. 2016), Greenland (Kroon et al. 2010;, Spitsbergen (Mercier and Laffly 2005;Sessford et al. 2015b;Strzelecki et al. 2017a;Zagórski et al. 2015) and Siberia Ogorodov 2011;Ogorodov et al. 2013). Most of these investigations concerned areas characterized by the presence of permafrost. ...
... Permafrost thaw and intensification of periglacial processes on local slopes supply large amounts of sediment to the shore zone. Based on research in Petuniabukta (the northern branch of Isfjord), Strzelecki et al. (2017a) linked shoreline changes with episodic sediment delivery from land, e.g. from snow-melt and permafrost catchments. The research conducted in Calypsostranda seems to confirm the importance of these factors. ...
Article
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The objective of this research is to determine the impact of waves on the segregation of sediment within the area of its supply in the context of meteorological conditions. The research was conducted on a 4 km section of the shore of Calypsostranda (Bellsund, West Spitsbergen), shaped by waves such as swell, wind waves, and tides. Particular attention was paid to the diversity and variability of the surface texture within the intertidal zone. Meteorological measurements, recording of wave climate, as well as analysis of the grain-size distribution of the beach sediments were performed. Nearshore bathymetry, longshore drifts, episodic sediment delivery from land, as well as resistance of the shore to coastal erosion and direction of transport of sediments in the shore zone are important factors controlling shore development. Data show that wind waves contribute to erosion and discharge of material from the nearshore and intertidal zone. The research also shows that oceanic swell, altered by diffraction, reaching the shore of Calypsostranda contributes to better sorting of sediment deposited on the shore through washing it out from among gravels, and longshore transport of its finest fraction. The grain size distribution of shore sediments is significantly changed already during one tidal cycle. The degree of this modification depends not only on wave height and period but on the direction of wave impact. The shore of Calypsostranda can be regarded as transitional between high and low energy coasts.
... Nansen (1922) was the first to describe coastal erosional processes in Svalbard and pointed out the role of frost action on coastal development. Few researchers showed that rocky coasts can be discussed in the context of paraglaciation and studies have been conducted on Svalbard rocky coasts (Wangensteen et al., 2007;Strzelecki, 2011;Strzelecki, 2016;Guégan & Christiansen, 2017;Swirad et al., 2017); as well as on unlithified coasts (Héquette & Ruz, 1990;Mercier, 2001;Mercier & Laffly, 2005;Ziaja et al., 2009;Zagorski, 2011;Zagorski et al., 2012;Sessford et al., 2015;Strzelecki et al., 2015;Zagorski et al., 2015;Bourriquen et al., 2016;Strzelecki et al., 2017Strzelecki et al., , 2018 and on Svalbard despite it providing an excellent field of investigation on coastal geomorphology in the High Arctic area in the context of global change. ...
Article
The aim of this paper is to quantify and map the impact of the post‐LIA climate change on the coastal evolution on three glacier catchments in the Kongsfjorden area in Svalbard. Climatic data at Ny‐Ålesund indicate an increase in the annual mean air temperature of +4°C from 1969 to 2016 and an increase in precipitation. On the northern coast of the Brøgger Peninsula, the Austre Lovénbreen, Midtre Lovénbreen and Vestre Lovénbreen glaciers have experienced a net retreat in response to changing meteorological conditions. Because of this retreat, the glaciers have disclosed a large area of 7 km² composed of terrigenous sediments. These sediments are transported by runoff and created coastal sandur deltas. Channel network behavior has been studied using the computation of the active floodplain width by photo‐interpretation, which decreased in average from 1966 to 2010. This demonstrated a contraction of the active braided belt and a decrease in the number of braided channels. A photo‐interpretation analysis combined with acquisition of dGPS data during field work shows a mean shoreline progradation of + 0.16 m/a‐1 from 1966 to 2016, with a maximal advance of + 82 m seaward. Since 1966 coastal progradation has decreased in time with higher mean values at the beginning of the studied period and an erosional trend from 1990. The sublittoral area was studied using analog side scan sonar in 2009, 2011, 2012 and 2017. Three pro‐deltas were identified and underwent a huge extension from 2009 to 2017. In the light of this knowledge, our main conclusion is that, by retreating, glaciers have an impact on the sediment availability and on the capacity of the fluvial system to effectively transport sediment to the shoreline. These two factors control the overall coastal evolution by regulating the sediment supply to the coastal area. The coastal zones that were fed with sediments by runoff have experienced a coastal progradation and those that lost this supply have undergone a coastal recession. Due to the contraction of proglacial floodplains, current progradation concerns restricted coastal areas.
... The spatial patterns in retreat rates were coupled to simple process characterizations by looking into ice charts (Hequette and Barnes, 1990;Manson et al., 2005), wind, wave, and storm data (Hequette and Barnes, 1990;Brown et al., 2003;Manson et al., 2005;Lantuit et al., 2011), and sediment characteristics (Hequette and Barnes, 1990). Previous work focusing on advancing Arctic coasts in Svalbard (Zagorski, 2011;Strzelecki et al., 2015;Bourriquen et al., 2016) and the Canadian Arctic Archipelago (St-Hilaire-Gravel et al., 2010) strongly correlate the shoreline changes with the abundance of sediment released by retreating glaciers. Only very limited work has been done on Arctic coasts in Greenland (Nielsen, 1994;Hansen, 2004;Kroon et al., 2011;Pedersen et al., 2011), and it is still unknown how sedimentary coasts in Greenland respond to a warming climate. ...
Article
Climate warming in the Arctic directly causes two opposite changes in Arctic coastal systems: increased melt-water discharge through rivers induces extra influx of sediments and extended open water season increases wave impact which reworks and erodes the shores. A shoreline change analysis along of the southern coast of Disko Island in western Greenland was conducted with aerial photos and satellite images from 1964, 1985, and 2012. The decadal morphologic evolution of this 85 km section showed that large parts of the coast had undergone very limited changes. However, two deltas were highly dynamic and popped up as hotspots. This article is protected by copyright. All rights reserved. The Tuapaat delta and Skansen delta showed large progradation rates (1.5 and 7 m y-1) and migration of the adjacent barriers and spits. The dynamic behavior at the delta mouths was mainly caused by classic delta channel lobe switching at one delta (Tuapaat), and by a breach of the fringing spit at the other delta (Skansen). The longshore and cross-shore transports are responsible for reworking the sediment with a result of migrating delta mouths and adjacent subaqueous mouth bars. Seaward progradation of the deltas is limited due to the steep nature of the bathymetry in Disko Bay. This article is protected by copyright. All rights reserved. Finally, a schematic conceptual overview of processes and associated morphological responses for deltas in Arctic environments is presented, including the climate drivers affecting delta evolution. This article is protected by copyright. All rights reserved.
... Szpikowski, Szpikowska, Zwoliński, Rachlewicz, et al., 2014). The morphological effects of large sediment loads reaching the fjord can be observed, for example, in the dynamic development of coastal landforms (Strzelecki, Long, & Lloyd, 2015; Strzelecki, Małecki, & Zagórski, 2015). There is a continuous permafrost on Svalbard, with a thickness of 100 m in the valley bottoms and near the coast to as much as 400–500 m in inland mountains (cf. ...
Article
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A 1:19,500 map of the Petunibukta region documents the spatial distribution of almost 300 colluvial and alluvial fans (together with their catchments) in the periglacial high-Arctic environment of Svalbard. Fan-shaped landforms were mapped using an orthophoto and digital elevation model generated from 2009 aerial photographs and a 2013 high-resolution satellite image using Geographic Information Systems. Four additional maps at a scale of 1:40,000 provide details about the morphometric characteristics of the studied fans: long- and cross-profiles, slope and aspect. Additionally, parameters such as fan and catchment area, relief, length, width, elevation (the lowest point at the fan toe, apex, and the highest point of the catchment boundary), fan mean plan and profile curvatures, fan relation to neighbouring fans, are also presented. Fans were classified according to the dominant processes shaping their surface: colluvial fans (n = 229), alluvial fans dominated by debris flows (n = 49), and alluvial fans dominated by fluvial flows (n = 19).
... This has led to rapid glacier retreat Małecki, 2016) and paraglacial landscape transformation (e.g. Stacke et al., 2013;Ewertowski and Tomczyk, 2015;Strzelecki et al., 2017). ...
Article
Sorted circles and polygons are widespread features of periglacial landscapes, but the controls on their development remain poorly understood, impeding their use as palaeoenvironmental indicators. We investigate the relationship of sorted circles and polygons to altitude in the northern Billefjorden area, central Svalbard. The patterns occur in two distinct elevation zones, below 200–250 m asl and above 600 m asl. The higher-elevated patterns have smaller diameters and shallower sorting depths due to a thinner active layer at higher elevations, suggesting that sorted patterns can indicate climate conditions and ground thermal state when the patterns initiated. Geology is believed to be of less importance for pattern morphology in the study area, causing only its fine-scale variations. The pattern diameter-to-sorting depth ratios have a median value of 3.57, consistent with previous studies and theoretical models of patterned-ground formation involving circulation mechanisms. Large-scale sorted patterns may develop over centennial timescales in this high-Arctic environment. They are probably not in equilibrium with present-day climate conditions and have probably formed throughout the Holocene.
... In general, over the last decade, Svalbard coastal studies have been concentrated on the coastal zone response to shifts in sediment supply associated with changes in local ice masses and paraglaciation (e.g., Bourriquen et al., 2016;Mercier & Laffly, 2005;Sessford, Strzelecki, & Hormes, 2015;Strzelecki et al., 2018;Zagórski, 2011); ephemeric pulses of sediments from snow-fed streams (Lønne & Nemec, 2004;Strzelecki, Long, & Lloyd, 2017); or the controls of coastal permafrost development . Recent years had also brought some advances in local rocky coast systems that dominate over coastal landscape in numerous Svalbard fjords (e.g., Kasprzak et al., 2017;Strzelecki, 2011;Strzelecki, 2017;Strzelecki et al., 2017;Świrad, Migoń, & Strzelecki, 2017). ...
Article
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Longyearbyen is the major administrative, touristic and scientific centre in Svalbard and so‐called ‘European Gateway’ to the Arctic. The number of inhabitants and tourists as well as community infrastructure has significantly expanded over the recent decade and present‐day community faces development thresholds associated with climate warming and disturbance of cold region landscape. Coastal zone is a key interface where severe environmental changes impact directly on Longyearbyen infrastructure. We applied the combination of environmental assessment methods (Leopold Matrix; Coastal Vulnerability Index) and GIS analyses (Digital Shoreline Analysis Systems) together with field mapping to investigate the scale of degradation of coastal zone in Longyearbyen and examine the impact of coastal hazards on major elements of community infrastructure. Rate of observed coastal changes, the diversity of natural and man‐made hazards mapped along the coast as well as observed damages in infrastructure suggest a need for coastal change monitoring in Longyearbyen. The part of the Longyearbyen coast that should be monitored and protected are sections spreading between new port and surroundings of Longyearelva delta significantly modified by coastal erosion and landsliding. In order to improve coastal zone protection and safety of town development we present arguments supporting the incorporation of Longyearbyen into recently established Circum‐Arctic Coastal Communities Knowledge Network.
... Detailed case studies have also examined the paraglacial context and timing of geomorphic and sedimentary systems from mountain (Ballantyne, 1995;Ballantyne & Stone, 2013;Curry, 1999;Orwin & Smart, 2004;Owen & Sharma, 1998), river (Jansen et al., 2011;Lane et al., 2017;Orwin et al., 2010;Passmore & Waddington, 2009), and coastal settings (Forbes & Syvitski, 1994;Knight & Burningham, 2014;Orford, Forbes, & Jennings, 2002). A subset of paraglacial coasts is that of arctic or high-latitude coasts, which are strongly influenced by permafrost, sea ice, glacitectonic rebound, and variations in glacigenic sediment supply by glacier retreat, river development, or coastal erosion (e.g., Grabiec et al., 2018;St-Hilaire-Gravel, Forbes, & Bell, 2015;Strzelecki, Long, & Lloyd, 2017). This type of paraglacial coast is not considered in this study, however. ...
Article
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Two main ways in which the progress of deglaciation in mountains can be identified and monitored are through (1) meltwater loss over time as glaciers and permafrost melt, and (2) enhanced sediment yield over time as loose sediments are released downslope. Conceptually, both these outcomes of glacier retreat can be considered through their relationship to models of paraglacial landscape evolution, which describe how volume fluxes of meltwater and sediments change over time in mountains that are becoming deglacierized, and the different landforms that exist during different stages of landscape evolution. This paper critically reconsiders paraglacial landscape evolution models with respect to the separate timings and magnitudes of meltwater and sediment fluxes, drawing from examples from past and present deglacierizing mountains worldwide. This analysis shows that constructions of paraglacial systems simply as sediment cascades cannot be uncritically supported, and that paraglacial systems can be best considered as reflecting transient stages of evolution in which meltwater and sediment fluxes vary over time and space. These transient properties of paraglacial systems have important implications for the ways in which the dynamics of these systems are conceptualized and modelled, with respect to the paraglacial evolution of mountain landscapes and mountain geohazards, especially under conditions of global warming and glacier recession.
... Nansen (1922) was the first to describe coastal erosional processes in Svalbard and pointed out the role of frost action on coastal development. Few researchers showed that rocky coasts can be discussed in the context of paraglaciation, and studies have been conducted on Svalbard rocky coasts (Wangensteen, Eiken, Ødegård, & Sollid, 2007;Strzelecki, 2011;Strzelecki, 2016;Guégan & Christiansen, 2017;Swirad, Migon, & Strzelecki, 2017), as well as on unlithified coasts (Bourriquen et al., 2016;Héquette & Ruz, 1990;Mercier, 2001;Mercier & Laffly, 2005;Sessford, Baeverford, & Hormes, 2015;Strzelecki et al., 2015;Strzelecki et al., 2018;Strzelecki, Long, & Lloyd, 2017;Ziaja, Maciejowski, & Ostafin, 2009;Zagorski, 2011;Zagorski, Gajek, & Demczuk, 2012;Zagorski et al., 2015) and on Svalbard despite it providing an excellent field of investigation on coastal geomorphology in the High Arctic area in the context of global change. ...
Conference Paper
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Only 1% of arctic areas have been studied enough to allow to describe the active quantitative processes. In the frame of Marine Bourriquen’s PhD thesis, we explored the way how polar coasts are impacted and record the actual climate changes. In the Kongsforden located in the northern part of the Svalbard, several costal systems, such as tidal flat areas and cliffs, have been studied using different methodologies. Results show that the glacier melting and the hydrographical network tend to increase the progradation of the deltas since the end of LIA. Since 1990, this trend is reversing with a major erosional phase, revealing the end of the paraglacial system. Regarding the cliffs, whatever are their lithologies and insolation, the marine actions have a noticeable influence on their evolution, but seem to be less determinant than the continental processes, although since 2005, the total sea ice cover has partially disappeared in the Kongsfjorden, and completely since 2012.
... The same is valid for the involved main controlling factors: coast-oblique incident waves that cause a significant longshore drift, the availability of a sediment source in the up-drift direction, and wave refraction around the growing tip of the spit leading to a reduction in alongshore-transport capacity and, as such, triggering sedimentation (Bluck et al., 2001;Nielsen and Johannessen, 2009). However, only few studies have focused on the dynamics of gravel beaches in polar regions (St-Hilaire-Gravel et al., 2012, 2015Lindhorst and Schutter, 2014;Strzelecki et al., 2015Strzelecki et al., , 2018 and there still is a gap in knowledge on the evolution, the sedimentary dynamics and the resulting internal architecture of gravel-spit systems developed under the circumstances of rapid atmospheric warming and associated changes of wind climate and relative sea level. This study aims at filling this gap by revealing the genesis of, and by providing a concept for, the evolution of polar gravel-spit systems that developed during a phase of accelerated deglaciation and subsequent crustal isostatic adjustment. ...
Article
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Sedimentary architecture and morphogenetic evolution of a polar bay‐mouth gravel‐spit system are revealed based on topographic mapping, sedimentological data, radiocarbon dating and ground‐penetrating radar investigations. Data document variable rates of spit progradation in reaction to atmospheric warming synchronous to the termination of the last glacial re‐advance (LGR, 0.45‐0.25 ka BP), the southern hemisphere equivalent of the Little Ice Age cooling period. Results show an interruption of spit progradation that coincides with the proposed onset of accelerated isostatic rebound in reaction to glacier retreat. Spit growth resumed in the late 19th century after the rate of isostatic rebound decreased, and continues until today. The direction of modern spit progradation, however, is rotated northwards compared to the growth axis of the early post‐LGR spit. This is interpreted to reflect the shift and strengthening in the regional wind field during the last century. A new concept for the interplay of polar gravel‐spit progradation and glacio‐isostatic adjustment is presented, allowing for the prediction of future coastal evolution in comparable polar settings.
... Many studies have used aerial photography, remote sensing images, and topographic maps to monitor long-term changes of the Russian and Canadian Arctic coastlines [11,[13][14][15], by combining ice, wind, wave, storm, and sediment data to analyze coastal erosion. Previous studies have focused on the Arctic coast of Svalbard [15][16][17], the Canadian Arctic Archipelago [18,19], the coast of Greenland [20][21][22], and the Arctic coast of Alaska [8], but fewer studies have examined the changes along the Siberian Arctic coastlines. ...
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In this study, remote sensing analysis of coastal erosion is conducted for three typical regions of Alaska and Eastern Siberia based on remote sensing data collected between 1974 and 2017. The comparative studies were made on the difference in coastal erosion at different latitudes and the difference and influencing factors in coastal erosion at similar latitudes. The coastline retreatment is used to indicate coastal erosion. It is found that the most extensive erosion occurred along Alaska’s coast, followed by that of the Eastern Siberian coasts. Based on the analysis of the historical time series of snow and ice as well as climate data, it is found that at similar latitudes, the erosion of the Arctic coasts is closely related to the trend and fluctuations of the sea surface temperature (SST). Specifically, it is found that in Alaska, coastal erosion is closely related to the fluctuation of the SST, while in Eastern Siberia, it is related to the increasing or decreasing trend of the SST. A decreasing trend is associated with low coastal erosion, whereas an increasing trend is associated with accelerated coastal erosion. In the Arctic, the strong fluctuations of the SST, the continuous decline of the sea ice cover, and the consequent increase of the significant wave height are the critical factors that cause changes in coastal permafrost and coastal erosion.
... Among them, pension is undoubtedly the most important issue. With the political wave of urbanization in China, a large number of young and middle-aged labor force leave their hometown, which directly leads to the increasingly empty rural areas [4,5]. The number of empty nesters in rural areas is amazing. ...
... This is true especially for west coast of Svalbard. However, main source of material in the central part, with more continental climate, low precipitation and relatively low number of glaciers, are fluvial sediments of snow fed streams and material originating from erosion of past coastal areas (Strzelecki, Long, and Lloyd 2017). ...
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Changes in the position of the shore in the vicinity of Kapp Napier in central Svalbard was described. The overall advance of the shore was probably related to high input of the sediment material originating from erosion of the coastal areas south of the Kapp Napier locality and high input of material from adjacent glacifluvial system of Nordenskiöld glacier with its marginal water streams. Fast evolution of glacier retreat related processes after the Little Ice Age was a secondary driver of the dynamic changes in the central Svalbard coastal areas especially in the first half of the 20th century. The highly dynamic longshore currents in the area altogether with still ongoing glacio-isostatic uplift played an important role in the process as well. The most active parts of the shore experienced advance of almost 100 meters since 1908 to 2009. On the other hand, a small part of the coast retreated of about 20 meters. Most of the study area experienced aggradation (65%), 30% of the coast was stable and about 5% of the coast has undergone minor retreat. The maximum aggradation rate of 0.96 m/year corresponds well with similar sites in the vicinity.
... Nansen (1922) was the first to describe coastal erosional processes in Svalbard and pointed out the role of frost action on coastal development. Few researchers showed that rocky coasts can be discussed in the context of paraglaciation, and studies have been conducted on Svalbard rocky coasts (Wangensteen, Eiken, Ødegård, & Sollid, 2007;Strzelecki, 2011;Strzelecki, 2016;Guégan & Christiansen, 2017;Swirad, Migon, & Strzelecki, 2017), as well as on unlithified coasts (Bourriquen et al., 2016;Héquette & Ruz, 1990;Mercier, 2001;Mercier & Laffly, 2005;Sessford, Baeverford, & Hormes, 2015;Strzelecki et al., 2015;Strzelecki et al., 2018;Strzelecki, Long, & Lloyd, 2017;Ziaja, Maciejowski, & Ostafin, 2009;Zagorski, 2011;Zagorski, Gajek, & Demczuk, 2012;Zagorski et al., 2015) and on Svalbard despite it providing an excellent field of investigation on coastal geomorphology in the High Arctic area in the context of global change. ...
... During the post-LIA period, paraglacial processes (sensu Ballantyne, 2002) have been erasing the effects of glacial legacy from the relief of mountains, valleys, coasts and fjords (e.g. Lukas et al., 2005;Mercier et al., 2009;Rachlewicz, 2009Rachlewicz, , 2010Szczuciński et al., 2009;Ewertowski and Tomczyk, 2015;Senderak et al., 2017;Strzelecki et al., 2017). The rapid exposure of land from Svalbard glaciers (over 20% of glacierized terrain decrease) activates sediment cascades through which exposed glacigenic sediments are transported and can then be stored in the form of solifluction slope covers, fluvial floodplains, lakes and within the coastal zone in the form of beaches, tidal flats or as marine sediments in the bottoms of fjords (e.g. ...
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Changes in the properties and dynamics of tidewater glacier systems are key indicators of the state of Arctic climate and environment. Calving of tidewater glacier fronts is currently the dominant form of ice mass loss and a major contributor to global sea‐level rise. An important yet under studied aspect of this process is transformation of Arctic landscapes where new lands and coastal systems are revealed due to the recession of marine‐terminating ice masses. The evolution of those freshly‐exposed paraglacial coastal environments is controlled by nearshore marine, coastal and terrestrial geomorphic processes, which rework glacial‐derived sediments to create new coastal paraglacial landforms and landscapes. Here, we present the first study of the paraglacial coasts of Brepollen, one of the youngest bays of Svalbard revealed by ice retreat. We describe and classify coastal systems and the variety of landforms (deltas, cliffs, tidal flats, beaches) developed along the shores of Brepollen during the last 100 years. We further discuss the main modes of sediment supply to the coast in different parts of the new bay, highlighting the fast rate of coastal transformation as a paraglacial response to rapid deglaciation in the Arctic. This study provides an exemplar of likely coastal responses to be anticipated in similar tidewater settings under future climate change. https://onlinelibrary.wiley.com/doi/abs/10.1002/esp.4819
... Meanwhile, GIS (the Geographic Information System) and remote-sensing imagery [15][16][17][18] are adopted to assess the risk assessment of urban rainstorm disasters. However, due to lack of sufficient data, urban rainstorm disasters are difficult to assess accurately [19]. ...
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An integrated index system for urban rainstorm risk evaluation has been developed. Meanwhile, an information diffusion method (IDM) and variable fuzzy sets (VFSs) were employed to evaluate the dangerousness, sensitivity, and vulnerability risk of urban rainstorm disasters, respectively. Then, the comprehensive risk zoning map was drawn. Finally, Jiangsu Province has been taken as a case study area. Due to heavy rainfall in short-term and low rainstorm resistance ability, Wuxi, Changzhou, Nanjing, and Suzhou have higher dangerousness while Wuxi, Changzhou, and Nanjing have higher sensitivity. And because of potential losses in urban rainstorm disaster, Wuxi and Suzhou have higher vulnerability than other cities. The comprehensive risk zoning map showed that most cities of Jiangsu Province are at the moderate risk level, and the northwestern cities have lower risk level than the southern cities. The results are consistent with the actual situation of Jiangsu Province, and the study can provide some decision-making references for the urban rainstorm management.
... The same is valid for the involved main controlling factors: coast-oblique incident waves that cause a significant longshore drift, the availability of a sediment source in the up-drift direction, and wave refraction around the growing tip of the spit leading to a reduction in alongshore-transport capacity and, as such, triggering sedimentation (Bluck et al., 2001;Nielsen and Johannessen, 2009). However, only few studies have focused on the dynamics of gravel beaches in polar regions (St-Hilaire-Gravel et al. 2012, 2015Lindhorst and Schutter, 2014;Strzelecki et al., 2015Strzelecki et al., , 2018 and there still is a gap in knowledge on the evolution, the sedimentary dynamics and the resulting internal architecture of gravel-spit systems developed under the circumstances of rapid atmospheric warming and associated changes of wind climate and relative sea level. This study aims at filling this gap by revealing the genesis of, and by providing a concept for, the evolution of polar gravel-spit systems that developed during a phase of accelerated deglaciation and subsequent crustal isostatic adjustment. ...
Thesis
Understanding the Holocene is particularly important for providing the context for recent ice sheet dynamics a i.e. understanding whether current ice sheet dynamics are unusual or part of Holocene natural variability (Bentley et al., 2014). Knowledge on the most recent millennia of Antarctic Ice Sheet history is vital for evaluating the response of the ice sheet to various forcing agents, such as sea-level rise, atmospheric and oceanographic temperature changes, and for constraining grounding-line retreat on Holocene to recent time scales (Bentley et al., 2014). The main objective of this thesis is to add new data to reconstruct the Holocene deglaciation history of King George Island, South Shetland Islands, northwest Antarctic Peninsula, by investigating morpho-sedimentary records of glacigenic and coastal landforms and associated sediments from the on-shore ice-free areas around Maxwell Bay (King George Island), namely Potter Peninsula and Fildes Peninsulas. In order to accomplish the thesis objectives, I used (i) cosmogenic exposure dating and radiocarbon dating for absolute chronological constraints; (ii) stratigraphy and sedimentology for relative chronological constraints and reconstruction of paleoenvironmental conditions; (iii) geomorphological mapping for spatial distribution of landsystems; (iv) and ground-penetrating radar (GPR) investigations for the study of internal sedimentary architecture of coastal landforms. Radiocarbon dating results yield new age constraints for the onset of deglaciation on Potter Peninsula, which occurred around at or before 7.8 ka cal BP instead of an earlier accepted age of 9.5 ka cal BP. I provide additional evidence for a short-lived glacier re-advance between 7.2 and 7.0 ka cal BP. This re-advance is likely linked to a glacier re-advance or still-stand documented on South Shetland Islands for that time period. Nevertheless, climatic conditions associated with this glacial re-advance remain unclear. In contrast, on Fildes Peninsula, exposure and radiocarbon dating indicate that glacial oscillations were minimal during the last 7 ka. I applied radiocarbon dating to remnants of mosses preserved in moraines. The moraines were formed close to the present glacier limit between 0.5 and 0.1 ka cal BP, during the last glacier re-advance in South Shetland Islands. This advance is linked to reductions in summer/annual insolation coupled with a shift to more intense Southern Hemisphere westerly winds in the Southern Ocean. Stronger, and possibly more poleward-shifted southern westerly winds produced more precipitation-laden storm fronts passing over the South Shetland Islands and thus, increased ice accumulation. The data also show that between 1.9 and 1.3 ka cal BP a climatic optimum was reached on Fildes and Potter Peninsula, which lasted until the last glacier readvance. GPR investigations and radiocarbon dating from a gravel spit system on Potter Peninsula document coastal progradation during the late phase of the last glacier re-advance, with a stable relative sea-level. Results also show an interruption of spit progradation that coincides with a proposed onset of accelerated isostatic rebound in reaction to glacier retreat subsequent to the last glacier re-advance. Spit growth resumed in the late 19th century after the rate of isostatic rebound decreased, and continues until today. The findings of this thesis support both, glacio-isostatic adjustment (GIA) models that show limited and those which show more pronounced ice-load changes on the South Shetland Islands during the late Holocene, suggesting that some GIA model parameters for the South Shetland Islands (e.g., lithospheric thickness, mantle viscosity) need to be better constrained. Furthermore, my findings have implications for regional paleoclimatic reconstructions and on ice sheet modeling for the Holocene of the northwest Antarctic Peninsula region.
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Schmidt hammer tests across a recently deglacierized rocky coastal zone in Spitsbergen - is there a "coastal amplification" of rock weathering in polar climates? A significant limit to current understanding of cold coast evolution is the paucity of field observations regarding development of rocky coastlines and, in particular, lack of precise recognition of mechanisms controlling rock coast geomorphology in polar climates. Results are presented from a pilot survey of rock resistance using Schmidt Hammer Rock Tests (SHRT) across the recently deglacierized Nordenskioldbreen forefield and coastal zone, in central Spitsbergen, Svalbard. The aim is to improve understanding of the effects of rock weathering on high latitude coasts. SHRT across a field of roches moutonnées of meta-morphic rocks, uncovered from ice over the last century and exposed to the operation of littoral processes, demonstrated significant relationships between rock surface resistance and distance from present shoreline, distance from the ice cliff as well as thickness of the snow cover. Sites closest to the present-day shoreline were characterized by lower resistance in comparison with more inland locations. The result support models that advocate intensification of weathering processes in cold region coastal settings.
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Melting Svalbard glaciers have been recognized as an early indicator of climate change. Large parts of Svalbard remain insufficiently investigated, including Dickson Land, in the quasi-continental interior of Svalbard. In this study, elevation and volume changes of seven glaciers located in the Pyramiden region are assessed by analysing contour lines from 1960 topographic maps and photogrammetrically derived 1990 and 2009 digital elevation models. Mass loss was documented for all seven glaciers. In the period 1960-1990, their average elevation change rate was -0.49 m a-1, while in the more recent period, 1990-2009, it was more negative at 0.78 m a-1, caused by a significant equilibrium line altitude shift with post-1990 rise in summer temperatures. Large variation in elevation change rates between individual glaciers was found and is attributed mainly to aspect and hypsometry. This highlights the importance of choosing a representative sample when investigating mass balance of whole regions. Evidence of a rapid increase in thinning rates in the upper parts of the studied glaciers, linked to decreasing albedo in former accumulation zones, was also found.
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Hørbyebreen surged in the 19th or early 20th century, as suggested by geomorphological evidences and looped medial moraines. In this study, we investigate its wide−spread geometry changes and geodetic mass balance with 1960 contour lines, 1990 and 2009 digital elevation models, in order to define the present−day state of the glacier. We also study its thermal structure from ground−penetrating radar data. Little is known about the glacier behaviour in the first part of the 20th century, but from its surge maximum until 1960 it has been retreating and losing its area. In the period 1960-1990, fast frontal thinning (2-3ma−1) and a slow mass build−up in the higher zones (~0.15 m a−1) have been noted, resulting in generally negative mass balance (−0.40 ± 0.07 m w. eq. a−1). In the last studied period 1990-2009, the glacier showed an acceleration of mass loss (−0.64 m ± 0.07 w. eq. a−1) and no build−up was observed anymore. We conclude that Hørbyebreen system under present climate will not surge anymore and relate this behaviour to a considerable increase in summer temperature on Svalbard after 1990. Radar soundings indicate that the studied glacial system is polythermal, with temperate ice below 100-130 m depth. It has therefore not (or not yet) switched to cold−bedded, as has been suggested in previous works for some small Svalbard surge−type glaciers in a negative mass balance mode.
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The functioning of the polar catchment is reflected in changes (geosuccession) of the structure of the natural environment (changes in the landscape). In the case of polar catchments, sediments can be transported and deposited in the coastal zone by glaciers (moraine sediments) or proglacial water in the area of outwash plains, deltaic fans or tidal flats (watt). The studies were carried out in four, partly glaciers covered catchments of Scottbreen, Renardbreen, Cramerbreane (Chamberlindalen) and Recherchebreen, and mouthing into the Recherchefjorden (NW part of Wedel Jarlsberg Land, Svalbard). The most significant changes concerned the areas in close vicinity of the fronts of the glaciers. The direct influence of the glacier systems and proximity of the outflow of proglacial waters facilitated intensive aggradation of the coastal zones where glacial, fluvioglacial and marine processes interacted. Approximately 30 km of the coast of Recherchefjorden was under the direct influence of glacier systems. The recession of the glaciers in the 20th century led to the formation of more than 20 km of new shoreline, especially in the forefield of the Renardbreen and Recherchebreen. The sections of the coastline located in the estuary area of the Scottbreen and Chamberlindalen catchments were supplied with terrigenous sediments with various intensity throughout the whole observations period (indirect influence). Moreover, in the case of Scottbreen catchment mouths, the direct interaction of marine processes (wind waving), their configuration and magnitude are important. The aggradation of the coastal zone occurred by widening of the storm ridge that surrounded the outwash plain. There is lack of accumulation within the tidal flat and the offshore zones, with its typical abrasion platform. The different situation was observed in the mouth section of the Chamberlindalen catchment subjected to direct waving influence. The surface of the tidal flat mainly aggraded during high water. Finegrain sediments were mostly deposited to the tidal flat. Whereas, during the ebbing tide, certain amounts of sediments are carried out of the catchment with a few tidal channels, subaqual delta cones are developed at their mouths. The delimitation of the upper border of the tide influences in the area of the contact between outwash plains and fiord waters is impossible according to the set of methods used.
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A contoured surficial geology and geomorphology map of the forelands of the Hørbyebreen, Svenbreen and Ferdinandbreen valley glaciers in Petuniabukta, Svalbard was compiled from an orthophotograph based upon aerial photographs taken in 2009. The map reveals typical polythermal glacial landsystems, comprising ice-cored latero-frontal moraine arcs grading up valley into fluted till surfaces draped by supraglacially-derived longitudinal debris stripes. The additional occurrence on the Hørbyebreen foreland of linear esker and debris ridges arranged in a geometric ridge network is thought to be related to the infilling of densely spaced crevasses, created during a period of elevated meltwater pressures and ice hydrofracturing. These landforms were associated either with a jökulhlaup that was blocked by the frozen snout or an historical surge. The Hørbyebreen landform assemblage therefore constitutes an analogue for either: (1) spatial and temporal landsystem overprinting (polythermal and surging activity); or (2) a more refined polythermal landsystem in which the build up and release of meltwater reservoirs in warm-based interiors of polythermal glaciers give rise to a particularly diagnostic landform at the up-ice junction with the cold-based snout.
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The beaches under study are characterized by distinctly different magnetic signatures in terms of their concentration and magnetic grain sizes. Seasonal variation in accumulation and erosion is seen at Vengurla Beach (Stations 1—7), which is moderate to very low premonsoon, high to low during monsoon season, and low to very low postmonsoon. Presence of fine single domain magnetic grains is moderate to high premonsoon, moderate to low during monsoon, and low postmonsoon at stations 1, 4, 7 (Vengurla beach), and 8 (Aravali beach). Aravali Beach has a very low concentration of magnetic minerals, precluding realistic assessment of its seasonal accretion—erosion pattern. At Redi Beach (Stations 15-20), the concentration levels of magnetic minerals are high premonsoon, which further increases during monsoon season, although at certain locations the rise continues postmonsoon. The sediments of these three beaches have variable proportions of magnetite, titanomagnetite, and hematite. The concentration of magnetic minerals is more at the northern (Stations 1 and 2) and southern (Stations 16-19) ends of Vengurla and Redi beaches, respectively. The provenance of magnetite and titanomagnetite can be attributed to Deccan traps and relict sands. This technique can complement the conventional methods and underlines the utility of magnetic parameters in studying sediment movement along the beaches.
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Distribution of precipitation in mountain areas is a complex problem and the subject of long-standing debate and controversy compounded by the paucity of high-altitude meteorological stations. This lack of knowledge is pronounced for the Arctic, where predictions of future climate suggest an amplified future response to various climatic forcing mechanisms. Against this background, knowledge on the late 20th-century precipitation in the Svalbard region is of specific interest because the major transport pathway of water vapour into the Arctic Basin is across the Svalbard region. In order to understand ongoing changes of geomorphic and glaciological activity on Svalbard, a mapping/modelling of the late 20th-century precipitation in central Spitsbergen is attempted. Existing meteorological observations and knowledge on the altitude of the approximate late 20th-century equilibrium line on glaciers within the study area are used. The modelling is a first approach only, and should subsequently be tested through field measurements at selected key sites within the study area.
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Twelve glaciers, representing various types, were investigated between 2000 and 2005, in a region adjacent to the northern reaches of Billefjorden, central Spitsbergen ( Svalbard ). On the basis of measurements taken using reference points, DGPS and GPS systems, analyses of aerial photographs and satellite images, geomorphological indicators and archival data their rates of deglaciation following the “Little Ice Age” (LIA) maximum were calculated variously on centennial, decadal and annual time scales. As most Svalbard glaciers have debris-covered snouts, a clean ice margin was measured in the absence of debris-free ice front. The retreat rates for both types of ice fronts were very similar. All studied glaciers have been retreating since the termination of the Little Ice Age at the end of 19th century. The fastest retreat rate was observed in the case of the Nordenskiöldbreen tidewater glacier (mean average linear retreat rate 35 m a-1). For land-terminating glaciers the rates were in range of 5 to 15 m a-1. Presumably owing to climate warming, most of the glacier retreat rates have increased several fold in recent decades. The secondary factors influencing the retreat rates have been identified as: water depth at the grounding line in the case of tidewater glaciers, surging history, altitude, shape and aspect of glacier margin, and bedrock relief. The retreat rates are similar to glaciers from other parts of Spitsbergen . Analyses of available data on glacier retreat rates in Svalbard have allowed us to distinguish four major types: very dynamic, surging tidewater glaciers with post-LIA retreat rates of between 100 and 220 m a-1, other tidewater glaciers receding of a rate of 15 to 70 m a-1, land terminating valley polythermal glaciers with an average retreat of 10 to 20 m a-1 and small, usually cold, glaciers with the retreat rates below 10 m a-1.
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In Northwestern and Central Spitsbergen geomorphological and botanical data were collected on slope deposits associated with infrequent meteorological events. In hillslope debris flows triggered by heavy rainfall, compact volumes of debris range from 1 to 600m3. Recurrence intervals of major episodes are tentatively estimated from lichenometry at 80 to 500 yr. Such debris flows are widespread in Spitsbergen and induce conspicuous geomorphological effects. Nevertheless, typical levees and lobes are small-sized because of the thinness of permafrost and they rarely survive more than one century. In contrast, catastrophic slush avalanches mobilize 1300 to 7000m3 of rock debris every 500 yr, forming long boulder tongues and fans. In Central Spitsbergen at least three generations of slush avalanche deposits have been identified and lichenometry suggests that such boulder tongues survive for at least 2000 yr. -from Author
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In this region eolian processes of deflation, transportation and accumulation can be traced which develop with different intensity and lead to different final effects. The observations permit the opinion that although wind action does not play a principal role in the morphogenesis of the investigated region it should nevertheless be taken into account when analyzing the whole complex of geomorphological processes taking place. -from Author
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The texture, composition, provenance, and transport of beach sediments and the roundness of sediment grains were studied on 22 beaches on the coasts of Crete in southern Greece. The studied beaches range from low-carbonate to high-carbonate beaches, where the texture and mineral composition of beach sediments and roundness of sediment grains display some degree of local variation. Beach sediments consist mainly of medium and coarse sand, being moderately well or well-sorted, symmetrical or negatively skewed and mesokurtic or leptekurtic. On beaches where no rivers enter the sea the mineral composition is closely related to nearby exposed coastal formations (sea cliffs, bluffs and rocks), the grain-size frequency distribution of beach sediments being nearly normal, and the roundness of sediment grains rather good. Where rivers discharge on to the beach or near to it, the mineral content of these beaches is related both to the coastal formations and the formations situated inland in the catchment basins of the rivers. Coastal abrasion and fluvial sediments on shores are mixed by waves and littoral drift, causing somewhat poorer sorting and roundness. Low-Mg calcite and quartz are the most common minerals (altogether 50-90%) in the beach sediments on Crete. The other common minerals are dolomite, feldspars, epidotes, pyroxenes, amphiboles, tourmaline, zircon, titanite and magnetite; the sources being mainly dolomites, phyllite-quartzites, ophiolites, flysch, and sandstones on the mountains and coasts of Crete. The direction of net littoral drift is determined mainly by the predominant wind and waves approaching from the direction of the greatest fetch, while the onshore winds and waves (the directions of the fetches arranged according to the length of the fetch) greatly determine the direction of seasonal littoral drift. These two wind factors together determine, to the large extent, the direction of seasonal littoral drift in the surf zone, whereas in the swash zone the direction is determined only by the onshore winds and waves. On the other hand, the prevailing wind and waves have a little effect on the direction of sediment movement on the coasts of Crete.
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Landward retreat (marine transgression) is a common response of coastal systems to rising relative sea level. However, given sufficient sediment supply, the coast may advance seaward. The latter response of gravel barriers has been recorded in parts of southeastern and northwestern Canada, where seaward-rising sets of beach ridges are observed in areas of Holocene RSL rise. Cape Charles Yorke, northern Baffin Island, is a 5 km long gravel foreland characterized by seaward-rising beach-ridge crest elevations. The prograded morphology of the Cape Charles Yorke foreland is a prime example of coastal response to a combination of rising RSL and abundant sediment supply, an unusual and little-documented pattern in the Canadian Arctic. The main gravel supply to Cape Charles Yorke is likely from eroding bedrock and raised marine deposits southwest of the foreland. Although not the dominant sediment source, the Cape Charles Yorke delta contributed to the formation of the foreland by sheltering it from easterly storm waves and providing an anchor point for the prograding ridges. The truncation of relict ridges by the modern shoreline suggests a recent regime shift from continuous deposition to predominant erosion. The cause and timing of this shift are unknown but could result from a recent dwindling in sediment supply, increased accommodation space, increased wave energy, and/or an accelerated rise of relative sea level.
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The general characteristics of arctic beaches are considered. Sample data on size distribution characteristics and roundness due to abrasion of modern beach material from three beaches in the Cape Ricketts-Radstock Bay area of southwest Devon Island are presented. The area is one of limited wave action due to the inhibiting effects of sea ice. Sorting and roundness values of the beach material provide indirect measures of wave energy and allow comparisons to be made with beaches in other environments. Changes in mean size, sorting and roundness values both along and across the beaches suggest longshore transport by wave action.
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The morphology, morphometry and active processes are described for two km long sections of one west facing and one east facing talus slope in central Spitsbergen. The rock delivery activity to the talus slopes was studied during three summers and compared with the meteorological conditions. The two slopes showed great differences in response to variations in direct sunshine, precipitation events and rapid temperature changes which may explain the observed differencies in morphology and morphometry. Thus, well developed debris flows were almost exclusively found on the east facing slope. A regional inventory of 570 1-km sections of debris slopes in central Spitsbergen showed that debris flows are more abundant in east and north facing slopes or on slopes in very narrow valleys, which supports this observation.
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The paper contains a description of soil processes and related forms in Spitsbergen--solifluction, rockfalls and avalanches. Two postglacial phases of solifluction are distinguished. A reactivation of solifluction processes has been discovered in recent years. It has been found that local hydrological conditions are particularly important for the development of these processes. The type of material is another conditioning factor. The process of slush avalanche is very dynamic in Spitsbergen; it occurs on slopes which possess conditions favouring retention of water and snow masses.
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Extensive ice-cored moraine complexes are common elements, marking the last advance of many Svalbard glaciers. Sediment gravity flows are among the most dynamic processes, transforming these landforms. The short-term (yearly and weekly) dynamics of mass-wasting processes were studied in a cm-scale using repetitive topographic scanning. We monitored several active sites on the forelands of two glaciers, Ebbabreen and Ragnarbreen, both of which are located near Petuniabukta at the northern end of Billefjorden in Spitsbergen. The surveys indicate high dynamic rates of landforms' transformation. The mean annual volume loss of sediments and dead-ice for the most active parts of the moraines was up to 1.8 m a− 1. However, most of the transformation occurred during summer, with the short-term values of mean elevation changes as high as − 104 mm day− 1. In comparison, the dynamics of the other (i.e. non-active) parts of the ice-cored moraines were much lower, namely, the mean annual lowering (attributed mainly to dead-ice downwasting) was up to 0.3 m a −1, whereas lowering during summer was up to 8 mm day− 1. Our results indicate that in the case of the studied glaciers, backwasting was much more effective than downwasting in terms of landscape transformation in the glacier forelands. However, despite the high activity of localised mass movement processes, the overall short-term dynamics of ice-cored moraines for the studied glaciers were relatively low. We suggest that as long as debris cover is sufficiently thick (thicker than the permafrost's active layer depths), the mass movement activity would occur only under specific topographic conditions and/or due to occurrence of external meltwater sources and slope undercutting. In other areas, ice-cored moraines remain a stable landsystem component in a yearly to decadal time-scale.
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The heavy rains of 10-11 July 1972 in Longyear valley, Spitsbergen were an extreme meteorological event Slides and debris flows corresponding to an average denudation of about 1 mm occurred in a small (6.8 km2) catchment area. The debris mantle of slopes in the area investigated has a wide range of particle sizes, and drainage is normally good. Debris flows were not triggered by longlasting rains, but when rainfall intensity increased to values higher than 2 mm/hour, risk of failure was reached. Factors which encouraged debris slides and flows, in addition to the intense rainstorm, were a permafrost table, pre-existing depressions on hillsides and hillside steepness. Judging from the morphology on Longyear valleys slopes and nearby areas, the rapid and sporadic mass movements have a considerable effect upon evolution of slopes in the high arctic area.
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Research into the magnitude of fluvial transport was carried out in the non-glacierised polar Dynamisk Bekken catchment in the region of Petunia Bukta, in the central part of West Spitsbergen. The study period included two ablation seasons (July–August) in 2008 and 2009. The stream flows from the glacial cirque cutting the north-western edge of the Wordiekammen Massif. The bedrock is composed of sedimentary rocks. The Dynamisk Bekken is periodic stream, mainly fed from snow cover from June to early September. The other components of the feeding in the ablation seasons are less effective precipitation and groundwater from the active layer of permafrost. Medium discharge was 27.4 dm3 s–1 ranging from 0.1 to 250.8 dm3 s–1. Average ionic composition of the water indicates the hydrogeochemical sulphate-bicarbonate-calcium type. A tendency of systematic increase in the proportion of sulphates and decreasing share of bicarbonate ions in the ionic composition of water during the ablation season was observed. This correlates with the gradual decrease in the discharge rate and the decrease of the meltwater in the stream feed. The proportion of geogenic components in the dissolved load material outflow from the catchment is 75%. It consists of mainly bicarbonates, sulphates and calcium, which are derived from the dissolving of limestone, gypsum and anhydrite. The average value of the chemical denudation was 0.35 t km–2 d–1 and the mechanical denudation 0.32 t km–2 d–1. The results are similar to those obtained in previous years, reflecting the relatively large stability of the polar environment.
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Sea ice limits the interaction of the land and ocean water in the Arctic winter and influences this interaction in the summer by governing the fetch. In many parts of the Arctic, the open-water season is increasing in duration and summertime sea-ice extents are decreasing. Sea ice pro-vides a first-order control on the physical vulnerability of Arctic coasts to erosion, inundation, and damage to settle-ments and infrastructures by ocean water. We ask how the changing sea-ice cover has influenced coastal erosion over the satellite record. First, we present a pan-Arctic analysis of satellite-based sea-ice concentration specifically along the Arctic coasts. The median length of the 2012 open-water sea-son, in comparison to 1979, expanded by between 1.5 and 3-fold by Arctic Sea sector, which allows for open water dur-ing the stormy Arctic fall. Second, we present a case study of Drew Point, Alaska, a site on the Beaufort Sea, characterized by ice-rich permafrost and rapid coastal-erosion rates, where both the duration of the open-water season and distance to the sea-ice edge, particularly towards the northwest, have in-creased. At Drew Point, winds from the northwest result in increased water levels at the coast and control the process of submarine notch incision, the rate-limiting step of coastal re-treat. When open-water conditions exist, the distance to the sea ice edge exerts control on the water level and wave field through its control on fetch. We find that the extreme values of water-level setup have increased consistently with increas-ing fetch.
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Abstract The sedimentary architecture of polar gravel-beach ridges is presented and it is shown that ridge internal geometries reflect past wave-climate conditions. Ground-penetrating radar (GPR) data obtained along the coasts of Potter Peninsula (King George Island) show that beach ridges unconformably overlie the prograding strand plain. Development of individual ridges is seen to result from multiple storms in periods of increased storm-wave impact on the coast. Strand-plain progradation, by contrast, is the result of swash sedimentation at the beach-face under persistent calm conditions. The sedimentary architecture of beach ridges in sheltered parts of the coast is characterized by seaward-dipping prograding beds, being the result of swash deposition under stormy conditions, or aggrading beds formed by wave overtopping. By contrast, ridges exposed to high-energy waves are composed of seaward- as well as landward-dipping strata, bundled by numerous erosional unconformities. These erosional unconformities are the result of sediment starvation or partial reworking of ridge material during exceptional strong storms. The number of individual ridges which are preserved from a given time interval varies along the coast depending on the morphodynamic setting: sheltered coasts are characterized by numerous small ridges, whereas fewer but larger ridges develop on exposed beaches. The frequency of ridge building ranges from decades in the low-energy settings up to 1600 years under high-energy conditions. Beach ridges in the study area cluster at 9.5, 7.5, 5.5, and below 3.5 m above the present-day storm beach. Based on radiocarbon data, this is interpreted to reflect distinct periods of increased storminess and/or shortened annual sea-ice coverage in the area of the South Shetland Islands for the times around 4.3, c. 3.1, 1.9 ka cal BP, and after 0.65 ka cal BP. Ages further indicate that even ridges at higher elevations can be subject to later reactivation and reworking. A careful investigation of the stratigraphic architecture is therefore essential prior to sampling for dating purposes.
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Ragnarbreen is a small glacier located in the central part of Spitsbergen Island (Svalbard archipelago) and fed by the larger ice mass of Mittag-Lefflerbreen. Glacier recession and landforms' development in the foreland of Ragnarbreen are quantified using time-series orthophotos and digital elevation models, which were generated based on aerial photographs from 1961 (black and white frame camera), 1990 (false infrared frame camera) and 2009 (colour digital camera), obtained from the Norsk Polar Institute. Receding from its maximum Little Ice Age extent, attained in the period 1900/1920–2013, the glacier margin retreated by 1658 m while the extent of the area of ice decreased by 26%. The glacier snout lost 135 million m3 of ice during the period 1961–2009, whereas landform changes (mainly due to dead-ice melting and debris flow activity) were more than twenty-five times lower, with the less than 5 million m3 of sediment and dead ice volume loss. In terms of landscape alteration between 1961 and 2009, the most important was the creation of a terminoglacial lake, which acted as a sedimentary trap and at the same time probably accelerated glacier retreat. The second most active component was the lateral moraines whose transformations were divided into four phases, with various magnitudes of debris flow and backwasting activity that changed with time. The end moraine complex was the most stable component, affected mainly by dead-ice downwasting and to a lesser extent by sporadic debris flows.
Article
Coastal erosion rates locally exceeding 30 m y−1 have been documented along Alaska's Beaufort Sea coastline, and a number of studies suggest that these erosion rates have accelerated as a result of climate change. However, a lack of direct observational evidence has limited our progress in quantifying the specific processes that connect climate change to coastal erosion rates in the Arctic. In particular, while longer ice-free periods are likely to lead to both warmer surface waters and longer fetch, the relative roles of thermal and mechanical (wave) erosion in driving coastal retreat have not been comprehensively quantified. We focus on a permafrost coastline in the northern National Petroleum Reserve–Alaska (NPR-A), where coastal erosion rates have averaged 10–15 m y−1 over two years of direct monitoring. We take advantage of these extraordinary rates of coastal erosion to observe and quantify coastal erosion directly via time-lapse photography in combination with meteorological observations. Our observations indicate that the erosion of these bluffs is largely thermally driven, but that surface winds play a crucial role in exposing the frozen bluffs to the radiatively warmed seawater that drives melting of interstitial ice. To first order, erosion in this setting can be modeled using formulations developed to describe iceberg deterioration in the open ocean. These simple models provide a conceptual framework for evaluating how climate-induced changes in thermal and wave energy might influence future erosion rates in this setting.
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A bar on the Brazos River near Calvert, Texas, has been analyzed in order to determine the geologic meaning of certain grain size parameters and to study the behavior of the size fractions with transport. The bar consists of a strongly bimodal mixture of pebble gravel and medium to fine sand; there is a lack of material in the range of 0.5 to 2 mm, because the source does not supply particles of this size. The size distributions of the two modes, which were established in the parent deposits, are nearly invariant over the bar because the present environment of deposition only affects the relative proportions of the two modes, not the grain size properties of the modes themselves. Two proportions are most common; the sediment either contains no gravel or else contains about 60% gravel. Three sediment types with characteristic bedding features occur on the bar in constant stratigraphic order, with the coarsest at the base. Statistical analysis of the data is based on a series of grain size parameters modified from those of Inman (1952) to provide a more detailed coverage of non-normal size curves. Unimodal sediments have nearly normal curves as defined by their skewness and kurtosis. Non-normal kurtosis and skewness values are held to be the identifying characteristics of bimodal sediments even where such modes are not evident in frequency curves. The relative proportions of each mode define a systematic series of changes in numerical properties; mean size, standard deviation and skewness are shown to be linked in a helical trend, which is believed to be applicable to many other sedimentary suites. The equations of the helix may be characteristic of certain environments. Kurtosis values show rhythmic pulsations along the helix and are diagnostic of two-generation sediments.
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Gravel beaches are a very important part of the world's coastline.Their morphodynamic behavior and the palaeoenvironmental implications of long-term changes in their morphodynamics are vital to coastal defense strategies, because these beaches protect many low-lying coastal zones from storm effects. In contrast to the wealth of research on hydrodynamics and sediment transport processes on sandy coasts, comparable studies on gravel beaches are few. The paucity of detailed process measurements on these beaches has been attributed to the difficulty of deploying sensitive equipment in energetic environments with mobile gravel-size clasts. Gravel beaches are, however, rather paradoxical in terms of mobility. The specific morphological features of gravel beach shorefaces, notably the lack or the poor development of a surf zone, imply a significant role by swash zone processes acting on the steep beachface, notably the control of swash asymmetry on beach gradients and in accretion or erosion phases. While swash processes are undoubtedly important in controlling the morphology of gravel beaches, the character of swash is dependent on the transformation of incident waves as they shoal, break, or surge and interact with the steep beachface.
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This paper compares means, standard deviations and standard errors for length, breadth, thickness and weight of samples of 500 quartzite and flint/chert pebbles from six beach crest sites on the shingle beach at Chesil Beach, Dorset, England. Because of the conditions prevailing, grading alongshore is especially well developed but the principles apply elsewhere. The data are used in examining various shape ratios and indexes including LÜTTIG 's (1956) sigma (σ) and pi (π), the Wentworth (1922)-Cailleux (1945) flatness index, Krumbein's (1941) sphericity index, and the maximum projection index of Sneed and Folk (1958). It is shown that the only comparable dimension or index between the quartzite and flint/chert population is thickness. Since the specific gravity of both lithological types is the same it would appear that over the range of pebble sizes and shapes present on this beach, thickness is the critical dimension in determining the overall sorting of pebbles by wave action.
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A university-level textbook which covers not only the physical and biological aspects of coastal evolution, but also deals at length with coastal management and coastal hazard. Topics covered include chapters on wave dominated coasts, the long-term development of coasts, sea level changes, coastal dunes and coastal management, management structure and organization. There are about 1600 references and an index. -K.Clayton
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On the basis of particle shape the surface layers of some South Wales beaches are subdivided into four zones:--a large disc zone landward, typified by cobble sized discs, having on its seaward side the imbricate zone composed mainly of imbricate disc-shaped pebbles. Seaward of the imbricate zone lies the infill zone where spherical and rod shaped pebbles (drawn from a reservoir, underlying the large disc zone, and in which there are particles with a shape and size making them potentially capable of rapid seaward transport) infill a framework of spherical cobbles fringing the seaward margin. The spherical cobble framework is called the outer frame. Particle shapes are not so much made as used on these beaches; and particle shape differentiation is related to settling velocity, pivotability, and ability to filter through the porous gravels. Discs are not produced by a special feature of marine abrasion: the most oblate discs are found in areas least worked on by the sea. Composition is a function of particle size and shape; particle size and shape vary systematically across the beach; so composition and maturity indices are also seen to vary in a similar way. In the reworking of the boulder clays, which forms a source for much of these marine gravels, two processes are recognised: the post glacial weathering of the boulder clays and abrasion on the beach. Both are selective in that they affect the labile (in this case a subgreywacke) more than the stable (in this case, quartzites). Weathering and abrasion work to split greywackes into discs. At the same time destruction of this kind in always reducing the number of large and increasing the number of small particles, produces a size maturity correlation where the coarser grains are more mature than equivalent sizes in the original boulder clay, but possibly the finer are less mature than equivalent sizes in the original boulder clay. As abrasion further continues, (exemplified here on one beach) the composition shape function begins to disappear, and maturity greatly increases with size. Particle size parameters vary across the beach. Changes in standard deviation and skewness are, to a considerable extent, effected by either the removal from, or addition of small coarse modes to large fine. Size frequency and shape frequency are combined in an attempt to understand more fully the type and extent of sediment movement taking place in these gravels. The beaches are divided into two types: the one on breakdown building up to the seaward a succession of coarse spherical cobbles infilled with spherical and rod shaped pebbles; the other an alternation of beds containing spherical and rod-shaped grains with beds of disc-shaped grains.
Article
Approximately 90% of Canada's ocean coastline is affected by seasonal or multiyear sea ice and winter ice develops on most lakes. Recent studies of ice effects in the shore zone have included investigations of ice-congested and protected shores in the north-west Canadian Arctic Archipelago, processes involved in the construction by ice of large shore ridges in the same region, direct ice scour and enhanced hydrodynamic scour in the presence of ice (strudel scour and ice wallow), particularly as potential hazards to buried pipelines in the Beaufort Sea, and the dynamics of boulder-strewn tidal flats and boulder barricades in eastern Canada. The extent and frequency of shore nourishment by ice and details of the processes involved, including die relative importance of ride-up versus pile-up, remain important research questions. Reports emphasizing the contribution of ice rafting to shoreface retreat along the Alaskan coast of the Beaufort Sea suggest the need for quantitative studies of this phenomenon in Canada, in particular with respect to prodelta sedimentation at the mouth of the Mackenzie River. The coastal zone in the Beaufort Sea is particularly sensitive to climate change through effects on thermokarst processes, rising sea level, the relation between ice cover and wave energy through fetch limitation, and potential changes involving ice dynamics and freeze-up processes.
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Sedimentation from suspensions was quantified, and its primary controls were investigated in Billefjorden, a subpolar fjord in Svalbard. Measurements of fjord hydrology,suspended particulate matter concentration, vertical downward flux of particulate matter, and distribution of grain size in material collected in sediment traps were conducted in the summer and autumn. Measurements were performed in two settings:glacier-contact and non-glacier contact. The first, Adolfbukta, is a bay with a large tidewater glacier and the second, Petuniabukta, is an inlet supplied by meltwater rivers that cross the tidal flat. The vertical particulate matter fluxes in both settings are as high as several thousand g/m�2/day during the short summer season and tens of g/m�2/day in the autumn. Sedimentation is dominated by settling from surface turbid water plumes and is largely the result of flocculation. This results in poorly sorted sediments, most of which are trapped either within a few hundred metres proximal to the meltwater inlet in the case of rivers ending on tidal flats, since flocculation occurs on the tidal flat; or within the first few km in the case of tidewater glaciers, where flocculation occurs after the sediments reach fjord waters. In the autumn, the fluxes diminish more than the concentration of suspended particulate matter, and the residence time of the suspended matter in the water lengthens. The major factors controlling particulate matter flux are the positions of freshwater inlets (surface/subsurface), meltwater discharge, suspended matter concentration in meltwater rivers, local wind damming effects, and tidal range (enhanced fluxes during spring tides). In the waters near the fjord bottom, the fluxes are usually higher due to resuspension and possibly turbidity currents or slumps.