Actual paraglacial progradation of the coastal zone in the Kongsfjorden area western Spitsbergen Svalbard

DENIS MERCIER1 & DOMINIQUE LAFFLY2 1 Department of Geography University of Paris 4 Sorbonne, 191 rue Saint Jacques 75 005 Paris, France (e-mail: denis. [email protected] sorbonne.fr) 2Department of Geography University of Pau avenue du Doyen Poplawski 64 000 Pau, France (e-mail: dominique. laffly @ univ-pau.fr)

Abstract: This research was carried out on the Br0gger Peninsula, northwest Spitsbergen, Svalbard (79°N 12°E). In the western part of Spitsbergen, cold-based valley glaciers have retreated more than 1 km from their Little Ice Age limits, and glacial meltwater has extensively reworked glacigenic sediments on exposed glacier forelands. In such areas, a paraglacial sediment transport regime has become predominant, with runoff as the dominant process. A combination of GIS, DEM, aerial photographic and field data was employed to estimate shoreline progradation at sandur outflows. Average shoreline progradation is estimated to amount to 3 m/annum over the last 30 years, a period of uninterrupted sediment provision from the glacial runoff system.

Since the end of the Little Ice Age, high-latitude glacier margins have undergone net retreat in response to changing meteorological conditions, with associated geomorphological consequences (Hansen 1999; Lefauconnier et al. 1999; F0rland & Hanssen-Bauer 2000; Hanssen-Bauer & F0rland 1998; Six et al. 2001; Hanssen-Bauer 2002; Humlum 2002; Rippin et al. 2003; Hagen et al. 2003). As a result, parts of Spitsbergen are experiencing a transition from a landscape dominated by glacial and periglacial processes to one in which paraglacial landscape response is predominant (Mercier 2000, 2002), as are other glacier margins all over the world (Ballantyne 2002). In western Spitsbergen (Kongsfjorden, Isfjorden, Bellsund, Hornsund areas) cold-based valley glaciers have retreated more than 1 km from their Little Ice Age maxima (Hagen et al. 1993), and glacigenic sediments exposed by glacier retreat are being extensively reworked by proglacial meltwater streams. This paper employs GIS-based analysis of geomorphological changes that have occurred since the end of the Little Ice Age to demonstrate how seaward progradation of the outwash plain is associated with periods of high glacifluvial sediment supply to the shoreface, whereas coastal erosion and shoreline recession predominate when glacifluvial sediment flux is reduced.

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