Pleiades and paraglacial dynamic in Arctic: the central Loven glacier and moraine unit (Spitsbergen, 79 ° N)

Abstract

In the Arctic the impact of contemporary global warming accelerates the melting of glaciers since the end of the Little Ice Age (LIA). Alongside great glaciers and ice caps that give the key trends and regional rhythms of contemporary dynamics it is interesting to focus the research on small systems foothills. These provide information on the dynamics paraglacial who help shape the landscape while the glacier is no longer while releasing surfaces for gas exchange with the atmosphere - especially soil organic carbon - previously blocked by ice. Moraines are so privileged place where spend most of the dynamics, while runoff is increasing because of the melting and remobilised chaotic shapes of glacial deposits, vegetation - if scattered is it - tends to contrary to stabilize the substrate while providing a diversity that is not found in the oldest areas equilibrium, such as the open tundra installed since the last major glaciation of the Weichselian (110 000 - 10 000 years) at the beginning Holocene. Spitsbergen (Svalbard) in the Bay of Roy on the western coast of the island, the site of glaciers Loven (79 ° N, 12 ° E) is the subject since the early 60's environmental research that diversified since the creation of the international base of Ny-Alesund in 2000. This research is based inter alia on geographic data that can keep pace with the melting since 1936 (topographic maps and aerial photographs). An integrated approach to the dynamics of the processes involved in the moraines also requires detailed knowledge of the terrain and its remobilization by runoff. The Digital Elevation Models (DEM) derived from ancient documents did not provide sufficient spatial resolution and accuracy to integrate survey data into the modeling of the phenomena studied. Since the early 90s we used to survey campaigns DGPS (Differential Global Positioning System) to obtain very sharp images of terrain but the approach is limited by the small surface that can be covered with a density sufficient points for honor details awaited. Stereoscopic data ASTER GDEM (Global Digitized Elevation Model) or SPOT 5 HRG (High Resolution Geometric) do not meet either of these requirements. Airborne LIDAR turns out very accurate but if it is only the cost of an airborne mission to Spitsbergen is unacceptable. The Pleiades data therefore seem ideal to meet our expectations, spatial resolutions and elevation details announced meet our requirements. We intend to demonstrate here the relevance of MNE Pleiades (tri-stereoscopic stereoscopic April 2013 and August 2013) to integrate the parameters of relief (elevation, slope, orientation, roughness, fractal dimension, watershed drains, niches ...) in the analysis of environmental phenomena involved in the moraines of the LIA.