| Summary: | International audience The aim of this research, carried out at Spitsbergen (Svalbard) over a 13-years period (2009-2022), is to monitor changes in the transfer of sedimentary and liquid flows from the continent to Konsfjiorden. The idea is to identify periods, threshold values, when the system switches from glacial to periglacial and to identify the associated processes. As a result of climate change, the deltas (the emmerged parts) and prodeltas (the submerged parts) will prograde, stagnate or even be eroded. These sedimentary structures are fed by sub-glacial rivers draining material from basal moraines formed by continental glaciers (Le Vestre and Middre-Lovenbreen). We used Edgetech 272 TD side-scan sonar and acquired acoustic mosaics, calibrated with sediment samples, to track the evolution of the prodeltas. Thus, we identified 3 phases: progradation, erosion and finally stabilisation of the prodeltas. At the same time, onshore acquisition of the coastline with a DGPS, enabled us to monitor the evolution of the deltas. By using this 'actual' in situ data to calibrate the 'Sentinel 2' satellite measurements, it is possible to trace this coastal line over the last 25 years, thanks to the processing carried out on the Sentinel2 images.Finally, to try and estimate the transfer of flows between the glaciers and the fjord, we are working on data from gravity satellites (GNSS and Grace) which measure mass transfers and enable us to assess the isostatic rebound of the continent, with millimetric resolution. These complementary approaches enable us to understand the system as a whole.
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