Using a small COTS UAV to quantify moraine dynamics induced by climate shift in Arctic environments

International audienceArctic regions are known to be places where climate shift yields the most visible consequences. In this context, glaciers and their environment are highly subject to global warming effects. New dynamics are observed and the behaviour of arctic systems (such as glaciers, moraines, beaches, etc.) changes at rates visible over yearly observations. According to recent works on climate change impacts on the cryosphere, short/violent events are recently observed and are one characteristic of these changes. As a consequence, an accelerating rate of glacial and pro-glacial activity is observed, especially at the end of each hydrological season (early fall). As an example, many phases of streamflow increase/decrease are observed, transforming glacier outflows, moraine morphology, and re-organizing intra-moraine processes. Within only a few days, the morphology of some parts of the moraine can be completely changed. In order to observe and quantify these processes, reactive methods of survey are needed. That is why the use of commercial off the shelf - DJI Phantom3 Professional - unmanned aerial vehicle (UAV) for aerial photography acquisition combined with structure from motion analysis and digital elevation model computation were chosen. The robust architecture of this platform makes it well suited as a reliable picture acquisition system for high resolution (sub-decimetre) imaging. These increasingly popular methods, at a convergence of technologies including inertial guidance systems, long lasting batteries, and available computational power (both embedded and for image processing), allow to fly and to acquire data whatever the conditions of cloud cover. Furthermore, data acquisition is much more flexible than traditional satellite imagery: several flights can be performed in order to obtain the best conditions/acquisitions at a high spatiotemporal resolution. Moreover, the low-flying UAV yielding high picture resolution allows to generate high-resolution digital elevation models, and therefore, to measure accurately dynamics on the field with decimetre resolution in all three directions. Our objective is to show an experimental campaign of small UAV data acquisition in an arctic basin (Austre Loven glacier, Svalbard, 78 degrees N) separated by a few days. Knowing the changing conditions at this period, similar UAV flights have been reiterated in order to catch moraine dynamics. This allowed us to select two sets of images whose processing highlights and quantifies morphological changes into the moraine while a rain event occurred between two cold periods