Verlag der Österreichischen Akademie der Wissenschaften

Abstract:
The Department of Geoinformatics of the University of Salzburg Z_GIS offers mapping products of camps of displaced people to support the operational work of Médecins Sans Frontières (MSF – Doctors Without Borders) and other humanitarian actors. These maps are usually based on very-high resolution satellite imagery, featuring a spatial resolution of up to 30cm/pixel. These very detailed satellite images allow the extraction of individual dwellings as the basis for a detailed estimation of the population of a particular camp. Such images are acquired on demand only, and are priced by square kilometre, making reconnaissance observations over larger areas or repetitive monitoring tasks very costly. In contrast, the European satellite Sentinel-2A, launched in June 2015, features global coverage, a ground resolution of 10m/pixel, and its imagery is available free of charge. In this ongoing study, we explore the potential of Sentinel-2A imagery for the monitoring of refugee camps and camps for internally displaced persons (IDPs), either using only Sentinel-2 images, or using a combination of Sentinel-2 and VHR imagery. As expected, the spatial resolution of Sentinel-2 is just at the limit of what is required for mapping such camps. Therefore, the operational use of it depends on the size and the structure of the camp (planned vs. spontaneously formed), and the season, governing the contrast between dwellings and soil/vegetation. Sentinel-2 imagery can be a valuable asset to increase situational awareness, can help guide the acquisition of VHR images, and, in conjunction with analyses on VHR images, can allow a semi-continuous monitoring of dwelling numbers with a reasonable margin of error, of around 10%, as compared to VHR analyses alone.