Abstract
The southwest of the Indian Ocean comprises numerous islands of less than 3000 sq km (Comoros, Seychelles, Mascarene Islands). These small island territories have very fragmented and diversified environments. Satellite imagery and products at low and medium spatial resolution (usually from 4 kilometers to 250 meters) are not or poorly suited to the study of these areas. This is particularly the case for ecological studies such as the study of vector-borne diseases where the evaluation of interactions at a fine scale is critical to understand their spatial dynamics. To overcome this need, we realized a homogeneous land cover mapping of these small islands, by analysing SPOT 5 satellite images acquired between July 2013 and July 2014 by SEAS-OI Station. We used an object-based image analysis method to identify the 12 major classes of land cover / land use of these tropical islands. This methodology together with a good knowledge of the field has enabled us to achieve an overall accuracy of 85%, making it an operational product. In order to illustrate the importance of this dataset, we present its use in health research to describe thelocation of health observations: whether the place of residence of patients or the points of capture of disease vectors through several examples in Reunion, Mayotte, the Union of the Comoros and the Republic of Seychelles. In these studies, high resolution allows to provide very fine information on the surrounding environment, while little data is usually available at this scale. In the statistical analyzes, these data were mainly used to differentiate between infected and non-infected individuals. This high resolution landcover is available on a web portal to allow a wider distribution to researchers and thematicians using land cover information in their field.