Dynamique des bassins-versants et vulnérabilité des récifs coralliens

L\u27intervention débute en pointant l\u27accentuation de l\u27érosion des sols sur les bassins versants, à cause de l\u27occupation du sol et des activités anthropiques. Une partie de ces particules érodées se retrouve à l\u27exutoire littoral, influant sur la qualité des eaux de mer, et donc sur la santé des récifs coralliens. Il faudrait donc pouvoir modéliser le transit de matière des bassins versants aux zones côtières. Pour ce faire, plusieurs étapes sont prévues : classification de l\u27occupation du sol par des images satellites SPOT5, développement d\u27un modèle de sensibilité à l\u27érosion, élaboration d\u27indicateurs spatialisés sur les bassins versants et à leur exutoire

Monitoring and mapping forest fires in the south-western Indian Ocean using very high resolution optical imagery

International audienceThe South-western Indian Ocean is characterized by various heterogeneous insular territories. Many of these islands are biodiversity hotspots and in order to preserve this heritage, some of them are protected. In La Reunion, the Parc National (created in 2007 and on the UNESCO world heritage list since 2010), covers 40 % of the territory while since 2006, Europa island (Shattered Islands) is a national natural reserve where some areas are integrally protected. Forest fires are a major threat to these areas of preserved biodiversity. Last main fires in La Reunion occurred in 2010, 2011 and 2013, and in june 2013 on Europa island.In 2013, the monitoring and mapping of the fires of Etang-Saint-Paul (July, La Reunion) and Europa (June) were carried out by the SEAS-OI (Survey of Environment Assisted by Satellites in the Indian Ocean), in collaboration with the ONF (Office National des Forêts) of La Reunion and the SDIS (Service Départemental d’Incendie et de Secours), using high resolution SPOT 5 imagery. These maps allowed the estimation of the fire extent, to about 4 and 70 hectares for Europa and Etang-Saint-Paul respectively, and to support field intervention during the crisis.In both cases, the monitoring of post-fire recovery of the affected areas was realized using PLEIADES images acquired by the SEAS-OI station in the frame of the CNES RTU. This part of the study is still ongoing and aim at taking advantage of the very high spatial resolution offered by PLEIADES products in order to quantify precisely the extent of the burned surface during both fires, and provide first insights on the post-fire evolution in terms of plant recolonization. This is an important issue in these protected areas where the ecosystems are threatened by the post-fire settlement of invasive species.This study was part of the operational mission of the SEAS-OI station, gathering local actors in the management of forest fire crisis in the south-western Indian Ocean. In particular, we demonstrate here the interest of the satellite approach in the management of natural disasters on remote territories like Europa island, and in protected areas where a rapid response is needed. Thanks to the combination of optical SPOT 5 and PLEAIDES high resolution products, SEAS-OI was able to provide operational products for the management of these fires. These applications led to a partnership between SEAS-OI, the ONF and the SDIS, whose objective is to use satellite images to monitor the protected territories of the Iles Eparses

Monitoring and mapping forest fires in the south-western Indian Ocean using very high resolution optical imagery

International audienceThe South-western Indian Ocean is characterized by various heterogeneous insular territories. Many of these islands are biodiversity hotspots and in order to preserve this heritage, some of them are protected. In La Reunion, the Parc National (created in 2007 and on the UNESCO world heritage list since 2010), covers 40 % of the territory while since 2006, Europa island (Shattered Islands) is a national natural reserve where some areas are integrally protected. Forest fires are a major threat to these areas of preserved biodiversity. Last main fires in La Reunion occurred in 2010, 2011 and 2013, and in june 2013 on Europa island.In 2013, the monitoring and mapping of the fires of Etang-Saint-Paul (July, La Reunion) and Europa (June) were carried out by the SEAS-OI (Survey of Environment Assisted by Satellites in the Indian Ocean), in collaboration with the ONF (Office National des Forêts) of La Reunion and the SDIS (Service Départemental d’Incendie et de Secours), using high resolution SPOT 5 imagery. These maps allowed the estimation of the fire extent, to about 4 and 70 hectares for Europa and Etang-Saint-Paul respectively, and to support field intervention during the crisis.In both cases, the monitoring of post-fire recovery of the affected areas was realized using PLEIADES images acquired by the SEAS-OI station in the frame of the CNES RTU. This part of the study is still ongoing and aim at taking advantage of the very high spatial resolution offered by PLEIADES products in order to quantify precisely the extent of the burned surface during both fires, and provide first insights on the post-fire evolution in terms of plant recolonization. This is an important issue in these protected areas where the ecosystems are threatened by the post-fire settlement of invasive species.This study was part of the operational mission of the SEAS-OI station, gathering local actors in the management of forest fire crisis in the south-western Indian Ocean. In particular, we demonstrate here the interest of the satellite approach in the management of natural disasters on remote territories like Europa island, and in protected areas where a rapid response is needed. Thanks to the combination of optical SPOT 5 and PLEAIDES high resolution products, SEAS-OI was able to provide operational products for the management of these fires. These applications led to a partnership between SEAS-OI, the ONF and the SDIS, whose objective is to use satellite images to monitor the protected territories of the Iles Eparses

Using the OpenStreetMap database to improve an object-based classification process. Application to a landcover product on small islands in the Indian Ocean

International audienceThe 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. To improve the results of this classification, we used some data from the free and participative OpenStreetMap (OSM) database as training data. These data were first checked and even completed to ensure their quality. This information helped us in particular to improve our results on agricultural areas (sugar cane, market gardening) and to define more precisely the main roads. 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 return, we fed the OSM database by integrating the classes for which we had the best accuracy (mangrove, surface water and forest). Indeed, OSM is a particularly interesting platform for releasing and disseminating land use data

GeoHealth and QuickOSM, two QGIS plugins for health applications

International audienceMaps and spatial analyses are increasingly used in the field of health to illustrate the spatial and temporal organization of data and to provide a geographical perspective on health data. Geographic Information Systems (GIS), and geomatics tools in general, are thus used by health organizations (local or international) to inform on the distribution of diseases, by managers to monitor and control epidemics, and by doctors and researchers to understand disease distributions. Scientific publications in the field of health also show the widespread use of spatial maps and analyses. Major organizations such as the World Health Organization, ministries of health in many countries, and research organizations have set up GIS laboratories with geomaticians or health geographers to conduct these tasks. However, many organizations do not have in-house expertise and still wish to conduct such analyses. More and more people in the field of health are thus being trained in geomatics, but implementation remains difficult due to the complexity of the tools and the often sporadic use

A free high resolution land cover on the small Indian Ocean islands, an example of its use with the study of vector-borne diseases

International audienceThe 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

Deux extensions de QGIS pour des applications en santé : GeoHealth et QuickOSM

International audienceDeux extensions de QGIS pour des applications en santé : GeoHealth et QuickOSM 7.1. Contexte de l'utilisation des SIG en santé et du développement d'extensions dédiées à la santé dans QGIS Les cartes et les analyses spatiales sont de plus en plus utilisées dans le domaine de la santé pour illustrer l'organisation spatio-temporelle des données et permettre un regard géographique sur les données sanitaires. Les systèmes d'information géographique (SIG), et plus généralement les outils de la géomatique, sont ainsi utilisés par les organisations de santé (locales ou internationales) pour informer sur la distribution des maladies, par les gestionnaires pour suivre et contrôler les épidémies, et par les médecins et les chercheurs pour comprendre les distributions des maladies. Les cartes et les analyses spatiales sont aujourd'hui régulièrement utilisées dans les publications scientifiques du domaine de la santé. Les grandes organisations comme l'Organisation mondiale de la santé, les ministères de la Santé de nombreux pays, des organismes de recherche, comme les Instituts Pasteur, se sont dotés de « cellules SIG » avec des géomaticiens ou des géographes de la santé pour réaliser ces tâches. Toutefois, beaucoup d'organismes n'ont pas les compétences en interne et souhaitent tout de même réaliser de telles analyses. De plus en plus de personnes du domaine de la santé se forment ainsi à la géomatique, mais n'en faisant usage que ponctuellement et avec des outils complexes, la mise en pratique reste concrètement difficile. Chapitre rédigé par Vincent HERBRETEAU, Christophe RÉVILLION et Étienne TRIMAILLE