4 research outputs found
Cartographier par télédétection l’occupation du sol et ses changements
Cet article présente une méthode de cartographie par Télédétection de l’occupation du sol et de ses changements à partir du cas de la Sénégambie méridionale. L’approche rétrospective adoptée s’appuie sur la comparaison entre les signatures spectrales dites de « référence » issues des vérités de terrain et celles des classes résultant de la classification multispectrale non supervisée des images prises à des dates antérieures. Le résultat est une cartographie des principales catégories d’occupation du sol à chacune des dates étudiées et de leur évolution dans le temps. Ont ainsi été mis en évidence les principaux changements des paysages forestiers sénégambiens : un important recul des boisements de terre ferme au nord de la région au cours de la dernière décennie et une régénération de la mangrove suite à l’amélioration des conditions pluviométriques.This article presents a method of mapping by remote sensing of land cover and its changes based on the case of Southern Senegambia. The retrospective approach adopted is based on the comparison between the so-called "reference" spectral signatures resulting from ground truths and those of the classes resulting from the unsupervised multispectral classification of images taken at earlier dates. The result is a cartography of the main land cover categories at each of the dates under study and their evolution over time. The main changes in the Senegalese forest landscape were thus highlighted: a significant decline in land afforestation in the north of the region over the last decade and a regeneration of the mangrove following the improvement in rainfall conditions
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Using co-production to improve the appropriate use of sub-seasonal forecasts in Africa
Forecasts on sub-seasonal to seasonal (S2S) timescales have huge potential to aid preparedness and disaster risk reduction planning decisions in a variety of sectors. However, realising this potential depends on the provision of reliable information that can be appropriately applied in the decision-making context of users. This study describes the African SWIFT (Science for Weather Information and Forecasting Techniques) forecasting testbed which brings together researchers, forecast producers and users from a range of African and UK institutions. The forecasting testbed is piloting the provision of real-time, bespoke S2S forecast products to decision-makers in Africa. Drawing on data from the kick-off workshop and initial case study examples, this study critically reflects on the co-production process. Specifically, having direct access to real-time data has allowed user-guided iterations to the spatial scale, timing, visualisation and communication of forecast products to make them more actionable for users. Some key lessons for effective co-production are emerging. First, it is critical to ensure there is sufficient resource to support co-production, especially in the early co-exploration of needs. Second, all the groups in the co-production process require capacity building to effectively work in new knowledge systems. Third, evaluation should be ongoing and combine meteorological verification with decision-makers feedback. Ensuring the sustainability of project-initiated services within the testbed hinges on integrating the knowledge-exchanges between individuals in the co-production process into shaping sustainable pathways for improved operational S2S forecasting within African institutions