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Dynamique des paysages dans les régions septentrionales des Rivières-du-Sud (Sénégal, Gambie, Guinée-Bissau)

Abstract : This thesis aims the mapping and quantification of vegetation land cover changes in West-African coastal zone using LANDSAT TM images. A multistage unsupervised classification has been designed for this purpose. The objective was the mapping of land cover, with a predefined typology, by means of a reproducible method that could be easily generalized to other regions. The first step is an interpretation of the unsupervised classification, the clusters of which are regrouped according to the typology. The classification is improved by stretching radiometric contrasts with Principal Component Analysis applied to LANDSAT bands followed by a second unsupervised classification to re-classify properly the previously ill-classified cells. The analysis of time series LANDSAT images has shown that, during the last three decades wooded areas (both in mangrove and savannah) had known few changes. Within 25 years, wooded areas increased of less than 1 percent of wooded areas in 1979. However, this quantitative balance results from a first trend of reduction of wooded areas during the 1980’s followed by a second trend of increase during the 1990’s.
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Contributor : Julien Andrieu Connect in order to contact the contributor
Submitted on : Tuesday, March 17, 2015 - 8:49:57 AM
Last modification on : Sunday, June 26, 2022 - 12:20:02 AM
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  • HAL Id : tel-01132321, version 1


Julien Andrieu. Dynamique des paysages dans les régions septentrionales des Rivières-du-Sud (Sénégal, Gambie, Guinée-Bissau). Géographie. Univeristé Paris Diderot Paris 7, 2008. Français. ⟨tel-01132321⟩



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