Etalement urbain et évaluation de son impact sur la biodiversité, de la reconstitution des trajectoires à la modélisation prospective. Application à une agglomération de taille moyenne : Rennes Métropole.

Abstract : Urban sprawl modifies the land cover and the appearance of the countryside, increases threats to peri-urban agriculture, and impacts the environment. It causes disruption of the ecosystems and presents a serious threat to the biodiversity. In the present context of the accelerated increase of urban areas, the study of urban sprawl as well as the assessment and anticipation of its impacts interest both scientists and land managers. The objectives of this thesis is to accurately retrace the evolution of urbanization in Rennes Metropolitan, to appraise its impact on the structure of ecological habitats, and model its evolution under different scenarios in order to assess their consequences on land cover and biodiversity. Therefore, the development of a method to recall the course of land cover changes, based on remote sensing data, is first done. This method evidences the urban sprawl patterns at different scales beginning from the department of Ille-et-Vilaine since 1984 till small sites of some km² since 1952. Then, past and current urban landscapes is characterized using landscape metrics before relating landscape to biological data. Finally, land cover changes have been modelled under different scenarios with a cellular automation in order to evaluate the impacts of each one on land cover and biodiversity. The land cover changes observed from remote sensing data shows a net increase of the urban areas at each of the three considered scales, a decline of forests and green spaces outside the urban tract, a progressive fragmentation of artificial and green surfaces, in addition to a low connectivity of these green areas between the city and the suburbs. The analysis of the relationship between landscape and biological data shows that the urbanization substantially decreases the quantity of species as we move from suburban to urban ranges. It, also, affects but differently the taxa depending on their ability to disperse. The analysis of 2020 land cover projections under different scenarios shows an obvious evolution between 2005 and 2020. However, the difference is low perceptible between land cover scenarios and hence their impacts on biodiversity. These results can be explained by the fact that land cover changes in Rennes Metropolitan are highly constrained by the various planning documents already set, and certainly explained by the model and the accuracy of the data used. Key-words: Urban sprawl, Land cover, Remote Sensing, Object-oriented method, Landscape Metrics, Biodiversity, Modelling, Cellular Automaton, Scenarios.
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Géographie. Université Rennes 2, 2009. Français
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Rahim Aguejdad. Etalement urbain et évaluation de son impact sur la biodiversité, de la reconstitution des trajectoires à la modélisation prospective. Application à une agglomération de taille moyenne : Rennes Métropole.. Géographie. Université Rennes 2, 2009. Français. 〈tel-00553665〉

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