Analyse à l'échelle régionale de l'impact de l'occupation du sol dans les corridors rivulaires sur l'état écologique des cours d'eau

摘要

This work focuses on the spatial characterization and quantification of the influence of surrounding pressures (land cover at different scales, from watershed to local riparian corridor) on the ecological status of rivers. Addressed at the regional level the study pays particular attention to riparian corridors for their interest in developing strategies for the preservation and restoration under the European Framework Directive on Water. It relies on the development of robust and reliable methodologies concerning (i) fine-scale mapping of land cover within riparian corridors, (ii) construction of spatial indicators reflecting this occupation and (iii) building pressures / impacts models quantifying links between land cover within riparian corridors and the ecological state of aquatic environments. The results using these methodological advances have demonstrated the value The results using these methodological advances have demonstrated the value of having a land cover data at Very High Spatial Resolution over large areas and using indicators calculated within a wide range of riparian footprints reflecting the impact mechanism of a given land cover category on the ecological status to improve the identification and location of sources of pressure in these spaces. They also highlight at regional level the significant role of riparian plant communities on ecological status of rivers, both on a band 20 m on either side of the watercourse.