A new tool to characterise the socio-environmental dimensions of urban rivers: Urban river socio-environmental index

Résumé : Numerous studies have highlighted the dramatic hydro-geomorphological and ecological alterations that are the hydrological consequences of urban sprawl. However, most studies did not include the social dimensions. We propose an innovative interdisciplinary approach that combines biophysical and social issues using an example in the Paris urban area. We developed an Urban River Socio-environmental index (URBS) as a practical tool to assess the socio-environmental quality of the stream environment and social connectivity. The URBS is a multi-criteria index composed of four indicators calculated at the reach scale: hydro-geomorphology, macroinvertebrates, riparian vegetation, and social connectivity. We used the index to assess the organisation of several reaches along the stream and to provide a detailed functional socio-environmental typology. To exemplify the discussion, we used the URBS to assess the current situation of the Morbras River. Our results highlight the marked longitudinal diversity of urban streams and call for a combination of watershed and territorial approaches to management and/or restoration. This approach makes it possible to account for the diversity of territories thereby avoiding a form of landscape standardisation or ‘blandscaping’.