L'Observatoire d'hydrologie urbaine un dispositif d'expertise innovant?

The environmental field is characterized by a variety of expertise systems that support local policies. "Urban hydrology observatories" are part of these public decision support systems: for several decades, they have been implementing an original dialogue on the topic of water management between scientists and practitioners of water and sanitation services. These observatories are set up in France in three large communities: Lyon, Nantes, and the Paris region. This article attempts to characterize this form of scientific collaboration, which reveals quite new practices: the co-construction of long-term programs, in-situ experiments, and the development of territorial research linked to local issues. The analysis underlines how the fact that researchers work with managers on a daily basis deeply transforms the working culture among technical services. Indeed, this scientific knowledge promotes a relatively cautious approach to innovation, by reintroducing doubt, reflexivity, and complexity.