Improving river restoration policy: a few discussion points following 10 to 20 years of actions.

International audienceReaching a “good ecological status” of rivers is a challenging issue for the EU state members in charge of implementing the Water Framework Directive. In this domain, acting on hydromorphological drivers is one way which is known as restoring rivers. After almost 10 to 20 years of actions in this domain, a few feedbacks can be discussed for improving policy. Especially, very basic questions can be reconsidered with the new lights of these feedbacks. Why should we restore rivers? Definition of river restoration evolved over the last two decades and a conceptual and social debate is still needed to reconsider objectives. The second question which is also in discussion is “where?”, where restoring rivers? There is a clear need to improve network understanding to establish a top down strategy to define priorities, improve planning design and target actions. “How restoring rivers” is another critical question. Should we primarily act on forms or on processes? Assessing the sensitivity of rivers to change is a clear challenge to evaluate the sustainability and efficiency of potential restoration actions and has also consequences in term of diagnosis. “How” is also related to gaining experiences and knowledge for implementing these new measures. Monitoring efforts combined with modeling are critical for assessing restoration success and then designing successful measures