Methodology for multifunctional assessment of riverine wetlands in the Seine river basin

A new policy for wetlands conservation in France induced the development of research on the main functions of these ecosystems. This paper summarizes the results of four studies initiated in the Seine River basin by scientists, the regional water agency and a water supply syndicate to assess some of the functions of wetlands, mainly of riverine wetlands. One was directly conducted at the scale of the whole basin, focusing on the role of wetlands in water supply, flood control and nutrient retention. A second one was centred on the importance of waterbodies more or less connected to the channel for fish communities and on the role of flooded grasslands for the reproduction of pike. From the results obtained in large sectors of the fluvial corridor, a method is proposed for a regionalization of the hydrosystem. Two other approaches were tested in large areas of fluvial corridors to classify nitrate removal capacities of riverine wetlands through the identification of physical and biological indicators or modelling. What emerges from these studies is the necessity to undertake a common classification of wetlands on a hydrogeomorphic basis and then to develop multifunctional assessment in reference zones from the identified indicators or tested models.