Impacts écologiques des éclusées hydroé lectriques. Caractérisaton des régimes d'éclusées et Retour d'expérience sur la Maronne

Abstract

Hydropeaking management can consistently alter fish populations, and particularly recruitment of diadromous species, like salmon. To progress in understanding the impacts and defining mitigation measures, it appears essential to combine long-term biological survey, hydrological analysis including hydropeaks characterization, and hydro-morphologic approach. In a first time, a methodology for hydrological characterization of hydropeaks is presented. Their diversity and high variability are illustrated. Then, we present operating experience on Maronne River, a tributary of the Dordogne River downstream Argentat affected by hydropeaks of Hautefage scheme. Biological surveys and hydrologic and hydro-morphologic studies allowed a better understanding and a quantification of some biological impacts (redds dewatering, stranding-trapping of alevins), to support mitigation measures and to assess its effectiveness. The relevance of work on morphology, in addition to measures on flow management, is also illustrated. Some positive results have already been obtained. Studies on the Maronne River are pursued to achieve a really satisfactory situation. This example shows that the current knowledge does not allow, on a given stream, to predefine mitigation measures and ensure their efficiency. This leads to advocate the setting up of similar approach on other river, to identify biological communities' responses depending on the characteristics of hydropeaks and hydrosystems. © 2012 Société Hydrotechnique de France.