Author(s): Veronique Gouraud; Fabio Tarena; Agnes Barillier; Julien Di Pane; Marie Lamour; Atle Harby; Herve Capra; Leah Beche; Nicolas Lamouroux

Linked Author(s): Atle Harby

Keywords: Ecological gains; Hydropeaking; Eco-hydrological indicator; Eco-thermal indicators; Habitat

Abstract: Hydroelectric plants can generate rapid flow variations to meet peak electricity demand (hydropeaking), which may impact aquatic organisms (stranding, drift, etc.) and their habitats (dewatering, hydraulic instability). To mitigate these impacts, while preserving as much as possible energy flexibility, it's necessary to accurately diagnose the nature and magnitude of the ecological impacts of hydropeaking, combined with other human pressures on the river stretches. To facilitate such diagnostics, we developed a conceptual framework to characterize how mitigation measures improve habitat conditions and the state of biological communities. In order to build this framework, we have identified and selected a set of appropriate ecological indicators that can be transferred to any site. To test them, we used a demonstration site where a large amount of ecological data and different models can be gathered, the section of the Ain River (50 km), located downstream of a hydropower plants chain in France. At this study site, a pumped storage facility is currently under construction and will mitigate the impacts of hydropeaking and improve the temperature conditions. First, abiotic and biotic conditions were assessed using results from hydrological, thermal, hydraulic and habitat modelling and biological monitoring surveys conducted over the past two decades. Second, based on these assessments, the application and the critical review of several available standardized frameworks assessing the impacts of hydropeaking allowed us to identify and select reliable indicators to estimate ecological gains. These indicators were applied to the Ain River under different climate change scenarios and with/without the refurbishment with the new pumped-storage unit . The results have led to a new methodological framework for evaluating the environmental benefits of refurbishment projects.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.227

Year: 2026