Wednesday 2nd of july -14:00
14:00
Fostering community engagement in small dam removal: Participatory approaches for restoration in the Alviela River, Portugal
AUTHORS
ALBA Maria, MIRANDA Ana Catarina, VAZ DE FIGUEIREDO Lígia, BATEL Susana, GATO Maria Assunção
Portugal
Short Abstract: Our project focuses on community engagement in a process of small dam removal in the Alviela River, Portugal, to tackle climate change and improve river connectivity. Engaging riparian communities early in ecological restoration processes, such as small dam removal, is essential for effective, equitable and just river management. Therefore, we used a participatory, multi-method qualitative approach that is structured around three primary objectives: (1) incorporating local knowledge to ensure that decisions are tailored to the Alviela’s specific context and aligned with the knowledge and concerns of local residents; (2) exploring local perspectives and representations by collecting community memories and analyze representations and social functions of the Alviela from the residents’ point of view, integrating people-place relations, such as identity and attachment, into the process, and ensuring these relationships are fostered and maintained throughout the process of removal; and (3) meaningful knowledge sharing by disseminating in a relatable way, formal and scientific knowledge on topics such as climate change, river connectivity, ecological restoration, and specially the role of small dam removal in addressing these issues. We discuss the challenges entailed by developing and co-constructing this process in a community where historically there has been a focus on other pressing topics regarding ecological restoration of rivers, namely pollution. Although we acknowledge the challenges associated with community participation processes, we show how they are crucial for successful and meaningful removals.
14:20
Is it possible to highlight an effect of flow releases downstream of the Mallemort dam (F) on the fish assemblage of the lower Durance in a context of strong hydro-sedimentary dynamics?
AUTHORS
CATTANÉO Franck, POLBLANC Antoine, LE COARER Yann, MOSSERI Julie, VERDIER Héloïse, BOUILLOUX Mélanie, BECHE Leah
Switzerland
Short Abstract: On the Durance, 8 dams have been built between Serre-Ponçon and the confluence with the Rhône, to supply water to 16 hydroelectric plants (with a capacity of 2,000 MW) as well as agricultural and drinking water intakes via a lateral canal (EDF canal). In this sector, fish populations are subject to significant natural variability in hydroclimatic conditions due to the Mediterranean climate, in addition to changes in the hydrological and sedimentary regimes linked to the presence and operation of the dams. In particular, the minimum flow reach located downstream of the Mallemort dam in the Lower Durance (a section of ca. 40 km long), can receive significant flow releases from the EDF canal. Releases are similar to hydropeaking, resulting in large and unpredictable flow variations, mainly depending on electricity demand. Here, we analyse fish data collected annually since 2003 at two stations in minimum flow sections downstream and upstream of the Mallemort dam (one subject to releases and the other not) to determine the effects of the main environmental factors (flow, temperature, suspended matter). We are especially seeking to disentangle the respective roles of natural flooding vs the influence of dam operations on the interannual dynamics of fish populations. Emphasis is placed on the detailed characterisation of hydropeaking and on the assessment of their potential effects.
14:40
A Methodology for River Connectivity Assessment: a case study in the Alviela River, Portugal
AUTHORS
VAZ DE FIGUEIREDO Lígia, MIRANDA Ana Catarina
Portugal
Short Abstract: The importance of river restoration and free-flowing rivers is increasingly recognized by European environmental policy, namely EU Biodiversity Strategy. Much of the anthropogenic pressures on river ecosystems are originated by barriers to river connectivity – built structures causing longitudinal, vertical or lateral discontinuity that interrupt or modify natural processes as the flow of water, the transport of sediments and the fish and wildlife movements and migrations. The aim of this paper is to discuss an integrated assessment methodology (developed within the framework of Rollin’Rivers project) to improve river connectivity by prioritizing dam removal and rehabilitation actions. This methodology is based on a scoring and ranking approach for barriers, which involves evaluating individual barriers using criteria assigned specific scores. These scores enable prioritization for removal, considering a particular set of objectives. The results show a prioritised list of obsolete barriers that allows us to determine the restoration potential of river stretches in the Alviela Subbasin, integrating ecological, socio-cultural, and economic criteria. We conclude that the prioritization process is essential for supporting decision-making and that it provides a systematic framework for identifying and addressing critical barriers. This approach ensures that restoration efforts maximize ecological benefits while considering local community needs and economic feasibility.
15:00
Influence of hydropeaking on young-of-the-year fish abundance: a field study of Austrian alpine rivers
AUTHORS
MERL Kevin, ZEIRINGER Bernhard, HAYES Daniel S., AUHSER Alexander, GREIMEL Franz, SCHMUTZ Stefan
Austria
Short Abstract: Hydropeaking (rapid sub-daily flow fluctuations) resulting from hydroelectric power generation is a major challenge for aquatic ecosystems, such as alpine rivers. The increasing importance of renewable energy sources could intensify this problem. Early life stages of fish are particularly vulnerable to the effects of rapid flow fluctuations due to their preference for habitats close to the riverbank. Also, their ability to swim and therefor ability to handle high flow velocities is still less developed than in adult fish. This study compares the abundance of young-of-the-year brown trout (Salmo trutta) and European grayling (Thymallus thymallus) in Austrian alpine rivers to determine whether the effect of hydropeaking is a dominant factor when other anthropogenic and natural parameters, including land use, morphology, hydrology, connectivity and typology are considered. The results show that the abundance of young-of-the-year brown trout and European grayling is influenced by a combination of hydropeaking frequency and intensity. While the response of European grayling is mainly influenced by hydropeaking parameters the abundance of Brown trout is further influenced by river dimension, with a preference for smaller headwater streams. This research feeds into the Austrian hydropeaking mitigation guideline and calls for better hydropeaking management, especially during early life cycle stages where fish are most vulnerable.
15:20
Spawning-to-nursery functional habitat connectivity modelling for river restoration planning and assessment
AUTHORS
FARÒ David, WOLTER Christian
Germany
Short Abstract: Habitat suitability modeling is widely used to plan and assess in-stream habitat enhancements. However, it only addresses the spatial distribution of habitats but not their connectivity.
This study integrates micro-scale habitat modeling and a larval drift model to assess functional connectivity between spawning and nursery habitats for four rheophilic and lithophilic fish species in a hydropower-impacted section of the lower Inn River (Bavaria, Germany). It compares two channels with differing sizes and morphologies: a recently constructed nature-like bypass channel and the straightened main river channel, which underwent habitat rehabilitation measures. The study aims to (1) map spawning and nursery habitats, (2) quantify their connectivity, and (3) optimize it by testing alternative habitat rehabilitation measures.Results show that channel morphology strongly influences habitat availability and connectivity. In the bypass channel, narrower width and higher sinuosity enable full use of habitats, while limited larval drift in the wider main channel restricts accessibility to the left riverbank, making only 33% of nursery habitat usable. However, functional connectivity in the main channel could reach 95.3% with habitat spatial configurations tested in two alternative restoration scenarios, emphasizing the need to consider functional connectivity in habitat assessments and restoration planning.