Tuesday 1st of july – 14:00
14:00
Resilience and River Restoration: what it is and is not
AUTHORS
Thoms Martin, Fuller Ian
Australia
Short Abstract: Resilience has become a buzzword in river science. This popularity has resulted in interpretations and use that are sometimes incorrect, which detracts from its role in the study and management of rivers as complex, coupled natural – human systems. River resilience is the ability of these coupled systems to cope with disturbances / stressors and to keep functioning in much the same way. Resilience is a measure of how much a river can change before it crosses a tipping point into some alternate state, which it tends to stay in. Resilience is not the ability to bounce back. It is the ability to absorb, adapt and transform, while coping with disturbance – it’s about changing in order not to be changed. This presentation will provide examples that illustrate the absorbing, adapting and transforming capacities that are the key components of river resilience, which must be understood if we are to restore function in our riverine landscapes.
14:20
Adapting to climate change on a major river undergoing change: from scientific theories to a territorial approach in the Val de Saône (France)
AUTHORS
Brosse Noé, Comby Émeline, Le Lay Yves-François,
France
Short Abstract: In 2022, stakeholders in the Saône valley organized an event called “Ca Saône” to acknowledge that the temperature of the Saône River has risen by 1.6 to 2°C since 1970, posing risks to human activities and the natural environment. As part of a partnered research financed by the Agence de l’eau Rhône Méditerranée Corse [water agency], we conduct a study of perceptions, representations and actions in the face of climate change in the Val de Saône [Saône Valley]. Our objectives are i) to identify indicators of the perception of climate change among local stakeholders and populations; ii) to understand the diversity of representations and associated risks of climate change; and iii) to better understand the actions taken in this context. To this end, we conducted a mixed survey: a questionnaire for residents (n=782) and interviews with local stakeholders (n=24). Our results show that the changes perceived by the population are in line with scientific observations. These perceptions do not always lead to an awareness of climate change. Representations are driven more by social and spatial contexts. Planned actions are driven by representations of climate change, but also by knowledge of the territory and its challenges.
14:40
Joint trends in river thermal and hydrological conditions: Implications for sustainable basin-wide water management
AUTHORS
MOATAR Florentina, SEYEDHASHEMI Hanieh, DROUINEAU Hilaire, AREVALO Elorri, MOATAR Florentina, HENDRICKX Frederic, MAIRE Anthony
France
Short Abstract: River discharge (Q) and water temperature (Tw) are critical environmental factors shaping aquatic ecosystems and fish migration. Climate change has significantly altered these factors, with rising Tw and contrasting Q trends raising challenges for ecosystems and human uses. This study examines the whole Loire River basin in France, analyzing ~60 years of reconstructed Q and Tw data at 368 sub-basin outlets. Using the “Choc” method, significant trends in co-occurrences of high Tw and low Q were identified, revealing sub-regions more impacted by climate change. Trends in these associations became significantly more frequent over six decades, particularly in the southern part of the basin during winter and summer. These trends raise ecological issues, as they favor species adapted to high Tw and less sensitive to low Q conditions, while threatening those more sensitive to unstable river conditions to complete their migration and spawning. The Increasing frequency of co-occurrences of high Tw and low Q could also compromise the availability of water for human activities, such as drinking water production, irrigation, and the cooling of nuclear power. These findings underscore the need for localized adaptation strategies to mitigate ecological and water resource issues in a context of climate change.
15:00
Technological and methodological developments in the airborne thermal infrared characterisation of river temperature
AUTHORS
Marteau Baptiste, Dugdale Stephen J., Caudron Arnaud, Piégay Hervé
France
Short Abstract: There is growing interest in using airborne TIR as a thermal diagnostic tool for rivers, in particular to assess the presence of potential thermal refuges. While some aspects of the technology are evolving and providing easier access to low-cost equipment, there are still limits as to how results can be used to address some of the issues (e.g. absolute temperatures). After a short description of the latest advances, the article presents the results of both technological (testing of a drone sensor) and methodological comparisons (semi-automated detection of cool-water patches). The main aim of this work is to move away from the more subjective methods used to date, especially the visual detection of thermal refuges, and their classification according to existing typologies. The paper ends with a proposal for a simpler and more parameter-based classification of cool-water patches, which remains comparable to the visual method used so far and so will open the door to large-scale analyses of data from different period, different rivers and even different countries.
15:20
Modelling the climate change impact on the SPM transfers of the Rhône river
AUTHORS
Fressard Mathieu, Fabre Clément, Bizzi Simone, Branger Flora, Hervé Piegay
France
Short Abstract: In accordance with the IPCC climate projections, the annual temperatures in the Rhône watershed are anticipated to increase by a range of 1.5 to 6°C, while the contrasts in seasonal precipitation are expected to become more pronounced. These changes will impact the solid transport dynamics of the river and its tributaries, influencing hillslope erosion rates and modifying the hydrological regime of the watercourses. In order to anticipate these changes, the Rhône Sediment Observatory (OSR) has developed a model of SPM transfers at the scale of the Rhône watershed and its main tributaries, which allows for the integration of prospective climate scenarios. In general, sediment transfers are projected to decline by between 5% and 20% at the Rhône outlet, depending on the models selected. All simulations indicate a reduction in sediment supply from the Alpine regions, while the trend remains more uncertain for the remainder of the watershed, particularly in the case of the Saône river.