For thousands of years, the inhabitants of the Causses du Quercy UNESCO Global Geopark in southwestern France have maintained a close relationship with the C茅l茅 river and its karstic landscapes, the result of millennia of limestone erosion. Today, the karstic limestone continues to be used as a major building resource, whilst much of the regional drinking water is sourced from the underground karstic springs. Despite this, little is known about the groundwater flow of these springs, hindering effective management of vital water resources that support 60% of the Lot department inhabitants and local biodiversity.
As climate change threatens to increase the frequency and severity of extreme events across our planet, sustainable water resource management is more critical than ever. Driven by this awareness hydrogeologist David Viennet and the Geopark鈥檚 team set out to investigate the characteristics of the C茅l茅 river and its karstic supply. Initial measurements indicated that the karst acts as an amplifier of extreme events, as stream flow in the area triples during times of flood, and karst springs dry out faster during droughts, prompting David and his team to dig deeper and launch a study to address the associated risks.
Last year in September, the Causses du Quercy UNESCO Global Geopark launched the project 鈥淪tudy of exchanges between Karst and rivers in the C茅l茅 valley鈥, selected within the second-year cycle of the UNESCO and abrdn Charitable Foundation (aCF) project, 鈥淧romoting sustainable development through UNESCO鈥檚 programmes and sites鈥.
Everything happens underground, it requires complex scientific investigations to understand how the river works today and be able to foresee what will happen in the future with global changes.
Pioneering methods in predicting water changes
To the Geopark鈥檚 team, the key lies in implementing sustainable water management by understanding and predicting changes in water flow and quality. To achieve this, data sampling and hydrodynamic studies have been carried out with the pioneering use of new and innovative methodologies, including the Acoustic Doppler Current Profiler (ADCP) system.
The results sparked David鈥檚 enthusiasm: 鈥渨ith this methodology, we have discovered an unknown spring, and were able to quantify the global water flow rate coming from the karst underground network to the river. Future management will be able to adapt its policies, especially for managing floods and droughts, and anticipate how the karst will react and thus its impact on the river.鈥
Of particular interest are the interactions between the Karst and C茅l茅 river, part of the thesis on karst hydrogeology that Lucie Noguera, a PhD student at the University of Bordeaux is writing. Her collaboration with the Geopark鈥檚 team relates to the sampling and analysing of the data, and thermally mapping the area with drones. 鈥淚n winter, the water coming from underground is hotter, so we are able to detect the springs and how they interact with the river they are flowing into,鈥 Lucie explains, sharing her excitement about the results achieved so far.
The core of Causses de Quercy is community
An essential component of the project is the involvement of the local community, particularly schools, recognising the importance of involving youth in sustainable development practices. Students from 3 selected local schools have directly benefitted from the activities, through interactive museum exhibits, classroom activities with experts, and caving and hiking field trips.
Through these exchanges and excursions, they learnt about water circulation in karst terrain from rainfall infiltration to its outlet. They traced water paths in caves and discovered a spectacular chasm, enhancing their knowledge and awareness of the importance of sustainable water management.
David accompanied middle school students of Sainte-H茅l猫ne, Gramat, and their science teacher Claire Denis in on-site experiences to discover the Causses groundwater. 鈥We went down into the Blaireau cave and did caving; for some of us it was the first time,鈥 Claire shares. 鈥淲e discovered what was under our feet, it was truly an incredible experience!鈥 The initiative is invaluable in instilling a deep understanding and appreciation of both regional and global environmental challenges in young generations. This is paramount as we strive towards a more sustainable future.
The project team is also working to involve the wider community by planning yearly meetings with locals to understand their perspectives and foster even greater involvement in the future. In this regard, the 鈥淪yndicat mixte du bassin C茅l茅 - Lot m茅dian鈥 and the 鈥渃onseil d茅partemental du Lot鈥 were pivotal in engaging with different segments of society, including local municipalities and communal organisations, as it mobilised the local communities along the rivers of the site.
Envisaging a future: self-sufficiency beyond the project
Moving forward, the outcomes of the initiative will continue to benefit local communities and advance karst research following its conclusion. David emphasises, 鈥the development of the new ADCP methodology will be instrumental in creating a set of tools for scientists to study karstic watersheds in similar regions across the world鈥. This represents a significant contribution to karst study and evidence-based policymaking worldwide.
As environmental pressures mount, the 鈥淪tudy of exchanges between Karst and rivers in the C茅l茅 valley鈥 project not only protects water resources but also educates and prepares future generations, ensuring the region's resilience and beauty endure.
Looking ahead, the Causses du Quercy UNESCO Global Geopark plans to amplify the outcomes of the project beyond the 12-month timeline of the UNESCO and aCF partnership in a larger local context; this in particular lies in its commitment to fulfilling SDG 6 - clean water and sanitation, and meeting the priorities set by the Intergovernmental Hydrological Programme of UNESCO.
