Impact of alteration corridors on karst reservoir organisation and evolution of groundwater flow path: An example from the southern border of the Larzac Causse, southern France

Alteration corridors, vertically elongated structures containing dissolution-collapse breccia, significantly influence the organization and evolution of karst reservoirs by facilitating fluid circulation between upper and lower aquifers that were once separated by a marly seal unit. These corridors, primarily oriented in a N-S direction on the Larzac Causse, enhance regressive erosion dynamics, capturing watersheds like the Vis River and determining the position of present-day pocket valley springs. The study used a 3D approach to correlate field observations with remote sensing, revealing that ghost-rock karstification plays a crucial role in the structure and evolution of the karstic reservoir. Additionally, residual alterites are evacuated during high-flow events, providing insights into connected reservoir volumes and associated flow dynamics. These findings highlight the importance of corridor networks as valuable targets for water exploration when located below the piezometric level.

Baral, C., Séranne, M., Camus, H., & Jouves, J. (2024). Impact of alteration corridors on karst reservoir organisation and evolution of groundwater flow path: An example from the southern border of the Larzac Causse, southern France. BSGF - Earth Sciences Bulletin, 195, 4. https://doi.org/10.1051/bsgf/2023017