Résumé
Karstic aquifers are highly reactive and heterogeneous hydrosystems, characterized by a strong interaction between surface water and groundwater. In the Mediterranean area, rapid recharge occurs in active losses located along temporary rivers, enabling a swift flow to infiltrate deep into the groundwater reservoir. However, this recharge can also occur more diffusely, with rain flowing over rock outcrops. These features make karst aquifers vulnerable to climate change: diffuse recharge appears to decrease with increasing temperatures, while rapid recharge is favored by the intensification of extreme events, particularly presents in the mediterranean area. The karst structures, often developed on tectonic features, enhance these concentrated rapid recharge areas, providing crucial replenishment for societal and agricultural needs. Improving our understanding of these concentrated recharge zones is important for preserving the present water quality at these vulnerable points and to characterizing the future quantitative flow of this recharge.The existence of losses associated with the karst network near fault zones sparks interest in understanding of the relationship between these fault zones and the karstification process. This study focuses on exploring the connections between fault zone architecture and karstification in proximity. It entails a comprehensive morphological and geological description of these elements, emphasizing the geomorphological characterization within these loss zones. This approach enhances anticipation, exploration, and comprehension of surface-to-underground transfer dynamics. Our research employs a multi-scale approach to characterize surface geological structures, involving high-resolution structural mapping through LIDAR-equipped drones and numerical analysis of fault zone fracturing using aerial orthophotographs. Geological investigations, field observations, and tectonic analyses in karstic cavities, further explore the link between surface features and subsurface structures.The comparison between subterranean and surface dual photogrammetry represents a novel approach, providing insights into the development of karstification from the surface to depth. It helps establish the spatial evolution of active loss zones, bridging the understanding between surface and subsurface dynamics in karst evolution.This study concentrates on the Lez spring catchment area, supplying water to Montpellier in southern France. This region constitutes a complex karstic system intersected by major faults significantly influencing the reservoir's structure. Multiple loss zones along these faults contribute to aquifer dynamics, particularly evident along the Corconne-Matelles fault, indicating rapid transfers facilitated by the karstic network at specific karstic loss points within the fault zone.Our research establishes connections between observed tectonic and karstic surface structures, emphasizing the critical role of fault zones in shaping the surrounding karstic network. It highlights specific fracture families' significant influence on fracture dissolution, applying substantial structural control over the karstic network. Furthermore, it identifies diverse fracture families and their distinct roles in the development of karstification, impacting the water transfer dynamics within this environment. Examining the morphology of these loss zones within karstic aquifers at fault locations aids in identifying analogous areas, facilitating the creation of a map outlining vulnerable zones within the aquifer system and aiming to establish mechanisms to promote recharge at these points.