Water and heat transfer modeling in karst environments to study the impact of climate change on the future of decorated caves: Application to the Villars Cave (Dordogne)

The effects of global warming have already been recorded in many decorated caves located in karst systems, and some prehistoric paintings are already deteriorating. Modeling the microclimate of caves under various climate change scenarios will enable to adapt the conservation strategy for rock art heritage. In this study, we consider the first step in this modeling approach: the simulation of water and heat transfers from the soil surface to the cave through the soil/epikarst/karst system.

Water transfer is modeled using a double-permeability approach. A sensitivity analysis was conducted to assess the influence of various parameters on the model's behavior. Calibration of the model was achieved by comparing the simulated water flux at the model's exit with the observed drip rates from stalagmites.

For heat transfer modeling, the thermal rock characteristics are calibrated using sensor data taken at various depths in the soil and in the karst over a few years, and in the cave thanks to long-term monitoring. To provide long-term climate forcing, a transfer function is established between meteorological data measured at a height of 2 meters by Météo France and the temperature measured at the ground surface.

Then, this heat and water transfer model is fed with projections from regional climate downscaling models. This modeling approach, which integrates both current data and climate projections, will be a significant step towards the effective management and conservation of decorated caves, which are not only exceptional geological sites but also hold important historical and archaeological significance.