Development of differently determined and differently targeted Cave Environment Protection Perimeters using hydrogeological basis
Résumé
Conserving a cave with important historical and archeological artifacts needs protection measures. Cave Environment Protection Perimeters (CEPP) operational framework is proposed as a conservation measure tool for the cave and its environment. In this study, Cussac Cave was examined. Water infiltration is the main identified threat as it can bring pollutants into the cave. Three nested CEPP zones were then identified covering three important resource safeguarding intentions. First is on determining the possible water path infiltration through fractures from surface to cave (CEPP 1). Second is on delineating watershed of water that can infiltrate above the cave after run-off (CEPP 2). And third is on determining the limits that can constrain groundwater circulation (CEPP 3). According to the objective, the CEPP were obtained using a combination of classical tools such as geomorphology, topography, hydrological parameters (water flow and chemistry), and artificial tracing. The immediate CEPP 1 is close and is small in size (0.5 km2) which can be prone to both chronic and acute pollution through direct infiltration above the cave. The hydrologic CEPP 2 is medium size (1.1 km2) which can entail risks concerning chronic and acute pollution that can be brought by surface run-off before infiltration. The hydrogeologic CEPP 3 is the largest of the three (3.9 km2). Recommendations in each zone on how to manage the cave environment are presented.