Contribution of artificial galleries to the knowledge of karstic system behaviour in addition to natural cavern data

The study of karstic systems is mainly based on hydrodynamic and hydrochemical data collected at system inlets (rainfall) and outlets (springs). Indeed, some complementary data base coming from speleological and hydrogeological explorations of natural cavities exist. However, they are not completely representative of all the types of flows. These kinds of flow which have a large part in general hydrodynamics of a system are already the result of a structured organization of karst due to complex phenomena of limestone dissolution. Artificial galleries have the advantage to be easily accessible. Moreover, they cut randomly flows which are much less structured or not. Both types of information seem to be complementary in order to understand a karstic aquifer. In this paper, we focus on the hydrochemical and hydrodynamic study of unstructured flows of the Low-Noise Underground Laboratory of Rustrel- Pays d’Apt (LSBB), a former military site with 3,4 km of buried galleries