Detection and characterization of near surface small karstic cavities using integrated geophysical surveys

Analyzing fluid and heat transfer in a karstic zone requires a good knowledge of reservoirs and "pipes" involved in water circulation. Exploration geophysics offers several tools to deal with such problems. The studied area, the Baget Massif, Ariège, France (tig 1) is characterized by the existence of decametric caves, acting as reservoirs and smaller features connecting them. The aim of this work is to test the ability of near surface geophysics to detect such karstic pipes. We chosed a test site where hydrological data suggest the circulation of water under the topographic surface. The studied area has been comprehensively surveyed using microgravity, high resolution seismics, radar and DC resistivity techniques. The intill of the valley is composed of recent alluvial sediments, covering the limestone bedrock.