Characterization of the Functionality of Karstic Systems Based on the Study of the SIc–Pco2 Relation

Abstract : This paper aims at characterizing the functionality of karstic systems. In order to do so, an extend of a method based on the saturated index with respect to calcite (SIc) and CO2 partial pressure (Pco2) is used. The initial method already applied by Peyraube et al. (2012) uses the Pco2 of water at equilibrium with atmosphere (Pco2_eq) and the Pco2 of water for a SIc equal to zero (Pco2_sat). The Pco2_sat variation gives information on flows conditions within the karstic system. It describes the degree of karstification of the system. Systems with developed saturated zone are characterized by under-saturated waters as well as saturated ones with variable Pco2_sat. At last, fissured system has Pco2_sat which vary only slightly. Moreover, variations of Pco2_sat show homogenization capacities of a karst.