Use of isotopic signatures for the determination of natural recharge and chemical characterization of groundwaters: the case of Horombe plateau area, SW Madagascar

The necessity for accurate determination of groundwater recharge is an important issue for the "smart mining" of groundwater resources, especially in hydrologically sensitive regions. Different techniques and methods have been widely reported in literature, and isotope hydrology has found to be one of the major fields of the study. This paper presents the combination of different techniques for analyzing the recharge/discharge mechanisms within a large catchment area in SW Madagascar, by correlating different isotopic signatures, piezometric conditions, major ion water chemistry from ground- and surface-water samples (including their physical characteristics from in situ measurements), and also geological structures present within the study area. It provides, among others, a detailed description on the geologic and hydrogeologic regime of the Horombe Plateau, based on field data obtained from a well-distributed monitoring network within the study area, which is envisaged to serve as the conceptual model for future groundwater modeling studies.