Relationship between hydraulic properties and material features in a heterogeneous vadose zone of a vulnerable limestone aquifer

Limestone aquifers constitute important drinking water resources but are vulnerable to groundwater contaminations. They also known be often heterogeneous. However, the hydraulic properties of their entire vadose zone and relationship these with mineralogical geochemical characteristics remain rarely studied. The soft (soil, powdery limestone, calcareous sand) hard (limestone rock) materials sampled throughout profile Beauce limestone aquifer (France) were determined multistep outflow method applied using a triaxial system. Physical, mineralogical, analysis brought valuable information about factors contributing heterogeneity helped understanding flow pathways within zone. strongly related physical proportion nature clay minerals. massive rock presented few thin microfissures where calcite was replaced by phyllosilicates, thus increasing its retention capacity. low conductivity could explain occurrence perched tables in weathered displayed fissures vugs characterized presence phyllosilicates. development secondary porosity footprints water–rock interactions mass transfers highlighted transformation into more permeable material. This study pointed out need characterize impact natural fractures observed at core scale on preferential field scale.