Investigation of groundwater dynamics in a mediterranean karst system by using multiple hydrogeochemical tracers

Abstract

The Lez karst aquifer, located in southern France, supplies the Montpellier metropolitan area with potable water and has a maximum exploitation capacity of about 1.700 L/s. The objective of this work is to improve the comprehension of groundwater dynamics in a particular Mediterranean karst system, using hydrogeochemical tracers. The different types of groundwater with similar chemical characteristics (major and trace elements) are identified. During rainy season periods, this multitracer characterization shows that deep mineralized waters emerge at the springs just before rapid infiltration waters. This phenomenon shows that hydrodynamic conditions imply water circuits, with participation of specific compartments or creation of short cuts for superficial percolating waters. The data also highlight the vulnerability of the system to natural or anthropogenic contamination.