HR: 0800h
AN: H21C-1362    [Abstracts]
TI: Behaviour of a Dual-Permeability Fractured Carbonate Aquifer from in situ Hydrochemical Measurements (Coaraze Experimental Site, Southeastern France)
AU: * Charmoille, A
EM: arnaud.charmoille@univ-fcomte.fr
AF: Laboratoire de Geosciences, EA 2642, Universite de Franche-Comte, 16 route de Gray, Besancon, 25030 France
AU: Bertrand, C
EM: catherine.bertrand@univ-fcomte.fr
AF: Laboratoire de Geosciences, EA 2642, Universite de Franche-Comte, 16 route de Gray, Besancon, 25030 France
AU: Guglielmi, Y
EM: guglielmi@geoazur.unice.fr
AF: Geosciences Azur, UMR 6526, CNRS/UNSA, 250 rue Albert Einstein, Valbonne, 06560 France
AU: Mudry, J
EM: jacques.mudry@univ-fcomte.fr
AF: Laboratoire de Geosciences, EA 2642, Universite de Franche-Comte, 16 route de Gray, Besancon, 25030 France
AB: Usually, the exchanges between low permeable and permeable compartments in karst or fractured aquifer are interpreted by analysing the global hydrochemical and hydraulic outputs of the natural spring draining a large aquifer. The experiments performed in the following study are realized at the scale of a group of single discontinuities including low permeable discontinuities (9.0 10-7 m.s-1<K<7.6 10-6 m.s-1) and permeable discontinuities (5.7 10-5 m.s-1<K<2.3 10-4 m.s-1). This field approach, at metric scale, enabled us to study the impact of permeability on water chemistry. We realized these measurements in the Coaraze aquifer, which is a fractured carbonated aquifer with a decametric size. The originality of this experimental site lies in the fact that the spring is equipped with a water-gate, which allows to control the volume of water stored in the reservoir. The experimental protocol allowed to reproduce on a small scale single aquifer, the flow conditions of unsaturated and saturated zone. Two chemical signatures have been clearly identified, depending of the flow area, and of the hydraulic conditions in the aquifer. The use of hydrochemical tools at the scale of single discontinuity allows to precise the hydrochemical interaction between the low permeable and permeable discontinuities in fractured carbonated aquifers. This study show that chemical signature of water is a parameter dependant of the fracture permeability.
DE: 1806 Chemistry of fresh water
DE: 1828 Groundwater hydraulics
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
DE: 1858 Rocks: chemical properties
SC: Hydrology [H]
MN: Fall Meeting 2005