Spatial and Temporal Hydrodynamic Variations of Flow in the Karst Vadose Zone (Rustrel, France) in Function of Depth and Fracturing Density

International audienc

Carbon 13 of TDIC to quantify the role of the unsaturated zone: the example of the Vaucluse karst systems (Southeastern France)

International audienceThe Total Organic Carbon (TOC) is an interesting tracer of fast infiltration within karstic systems [3,7]. Regular sampling on several aquifers, from the experimental site of Vaucluse, made it possible to demonstrate the high sensitivity of this tracer compared with other commonly used chemical and isotopic tracers in karstic hydrogeology. The complementarity of magnesium, indicator of the residence time of water within the system, and TOC appears as a relevant tool in order to characterize the behaviour of the aquifer, to differentiate the water types which participate to the karstic flow (fast infiltration, unsaturated zone, saturated zone) and then, to evaluate their vulnerability.Le carbone organique total (COT) est un bon marqueur de l'infiltration rapide de l'eau au sein des systèmes karstiques [3,7]. Son suivi régulier sur plusieurs aquifères appartenant au site expérimental de Vaucluse a permis de mettre en évidence la grande sensibilité de ce traceur par rapport à celle des traceurs chimiques et isotopiques couramment utilisés en hydrogéologie karstique. La remarquable complémentarité du magnésium, indicateur du temps de résidence de l'eau dans le réservoir calcaire, et du COT s'est révélée fort pertinente afin de caractériser le fonctionnement des systèmes, de différencier les types d'eau s'écoulant à l'exutoire (infiltration rapide, zone non saturée, zone noyée), et ainsi d'évaluer leur vulnérabilité

Historical monthly rainfall-runoff database on Fontaine de Vaucluse karst system: review and lessons,

International audienceMany studies have been carried on the Fontaine de Vaucluse karst system (south-east of France) and have proved the complexity of the hydrodynamic behaviour of this system. The question of water storage and water movement in this karst system must still be considered. This spring, famous for its considerable mean flow rate of around 20 m3/s, with maximum flow rate of 100 m3/s, has been time object of curiosity for a long, and, since 1877, the runoff of the spring has been regularly noted. Thus, at present, a 127 years long database of runoff measurement is available. After a review of the old data (1877-1965), the bias induced by the displacement of the gauging station in 1965 has been quantified. We then built a complete and homogeneous monthly runoff database. The analyse and the comparison of monthly runoff and rainfall databases confirms a rapid time response of the system, compared to the large surface of the recharge area. But this analyse has also pointed out unusual high runoff during dry periods occurring after long humid periods (several decades). Whereas an expected deficit is observed on runoff if the dry period occurred after a period characterised by mean amount of precipitation. This seems to confirm the existence of a routing zone of great capacity, characterised by slow water transfer. Thus, it is of great importance to take correctly into account the role of this zone in the response of the system to precipitation, especially to improve the rainfall-runoff simulation

Complementarity of monitoring sites in natural caves and man-made galleries in the knowledge of flowpath organization within fissured medium

International audienc

Carbon 13 of TDIC to quantify the role of the unsaturated zone: the example of the Vaucluse karst systems (Southeastern France)

International audienceThe Total Organic Carbon (TOC) is an interesting tracer of fast infiltration within karstic systems [3,7]. Regular sampling on several aquifers, from the experimental site of Vaucluse, made it possible to demonstrate the high sensitivity of this tracer compared with other commonly used chemical and isotopic tracers in karstic hydrogeology. The complementarity of magnesium, indicator of the residence time of water within the system, and TOC appears as a relevant tool in order to characterize the behaviour of the aquifer, to differentiate the water types which participate to the karstic flow (fast infiltration, unsaturated zone, saturated zone) and then, to evaluate their vulnerability.Le carbone organique total (COT) est un bon marqueur de l'infiltration rapide de l'eau au sein des systèmes karstiques [3,7]. Son suivi régulier sur plusieurs aquifères appartenant au site expérimental de Vaucluse a permis de mettre en évidence la grande sensibilité de ce traceur par rapport à celle des traceurs chimiques et isotopiques couramment utilisés en hydrogéologie karstique. La remarquable complémentarité du magnésium, indicateur du temps de résidence de l'eau dans le réservoir calcaire, et du COT s'est révélée fort pertinente afin de caractériser le fonctionnement des systèmes, de différencier les types d'eau s'écoulant à l'exutoire (infiltration rapide, zone non saturée, zone noyée), et ainsi d'évaluer leur vulnérabilité

Contribution of time tracers (Mg 2+ , TOC, δ 13 C TDIC , NO 3 − ) to understand the role of the unsaturated zone: A case study-Karst aquifers in the Doubs valley, eastern France

International audience[1] Time tracers (NO 3 À , TOC, d 13 C TDIC , Mg 2+) have been used to define the hydrodynamic behavior of a karst system: high values in NO 3 À and TOC reflect rapid infiltration and consequently a short residence time within the aquifer, whereas enriched d 13 C TDIC and high Mg 2+ are expected for ''old water''. 9 Springs and 5 boreholes have been sampled during three field campaigns in the Doubs valley karst aquifer: low water, flood and recession periods. A clear differentiation can be highlighted between boreholes, characterized by a long residence time, and springs that show a rapid infiltration. Considering only the springs values, it appears that TOC and d 13 C TDIC contents can easily be correlated to the sampling period. We show then the contribution of the unsaturated zone to the discharge during the low-water period, and the existence of reserves that seem badly connected to the drainage network, and that contribute poorly to the minimal flow

Groundwater Tracing Using Stable Isotope in the Western Mediterranean (Case of Rif Chain in the North of Morocco)

International audienc

Minéralisation de l’eau de la zone non-saturée du karst : résultats de prélèvements dans des cavités du plateau d’albion (Vaucluse & Alpes de Haute Provence,

International audienc

Imaging the lsbb environment from GPR data, along the tunnel and from the surface

ACTInternational audienc

Apports conjoints de suivis climatologique et hydrochimique sur le rôle de filtre des aquifères karstiques dans l’étude de la problématique de changement climatique; Application au système de la Fontaine de Vaucluse

International audienc