Abstracts Session 1

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SESSION 1: Groundwater flow an d storage in karst aquif ers / Stockage souterrain d’eau dans le karst Babić D., Zwahlen F. & Surbeck H. Assessing water origin in a karst system using Radon, CO 2 and supersaturation The Alpeau project aims at strengthening the protective role of forest soils with an eye to the sustainable management of groundwater resources and their quality. In karstic areas, it is important to discriminate between water originating from the soil reservoir, the epikarst (interface between soil and karst), the low permeability volume (the rock volume between the epikarst and the system outlet) and the freshly infiltrated rainwater. To do so, the Gorges de l'Areuse test site (Swiss Jura Mountains) was investigated by a combined monitoring of radon, CO2 and TDGP (total dissolved gas pressure). These gases, produced in large quantities in the soil and dissolved in rainwater, were used as natural tracers. Electrical conductivity (EC), temperature, turbidity, TOC (total organic carbon), nitrogen isotopic composition and dissolved ions were also part of th e survey program. The same origin of both radon and CO 2 , their different behaviour in the system, and their temporal variations at the outlet allowed to put forward the following premises: (i) high radon and CO2 concentrations are typical for water originating from the forest soil, (ii) low radon and high CO2 levels for the epikarst, (iii) low radon and CO2 concentrations along with high EC values are representative of the saturated zone, (iv) whereas freshly infi ltrated water shows low levels of EC, radon and CO2. The radon and CO2 signals are likely to show periodic oscillation features. Soil radon concentrations are affected by various seasonal and daily changes, such as precipitations, atmospheric pressure and temperature, leading to complex time series. In order to obtain manageable data, these components needed to be removed. A Fourier transfom was therefore applied on this set of measurements. This investigation allowed getting insight into the travel time, the storage location and the quality of water in a karstic and forested watershed. Bicalho C.C., Batiot-Guilhe C., Seidel J.L., Taupin J.D., Patris N., Van Exter S. & Jourde H. A conceptual model for groundwater circulation by using isotopic ( 18 O,  2  H and 87 Sr/ 86 Sr) and geochemical tracers in a Mediterranean karst system The Lez karst spring, located in the Mediterranean basin (southern France), supplies with water the metropolitan area of Montpellier (France) since the 19th century. Since 1981, an intense pumping is being performed directly in the main conduit with a mean pumping rate of 1300 L/s. To i mprove the understanding of groundwater origins and circulation dynamics in this karst system, physico-chemical parameters have been monitored and groundwater samples have been collected from the Lez spring and surrounding springs and wells, under a wide range of hydrologic conditions. Since March-2006, Hydrochemical and isotopic tracers have been determined. During the first recharge events of autumn, highly mineralized waters have been observed at the Lez spring. Their groundwater chemistry was monitored in a fine time-step, in the aim of characterizing their circulation and origins. For this characterization, a coupled approach integrating geochemistry and isotopical data has been applied in foremost applications for this karst system: water stable isotopes ( 18 O and 2 H) and strontium isotope ratios ( 87 Sr/ 86 Sr). Results showed that high mineralized groundwaters are characterized by enriched 87Sr/86Sr, which are associated to long residence-time and deep water rising, where evaporite fingerprinting has been identified. This approach provides insight into the different water end-members, the associated lithologies and the mineral- solution reactions that control groundwater chemistry and allows to propose a conceptual model for the groundwater circulation in this karst system. Key words: karst, hydrodynamics, hydrochemistry, natural tracing, stable isotopes. Blondel T., Fanget B., Perrette Y ., Tissier G., Poulenard J. & Malet E. Contribution de l’étude des Matières Organiques Dissous à la compréhension des hydrosystèmes karstiques.  Application à l’hydrosystème de Chevaline (Choranche [38])  This work is about combination between hydrochemical data, classically used to environmental tracing, and monitoring of different Dissolved Organic Matter (DOM) types. Chosen studied area is karst system of Choranche caves in Vercors (38) because several previous works and measuring equipment allowed a good knowledge of its behaviour. Thanks to daily sampling of Chevaline outlet, from August to November 2009, and usual

Transcript of Abstracts Session 1

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SESSION 1:

Groundwater flow and storage in karst aquifers / Stockage souterrain d’eau dans le karst 

Babić D., Zwahlen F. & Surbeck H. 

Assessing water origin in a karst system using Radon, CO 2 and supersaturation 

The Alpeau project aims at strengthening the protective role of forest soils with an eye to the sustainablemanagement of groundwater resources and their quality. In karstic areas, it is important to discriminate betweenwater originating from the soil reservoir, the epikarst (interface between soil and karst), the low permeabilityvolume (the rock volume between the epikarst and the system outlet) and the freshly infiltrated rainwater. To doso, the Gorges de l'Areuse test site (Swiss Jura Mountains) was investigated by a combined monitoring of radon,CO2 and TDGP (total dissolved gas pressure). These gases, produced in large quantities in the soil and dissolvedin rainwater, were used as natural tracers. Electrical conductivity (EC), temperature, turbidity, TOC (total organiccarbon), nitrogen isotopic composition and dissolved ions were also part of the survey program. The same originof both radon and CO2, their different behaviour in the system, and their temporal variations at the outlet allowedto put forward the following premises: (i) high radon and CO2 concentrations are typical for water originating fromthe forest soil, (ii) low radon and high CO2 levels for the epikarst, (iii) low radon and CO2 concentrations along with

high EC values are representative of the saturated zone, (iv) whereas freshly infi ltrated water shows low levels ofEC, radon and CO2. The radon and CO2 signals are likely to show periodic oscillation features. Soil radonconcentrations are affected by various seasonal and daily changes, such as precipitations, atmospheric pressureand temperature, leading to complex time series. In order to obtain manageable data, these components neededto be removed. A Fourier transfom was therefore applied on this set of measurements. This investigation allowedgetting insight into the travel time, the storage location and the quality of water in a karstic and forestedwatershed.

Bicalho C.C., Batiot-Guilhe C., Seidel J.L., Taupin J.D., Patris N., Van Exter S. & Jourde H.

A conceptual model for groundwater circulation by using isotopic ( 18

O,  2 H and 

87 Sr/ 

86 Sr) and geochemical 

tracers in a Mediterranean karst system 

The Lez karst spring, located in the Mediterranean basin (southern France), supplies with water the metropolitanarea of Montpellier (France) since the 19th century. Since 1981, an intense pumping is being performed directly inthe main conduit with a mean pumping rate of 1300 L/s. To improve the understanding of groundwater origins andcirculation dynamics in this karst system, physico-chemical parameters have been monitored and groundwatersamples have been collected from the Lez spring and surrounding springs and wells , under a wide range ofhydrologic conditions. Since March-2006, Hydrochemical and isotopic tracers have been determined.During the first recharge events of autumn, highly mineralized waters have been observed at the Lez spring. Theirgroundwater chemistry was monitored in a fine time-step, in the aim of characterizing their circulation and origins.For this characterization, a coupled approach integrating geochemistry and isotopical data has been applied inforemost applications for this karst system: water stable isotopes (18O and 2H) and strontium isotope ratios (87Sr/ 86Sr).

Results showed that high mineralized groundwaters are characterized by enriched 87Sr/86Sr, which areassociated to long residence-time and deep water rising, where evaporite fingerprinting has been identified. Thisapproach provides insight into the different water end-members, the associated lithologies and the mineral-solution reactions that control groundwater chemistry and allows to propose a conceptual model for thegroundwater circulation in this karst system.

Key words: karst, hydrodynamics, hydrochemistry, natural tracing, stable isotopes.

Blondel T., Fanget B., Perrette Y., Tissier G., Poulenard J. & Malet E.

Contribution de l’étude des Matières Organiques Dissous à la compréhension des hydrosystèmes karstiques.

 Application à l’hydrosystème de Chevaline (Choranche [38]) 

This work is about combination between hydrochemical data, classically used to environmental tracing, and

monitoring of different Dissolved Organic Matter (DOM) types. Chosen studied area is karst system of Choranche

caves in Vercors (38) because several previous works and measuring equipment allowed a good knowledge of itsbehaviour. Thanks to daily sampling of Chevaline outlet, from August to November 2009, and usual

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hydrochemical analyses (alkalinity, hardness, TOC), knowledge about hydrogeological behaviour of system has

been allowed to improve. Analytical methods of DOM characterization have been used simultaneously to observe

their temporal evolution (UV-Vis absorbance spectrometry, spectrofluorescence). They allowed (i) a

methodological development to monitor non-absorbent organic molecules, until then not easy to observe, and (ii)

to show that, thanks to detailed DOM studies, complementary informations about kart aquifer behaviour can be

obtained, when usual environmental tracing methods seem not to be enough distinguishing.

Résumé 

Ce travail propose de combiner des données hydrochimiques classiquement utilisées pour le traçage naturel avec 

le suivi de différents types de Matière Organique Dissoute (MOD). Le site d’étude choisi est le système karstique

des Grottes de Choranche dans le Vercors (38), car les nombreuses études précédentes et l’équipement en

appareils de mesure du site ont permis une connaissance approfondie de son fonctionnement. Grâce à des 

 prélèvements journaliers de l’exutoire du système de Chevaline, pendant une période s’étalant d’août à novembre

2009, et aux analyses hydrochimiques habituelles (alcalinité, dureté, COT), nos connaissances sur le 

fonctionnement hydrogéologique du système ont pu être améliorées. Parallèlement à cela, des méthodes 

analytiques de caractérisation de MOD ont été utilisées afin d’observer leur évolution temporelle (spectrométrie 

d’absorbance UV - Vis, spectrofluorescence). Elles ont permis d’une part le développement d’une méthode de suivi 

des molécules organiques non absorbantes, jusque-là difficilement observables, et d’autre part de montrer que

l’étude approfondie des MOD naturelles apportaient, à elles-seules, des informations complémentaires sur le 

fonctionnement des aquifères karstiques lorsque les méthodes de traçage naturel couramment utilisées semblent 

ne pas être assez discriminantes.

Collignon B. & Ondo C.

Mise en exploitation d’aquifères karstiques insoupçonnés pour alimenter en eau Libreville (Gabon) 

The capital city of Gabon (Libreville) has an 800,000 population and the demand for water is larger than present

production capacity. Supplying the city with water has always been hectic, because surface water resources are

scarce in the peninsula where the city is located. In 2005, the water utility (SEEG) has decided to mobilize

additional water resources and karstic aquifers proved to be the cheapest option, as well as the most easy to

implement in short period of time.Two well fields have been built. They extract water from the Madiela limestone formation, explored by deep oil

wells. The first well field (near Ntoum) has been implemented along a small limestone compartment (4 km2). It is

producing 4.4 million m3 /year since 3 years and meets the water demand for 7% of Libreville. Three wells have

been equipped with divers with the purpose to monitor sea water intrusion and outcomes are interesting: (a)

although the aquifer is very near a salty river, no sea intrusion has been recorded, (b) permanent storage is

limited but (c) recharge by rain is very efficient (> 6 million m3/year).

The present exploitation rate (12 000 m3/day) is sustainable and will be expanded to 50,000 m3/day. Investment

costs as well as O&M costs are smaller with these karstic aquifers than with present surface water alternatives.

For this reason, a second well field (near Meba) will be equipped in 2012 with a 10,000 m3/day scheduled

production capacity.

Résumé 

La capitale du Gabon (Libreville) est située sur une péninsule, où les ressources en eau sont limitées. La 

demande en eau dépasse la capacité de production actuelle de l’usine de traitement des eaux de surface de 

Ntoum. La compagnie des eaux (SEEG) a donc décidé en 2005 de mobiliser des ressources en eau 

supplémentaires et les aquifères karstiques se sont révélés l’option la plus économiquement avantageuse et la

 plus rapide à mettre en œuvre. 

Depuis 2005, deux champs captants ont été développés dans la formation des calcaires de Madiela, qui étaient 

connus dans la région grâce aux forages pétroliers. Le premier champ (à Ntoum) a été installé le long d’un petit 

bloc calcaire (4 km 2  ). Il est exploité depuis 3 ans au rythme de 4,4 millions de m 

3  /an et couvre 7% des besoins en 

eau traitée de la ville. Les trois forages (200 mètres de profondeur) ont été équipés de sondes de mesure pour 

garantir un monitoring rigoureux du biseau salé. Ce système de surveillance a permis de faire plusieurs 

observations intéressantes: (a) bien que l’aquifère soit situé à moins de 1 km d’un estuaire aux eaux saumâtres, il 

n’y a pas d’intrusion saline, (b) les réserves permanentes de l’aquifère sont limitées mais (c) la recharge par les 

précipitations est extrêmement efficace (> 6 millions de m 3 

 /an).Le rythme d’exploitation actuel (12 000 m

3  /jour) est donc compatible avec une exploitation durable de la 

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ressource et va être être quadruplé. Les charges d’équipement et d’exploitation de ces aquifères karstiques sont 

plus faibles que celles des solutions alternatives (eaux de surface + usines de traitement). Pour cette raison, un 

second aquifère karstique est en cours d’équipement (à Meba), avec une capacité de production at tendue en 

2012 de 10 000 m 3  /jour.

El Janyani S., Dupont J.P., Massei N., Jardani A. & Dörfliger N.

Variabilité régionale des fluctuations piézométriques dans l'aquifère crayeux karstique de la craie du Bassin de 

Paris 

Le cadre de l’étude correspond à la région Haute Normandie, située à l’ouest du bassin de Paris. Dans cette

région, l’aquifère poreux fissuré de la craie est un aquifère l ibre sous couverture, drainé par des conduits

karstiques. Dans cette étude, nous avon s défini l’influence de l’organisation morphostructurale des plateaux 

crayeux de la région Haute Normandie sur les modalités de recharge de l’aquifère de la craie. Les relations entre

la variabilité piézométrique et les caractéristiques lithologiques et structurales ont été étudiées par l'analyse de 

séries temporelles de niveau de la nappe de la Craie en différents points de l'aquifère.  L'analyse par transformée 

en ondelettes continue des chroniques piézométriques nous a permis d’identifier les principales composantes 

temporelles de ces signaux, à savoir le cycle annuel et une variabilité interannuelle. Ces mêmes composantes se 

retrouvent également dans les signaux pluviométriques régionaux. Les contributions relatives de chacune de ces 

composantes ont été estimées en rapportant l'écart-type de chaque composante extraite à l'écart-type total de 

chaque série temporelle étudiée. La variabilité hydrologique ainsi caractérisée a ensuite été interprétée dans le 

contexte géologique régional, par confrontation avec la distribution spatiale des caractéristiques géologiques et 

les hétérogénéïtés structurales. Il ressort que les valeurs les plus importantes sont enregistrées dans le 

département de la Seine Maritime, avec une localisation préférentielle dans les zones où la puissance de 

l’aquifère est maximale, ainsi que les épaisseurs des argiles à silex et du loess.

Mots-clés: Haute Normandie, piézométrie, aquifère de la Craie, karst, variabilité interannuelle.

Abstract

This work examines how the chalk plateaus organization in Upper Normandy can influence the recharge of the

chalk aquifer. The relationships between the piezometric levels, hydrological variability, the surface properties and

structural properties were studied by wavelet and Fourier spectral analysis. The treatment of the piezometricsignal allowed us to identify the main temporal components of the signal: (i) the first one corresponding to the

annual cycle and (ii) the second corresponding to a multi -year variability. These same components are also found

in regional precipitation signals. The relative contributions and standard deviations of each component were

estimated by comparing the standard deviation of each extracted component and the total standard deviation of

each time series studied. The hydrological variability characterized has been interpreted in the geological region

setting, by comparison with the spatial distribution of lithological characteristics and structural heterogeneity. It

appears that the most important values are recorded in the department of Seine Maritime, with preferential

localization in areas where the thickness of the aquifer and the thickness of the clay with flint and loess are

maximum.

Key words: Upper Normandy, piezometric level, chalk aquifer, karst, multi-year variability.

El Ouali A., Sefrioui S., Mudry J., Fassi Fihri O., Essahlaoui A. & Marah H.

Contribution of water isotopic signatures to determine the recharge altitude of major springs in the Middle Atlas 

limestone (Morocco).

La présente étude est menée au Maroc sur le Moyen Atlas calcaire à caractère karstique. Son objectif est de 

contribuer à la caractérisation des aquifères moyens atlasique et à la détermination des altitudes de recharge des 

 principales sources issues des calcaires dolomitiques liasiques afin d’aider à la détermination de l eurs zones 

d’alimentation pour leur protection. La méthodologie utilisée est basée sur l’utilisation des isotopes stables de la

molécule d’eau. La caractérisation chimique des eaux de ces sources montre que leur composition est le reflet de

celle des roches- réservoirs qu’elles drainent d’une part et de l’évolution qu’elles subissent au cours de leur transit 

au sein de ces réservoirs d’autre part. L’analyse de l’évolution du deutérium en fonction de l’oxygène 18 permet 

de tracer une droite locale similaire à celle des pluies analysées au sein de la station de Fès, ce qui montre que 

les aquifères concernés se rechargent par une infiltration rapide, sans évaporation notable des eaux de pluie. Le gradient altimétrique pour l’oxygène 18 est établie à - 0.27‰ par 100m. L’application de ce gradient aux teneurs

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isotopiques des autres sources analysées permet de remonter aux altitudes de recharge de ces sources. La 

confrontation de ces résultats aux données hydrogéologiques locales et régionales montre une concordance 

notable pour les sources dont les bassins versants étaient connus, et une orientation précieuse pour les sources 

dont les bassins étaient mal connus, avec des altitudes de recharge qui peuvent être 1090m plus élevées que les 

zones d’émergence. Ces résultats aident d’une manière certaine à déterminer les zones de recharge des

sources, et donc à définir une stratégie de protection de cette ressource.

Mots clés : Moyen Atlas, Sources, Karstique, caractérisation chimique, Oxygène 18, Deutérium, altitude de 

recharge, zone de protection, gradient isotopique.

Abstract

The present study contributes to the characterisation of Middle Atlas limestone karst aquifers by implementing

water stable isotopic techniques to determine the recharge altitudes of major springs issuing from liassic dolomitic

limestones, helping to delineate protection areas for the springs. Chemical analyses of spring waters show a

composition that reflects both reservoir lithology and a chemical evolution over the course of flow within the

reservoir. Analysis of the evolution of deuterium as a function of oxygen-18 suggests a local water line similar to

that derived for rainwater at a station in Fez, indicating that the aquifers in question are recharged through rapid

infiltration, without appreciable evaporation of the rainwater. Application of the established -0.27‰ per 100maltimetric gradient for oxygen 18 to the isotopic signatures of other analyzed sources allows us to backtrack

recharge altitudes for these springs. Comparison of these results with local and regional hydrogeologic data

shows a notable agreement among springs for which the drainage basin is known, and allows for more precise

localization of springs for which the drainage basin is poorly known, with recharge altitudes reaching 1090m

higher than emergence zones. To a certain extent, these results help to determine recharge zones for Middle

Atlas springs and thus aid in strategizing protection for this resource.

Keywords: Middle Atlas, springs, karst, chemical analysis, oxygen 18, deuterium, recharge altitude, protection

area, isotopic gradient

Emblanch C., Garry B., Perineau A. & Danquigny C. 

Utilisation du magnésium et du carbone organique total dans l'estimation du volume d'eau écoulé avant l'arrivée 

des eaux d'infiltration "directe" en période de crue.

A partir des suivis des concentrations en Carbone Organique Total (COT) et en Magnésium (Mg 2+  ), Garry (2008)

a proposé une classification en trois grands groupes des écoulements suivis au Laboratoire Souterrain à Bas 

Bruit (LSBB), dans la zone non saturée (ZNS) de l’aquifère karstique de Fontaine de Vaucluse,.

Il a ainsi différencié : (i) un groupe d’écoulements défini par de fortes concentrations en Mg2+ et de faibles

concentrations en COT, caractérisant des eaux à long temps de séjour, associées à des écoulements de type «

capacitifs », (ii) un deuxième groupe défini par des eaux à fortes concentrations en COT et très faibles 

concentrations en Mg 2+ 

, caractérisant des eaux récentes, donc des écoulements de type « transmissifs », (iii) un 

troisième groupe, intermédiaire entre les deux autres, possédant à la fois de faibles concentrations en Mg 2+ 

et 

des concentrations en matières organiques comprises entre 1 et 2 mg/L , caractéristiques d’eaux infiltrées depuis

environ deux mois.

 A partir de cette classification et dans l’optique d’ une meilleure compréhension du rôle et du fonctionnement de la ZNS des aquifères karstiques, la signature de ces groupements d’eaux a été recherchée dans le signal à

l’exutoire du système. Il s’agit de déterminer les périodes durant lesquelles tel ou tel g roupement intervient 

majoritairement dans le flux à l’exutoire. 

Complétant des travaux qui ont montré la participation d’eaux habituellement non mobilisées à la vidange des

drains (Emblanch, 1999), cette analyse met en évidence une phase intermédiaire entr e l’étiage et la participation

« directe » des eaux de pluie récente.

Ce phénomène avait déjà été observé (Emblanch, 1998) mais à partir d’une étude beaucoup plus lourdenécessitant notamment des suivis isotopique en 

18 O et 

13 C CMTD . Cette étude montre donc la pertinence du 

couplage COT - Mg 2+ 

dans les études de vulnérabilité des aquifères karstiques. Avec un coût raisonnable, il est  possible de proposer une méthodologie d’estimation du volume d’eau qui s’écoule avant l’arrivée des eaux 

d’infiltration « directe ».

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Erőss A., Mádl-Szőnyi J., Surbeck H., Horváth Á , Goldscheider N. & Csoma A.É. 

Radionuclides for end-member fluid characterization, Buda Thermal Karst, Hungary 

The springs and wells that supply the spas of Budapest discharge from a regional Triassic carbonate aquifer

system. Already in 1912, Weszelszky has reported on elevated radioactivity of the thermal waters of Budapest,especially around the Gellért Hill, but since then, there has been no detailed study and explanation for its origin.

The dissimilarity of the discharging waters within Budapest was long recognized on the basis of

hydrogeochemical studies (e.g. Papp 1942; Alföldi et al. 1968). The different discharge characteristics of the

Rózsadomb (North System) and Gellért Hill (South System) was suggested also by the study of Erőss et al. 

(2008). The application of radionuclides provided a new approach for end-member characterization of

discharging waters and further supported the differences between the two areas.

With the aid of radionuclides, for the North System a meteoric end member with the temperature of 12 °C and

775 mg/L TDS, and a hydrothermal end member with the temperature of 76.5 °C and 1440 mg/L TDS were

inferred, respectively. However, in case of the South System, mixing components could not be identified.

Accordingly, the hydrothermal waters with 35-47°C temperature and 1400-1800 mg/L TDS discharge directly.

These results have direct consequences on the understanding of cave forming processes. In the Buda Thermal

Karst mixing of cold and hot karst waters was generally assigned to be responsible for the formation of caves

(e.g. by Takács-Bolner & Kraus 1989; Leél-Őssy 1995). However, based on the results of this study, in case ofRózsadomb mixing corrosion might indeed be the dominant cave forming process, whereas in case of the

Gellért Hill due to the lack of mixing members possibly other processes are responsible for cave development.

Additionally, this study revealed an explanation regarding the origin of the elevated radioactivity of the

thermal waters of the South System. This study suggests that the source of radon in water is the iron-hydroxide

precipitates that accumulate in the spring caves.

This study confirmed that radionuclides of the238

U decay series, which can be naturally found in groundwater,are powerful natural tracers to characterize fluid end-members at regional discharge areas, where differentorder flow systems conveying waters with different temperature, TDS and redox-state to the discharge zone

Hanin G., Laignel B., Massei N., Hauchard E., Ladhui V. & Chedeville S.

Hydrological variations and sediment transfer in a karst system (Radicatel springs, Upper Normandy, France)controlled by climate fluctuations 

The hydrological variability and dynamics of hydrosystems, either surficial or subterranean, can be stronglycontrolled by climate fluctuations whatever the spatial scale of observation (e.g., Labat, 2008 ; Massei et a l.,2010, Mesquita, 2009). Such studies are sometimes based on the charactrization of the relationships betweenhydrological records (precipitation, water table variations, streamflow) and climate indices (e.g. NAO, ENSO,SOI, …).The originality of this work is to show that within the framework of a karst system (Radicatel) in chalky context ofthe Western North of the Basin of Paris, it is possible to highlight the influence of the variations of the climaticsignal on the hydrological parameters but also on particulate transport and the sedimentary recording. We usein this aim 22 year-long precipitation, piezometry and turbidity time series (from 1987 to 2009) and asedimentary recording in the gallery of a spring water supply. The study of hydrological and sedimentary signalsof precipitation, Chalk aquifer water level and turbidity over the period 1987 to 2009 by continuous wavelet

analysis highlighted the presence of three frequency components corresponding to 1 year (hydrological cycle),2-3 years (quasi-biennial) and 5-7 years (interannual). The identification of these frequency bands is consistentwith the work of Massei et al. (2007, 2010), as shown in Laignel et al . (2010) highlighting a common structurebetween the hydrological signals and the North Atlantic Oscillation (NAO), which characterize the climate ofNorth West Europe. The study of the sedimentary recording was carried out in two stages:

(i) we first highlighted the existence of small sedimentary structures (alternating laminae of light and darklaminae), each corresponding to a turbid flood event eventually used for calibration of an « age model » bycomparison with the turbidity signal.

(ii) wavelet analysis of the sedimentary record has revealed a spectral composition of three frequency bandsto 1 cm, 3-4 cm and 7 cm. Thanks to the age calibration, we could deduce that these three frequency bandscorrespond to 1 year, 2-3 years, 5-7 years. This shows sensitivity of the karst system of Radicatel in response toclimate trends.This work confirms that the hydrological parameters variations (precipitation and water level) atthe very local scale are clearly under the influence of the climate regime generally dominated by the NAO, andthat this influence is also reflected through turbidity resulting from the complex combination of processes of

runoff, erosion, particle transport and storage intrakarstique. We have also shown that sediment accumulation inthe form of alternating lamination (laminated light / dark laminae) is the result of turbid flood events (event-level)and trapping sediment in the long term (22 years) is under the influence of climatic fluctuations.

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discharge indicators serve as cave-level marker. These findings highlight the importance of flow-system contextin the understanding of the porosity-generating and -plugging hypogenic processes, transport of heat, petroleumand ore components in carbonate systems which have geothermal, petroleum and ore geological importance.

Maréchal J.C., Ladouche B., Dewandel B., Fleury P. & Dörfliger N.

Diagnostic plots applied to well-tests in karst systems 

Pumping tests conducted on wells intersecting karst heterogeneities such as the conduit network are difficult to

interpret. Nevertheless, this case can be solved by assimilating the horizontal karst conduit to a finite-

conductivity vertical fracture. In this case, several flow patterns corresponding to the respective contributions of

karst subsystems (fractured matrix, small conduits and main karst drainage network) can be identified on the

diagnostic plot of drawdown derivative.

This is illustrated on two examples from Mediterranean karst systems. A pumping test on a well crossing the

main karst drainage network of the Cent-Fonts karst system shows (i) a preliminary contribution of the karst

conduit storage capacity followed by (ii) linear flows into the fractured matrix. A pumping test on a well

intersecting a small karst conduit of the Corbières karst system shows the existence of (i) bi-linear flows within

both the karst conduit an the fractured matrix at early times, followed by (ii) radial flows within the fracturedmatrix and (iii) finally the contribution of a major karst cavity.

The use of diagnostic plots allows identifying the various flow regimes during pumping tests, corresponding to

the response of the individual karst aquifer subsystems. This is helpful in order to understand the structure of

the karst aquifer and flow exchanges between subsystems.

Résumé 

Les essais de pompage menés sur des puits traversant des hétérogénéités du karst telles que le réseau de 

drains sont difficiles à interpréter au moyen des techniques traditionnelles. Néanmoins, ce cas peut être abordé 

en assimilant le conduit karstique horizontal à une fracture verticale de perméabilité finie. Dans ce cas,

 plusieurs types d’écoulements correspondant aux contributions respectives des sous-systèmes du karst 

(matrice fracturée de la zone noyée, petits conduits, réseau de drainage principal) peuvent être identifiés sur la 

courbe diagnostic de la dérivée du rabattement.Cette méthode est illustrée sur deux cas réels provenant d’aquifères karstiques méditerranéens. Un essai de

pompage réalisé sur un puits traversant le réseau de drainage karstique principal du système des Cent-Fonts 

montre (i) une première contribution du stockage capacitif au sein du conduit karstique suivi (ii) d’écoulements

monodimensionnels au sein de la matrice fracturée. Un essai de pompage sur un puits traversant un petit 

c onduit karstique du système des Corbières montre l’existence (i) d’écoulements bilinéaires au sein du conduit 

et de la matrice fracturée au début, suivis (ii) d’écoulements radiaux au sein de la matrice fracturée et enfin (iii)

la contribution d’une cavité karstique majeure.

L’utilisation de la courbe diagnostic de dérivée des rabattements permet d’identifier les différents régimes

d’écoulements durant un essai de pompage, correspondant aux réponses successives des sous-systèmes de 

l’aquifère karstique. Ceci contribue à comprendre la structure de l’aquifère karstique ainsi que les échanges de

flux entre sous-systèmes.

Parise M.

Managing water resources in the karst of southern Italy : an historical survey 

Karst landscapes are characterised by lack or scarce presence of water at the surface. This resulted in the

need, for ancient populations, to gain a deep knowledge of the territory in order to exploit the few available

water resources. Several techniques were developed at this aim, until reaching a high level of capability to

collect, transport, and distribute water, even at long distances. Many areas in southern Italy still nowadays

present hydraulic works of remarkable interest and historical values, which are briefly described in the present

paper, together with other features used for water storage in karst. The lessons learned from such ancient ability

should not get lost, in times when we are periodically facing hydric crisis and droughts.

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 Sinreich M.

Contaminant attenuation in karst aquifers  – a paradigm shift