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Communication dans un congrès

Comparing hydrogeological properties of volcanic aquifer by combining piezometric and hydrochemical data: the Martinique Island example

Abstract : The management of freshwater resources is crucial for water supply to population and particularly in volcanic islands. Martinique Island, a French overseas department of 1080 km² in the Lesser Antilles, is marked by a high population density with an insufficient volume of distributed water during dry seasons with water shortages that preclude ensuring a continuous distribution of drinking water. Around 90% of the water supply is actually provided by surface water and groundwater should thus be an alternative resource. Up to now, around 4 boreholes and 12 springs are used for drinking water supply. For a better knowledge of the hydrogeological functioning of groundwater resources, a monitoring network of twenty boreholes, with a daily monitoring of water level and bi-annual characterization of chemical data (during the dry season and the rainy season) has been set up in 2004. But scarce information's are available on these boreholes as pumping tests have been made only on few of them, and only water level and chemical data are available. To distinguish between the aquifers, water levels measured during dry and rainy seasons were compared to the chemical elements measured at the same time. Comparisons between seasons were also conducted to determine the capability of the aquifer to return to the initial state (chemical and/or water level) after one or more complete hydrological cycles and also to evidence the impact of recharge on water systems. Several behaviors can be identified and several hypotheses are proposed to characterize the hydrogeological functioning of the aquifers. Particularly, relatively significant aquifers barely influenced by rainy seasons are highlighted. Moreover, small aquifers, confined aquifers and unconfined aquifers are also revealed through this approach. The origin of the dissolved elements is also determined, and changes in their origin between rainy and dry season is suspected for some aquifers. The approach presented here proved to be an interesting tool to characterize aquifers; particularly in areas were scarce information's are available. Martinique aquifers are not homogeneous and the hydrogeological functioning in the island seems characterized by the presence of many disconnected and juxtaposed aquifers with limited extension. This information also confirms that the conceptual model of the aquifer functioning is different from the Canary and Hawaiian models.
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Communication dans un congrès
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https://hal-brgm.archives-ouvertes.fr/hal-00657830
Contributeur : Benoit Vittecoq <>
Soumis le : lundi 9 janvier 2012 - 13:23:21
Dernière modification le : mercredi 3 juin 2020 - 06:06:02

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  • HAL Id : hal-00657830, version 1

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Benoit Vittecoq, Philippe Négrel. Comparing hydrogeological properties of volcanic aquifer by combining piezometric and hydrochemical data: the Martinique Island example. GwFR 2012 - International Conference on Groundwater in Fractured Rocks, May 2012, Prague, Czech Republic. ⟨hal-00657830⟩

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