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Communication Dans Un Congrès Année : 2011

New elements toward hydrogeological schemes of Martinique aquifers

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Résumé

The majority of the Lesser Antilles islands are characterized by andesitic volcanism. However, their hydrogeological functioning and associated structures are little known and little studied, while water needs are obvious. Indeed, at the end of dry seasons, water cuts mark the daily routine of the population, although,significant volumes of water could be collected through water boreholes. Volcanic aquifers are complex in terms of geological structure (geometry) and spatial distribution of hydrodynamic parameters. Indeed, only basaltic islands have hydrogeological schemes: the Hawaiian model (low-lying basal aquifer and perched aquifer) and the Canary Island model (continuous basal aquifer). The objective of this presentation is to summarize the results of geological, hydrogeological and geophysical prospecting conducted in Martinique since 2006. Dozens of electrical profilings were conducted to characterize the geological structure. Boreholes were then carried out firstly to calibrate the electrical profiles and also to identify the aquifers. Finally, pumping tests were conducted to determine the hydrodynamic parameters of the encountered aquifers. These researchs have provided new evidence showing that the hydrogeological scheme of the Martinique aquifers is different from the two previously mentioned: Martinique is not marked by lava flows of large extension with high permeability and has not any basal aquifer. The Martinique aquifers are on the contrary very heterogeneous. Their structure and groundwater flow are mainly controlled by embricated and tight paleo-valleys and, for lavas, fissures resulting from cooling stress. Thus, the aquifers are often characterized by a high spatial variation in hydraulic properties, a low storage coefficient and bounded by several no-flow boundaries. Some low permeable layers, resulting from weathering processes (which transforms primary minerals into clay-rich materials) also play an important role as capacitive layers. In some conditions, they can be drained by underlying lavas groundwaters, thus increasing the sustained yield of water boreholes.
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Dates et versions

hal-00641747 , version 1 (16-11-2011)

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  • HAL Id : hal-00641747 , version 1

Citer

Benoit Vittecoq, Nicolas Coppo, Benoît Dewandel, Luc Arnaud. New elements toward hydrogeological schemes of Martinique aquifers. 19ème Conférence Géologique de la Carîbe (19th caribbean geological conference 2011), Mar 2011, Le gosier - Guadeloupe - FWI, France. pp.24. ⟨hal-00641747⟩

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