Title: Hydro-geochemical behaviour of two coastal aquifers under severe climatic and human constraints: comparative study between Essaouira basin in Morocco and Jeffara basin in Tunisia

Authors: Mohammed Bahir; Najiba Chkir; Rim Trabelsi; Haj Ammar Friha; Kamal Zouari; Hamid Chamchati

Addresses: Faculty of Science-Semlalia, Cadi Ayyad University, 3GEOLAB, Prince Moulay Abdellah Boulevard, P.O. Box 2390, Marrakech, Morocco. ' Geology Department, Faculty of Letters and Human Sciences of Sfax, Laboratory of Radio-Analysis and Environment (LARAE), P.O. Box W 3038, Tunisia. ' Geology Department, Faculty of Letters and Human Sciences of Sfax, Laboratory of Radio-Analysis and Environment (LARAE), P.O. Box W 3038, Tunisia. ' Geology Department, Faculty of Letters and Human Sciences of Sfax, Laboratory of Radio-Analysis and Environment (LARAE), P.O. Box W 3038, Tunisia. ' Geology Department, Faculty of Letters and Human Sciences of Sfax, Laboratory of Radio-Analysis and Environment (LARAE), P.O. Box W 3038, Tunisia. ' Faculty of Science-Semlalia, Cadi Ayyad University, 3GEOLAB, Prince Moulay Abdellah Boulevard, P.O. Box 2390, Marrakech, Morocco

Abstract: Since surface waters are mostly irregular and rare, groundwater in arid and semi-arid regions are submitted to high human constraints enhanced by severe climatic conditions. Multiple isotope analyses and chemical tracing of groundwater from the Essaouira basin (South-Western Morocco) and from the Jeffara basin (South-Eastern Tunisia) reveal that salinisation processes are mainly related to natural conditions such as dissolution of evaporate rocks (gypsum and halite minerals) along the recharging outcrops. However, since these basins are coastal, seawater intrusion is one of multiple salinity sources that could affect the quality of groundwater if intense exploitation goes on. The comparison of hydro-geochemical and isotopic data available for the two basins provide a framework for a comprehensive diagnostic in which different states of risks could be defined according to climatic and human constraints. We argued that these heavily exploited coastal aquifers have exacerbated vulnerability given relatively low current recharge and salinisation processes.

Keywords: geochemical tracers; stable isotopes; seawater intrusion; Morocco; Tunisia; hydrogeochemical behaviour; coastal aquifers; climatic constraints; human constraints; groundwater; arid regions; semi-arid; salinisation; salinity sources; vulnerability; risk; recharge.

DOI: 10.1504/IJHST.2012.045940

International Journal of Hydrology Science and Technology, 2012 Vol.2 No.1, pp.75 - 100

Published online: 16 Aug 2014 *

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