Geochemical and Isotopic Study of a Coastal Phreatic Aquifer from the NE of Tunisia: Guenniche Basin

International audienceThe geochemistry and isotopic composition (18O, 2H) of groundwater from the alluvial phreatic aquifer in the Wady Guenniche basin (NE of Tunisia), were investigated in order to reveal the origin of the water salinity. The major geochemical processes in the aquifer are evaporite mineral dissolution and mineral exchange with clays. The salinization of groundwater would be a limiting factor in their use for irrigation. The stable isotopic composition of water indicates a groundwater recharge in current climate condition and the point closest to the sea indicates the possible beginning of a seawater intrusion as a result of the intensive exploitation of resources. The tritium data confirm a recent recharge younger than 1950

Hydrogeochemical characterization of the Menzel Bourguiba aquifer system (north-eastern Tunisia)

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Naturel Tracer and Isotopic Approach to Describe Groundwater Behaviour: An Example of the Mateur Plain (North-Eastern Tunisia)

International audiencePhysical and chemical data, have been taken from the whole of Mateur plain (NE Tunisie) (Fig. 1a). In Mateur region, most waters come from phreatic aquifer and deep aquifers. These aquifers show indications of advanced overexploitation, revealed by decreasing piezometric surfaces and degradation in water quality. The total dissolved solids (TDS) were measured in September–October 2015 at 72 water points drilled in the phreatic aquifer and deep aquifers. The upstream zone of Mateur shows good chemical quality water, with a TDS varying from 0.7 to 1 g/l. However, highly mineralized waters (over 1.5 g/l) were found in the middle-Mateur plain and downstream zone

Enhanced machine learning model to estimate groundwater spring potential based on digital elevation model parameters

In the current work, an enhanced model was developed to map groundwater spring potential using parameters derived uniquely from digital elevation model (DEM) as inputs. The proposed method is based on combining Quantum Particle Swarm Optimization (QPSO) and the Credal Decision Tree (CDT) groups (QPSO/CDT model). The principle of the suggested algorithm is to establish a CDT tree realized according to Random Subspace model (RSS). Then, we integrated QPSO to improve the three indices (subspace size, number of CDT sub-groups, and the CDT highest-range-of-trees). To reach this goal, a case study area in northeast Tunisia (region of Mornag) was chosen and 10 parameters were derived from the DEM. The result shows high accuracy of the QPSO/CDT model outputs compared to other machine learning models. Across the ten parameters, the convergence index, topographic wetness, drainage density, and altitude are the most relevant parameters

A Hydrogeological Conceptual Model Refines the Behavior of a Mediterranean Coastal Aquifer System: A Key to Sustainable Groundwater Management (Grombalia, NE Tunisia)

The Mediterranean coastal aquifer system of the Grombalia basin (NE Tunisia) offers immense potential as a source of fresh water for agriculture, industry, and drinking water supply. Nonetheless, due to its intricate hydrogeological characteristics and the prevailing issue of groundwater salinity, comprehending its groundwater system behavior becomes crucial for the effective and sustainable management of this aquifer system. Based on the hydrogeological characterization of the Grombalia basin, a novel 3D hydrogeological conceptual model was developed to enhance the understanding of its complex aquifer system. The integration of insights from geological, hydrogeological, hydrodynamic, and hydrochemical components facilitated the construction of the hydrogeological conceptual model. Although the model’s validity faced initial uncertainties due to spatial interpolation of lithological sequences, this study’s thorough and encompassing hydrogeological investigation overcame these limitations. As a result, a more informed comprehension of the aquifer system complexities was achieved. This study reveals that the basin is underlain by an extensive, cohesive Mio–Plio–Quaternary aquifer system. The model demonstrates vertical and lateral hydrogeological continuity between the Quaternary and underlying Mio–Pliocene deposits, enabling groundwater flow and exchange between these layers. Over-abstraction of the Mio–Plio–Quaternary aquifer system has led to a significant drop in piezometric levels and raised the risk of seawater intrusion. These findings emphasize the critical necessity of taking into account the interconnections among hydrogeological units to ensure sustainable groundwater management. The developed conceptual model offers a key tool for understanding the hydrodynamic functioning of the Grombalia aquifer system with a view toward guiding future groundwater management strategies. The application of this approach in the Grombalia basin suggests its potential applicability to other regional aquifers facing comparable challenges