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EN
Water scarcity is severely high in the North Africa and the Middle East (MENA) regions. The deterioration of water quality has an impact on the human health as well as on the development of agricultural activities, especially in arid regions, where precipitations are less frequent. The aim of this work is to identify and evaluate the chemistry of the groundwater aquifer in the region of Messaad plateau. This region is located 370 km south of Algiers in southern Algeria. A dozen of samples were collected from wells and analyzed using physic-chemical technics, and the results were processed statistically. The distribution of the conductivity values and the various chemical parameters suggest that the groundwater in the Messad wadi area is overall highly mineralized, with the EC ranging from 550 μS . cm–1 to 8790.13 μS . cm–1, with a predominance of calcium sulphate facies and calcium chloride facies. The level of mineralization noted in the southern and southeastern portions of the research area sheds light on the source of natural contamination. The SO42–, Cl– , Ca2+ , Na+ ions are the most important factors influencing the electrical conductivity of water and the groundwater chemistry. These ions are the result of the continuous dissolution of gypsum and halite in the clays and marls of the Barremian formations.
EN
Sinkhole (doline) collapse is one of the major natural hazards threatening people and property in the Middle East and North Africa (MENA) region, especially if the bedrock structure is epi-karstic, covered by encrusted material. Many dolines-avens collapses have been recorded in urban and rural areas in Northeast Algeria. Our study identifies localized deformation that may be caused by a sinkhole activity based on the electrical resistivity tomography (ERT) imaging in Setifian high plains. For this task, we conducted 2-D Wenner and Wenner-Schlumberger transects profiles. The geological and hydrogeological study helped to calibrate the resistivity model, and in this regard, expound on the proneness of the limestone layer to collapse. The obtained model highlights the heterogeneity of the subsurface. The inverted transects allowed the investigation of 20 m depth with Wenner array and 52 m with Wenner-Schlumberger. The Wenner inverted models imaged the chimney and different karst networks until 20 m depth; even as the Wenner-Schlumberger models imaged a new karstic cavity in the limestone layer. ERT imaging has once again proven its effectiveness in mapping sinkholes based on its ability to detect resistivity. Our research can certainly benefit karst collapse monitoring in other areas of the high plain region.
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