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    Fehdi Naoufel

    The aim of this study was to perform a pre-liminary assessment of the hydrochemical and microbial groundwater quality of the Merdja plain (Te´bessa area). Twenty samples of groundwater collected from Bekkaria (Site 1) to Ain Chabro (Site... more
    The aim of this study was to perform a pre-liminary assessment of the hydrochemical and microbial
    groundwater quality of the Merdja plain (Te´bessa area).
    Twenty samples of groundwater collected from Bekkaria
    (Site 1) to Ain Chabro (Site 2) were assessed for their
    suitability for human consumption. Groundwater from the
    aquifer in the Merdja area can be divided into two major
    groups according to geographical locations and chemical
    compositions. Water in the center part of the study area is
    characterized by the dominance of chloride, sulfate,
    sodium, and potassium; whereas waters in the limestone
    aquifers in the west are dominated by the same cations but
    have higher concentrations of bicarbonate. Microbiological
    parameters were determined in 13 groundwater samples
    collected from the study area. Total coliforms, thermotol-erant coliforms,E. coli, Enterococcusspp.,Salmonellasp.,
    Staphylococcusspp., and P. aeruginosawere detected in
    96.36, 88.18, 100, 47.5, 97.27, 96.7, and 75 % of the
    groundwater samples, respectively. The pollution of
    groundwater comes from a variety of sources, Ouadi El
    Kebir River, including land application of agricultural
    chemicals and organic wastes, infiltration of irrigation
    water, septic tanks, and infiltration of effluent from sewage
    treatment plants, pits, lagoons, and ponds used for storage.
    Sinkhole collapse is one of the main limitations on the development of karst areas, especially where bedrock is covered by unconsolidated material. Studies of sinkhole formation have shown that sinkholes are likely to develop in cutter... more
    Sinkhole collapse is one of the main limitations on the development of karst areas, especially where bedrock is covered by unconsolidated material. Studies of sinkhole formation have shown that sinkholes are likely to develop in cutter (enlarged joint) zones as a result of subterranean erosion by flowing groundwater. Electrical resistivity imaging or tomography (RESTOM) is well suited to mapping sinkholes because of the ability of the technique for detecting resistive features and discriminating subtle resistivity variations. Two-dimensional electrical resistivity tomography surveys were conducted at two sinkhole sites near Cheria city where limestone is covered by about 10 m of clayey soils. A Wenner transect was conducted between the two sinkholes. The electrode spacing was 2 m. The length of transect is about 80 m. The survey results suggest that RESTOM is an ideal geophysical tool to aid in the detection and monitoring of sinkholes and other subsurface cavities. الانهيارات الناتجة عن الفجوات الصخرية هي واحدة من أهم العوامل المؤثرة في تنمية المناطق الكارستية ، وخصوصا عندما يكون الأساس الصخري مغطى بتربة غير معززة. أظهرت الدراسات لتشكيل مثل هده الانهيارات أنه من المرجح أن تتطور في شكل القاطع نتيجة لتآكلت ناتجة عن تدفق المياه الجوفية. تعتبر المقاومية الكهربائية أو التصوير المقطعي (RESTOM) مناسبة تماما لرسم الخرائط الصخرية بسبب قدرة هده التقنية للكشف عن ميزات المقاومية و اختلافات المقاومية الخفية. أجريت عملية المسح المقطعي بطريقة المقاومية الكهربائية ثنائية الأبعاد في موقعين بالقرب من مدينة الشريعة حيث أن الطبقات الجيولوجية والمكونة أساسا من الحجر الجيري مغطاة بحوالي 10 أمتار من التربة الطينية. أجري مقطع جيوفيزيائى بطريقة Wenner بين اثنين من الفجوات الصخرية حيث كان التباعد بين كل قطب 2م و طول المقطع حوالي 80 متر. وتشير نتائج دراسات المسح عن طريق التصوير المقطعي RESTOM أنها أداة جيوفيزيائية مثالية للمساعدة في كشف ورصد الفجوات الصخرية وغيرها من التجاويف تحت سطح الأرض.