ORIGINAL ARTICLE Hydrochemistry and isotopic exploration for a karstic aquifer in a semi-arid region: case of Cheria Plain, Eastern Algeria F. Baali • C. Fehdi • A. Rouabhia • R. Mouici • E. Carlier Accepted: 24 June 2014 / Published online: 25 July 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract Groundwater from karst aquifers is among the world’s most important sources of drinking water supplies, and the hydrochemical characteristics of karst water are affected by both natural environment and people. There- fore, the study of karst groundwater hydrochemistry and its solutes’ sources is very important to ensure the normal function of life support systems. In this paper, hydrogeo- chemistry and isotope hydrogeology approaches have been used to investigate the karst groundwater systems at Cheria region in recent years. Hydrochemical types of karst groundwater in the study area were mainly of the Ca– HCO 3 type or Ca(Mg)–HCO 3 type indicating that weath- ering of limestones and dolostones is the most important factor controlling the hydrogeochemistry of underground waters, and weathering of sulfate and evaporite rocks is less important. Moreover, the precipitation and human activities also have a definite influence on the hydrogeo- chemistry of underground waters in the region studied. Using stable isotope analysis data, d 18 O and d 2 H rela- tionships show that all waters are meteoric in origin. Keywords Isotope Á Karst Á Hydrogeochemistry Á Cheria Á Tebessa Á Algeria Introduction The studied area is located within the arid zones of Algeria, situated 60 km to the south-west of Tebessa city. It belongs to the high plains area, with an average alti- tude of 1100 m, situated in north-east of Algeria between 7°30 0 –8°00 E; and 35°–35°30 0 N, bounded by Hammamet to the north, the Thelidjen to the south, and the El Ma Labiod plain to the east (Fig. 1). The region is characterized by a semi-arid climate; the average annual precipitation is 340 mm/year and an aver- age annual temperature is 15 °C (Baali 2007). The snow covers the mountains in the region of 10–15 days on average per year. The average water balances are in deficit except for a few years when the surplus exceeds the maximum annual rainfall (350 mm), which can be explained by the imbalance between output and input. This has caused a serious drought in the last two decades (Fig. 2). Groundwaters play a dominant role in this part of Algeria. Because of the lack of permanent surface water reservoirs owing to the hard climatic conditions, it con- stitutes the most widely available source of fresh water. In this region, groundwaters are used for domestic, agricul- tural, and industrial purposes. Overexploitation of this resource has caused a progressive degradation of the water quality in the irrigated area with the occurrence of high- salinity zones (Rouabhia et al. 2004). Geological and hydrogeological context The Cheria plain is a subsident basin, which was formed during the Miocene; it is a part of a narrow trough which forms a small portion of the great Mio-Plio-Quaternary F. Baali (&) Á C. Fehdi Á A. Rouabhia Á R. Mouici Labo Eau et Environnement Te ´bessa Algeria, Department of Geology, University of Te ´bessa, Avenue 4 Mars. 1956, Te ´bessa 12000, Algeria e-mail: baali_fr2000@yahoo.fr E. Carlier Polytech’Lille, Universite ´ de Lille I, Villeneuve-d’Ascq, France 123 Carbonates Evaporites (2015) 30:99–107 DOI 10.1007/s13146-014-0214-5