Potential pollution of groundwater in the valley of the Seybouse River, north-eastern Algeria L. Djabri Æ A. Hani Æ R. Laouar Æ J. Mania Æ J. Mudry Æ A. Louhi Abstract In north-eastern Algeria, the Seybouse River is an important source of water used mainly for irrigation of large agricultural areas extending from the Guelma region to Annaba city. Industrial activities in this region contribute substantial water pollution to the river and the groundwater. Based on the different sources of pollution, mapping of areas vulnerable to groundwater pollution has been accomplished by combining land use and data on groundwater levels. The resulting maps show that the most vulnerable areas are those with large industrial activities—in Meboudja, Bouchegouf and Guelma. Infiltration and runoff contribute to pollution, and the highest infiltration rate is generally observed in areas of agricultural and industrial activities. Pollution of the aquifers in this area is of concern. Mountains, such as the Edough and Gelaat Bou Sbaa, contribute high runoff that carries pollutants towards the groundwater. Keywords Groundwater pollution Æ Vulnerabil- ity Æ Oued Seybouse Æ Algeria Regional setting Geomorphology The area is within the territories of the Wilayas of Guelma, El-Tarf and Annaba. It is limited in the north by the Mediterranean Sea, in the south by the Wilaya of Souk- Ahras, in the west by the Edough Massif, Lake Fetzara, Ain Berda Dj. Debar and Dj. Taya, and in the east by the Annaba plain (Fig. 1). The watershed of the Oued Seybouse covers an overall area of 6471 km 2 (Fig. 1). From its source in the highlands of Sellaoua and Heracta, the Seybouse River drains water very slowly over a gentle relief. In the uplands, it flows through a very fractured and complexly structured terrane, where the hydrographic net is rarely adapted to the structure (Ghachi 1986). The effluents are torrential and the longitudinal contours are irregular and stretched. The Seybouse River flows through some depressions containing an alluvial water table (Hannouche 1990; C.G.G. 1971). This allows regulation of a great quantity of winter precipitation received by the mountain range. When the river reaches the plain of Annaba, it loses its energy and leaves behind a great load of sediments. The geomorphologic characteristics of the plain, gentle slope, sand dune barrier, and inundation-prone areas allow the river to flow easily into the sea. Geology The geology of the area is characterised by a metamorphic core complex of Precambrian to Palaeozoic age (the Edough Massif), overlain by a sedimentary cover of mainly Mesozoic to Cenozoic formations (Fig. 1). The Edough Massif constitutes the easternmost meta- morphic complex of the Algerian coast. It is characterised by high relief (up to 1,008 m) and very complex structures. This massif is composed of a variety of metamorphic lithologies (Hilly 1962) of Precambrian and Palaeozoic age, distributed in a NE-striking antiform. The gneisses which form the core are calc-alkaline rocks (Ahmed-Sa and others 1993). The metapelites overlying the gneisses con- sist of two units: (1) garnet- or, more commonly, kyanite- mica schist alternating with metric slabs and layers of marble and skarn; and (2) a Palaeozoic upper unit (Ilavsky and Snopkova 1987) comprising andalusite-bearing alu- minous schists alternating with feldspathic quartzites. Microgranitic and rhyolitic magmas have intruded the Edough Massif during the Miocene. They outcrop as do- Received: 4 December 2001 / Accepted: 9 April 2003 Published online: 20 June 2003 ª Springer-Verlag 2003 L. Djabri (&) Æ A. Louhi 11 Rue Asla Hocine, 23000 Annaba, Algeria E-mail: Djabri_Larbi@yahoo.fr Tel.: +213-38-871448 A. Hani Æ R. Laouar Geology Department, F.S.T., Badji Mokhtar University, B.P. 12, 23000 Annaba, Algeria J. Mania De ´partement Ge ´otechnique et Ge ´nie-civil, Cite ´ Scientique, Avenue Paul Langevin, 59655 Villeneuve d’Ascq, Lille, France J. Mudry Laboratoire de Ge ´ologie Structurale et Applique ´e, 1 Place Leclerc, 25000 Besanc ¸on, France 738 Environmental Geology (2003) 44:738–744 DOI 10.1007/s00254-003-0824-z Original article