HYDROGEOLOGIE D’UN SYSTEME AQUIFERE EN ZONE SEMI-ARIDE.CAS DE LA REGION DE KHENCHELA (ALGERIE)

L'hydrogéologie des zones arides et semi-aride de l'Algérie, est un thème complexe. La région de Khenchela, qui se trouve touchée par une sècheresse chronique et un bilan climatique toujours négatif ne permet pas de justifier ou de préciser l'existence d’une recharge des nappes aquifères. Or cette recharge, même si elle est limitée, existe souvent dans ces régions arides où l'irrégularité du climat peut provoquer certaines années quelques événements pluvieux exceptionnels [1, 2, 3, 4]. Trois systèmes aquifères sont distingués dans la wilaya de Khenchela : le Quaternaire, le Crétacé et le Miocène. On dénombre quatre nappes aquifères, l’une est superficielle, il s’agit de nappes phréatiques hétérogènes et le reste sont des nappes profondes représentées par la nappe des plaines d’effondrement, la nappe des calcaires fissurés et la nappe des formations continentales. La profondeur de ces formations aquifères varie de 5 à 600 m. Le volume total prélevé à partir de l’ensemble des aquifère est de 34 millions de m3/an [1]. L’objectif essentiel est d'identifier les aquifères de la région afin de constituer une base de données sur les possibilités hydriques des formations de la région de Khenchela.  The hydrology of arid and semi-arid Algeria is a complex subject. Khenchela region, which is affected by chronic drought and climate always negative balance does not justify or clarify the existence of a groundwater recharge. Now this charge, even if limited, often exists in these arid regions where the climate can cause irregularity in some years a few exceptional rainfall events [1, 2, 3, 4]. Three aquifer systems are distinguished in the wilaya of Khenchela: Quaternary, Cretaceous and Miocene. There are four aquifers, one is superficial, it is heterogeneous aquifers and the rest are represented by the deep groundwater aquifer plains of collapse, the web of cracked limestone formations and the water inland. The depth of these aquifers ranges from 5 to 600 m. The total collected from all aquifer is 34 million m3/year [1]. The main objective is to identify the aquifers in the region to establish a database on water training possibilities in the region of Khenchela

Hydrochemical and isotopic characterization of a complex aquifer system

A methodology was developed and applied to the Tindouf basin (south-western Algeria) to understand the hydrogeology of a complex aquifer system with a limited number of data, to identify the favorable areas for the design and building of new wells, and to know whether there is still current recharge of these aquifers. The principal components analysis (PCA), diagram of deuterium versus oxygen-18, and equilibrium diagrams Mg/Na and Ca/Na were the techniques used to combine different datasets in order to identify chemical and isotopic groups, which were in turn used to define the groundwater flow paths. In addition, on the basis of thermodynamic equilibrium, it is possible to define the chemical evolution of the Tindouf basin aquifer. The results of this study are consistent with the generally accepted hydrogeological conceptual model. The combination of the different methods made possible to define and and to characterise the main groundwater flow paths from their sources to the discharge zones. These flow paths are defined by water categories, which are represented by salinity and groundwater origin. This approach can be used to analyze aquifers characterized by a lack of data and can also be useful for studying other complex groundwater basins

Evaluation des ressources en eaux du plateau de Cheria (Algerie) : synthese et analyse des donnees

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Use of discriminant statistical analysis to determine the origin of an industrial pollution type in the aquiferous system of the area of Berrahal, Algeria

International audienceThe continuous increase of industrial activities in the area of Berrahal (northeast of Algeria) resulted in an increase of waste disposal, inducing environmental pollution and contamination of groundwater. Available data on groundwater contamination were used to develop a statistical study for contaminated regions and to identify exposure scenarios of pollution. Chemical analysis of the samples shows that water of most wells and drillings is in bad quality or not drinkable, whereas statistical processing of these data by principal component analysis and discriminant factor analysis suggests that wastewater coming from companies of the industrial park of Berrahal is very rich in organic pollutants (high percentages of BOD5 and NO2−) and has high mineralization (has strong concentration in major elements and high electric conductivity); these constitute the main factors of the deterioration of the quality of this water. The considered exposure pathways were drinking water exploited from wells and drillings implanted in this area and its contact with soil (ingestion and dermal contact) that could threaten either humans or wildlife, on site or off site. In addition, groundwater was considered to be a potential risk pathway, especially for the ecosystem of Lake Fetzara and for the aquiferous system

Hydrochemical study of Drean–Annaba aquifer system (NE Algeria)

Water quality is subject to frequent changes in the Drean-Annaba alluvium aquifer. Water-rock interaction can not be the only process that produces the observed modification, but dryness that the country knew during the last two decades has highly contributed to the water quality changes. During this period, irregularities in the distribution of rainfalls, in time and space, have been observed. As a result, a periodicity in hydrochemical changes in water of wells and rivers is noticed. Statistical, the principals components analysis (PCA) tools and Tickel diagram have been used to show, through chemical presentation, these effects. The results show, indeed, seasonal changes of water quality for the period 1999-2000. From a cationic point of view, a competition between alkaline and alkaline earths is shown. On the other hand, from an anionic point of view, there is a transition from chlorides to sulphates and may be to bicarbonates. The present work was carried out in a relatively small area and this was useful to show the relationship that existed between dryness and water quality of both the aquifer system and surface water

Hydrochemical study of Drean–Annaba aquifer system (NE Algeria)

Water quality is subject to frequent changes in the Drean–Annaba alluvium aquifer. Water-rock interaction can not be the only process that produces the observed modification, but dryness that the country knew during the last two decades has highly contributed to the water quality changes. During this period, irregularities in the distribution of rainfalls, in time and space, have been observed. As a result, a periodicity in hydrochemical changes in water of wells and rivers is noticed. Statistical, the principals components analysis (PCA) tools and Tickel diagram have been used to show, through chemical presentation, these effects. The results show, indeed, seasonal changes of water quality for the period 1999–2000. From a cationic point of view, a competition between alkaline and alkaline earths is shown. On the other hand, from an anionic point of view, there is a transition from chlorides to sulphates and may be to bicarbonates. The present work was carried out in a relatively small area and this was useful to show the relationship that existed between dryness and water quality of both the aquifer system and surface water.W systemie aluwialnych poziomów wodonośnych Drean–Annaba jakość wody podlega częstym zmianom. Oddziaływania woda–podłoże skalne nie mogą być jedynymi procesami odpowiedzialnymi za obserwowane zmiany, natomiast susze, jakich kraj doświadczał w ciągu minionych dwóch dziesięcioleciach znacząco przyczyniły się do zmian jakości wody. W tym okresie obserwowano nieregularny rozkład opadów w czasie i przestrzeni. W konsekwencji zanotowano okresowość zmian hydrochemicznych właściwości wody w studniach i rzekach. Użyto statystycznych narzędzi, takich jak analiza składników głównych (PCA) i diagram Tickela do prezentacji wymienionych efektów. Uzyskane wyniki dowodzą sezonowych zmian jakości wody w okresie 1999–2000. W odniesieniu do kationów wykazano konkurencję pomiędzy pierwiastkami alkalicznymi i pierwiastkami ziem alkalicznych. W grupie anionów stwierdzono przejście od chlorków do siarczanów i prawdopodobnie do wodorowęglanów. Przedstawione badania prowadzono na stosunkowo małym obszarze, co okazało się korzystne dla wykazania zależności pomiędzy suszą a jakością wody zarówno w systemie poziomów wodonośnych, jak i w wodach powierzchniowych