Younes Hamed

Geochemical and isotopic study of the multilayer aquifer system in the Moulares-Redayef basin, southern Tunisia / Etude géochimique et isotopique du système aquifère multicouche du bassin de Moulares-Redayef, sud tunisien

Abstract Major ion geochemistry, and water molecule isotopes (18O, 2H) and radiogenic carbon (14C) of dissolved inorganic carbon (DIC) were used to investigate the hydrodynamic functioning of the multilayer aquifer system in the Moulares-Redayef basin, southern Tunisia. The groundwater of different aquifer levels is characterized by sulphate to calcium sulphate water type. The major geochemical processes in the aquifer system are evaporite mineral dissolution and mixing. The isotopic study allows two groundwater types to be identified: an old palaeoclimatic groundwater, marked by low 14C activity and relatively depleted stable isotope (18O and 2H) content characterizes the shallowest aquifers of the Plio-Quaternary and Miocene formations; however, a recent groundwater, distinguished by relatively high 14C activity and slightly enriched 18O and 2H content, characterizes the deep Upper Cretaceous artesian aquifer. In addition to these two water groups, other groundwaters are identified, indicating a mixing effect.

Groundwater evolution of the Continental Intercalaire aquifer of Southern Tunisia and a part of Southern Algeria: use of geochemical and isotopic indicators

AbstractThe expansion of irrigated agriculture and the overexploitation of groundwater aquifers are leading to saltwater intrusion, severe deterioration of groundwater quality and soil subsidence at arid areas. The geochemical processes taking place along an 800 km flow line in the non-carbonate Continental Intercalaire aquifer (CI) in North Africa are described using chemical (major and trace element) and isotopic indicators. The aquifer is hydraulically continuous from the Atlas Mountains in Algeria to the Chotts of Tunisia and the geochemical evidence corroborates this. The CI aquifer of North Africa is one of the largest confined aquifers in the world. The aquifer is hydraulically continuous from the Atlas Mountains in Algeria (recharge area) to the Chotts of Tunisia (discharge area) and the geochemical evidence corroborates this. The isotopic study (Delta18O, Delta2H) permits classifying groundwater into three groups. The first group is characterized by low 3H concentrations, low 14C activities and d...

The hydrogeochemical characterization of groundwater in Gafsa-Sidi Boubaker region (Southwestern Tunisia)

Gafsa region is one of the most productive artesian basins in Southern Tunisia. It is located in the southwestern part of the country, and its groundwater resources are developed for water supply and irrigation. Proper understanding of the geochemical evolution of groundwater is important for sustainable development of water resources in this region. A hydrogeochemical survey was conducted on the Plio-Quaternary shallow and on the Complex Terminal aquifers system using major (Ca, Mg, Na, SO4, Cl, NO3 and HCO3) and minor (Sr) elements, in order to evaluate the groundwater chemistry patterns and the main mineralization processes occurring in this system. Hydrochemical and isotopic data were used in conjunction with hydrogeological characteristics to investigate the groundwater composition in these aquifers. It has been demonstrated that groundwaters acquire their mineralization principally by water–rock interaction, i.e. dissolution of evaporites (halite/gypsum, pyrite, etc.) and return flow of irrigation waters, and by anthropogenic activities due to the use of nitrogen (N) fertilizers–pesticides in agriculture. The isotopic study of “stable isotopes, radiocarbon and tritium” (Yermani 2002) shows that a paleoclimatic recharge is corroborated by the relatively low carbon-14 activities (5–25.3%) of the referred groundwater group samples, which were interpreted as recharge occurring during the late Pleistocene and the early Holocene periods. The water feedings of these aquifers are mainly provided by infiltration of precipitations, infiltration of irrigation water, lateral feeding from Cretaceous relieves from the South and the North and along recent and fossil drainage networks that constitute major freshwater sources in groundwater tables (Hamed et al., J Environ Protect 1:466–474, 2010a).

Atmospheric pollution in North Africa (ecosystems–atmosphere interactions): a case study in the mining basin of El Guettar–M’Dilla (southwestern Tunisia)

Air quality transcends all scales with in the atmosphere from the local to the global with handovers and feedbacks at each scale interaction. Air quality has manifold effects on health, ecosystems, heritage and climate. New insights into the characterisation of both natural and anthropogenic emissions are reviewed looking at both natural (e.g. dust and lightning) as well as plant emissions. In the phosphate mining area (El Guettar–M’Dilla basin: Southwestern Tunisia), several diseases have been known as cancer, respiratory, allergies, cardiovascular, dental fluorosis, stress, etc. These diseases are directly related with the installation of the industrial sector of the CPG (from 1896) and the deforestation and the ecosystem degradation (fauna and flora).

Palaeoenvironments of the Continental Intercalaire fossil from the Late Cretaceous (Barremian-Albian) in North Africa: a case study of southern Tunisia

Through the Late Cretaceous, the southern shore of the Tethys Ocean migrated north and south over short distances. These vicissitudes are documented in the Continental Intercalaire, a long series of mainly non-marine sediments deposited in which dinosaur or other reptiles tracks and floral fossils are common across southern Tunisia (North Africa). A combined taxonomic, climatological, and palaentological studies provides independent lines of evidence for reconstruction of palaeoenvironments. The Bou Hedma/Boulouha and Sidi Aïch/Douiret Formations from southern Tunisia span the later part of the Late Cretaceous. During the Late Cretaceous the Tunisian territory was an archipelago, thus a particularly suitable area for a more detailed study. We investigated the area’s plant palaeo-biogeography, using fossil wood, with information from both a literature survey and investigation of new samples. The presence of fossils at great depths and distances from the present coastline, without signs of abrasion and far from areas of fluvial discharges does indicate that these remains have not been transported from the continent to the shelf, but have been preserved directly on the area that today correspond to the continental shelf. The climate during the accumulation of Barremian-Albian deposits in this region is inferred to have been warm and humid.

Climate Change and Water Resources Management in Arab Countries

Climate change has a multitude of immediate and long-term impacts on water resources in Arab countries.

GIS-Based Approaches for the Landslide Susceptibility Prediction in Setif Region (NE Algeria)

The present study is focused on a comparative evaluation of logistic regression (LR), frequency ratio (FR), information value (IV), and weight of evidence (WoE) methods for landslides susceptibility assessment in Bouandas region, North of Setif (NE Algeria). Information about landslide inventory and 17 pre-defined causative factors were prepared from multiple sources. The four methods are used to derive the weighted value of causative factors along the study area. The results were validated using receiver operating characteristic and the areas under the curves obtained using the FR, LR, IV and WoE methods are 0.86, 0.84, 0.81 and 0.79, respectively. The landslide susceptibility map produced from FR model is proposed to be more useful for the study area. It could reveal the relative importance of different factors in explaining landslides, and it may assist engineers in land-use planning.

Hydro-geophysical and geochemical studies of the aquifer systems in El Kef region (Northwestern Tunisia)

In El Kef region, Northwestern Tunisia, the evolution of the agricultural and industrial sectors has exacerbated the need for water which caused a significant increase in groundwater extraction. In this context, several geologic and geophysical studies conducted on the groundwater resources of the concerning area were meant to give us insight into the geometry of the reservoirs and structural architecture of the basin and to identify the various reservoirs such as the Mio-Plio-Quaternary, the Lower Eocene and the Campanian–Maastrichtian aquifers. In this study, we used the geochemical study and analysis of gravity data (Horizontal and vertical derivative, horizontal gravity gradient maxima…) to improve the knowledge of the dip and direction fault and the geological structures in El Kef region (NW Tunisia) that control the groundwater hydrodynamic. Furthermore, the techniques of horizontal gradient and upward extension were applied to determine the gravity lineaments that represent the location of density contrasts and to locate the various faults that contribute to the structuring of the study area. Additionally, this study aims to assess the spatio-temporal evolution of the hydrodynamic parameters of the aquifers and to characterize the groundwater mineralization (salinity, chemical facies relationship, etc.). Our study showed the presence of four types of water facies: Ca–Mg–SO4; Na–Cl–NO3; Ca–Mg–HCO3 and Na–K–HCO3. The isotopic study is used to provide some information about the groundwater recharge and to define the different sources of water mixing. That way we could have better understanding to the hydrologic cycle and to the paleoclimate of the study area. Generally, the geochemically evolved groundwaters of the aquifer systems of El Kef region are relatively isotopically depleted when compared to the present day meteoric waters reflecting recharge under cold climate and high altitude. Conversely, the continuous increase of the annual mean temperature and the decrease of precipitations have been observed for the second half of the 20th century in North Africa. It is likely related to the warmer and drier conditions associated with the climate change phenomenon.

Using GIS and RS for Slope Movement Susceptibility Mapping: Comparing AHP, LI and LR Methods for the Oued Mellah Basin, NE Algeria

GIS-based approaches are often used for Geo-hazards environmental impact assessment (Mezaal et al. 2017). It allows the integration of different data layers in complex environments (Pradhan et al. 2011). In this research the zoning of the spatial occurrence of a slope movement (SM) could help effectively to reduce their damages (Hadji et al. 2017).