This study focuses on coastal aquifers subject to uncontrolled land use development by investigating the combined effects of seawater intrusion and nitrate contamination. The research is undertaken in a Mediterranean coastal agricultural area (Plain of the El-Nil River, Algeria), where water resources are heavily impacted by anthropogenic activities. A multi-tracer approach, integrating hydrogeochemical and isotopic tracers (δ2HH2O, δ18OH2O, δ15NNO3 and δ18ONO3), is combined with a hydrochemical facies evolution diagram, and a Bayesian isotope mixing model (MixSIAR) to assess seawater contamination with its inland intrusion, and distinguish the nitrate sources and their apportionment. Results show that seawater intrusion is circumscribed to the sector neighboring the Mediterranean Sea, with two influencing functions including classic inland intrusion through the aquifer, and upstream seawater impact through the river mouth connected to the Mediterranean Sea. Groundwater and surface water samples reveal nitrate concentrations above the natural baseline threshold, suggesting anthropogenic influence. Results from nitrate isotopic composition, NO3 and Cl concentrations, and the MixSIAR model show that nitrate concentrations chiefly originate from sewage and manure sources. Nitrate derived from the sewage is related to wastewater discharge, whereas nitrate derived from the manure is attributed to an excessive use of animal manure to fertilise agricultural areas. The dual negative impact of seawater intrusion and nitrate contamination degrades water quality over a large proportion of the study area. The outcomes of this study are expected to contribute to effective and sustainable water resources management in the Mediterranean coastal area. Furthermore, this study may improve scientists' ability to predict the combined effect of various anthropogenic stressors on coastal environments and help decision-makers elsewhere to prepare suitable environmental strategies for other regions currently undergoing an early stage of water resources deterioration.
The Cenomanian ‘Marnes de Smail’ Formation in Djebel Sabaoune (Batna, Algeria) contains many fossil ostracods with 73 species taxa that are identified for the first time from this area. The ostracod assemblages are consistent with the Cenomanian age formerly assigned by means of invertebrate macrofossils: ammonites, corals, bivalves, echinoids and gastropods. The diverse ostracofaunal assemblages allowed us to reconstruct the palaeoenvironmental parameters that prevailed during the Cenomanian. Both qualitative and quantitative analyses of ostracod assemblages, along with foraminiferal associations and lithofacies, documented progressive environmental change from a relatively deep marine or outer distal platform (at the base of this series) to a middle, inner platform and, finally, to a reefal environment (at the top). The ostracod taxa are mostly endemic species. However, the occurrences of species already known from North and West Africa, the Middle East and the Atlantic clearly demonstrate that migrations still occurred during the Cenomanian.
The Algero-Tunisian confines (Tebessa region) belong to the southern Tethyan domain and the Monts Mellegue. This region is partly composed of Cenomano-Turonian carbonate outcrops; therefore, the investigated sections highlight the black shale levels reported over a short period, around the Cenomanian-Turonian boundary. The lithostratigraphic study designated a depositional environment that emphasized a relatively deep, calm, and often confined ocean environment significantly shallower on the northern part of the study area. The facies lithology and distribution leads to underline the pelagic influences during the upper Cretaceous and neritic throughout the lower Cretaceous period. The maximum thickness of the Cenomano-Turonian (1000 m) was recorded in the southern zones and the minimum (100 m) occurred further north. This palaeogeographic organization persists laterally in Tunisia as the extension of the Constantine mole. The geochemical analyses reveal that the maturity of the Cenomanian source rock is variable. Nevertheless, the Turonian source rock seems to be at the beginning of the oil phase.
This study aims at the mineralogical and physicochemical characterization of the clay formations of the Miocene age from the Timgad Basin (Massif of Aurès, NE Algeria), in order to evaluate their possible valorization, notably for their potential use in the manufacturing of bricks and ceramic industry. For this purpose, four samples were taken from a clay-dominated formation that outcrops 5 km east of the Timgad city. Each sample was collected, prepared, and analyzed by the appropriate analytical methods of characterization such as X-ray diffraction, X-ray fluorescence, and scanning electron microscopy. Moreover, other complementary analyses are performed in this study such as laser granulometry and geotechnical tests. The results of the different tests revealed that the clay formations of the Timgad Basin are non-refractory clays and characterized by medium plasticity. These clays are constituted of more than 50% of fine fraction, mainly represented by kaolinite in association with non-negligible proportions of illite, chlorite, mixed-layer clay minerals, and traces of smectite. Besides, this clayey assemblage is accompanied by some proportion of quartz and calcite, as well as traces of hematite, feldspar, and gypsum. In the light of these results and in combination with the particle size distribution, as well as the results of geotechnical tests, it is concluded that the Neogene clays of the Timgad Basin present high limits of Atterberg. Consequently, their use in the field of manufacturing of bricks and terra cotta ‘Terre Cuite’ products is subordinated to a preliminary treatment with addition of a degreasing agent, in the form of coarse sand, in order to improve their plasticity.
Trace fossils provide detailed palaeoenvironmental and palaeoecological information of both ancient and modern sedimentary systems. During middle Miocene times the Aures Massif located in the northeastern part of Algeria, was affected by, at least, one marine transgression. The latter led to the installation of a carbonate platform, which is placed, for the first time, in a Mediterranean context. In the Rhassira basin, the Middle Miocene marine succession is characterised by carbonate platform deposits dominated by rhodolith beds, typical of those known throughout the Mediterranean area. This succession can be divided into many units separated by discontinuities interpreted here as omission surfaces. The Djebel Arhane section shows two omission surfaces characterised by a pre-omission suite (firmground) represented by Balanoglossites burrows for the first surface and Gastrochaenolites ornatus burrows/borings for the second one, and an omission suite (hardground) as evidenced by the bioerosive structures Trypanites and Caulostrepsis, in both surfaces, respectively. Gastrochaenolites ornatus traces were formed and preserved in firm, compact, semi-lithified and fine-grained substrates (firm- to hardground), indicating the Glossifungites ichnofacies. They show bioglyphs which have been formed during contraction of the posterior adductor muscles. These suggest that their tracemakers were represented by suspension-feeding bivalves, most probably Pholadidae or Mytilidae, which rotated during penetration. The fill of these traces is composed of marine deposits related to a transgressive lag. The omission suite is divided into two ichnocoenoses: (i) pre-lithification burrows/borings, and (ii) post-lithification borings. This is the first report of the ichnotaxon G. ornatus from Algeria.
In NE Algeria and the Tunisia–Algeria border chains, detailed stratigraphic investigations across the Jurassic– Cretaceous boundary (JKB) are scarce and this important stratigraphic interval remains poorly known. This work attempts fulfilling this gap of our knowledge on the JKB successions in this area. It represents unpublished data on calpionellid zonations, based on bed-by-bed sampling, of two sections from the “Ravin Bleu” site of Batna Mountains. In the Jebel Kasserou and J. Bou Merzoug study sections, most of the standard Upper Tithonian–lowermost Valanginian calpionellid zones and subzones are first identified here. Their limits correspond to main calpionellid bioevents allowing to recognize a new Alpelliptica Subzone of the Calpionella Zone in the Lower–Middle Berriasian; subsidiary bioevents being useful to delimit six horizons in the Upper Tithonian Crassicollaria Zone and two others in the Middle Berriasian Elliptica Subzone. All these biostratigraphic units are correlated with their lateral equivalents in other Tethyan sections, mainly from Morocco, Tunisia, SE France, Spain, the Carpathian Ranges and the Balkanides. Chitinoidellid and most of the calpionellid species from Eastern Algeria are first illustrated here. In addition to their easy access and good outcrops, the continuous, complete and thick marine study successions are devoid of strong diagenetic alteration, synsedimentary features and tectonic effects. The “Ravin Bleu” site is proposed herein as a potential reference section for the JKB interval in the North Africa Maghrebian Ranges of the SW Tethys Margin.
The risk related to embankment dam breaches needs to be evaluated in order to prepare emergency action plans. The physical and hydrodynamic parameters of the flood wave generated from the dam failure event correspond to various breach parameters, such as width, slope, and formation time. This study aimed to simulate the dam breach failure scenario of the Yabous dam (northeast Algeria) and analyze its influence on the related areas (urban and natural environments) downstream of the dam. The simulation was completed using the sensitivity analysis method to assess the impact of breach parameters and flooding on the dam break scenario. The flood wave propagation associated with the dam break was simulated using the one-dimensional HEC-RAS hydraulic model. This study applied a sensitivity analysis of three breach parameters (slope, width, and formation time) on five sites selected downstream of the embankment dam. The simulation showed that the maximum flow of the flood wave recorded at the level of the breach was 8768 m3/s, which gradually attenuated along the river course to reach 1972.7 m3/s at about 8.5 km downstream the dam. This study established the map of flood risk areas that illustrated zones threatened by the flooding wave triggered by the dam failure due to extreme rainfall events. The sensitivity analysis showed that flood wave flow, height, and width revealed positive and similar changes for the increases in adjustments (±25% and ±50%) of breach width and slope in the five sites. However, flood wave parameters of breach formation time showed significant trends that changed in the opposite direction compared to breach slope and width. Meanwhile, the adjustments (±25% and ±50%) of the flood hydrograph did not significantly influence the flood parameters downstream of the dam. In the present study, the HEC-RAS 1-D modeling demonstrated effectiveness in simulating the propagation of flood waves downstream of the dam in the event of dam failure and highlighted the impact of the breach parameters and the flood hydrographical pattern on flood wave parameters.
The relative scarcity of water resources in Algeria and their unequal distribution induce a rational use of available resources. The Zana-Gadaïne plain appears as an exemplary case study, where the difficulties posed by the problem of crop water needs versus the availability of water resources appear. This article, based on field surveys and in-situ measurements, aims to identify the pressure of irrigation on water resources and the optimization of their use in an agricultural area, where irrigated agriculture represents 85% of the water consumption of the Zana-Gadaïne plain. The piezometric study in correlation with hydrogeological data reveals that groundwater resources are limited, aggravated by wastage resulting in a consequent drawdown of 24 meters over 11 years. The analysis of interannual climate variability has enabled us to draw rainfall maps characteristic of the evolution of rainfall over the past decades where we observe a net deficit in precipitation. We calculated the evapotranspiration and the requirements in irrigation water for each crop in order to compare them with the available hydric resources and the establishment of irrigation schedules for the principal irrigated crops. The analysis of interannual climate variability has enabled us to draw rainfall maps characteristic of the evolution of rainfall over the past decades where we observe a net deficit in precipitation. We calculated the evapotranspiration and the requirements in irrigation water for each crop in order to compare them with the available hydric resources and the establishment of irrigation schedules for the principal irrigated crops.
The risk related to embankment dam breaches needs to be evaluated in order to prepare emergency action plans. The physical and hydrodynamic parameters of the flood wave generated from the dam failure event correspond to various breach parameters, such as width, slope, and formation time. This study aimed to simulate the dam breach failure scenario of the Yabous dam (northeast Algeria) and analyze its influence on the related areas (urban and natural environments) downstream of the dam. The simulation was completed using the sensitivity analysis method to assess the impact of breach parameters and flooding on the dam break scenario. The flood wave propagation associated with the dam break was simulated using the one-dimensional HEC-RAS hydraulic model. This study applied a sensitivity analysis of three breach parameters (slope, width, and formation time) on five sites selected downstream of the embankment dam. The simulation showed that the maximum flow of the flood wave recorded at the level of the breach was 8768 m3/s, which gradually attenuated along the river course to reach 1972.7 m3/s at about 8.5 km downstream the dam. This study established the map of flood risk areas that illustrated zones threatened by the flooding wave triggered by the dam failure due to extreme rainfall events. The sensitivity analysis showed that flood wave flow, height, and width revealed positive and similar changes for the increases in adjustments (±25% and ±50%) of breach width and slope in the five sites. However, flood wave parameters of breach formation time showed significant trends that changed in the opposite direction compared to breach slope and width. Meanwhile, the adjustments (±25% and ±50%) of the flood hydrograph did not significantly influence the flood parameters downstream of the dam. In the present study, the HEC-RAS 1-D modeling demonstrated effectiveness in simulating the propagation of flood waves downstream of the dam in the event of dam failure and highlighted the impact of the breach parameters and the flood hydrographical pattern on flood wave parameters.
In the northeastern Algerian Sahara, the Oued Righ region is one of the most prominent geothermal areas and it is defined by a hot arid climate. Water resources in Oued Righ valley are heterogeneous in terms of geological and environmental conditions; this is marked by multi-layer groundwater system through the formations of the Continental Intercalary aquifer, the Terminal Complex, and the Phreatic water. The Phreatic water is an important aquifer system used for public water supply and irrigation purposes. The main objective of this paper is to study the quality of Phreatic water through, the hydrogeochemistry characteristics in order to investigate how it mineralizes. Thirty water samples were collected in July 2019 and September 2020 and were analyzed for major dissolved chemical components. The water samples are characterized by conductivities ranged from 6360 to 193900 μS/cm (July 2019) and 6890 to 226400 μS/cm (September 2020). The water is mostly of sodium chlorinated, sodium, and magnesium sulfated types. Results of mineral equilibrium modeling showed that the Phreatic waters of Oued Righ are undersaturated with respect to evaporite minerals. Gibbs plot revealed that, the evaporations and crystallization dominance activities and oceanic tides are the primary causes of increased salinity in the Phreatic water of the studied area. The Phreatic water of Oued Righ perceived a change in its chemical characteristics during the tow sampling periods, caused by water-rock interactions and mixing processes.
Polluted water poses significant health risks when it is part of the water sources used for irrigation, leading to the contamination of soil and plants by various pollutants. This work aims, firstly, to assess the degree of pollution of Wadi El Gourzi water (Batna, Algeria), and then to verify the consequences on their use for the irrigation of market garden plants for everyday consumption (lettuce, cilantro, parsley and spinach), both in the aerial part (stems and leaves) and in the soil where they are grown. This study focuses on trace metals (Cr, Pb, Zn and Cd). Soil pollution was assessed by calculating the soil pollution index (PI), while the uptake of these elements by plants was monitored by the transfer factor (TF). The analyses of the Wadi El Gourzi water with the flame atomic absorption spectrophotometer (FAAS) show a maximum abnormal concentration of Cr (17.37 mg∙dm–3), Pb (0.71 mg∙dm–3) and Cd (0.45 mg∙dm–3). For the analysis of the soils irrigated by these waters, the results of the PI show that the soils used for the cultivation of parsley and lettuce are polluted by several metals (PI > 1). The concentrations of trace metals elements (TMEs) in the sampled plants show a significant accumulation of Zn, Cd, Pb and Cr by the vegetables (coriander, parsley, spinach and lettuce). These concentrations are above the permitted standards.
The Teleghma plain is located in northeastern Algeria, in the upper valley of Oued Rhumel. It is characterised by a semi-arid climate with average annual precipitation of 300 mm/ year. The shallow aquifer of Mio-Plio-Quaternary is powered mainly by carbonate formations of the Eocene surrounding the région. The uncontrolled use of groundwater for irrigation has caused water stress in the area which has threatened the degradation of water quality. On the other hand, the intense use of chemical fertilisers for agriculture aims has caused groundwater pollution by nitrates where concentrations exceeded the standard limit recommended by the world health organisation.
The relative scarcity of water resources in Algeria and their unequal distribution induce a rational use of available resources. The Zana-Gadaïne plain appears as an exemplary case study, where the difficulties posed by the problem of crop water needs versus the availability of water resources appear. This article, based on field surveys and in-situ measurements, aims to identify the pressure of irrigation on water resources and the optimization of their use in an agricultural area, where irrigated agriculture represents 85% of the water consumption of the Zana-Gadaïne plain. The piezometric study in correlation with hydrogeological data reveals that groundwater resources are limited, aggravated by wastage resulting in a consequent drawdown of 24 meters over 11 years. The analysis of interannual climate variability has enabled us to draw rainfall maps characteristic of the evolution of rainfall over the past decades where we observe a net deficit in precipitation. We calculated the evapotranspiration and the requirements in irrigation water for each crop in order to compare them with the available hydric resources and the establishment of irrigation schedules for the principal irrigated crops. The analysis of interannual climate variability has enabled us to draw rainfall maps characteristic of the evolution of rainfall over the past decades where we observe a net deficit in precipitation. We calculated the evapotranspiration and the requirements in irrigation water for each crop in order to compare them with the available hydric resources and the establishment of irrigation schedules for the principal irrigated crops.
Tolga groundwater is one of Biskra's most important water supplies for both drinking and agriculture. The purpose of this study is to assess the hydrochemical and isotope (2H and 18O) signature of water in the Tolga area. To evaluate the hydrogeology of groundwater in the Tolga region, a chemical, piezometric, and isotopic research was employed. The results of the Piper diagram revealed that there is just one major hydrochemical facies in the research region, which corresponds to Ca–Mg–Cl–SO4. The piezometry of limestone sheets shows that as one goes westward, the turns become less substantial, with turns about 20 meters and a piezometric level of 140 m. For the rst time, the local meteoric water line (LMWL) was drawn for Complexe Teminal (CT) and Continental Intercalaire (CI) on Tolga groundwater. The Tolga area LMWL refers to the equation δ2H= 7,18 δ18O + 4.17 with R2 about 0.85. CI and CT measurement locations indicate deuterium excess values ranging from 8.35 to 12.57. Indeed, the majority of values were more than 10‰ (mean of 10.36 ± 2.01‰). Furthermore, waters from Eocene have an isotopic composition of-7.57 ± 0.68‰ in δ18O and − 49.04 ± 4.69‰ In δ2H. The results of the sample characterisation analysis show that the majority of the groundwater samples analysed are of the Ca-Mg-SO4 water type. In addition, the intense exploitation aquifer water and the region's arid climatic conditions resulted in a large decrease in the piezometric limestone level. Finely, the signature of 2H and 18O data indicate that water comes from local precipitation and recent water, and groundwater recharge is in uenced by quick in ltration.
The relative scarcity of water resources in Algeria and their unequal distribution induce a rational use of available resources. The Zana-Gadaïne plain appears as an exemplary case study, where the difficulties posed by the problem of crop water needs versus the availability of water resources appear. This article, based on field surveys and in-situ measurements, aims to identify the pressure of irrigation on water resources and the optimization of their use in an agricultural area, where irrigated agriculture represents 85% of the water consumption of the Zana-Gadaïne plain. The piezometric study in correlation with hydrogeological data reveals that groundwater resources are limited, aggravated by wastage resulting in a consequent drawdown of 24 meters over 11 years. The analysis of interannual climate variability has enabled us to draw rainfall maps characteristic of the evolution of rainfall over the past decades where we observe a net deficit in precipitation. We calculated the evapotranspiration and the requirements in irrigation water for each crop in order to compare them with the available hydric resources and the establishment of irrigation schedules for the principal irrigated crops. The analysis of interannual climate variability has enabled us to draw rainfall maps characteristic of the evolution of rainfall over the past decades where we observe a net deficit in precipitation. We calculated the evapotranspiration and the requirements in irrigation water for each crop in order to compare them with the available hydric resources and the establishment of irrigation schedules for the principal irrigated crops.
