Seasonal variations of sea level have an important impact on coastal groundwater level and salinity. Consequently, they cause spatiotemporal changes in the seawater/freshwater interface. The oceanic ...tide effect on groundwater dynamics and salinity was investigated in the coastal aquifers of Sahel Doukkala, Morocco. Continuous monitoring of water level and electrical conductivity (EC) was carried out in two coastal wells (drawing from two different aquifers) over a period of 9 months. The main objective of the study was to characterize the aquifers’ exposure to anthropic pumping operations and oceanic tide oscillations. The obtained results showed that oceanic tide has a significant effect on groundwater level as well as on water salinity. The fluctuation periods of groundwater level and tidal level were found to be equal, with a specific time lag. Hydraulic diffusivity was calculated using both confined- and semi-confined-aquifer methods and by analyzing both the time lag and amplitude damping factor. Results indicate hydraulic diffusivity differences between the two aquifers. In addition, there were apparent differences depending on whether time lag or amplitude was analyzed, possibly due to effects of heterogeneity within the aquifers. A detailed study of water EC variation revealed the significant influence of daily and synodic tide on groundwater salinity. Water EC variations were significant when hydraulic diffusivity is higher, indicating that sea-level oscillations induce freshwater/seawater interface movement and consequently influence the groundwater quality.
This study aims to establish susceptibility maps for the Moroccan Safi region, which is affected by karstification processes. This process is the predisposing factor for various landslide types such ...as debris flows and rock falls. In the first phase of this study, a landslide inventory was prepared by geomorphological approach based on visual interpretation of aerial photographs combined with direct observations in the field. The obtained inventory included 234 landslides: 14 rock slides and 75 debris flows in Brown Clay Formation, 74 rock falls in sandstone and 71 rock topples in Dridrat Limestone Formations. The inventory map showed that landslide phenomena occur mainly in the northwest and along the active coastal cliffs in the south of Safi. In the second phase, four landslide susceptibility maps were realized using the bivariate statistical method of Geographical Information System (GIS) matrix method (GMM). The established landslide susceptibility maps were validated by the
degree of fit
method. Obtained results showed that landslide phenomenon occurs mainly in the northwest and along the coastal cliffs in the south of the study area. Moreover, very high and high susceptibility levels were limited to the area including industrial and touristic activities as well as historical monuments. Overall, landslides were associated to karstification, lithology, karstic rocks and karstic spring presence, which are considered as predisposing and causal factors.
The Bleida fractured aquifer is not well studied in terms of water resources as previous geophysical investigations in this area were undertaken for mining purposes. This study utilized magnetic ...resonance sounding surveys in order to define the distribution of water resources in the region of Bleida and to locate areas favorable for the drilling and construction of productive hydraulic boreholes. For this purpose, eight magnetic resonance sounding surveys were conducted in two sites at the intersection of faults in basement rocks. The results of these surveys indicated that there were two distinct levels of saturation in fractured rock that decreased with depth.
The Say’un-Masilah basin is one of the most prolific sedimentary basins in Yemen, and therefore it has attracted the attention of geologists and geophysicists for hydrocarbon prospection and ...exploration. The main objective of this research is to study the structural and stratigraphic subsurface features as well as to determine the lithological contents of the Sharyoof oil field, Block 53, in the Mesozoic rift basin, eastern Yemen, using seismic and well log data. The basic inputs in this study include log data, collected from six wells, such as gamma ray (GR), caliper, deep, and shallow laterlog resistivity (LLD, LLS), micro-spherically focused log (MSFL), photoelectric absorption index (PEF), and porosity tools (density, neutron, and sonic). In addition, seismic sections including 15 lines 2D, well tops, bottom, sheck shot, well header, and deviations were used to accomplish this study objective. The obtained results from the seismic profiles interpretations demonstrated the existence of a series of normal faults dissecting most of the mapped horizons toward NE-SW (major faults) and NW-SE and W-E (secondary faults) creating several graben and horst structures. Moreover, results analysis of the well log data indicates that the main lithology content is dominated by the presence of the carbonates (limestone and dolomite) in the Sa’ar Formations and Qishn Carbonates Member while the sandstones for the Qishn Clastics, Harshiyat, and Mukalla Formations. The lithostratigraphy succession consists of rock units ranging in age from Early to Upper Cretaceous age (from Sa’ar to Mukalla Formations). Furthermore, seismic section data allowed determining the subsurface feature styles from reflections maps of both isochronous (two-way travel time) on the tops of the Sa’ar to Mukalla Formations. They reflect the occurrence of several distinct structures (anticlines, synclines, and faults), added to trends of faulting (NW-SE dissected by NE-SW). The novel contribution of the present work consists in the identification of the structural characteristics of the Lower and Upper Cretaceous formations of Block 53 using new seismic lines. Therefore, the obtained results of this study allow determining the sections and composition holding the hydrocarbon reservoir characteristics. As such, this research can be used as a reference study.
The metal content in surface sediments (0–2 cm, 26 samples), in a sediment core (120, 1 cm slices), taken from Moulay Bousselham (Morocco) was investigated. Concentrations of Al, Fe, Mn, Pb, Zn, Cu, ...Ni, Cr, Cd, As, and Hg were evaluated in surface and cored sediments of Moulay Bousselham lagoon. Significantly high concentrations in μg g
−1
dw of Pb (31.7–6.2), Zn (758.9–167), Cu (310.7–22), Ni (96–10.5), Cr (113–18.9), Cd (0.84–0.02), As (1–0.1), and Hg (0.61–0.02) were found in sediment samples from Moulay Bousselham lagoon. Calculated enrichment factors EF
Me
= (Me/Al)
sample
/(Me/Al)
background
, using Al as a normalizer, and correlation matrices showed that metal pollution in Merja Zerga of Moulay Bousselham lagoon was the product of anthropogenic sources, while the metal content in Merja Kehla was of natural origins. The results suggest that a major change in the sedimentary regime of the lagoon, associated with internal trapping and re-distribution of heavy metal, has been occurring in the past few decades. The cause would appear to be the construction of a Nador Canal at the lagoon. Probable effects concentrations (PEC) were often exceeded for heavy metals in the lagoon sediments, especially for Zn, Cu, Ni, and Cr, and four stations, stations MZ-11, MZ-12, MZ-13, MZ-14, MZ-16, and MZ-17, had multiple metals at presumptively toxic levels. These comparisons suggest that sediment metal levels in the river are clearly high and probably pose an environmental risk at some stations. The levels of most of the metals were not greatly enriched, a consideration that is of the utmost importance when contamination issues are at stake. Metal concentrations found in Moulay Bousselham lagoon were comparable to aquatic systems classified as contaminated from other regions of the world.
This study aims to identify groundwater salinization origin and to determine seawater intrusion extension toward the inland in Chaouia, Morocco. To reach these objectives, firstly, 46 groundwater ...samples were analyzed for major chemical elements during January 2012 and, secondly, 10 electrical resistivity tomography (ERT) profiles were performed perpendicularly to the coastal fringe. Statistical analysis provided the distinction between three Clusters reflecting different hydrochemical processes. Cluster I and Cluster II-a showed a high water electrical conductivity (EC) (from 2.3 to 11.2mS/cm) with the dominance of Na+ (668mg/L on average) and Cl− (1735mg/L on average) ions as a consequence of seawater intrusion. However, Cluster II-b presented low ECs (from 0.5 to 1.7mS/cm) and Ca2+ (99.6mg/L on average) and HCO32− (235.2mg/L on average) ions dominance. Water chemistry in these wells was controlled by water-rock interaction, cation exchange, and anthropogenic activities. The Hydrochemical Facies Evolution Diagram highlighted the succession of different water facies developed between intrusion and freshening phases. The formation of Na-HCO3 facies, which characterizes the last facies of freshening phase, followed the succession of Na-Cl, MixNa-MixCl, MixCa-MixCl, MixCa-MixHCO3, and Na-HCO3. In contrast, Na-Cl facies formation, which characterizes the last facies of intrusion phase, followed the evolution of Ca-HCO3, Ca-MixHCO3, Ca-MixCl, MixCa-MixCl, MixCa-Cl, and Na-Cl. Moreover, the obtained ERT results allowed determining the extent of different hydrochemical facies and provided more details about seawater intrusion extension. The conductive level assigned to seawater contamination showed a resistivity less than 36Ω.m, which remains limited to 3000m from the ocean, where Na-Cl water type dominates. The seawater intrusion depth varied between 5 and 40m from the surface. Overall, this original study in Chaouia region demonstrated the effectiveness of combining hydrochemical and ERT methods to investigate seawater intrusion, particularly in areas with restrictive water chemistry data.
•Water salinization origin was determined by hydrochemical study in Chaouia, Morocco.•HFE-Diagram highlights water facies succession between intrusion and freshening.•Highly contaminated area by seawater intrusion was delimited using ERT study.•Seawater intrusion was significant at 3km from the ocean and over 40m depth.
The complex geological structures, of the Sharyoof field in the Say'un-Masilah Basin of Yemen, make obtaining accurate information about the hydrocarbon entrapment style difficult. This situation ...adversely affects the efficiency of the exploration. Therefore, the present study provides a detailed character analysis of subsurface structural features as well as determines the entrapment style of Early Cretaceous age hydrocarbons (the Qishn Sandstone Reservoir) in the Sharyoof oil field. To identify accurate structural features, calculate petrophysical parameters of the Qishn sandstone member and predict their complex geometry in a 3D model, this investigation is based on the analysis of a multidisciplinary data set. The three-dimensional modeling was based on the interpretation of 2D seismic profiles and well logs data analysis. The obtained results indicate two types of a normal faults, consisting of plane faults and antithetic faults, which are oriented NE-SW and NW-SE with a thickness variation from 76 to 153 m. The intersection of these faults resulted in horst structures, in the northwest and southwestern parts, and graben and half-graben structures, in the southern and southeastern parts of the study area. The dips of these faults are between 20 and 90°. The 3D models of petrophysical parameters and the cross section extracted from the 3D model demonstrated that the Qishn sandstone reservoir has a low clay volume while having high porosity, permeability and hydrocarbon saturation values. Furthermore, the Qishn Sandstone is overlain by layers of the Qishn Carbonate Member, which has very low porosity and permeability and high clay volume, making it an effective seal. Therefore, these novel findings could be used to propose a drilling site for exploration wells within the Qishn Clastics membership.
•This study provides detailed structural features of Qishn sandstone Member.•Petrophysical parameters of Qishn sandstone Member were calculated.•Structural and petrophysics features were studied using 3D modeling.•Qishn Clastics Member represents a good reservoir suitability.•New sites for drilling exploration wells are proposed.
In this study, the geohydraulic parameters of aquifers in the Sahel Doukkala region, western Morocco were estimated using a geostatistical method to transform vertical electrical soundings (VES) data ...into electrical resistivity tomography (ERT) profiles. The resulting ERT profiles covered a larger area than the original VES data, allowing for a more comprehensive analysis. The obtained results indicated that the apparent and inverted resistivities range from 16 to 1558 Ohm.m and from 4 to 6980 Ohm.m, respectively, with a low inversion error (RMS) of 6.1–13.1%, demonstrating the reliability of the proposed approach. Using the inverted resistivities, the estimated hydraulic conductivity, effective porosity, and transmissivity ranged from 0.2 to > 103.7 m/day, 11.6% to > 45.8%, and 1.7 to > 2028.6 m
2
/day, respectively. These values reflect the sand, clayey sand, and limestone lithology prevalent in the study area, with medium to high aquifer potential. The validation of our results with pumping test data showed that the estimated geohydraulic parameters are representative of the geological formations in the study area. In addition to providing a rapid interpretation of the data, the present study offers fundamental insights for future research, contributing to better planning and management of groundwater resources.
The coastal aquifer system of Chaouia is recognized as one of the most important aquifers in Morocco that is affected by salinization in the coastal fringe. The purpose of this study is to highlight ...the origin of salinization by sampling and analyzing groundwater from 44 wells for major elements. This study was carried out in May 2011. The results indicate that, in the central and downstream parts, the dominant facies are Mg2+, Na+ and Cl−, while Ca2+ and HCO3− dominate in the upstream zones. Ion exchange processes, under seawater intrusion, control the concentration of ions such as calcium, magnesium and sodium. Moreover, groundwater is oversaturated with respect to carbonate minerals (calcite and dolomite), and under-saturated with respect to evaporate minerals (gypsum, halite). The contribution of dissolved halite and gypsum in the groundwater mineralization is revealed by their positive correlation between (Na + Cl) and (Ca + SO4), respectively. Furthermore, the comparison of the hydrochemical results to drinking water quality standards by World Health Organization (2008) shows that more than a half of the water sampled is not suitable for drinking purposes, especially with respect to high levels of EC, TDS, Cl− and NO3−. In addition, high mineralization is found to be a consequence of seawater intrusion and anthropogenic activities.
•Samples were taken from 44 wells during May 2011 period.•This study aims to investigate origin and process of groundwater mineralization.•Distance from coast and anthropogenic activities emphasized mineralization.•Groundwater salinity was due to seawater intrusion in areas at 2 km from ocean.•Cation exchange, evaporation and evaporate dissolution induce groundwater salinity.
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