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81.
82.
Adel Kharroubi Faten Tlahigue Belga?em Agoubi Chafai Azri Salem Bouri 《Environmental Earth Sciences》2012,67(7):2089-2100
Coastal aquifers are considered as major sources for freshwater supply worldwide, especially in arid zones. The weak rainfall as well as the intensive extraction of groundwater from coastal aquifers reduce freshwater budget and create local water aquifer depression, causing both seawater intrusion and a threat to groundwater. This phenomenon was observed in the Jerba Island which is located in southeast Tunisia. Jerba??s unconfined aquifer shows high values of groundwater salinity reaching, locally, 17?g/l and a strong contrast between some zones of the aquifer. High pumping rates and weak recharge disturb the natural equilibrium between fresh and saline water causing water salinization in most areas of the island. This study aims at establishing the salinity map of the aquifer and identifying the origin of groundwater salinization. The salinity map shows that zones characterized by low groundwater salinity are located in the center of the study area. High groundwater salinities are observed near the coast and in some parts having low topographic and piezometric levels. Groundwater geochemical characterization, and Br/Cl and Na/Cl ratios suggest that the origin of abnormal salinity is seawater intrusion. Considering groundwater salinity values and Br concentrations, a seawater intrusion map is established. It shows that many areas of the unconfined aquifer are contaminated by mixed groundwater and seawater. The statistical analysis demonstrates that high mineralization of the groundwater is due to gypsum and carbonate dissolution coupled with the mixed groundwater and seawater in many areas. 相似文献
83.
Ibrahim A. Salem Mohamed E. Ibrahim Mohamed Abd El Monsef 《Arabian Journal of Geosciences》2012,5(3):385-406
The present work deals with the geology, mineralogy, geochemistry, and origin of the metagabbroic-hosted manganese deposits at Wadi Maliek in the southern Eastern Desert of Egypt. The manganese veins are found in the shear zones and channel ways of the fault planes within the metagabbroic rocks pointing to those hydrothermal solutions carrying manganese and iron load penetrating along these fractures. These faults are striking N 80° E?CS 80° W with dipping 65°. These veins vary in thickness from 15?cm up to 125?cm wide; each vein may show difference in thickness from bottom to top. Microscopic examinations, X-ray diffraction, infrared spectral, differential thermal (DTA), thermogravimetric (TGA), and ESEM-EDAX analyses revealed that the manganese minerals consist mainly of pyrolusite, psilomelane, and ramsdellite. Goethite and hematite are the common iron minerals. Petrographically, the manganese deposits can be classified into three ore types based on the predominance of manganese and iron minerals: manganese, manganese?Ciron, and iron ore types. The geochemistry of Maliek deposits indicated that the total averages of some major oxides in manganese, manganese?Ciron, and iron ore types are respectively as follows: SiO2 (15.64%, 11.52%, and 20.58%), MnO (39.9%, 17.81%, and 0.77%), FeO* (7.13%, 33.31%, and 37.08%), CaO (5.89%, 5.82%, and 5.32%), and Na2O (1.04%, 1.61%, and 1.53%). With regard to trace elements, the Maliek manganese deposits are rich in Zn, Ba, Pb, Sr, and V. Based on the geological, mineralogical, and geochemical results, the studied manganese deposits are considered to be precipitated from hydrothermal solution. 相似文献
84.
A synthetic approach integrating surface and subsurface data for prospecting deep aquifers: the Southeast Tunisia 总被引:2,自引:0,他引:2
The Southeast Tunisia has remarkable thermal springs that have been used for bathing since many years. Currently, studies
are being carried out to investigate the possible use of the hot water for heating buildings and for greenhouses. Springs
with discharge temperatures between 26.8 and 58°C exist in the area. The flow rates range between 7 and 66 l/s with total
dissolved solids (TDS) varying between 2,020 and 4,030 mg/l. Both geological–hydrogeological setting and the similarity in
chemical characteristics between the Zarat spring and nearby water wells suggest that the hot water from this spring may be
related to the Senonian aquifer. However, the hydrogeothermal approach shows that the depth of the reservoir that supplies
the Zarat spring is greater than that of the Senonian aquifer. In fact, geothermometry approach indicates that fluids emerging
from the Lower Cretaceous sandstones reach temperatures of approximately 78°C at depth, while the fluid temperature from the
nearby water wells is 32°C. Through the integration of various types of data we found that the thermal water of Southeast
Tunisia is of meteoric origin. This water infiltrates deeply into the Lower Cretaceous sandstones and reaches a high temperature
before rising upwards to supply the hot springs and well discharge zones. It appears that the upward movement of hot water
from the deep aquifers to shallow ones is probably due to the abundant fractures in the area. 相似文献
85.
Zied Haj-Amor Henk Ritzema Hossein Hashemi Salem Bouri 《Arabian Journal of Geosciences》2018,11(2):27
In this paper, a study on the performance of surface irrigation of date palms in a Tunisian arid area (Douz oasis) is presented. The study is conducted in 16 plots with various sizes and soil textures over a 4-year period (2012–2015). In the first step, an assessment of total water requirements of the date palms is carried out. Then, the surface irrigation performance is analyzed using three indicators, i.e., the relative water supply (RWS) indicator, the uniformity index of water distribution (D U ), and the water application efficiency (E a ). Finally, the irrigation management problems are identified. The results indicate that in the arid Tunisian Saharan oases, the soil texture, plot size, and farmers’ practices (especially irrigation duration) have significant effects on surface irrigation performance. The average annual net irrigation requirements of date palms are about 2400 mm. The RWS increases from 1.8 in the smaller plots (0.5 ha) to 3.6 in the largest plots (2.5 ha), implying that the increase in the plot size requires an excessive water supply. D U decreases from 80.7 in the 0.5 ha plots to 65.4 in the 2.5 ha plots; however, no significant difference in the E a is observed. The results show that the soil texture has no influence on the RWS and D U , but the E a is significantly higher in the loamy-sand soils (46.7%) compared to the sandy soils (36.3%). Overall, RWS indicator is higher than 1 (RWS?=?2.6) implying excessive irrigation supply to the system. Although D U is relatively uniform (>?60%), E a is relatively low (<?50%) indicating that the current irrigation management is inefficient. These findings have a paramount importance for improving irrigation water management in the Tunisian Saharan oases. 相似文献
86.
El-Sayed Mohamed Salem 《Arabian Journal of Geosciences》2009,2(2):185-197
The characteristics of the recent tsunami deposits threw light on some sources of deposition on the beach of the Red Sea. The studied area is delineated by latitudes 25°6′ N and 25°9′ N and longitudes 34°50′ E and 34°53′ E; it covers an elongate area of about 12 km2 along the Red Sea coast, North Marsa Alam City (4 km). The area is bounded by Wadi Asalay to the north and Wadi Sifayn from the south. For evaluation of the area, a lot of information allows us to interpret the conditions prevailing during deposition of the sediments especially at the coast. To achieve the target, five wells were drilled to study core samples, well logging measurements, and 69 vertical electrical sounding stations were carried out. The studied area and adjacent areas were geologically surveyed to note geological features related to Paleo-earthquakes. From geological and geophysical studies, the dominant rock types at the western portions of the studied area are sandstone, sandy clay, clay, clayey sandstone, and gravels; at the middle portion of the studied area, the rocks are hard, but the eastern side of the area, especially at the beach of the Red Sea, several cycles of depositions of coral reefs occurred with intercalations of clastic deposits such as clay, sand, sandstone, conglomerate, gravels, pebbles, and a lot of fossils and shell fragments. The rocks are characterized by heterogeneous properties and ill-sorted. The area includes large numbers of faults due to highly tectonism of the area. The results indicated that the area has lateral variation of sediments. The carbonate rocks at the beach contain clastic fragments, and carbonate blocks are included within clastic rocks. With increasing the distance from the beach to the west, the sediments are less heterogeneous. The beach of the Red Sea was subjected to Paleo-tsunami waves due to highly Paleo-seismic activity inside the Red Sea and left their signature in geological column especially at the beach. The observation of some geological features such as Paleo-liquefaction and landslides indicate that the area subjected to strong earthquakes related to rifting of the Red Sea. 相似文献
87.
Amer A. Al-Rawas Yahia E-A. Mohamedzein Abdulaziz S. Al-Shabibi Salem Al-Katheiri 《Geotechnical and Geological Engineering》2006,24(5):1365-1383
Absrtract This paper investigates the potential use of sand–attapulgite (palygorskite) mixtures as a landfill liner. The sand and attapulgite
clay used in this study were brought from Wahiba (eastern Oman) and Al-Shuwamiyah (southern Oman), respectively. Initially
the basic properties of the sand and clay were determined. Then the attapulgite clay was added to the sand at 5, 10, 20 and
30% by dry weight of the sand. The sand–attapulgite clay mixtures were subjected to mineralogical, chemical, microfabric and
geotechnical analyses. The X-ray diffraction (XRD) qualitative analysis showed that attapulgite is the major clay mineral.
The chemical compounds, exchangeable cations and cation exchange capacity (CEC) for the␣samples were determined. The CEC for
the sand–clay mixtures is low but increases with the increase in clay content. The scanning electron microscope (SEM) examination
showed that the addition of clay developed coating between and around the sand grains which results in filling the voids and
reducing the hydraulic conductivity of the sand–clay mixtures. The hydraulic conductivity values for the pure clay and sand
+ 30% clay mixture prepared at 2% above optimum water content are slightly higher than hydraulic conductivity requirements
for landfill liners but can be acceptable. The geotechnical study which included grain size distribution, Atterberg limits,
specific gravity, compaction, hydraulic conductivity and shear strength tests showed that the sand+30% clay mixture prepared
at 2% above optimum water content can be considered to satisfy the requirements for landfill liners. For all sand–clay mixtures
no swelling was recorded and the addition of clay to the sand improved the shear strength. 相似文献
88.
Mouez Gouasmia Mohamed Gasmi Abdelkader Mhamdi Salem Bouri Hamed Ben Dhia 《Comptes Rendus Geoscience》2006,338(16):1219-1227
The Hmeïma–Boujabeur zone is considered as an important geothermal province for Tunisia. The reef limestone, characterized by intense fracturation and important karstification, confers them the property to be a regional thermal aquifer. A geophysical study based on two complementary geoelectrical methods, the Electrical Sounding (ES) and Magneto-Telluric Sounding (MTS), turned out to be very efficient to provide a complete electrical image of the underground until about 1-km depth. The synthetic approach integrating all data allowed us to delimit the favourable area for thermal water exploitation. To cite this article: M. Gouasmia et al., C. R. Geoscience 338 (2006). 相似文献
89.
90.