Hydrochemical assessment of groundwater from shallow aquifers in parts of Wadi Al Hamad,Madinah, Saudi Arabia

The present study was carried out in the Mulaylih area which forms a part of Wadi Al Hamad in the Madinah Province of Saudi Arabia. Thirty groundwater samples from agricultural farms were collected and analyzed for various physio-chemical parameters including trace elements. The area is occupied by the Quaternary alluvium deposits which form shallow unconfined aquifers. Evaporation and ion exchange are the major processes which control the major ion chemistry of the area. The extreme aridity has results in high total dissolved solid values (average of 9793.47 mg/l). Trace element concentrations are low and are mainly attributed to geogenic sources (silicate weathering). Na-Cl groundwater type is the main hydrochemical facies found in the area. The waters are found to be oversaturated with calcite/aragonite and dolomite. The average nitrate concentration was found to be 134.10 mg/l and is much higher than the WHO recommended limit of 50 mg/l in drinking water. Their high values are mainly associated with the application of N-fertilizers on the agricultural farms. The average fluoride concentration in the study was found to be 1.54 mg/l. The relation between F and Cl and Cl and Na reveals that the fluoride concentrations are mainly attributed to geogenic sources. A comparison of the groundwater quality with the Saudi drinking water standards shows that the water is unfit for drinking. The high salinity and sodicity of the groundwater make it unfit for irrigation. Principal component analysis resulted in extraction of four principal components accounting for 79.5% of the total data variability and supports the fact that the natural hydrochemical processes (evaporation and ion exchange) control the overall groundwater chemistry.     

Depositional environments and facies of the Late Triassic Abu Ruweis Formation, Jordan

The Abu Ruweis Formation is composed of carbonates, evaporites, and mudstones, with some locally developed pelletic, oolitic and stromatolitic limestones. The lateral persistence of bedding, the purity of the evaporite rocks, the alternating arrangement of marine carbonates and evaporites indicates periodic deposition in subaqueous conditions (salina). Petrographic investigations, X-ray diffraction analysis as well as chemical analysis have shown that the outcropping evaporite beds are mainly composed of secondary gypsum, with rare anhydrite relics. Five microfacies of gypsum were recognized according to their fabrics: porphyroblastic and granoblastic gypsum showing polarization texture, gypsum pseudomorph after anhydrite laths, and satin spar gypsum. The textures they display indicate a hydration origin of precursor anhydrite, which is in turn rehydrated from primary gypsum. Some of these anhydrites were formed as a result of replacement processes of the carbonate sediments associated with the evaporites, as evidenced from the textural relationships of the carbonate and sulfate minerals. The O¹⁸ content ranges from 1.45 to 8.38% PDB and the C¹³ content ranges from −1.52 to 4.73% PDB. Trace elements analysis has shown that the Abu Ruweis dolomites are rich in strontium (up to 600 ppm), and sodium (up to 835 ppm). The isotope composition and trace elements content, as well as the petrographic characteristics point to a penecontemporaneous hypersaline dolomitization origin for the Abu Ruweis dolomites. The evaporites were deposited during a regressive lowstand systems tract, whereas the carbonates were deposited under shallow water marine conditions during a highstand systems tract. The Abu Ruweis succession represents a relatively stable arid climate within a rapidly subsiding basin. Restricted conditions were provided by the development of beach barriers.     

A New Equation for the Shear Strength of Cable Bolts Incorporating the Energy Balance Theory

The application of cable bolts as a secondary support system is an increasing trend in underground coal mines worldwide. The performances of cable bolts have been evaluated under both axial and shear loading conditions. Two methods of testing cables for shear, single and double shear, have been recognised. This paper examines the shear behaviour of a variety of cable bolts under different pre-tension loads by double shear testing. Plain, spiral and the combination of both cable types were used in this study. The initial axial load and the type of cable bolts are the main factors affecting their shear strength. By increasing the axial pre-tension load, the peak shear load occurs at lower shear displacement. The failure angle due to cable bending across the joint at different pre-tension loads varied between 41° and 49°. This demonstrates that the ratio of axial and perpendicular displacements is almost constant and on average the failure occurs at about 45°. A novel analytical model is proposed to evaluate the shear behaviour of pre-tensioned fully grouted cable bolts subjected to double shearing. Energy and Fourier Series methods were incorporated in the model to simulate the shear behaviour of cable bolts. The comparison of the experimental results with the proposed model shows a good agreement.     

Role of γ-ray spectrometry in detecting potassic alteration associated with Um Ba’anib granitic gneiss and metasediments, G. Meatiq area, Central Eastern Desert, Egypt

The radiometric responses of the Gebel (G., which means mountain in Arabic) Meatiq area display the overall high radiation of the high grade metamorphic Um Ba’anib granite gneiss, metasediments, as well as Arieki adamellite rocks. Whereas, the low grade metamorphic ophiolitic nappes country reveal the lowest radiometric response. The eU, eTh, and K contents tend to increase with the youthfulness of the plutons with a maximum amounts in the more alkali varieties, e.g., Arieki adamellite (580 Ma), then the high grade metamorphic rocks of the younger Meatiqian orogeny (626?±?2 Ma). Also, these rocks reveal that the major radiometric anomaly with exposure rates ≈139 nGy/h, more than double of the global terrestrial values. While, the low grade metamorphic ophiolitic rocks reveal the lowest average exposure rates ≈46.8 nGy/h. The areas of high gamma ray values of F-parameter of Efimov (K × U/Th), ternary composite map, K map, K/eTh, and K/eU ratios maps are related to K enrichment conditions during formation (diagenesis) or deformation of the high grade metamorphic rocks and the Arieki adamellite intrusion. From the geochemical point of view, these areas are associated with rocks that are characterized by high-K calc-alkaline, calc-alkaline affinity, and enriched in REE.     

Geospatial analysis of land use driving force in coal mining area: case study in Ningdong,China

GeoJournal - Geospatial techniques such as remote sensing and Geographic Information System are very important for studying the dynamic process of land use. To analyze the land use change and...     

The impact of neighborhood services on land values: an estimation through the hedonic pricing model

A strong need exists to increase the knowledge and recognize the values of neighborhood services. This paper makes an attempt to examine the impact of neighborhood services on land values, through analysis based on results obtained from multi linear regression analysis. This case study was done in area of dense urban settlement to check the consequence of neighborhood services through the hedonic pricing model base variables which include the structural, locational, community and neighborhood services. The regression coefficient was checked at (p?<?0.05) level of significance for each variable. The primary data was collect through the questionnaire filling by random sampling and Punjab Urban Gazette was used for the verification of land values in study area. The results found a valuable potential on land and property values of neighborhood services through the regression analysis results express through R (0.926), R² (0.856) and coefficient tables to represent the effect of each individual variable on property and land values. Every individual variable play role in defining the values of land and property based upon its utilization such as larger the structure of a property, more the covered area, larger size of a property more the land area higher price. Similarly, for locational factor study in geography, a piece of land adjacent to the road have high land values 50–70% compare to those located at distance. Very less attention has been paid on such issues in the world due to lack of effective urban planning and research on such crucial issues. If empirical studies on such issue has been done, effective way can be obtained for urban planning.

     

Contribution of remote sensing and GIS to analysis of the risk of flooding in the Zat basin (High Atlas-Morocco)

Natural Hazards - Despite the controversy regarding their use, school buildings are often assigned as emergency evacuation shelters, temporary accommodation and aid distribution hubs following...     

Response of Mollusk Assemblages to Environmental Conditions: A Case Study from the Burullus Lagoon,Egypt

The identified mollusks from the Burullus lagoon of Egypt (Eastern Mediterranean) are represented by four bivalve species and four gastropod species. Sources of heavy metals pollution in the Burullus lagoon include phosphate fertilizers, sewage and oil spills from fishing boats.The Cerastoderma glaucum species has a wide distribution in the central part of the studied area with satisfying criteria required for good bio-monitors of pollution. High concentrations of heavy metals are found in water, at the eastern side of the lagoon, while low concentrations were detected in the central and western sides of the lagoon. Pirenella conica constitutes the total gastropods assemblages, reflecting this species tolerance to the high concentration of heavy metals. Meanwhile, the total pelecypods in bottom lagoon sediments are completely absent in the eastern parts of the lagoon, which may be due to the sensitivity of pelecypods to the accumulation of heavy metals.     

Pollution vulnerability of the Quaternary aquifer near Cairo, Egypt, as indicated by isotopes and hydrochemistry

The present study was conducted to delineate the pollution vulnerability of the Quaternary aquifer in two areas, Imbaba and Shobra El-Khima, near Cairo, Egypt. Environmental isotopes combined with hydrochemistry were used for this purpose. The groundwater in the Imbaba area (average total dissolved solids about 900 mg/L; sodium/chloride, sulfate, and bicarbonate water types) is more mineralized than groundwater in the Shobra El-Khima area (average total dissolved solids 500 mg/L; calcium and sodium/bicarbonate water type). A high nitrate content and significant mineralization in the groundwater are probably due to contamination of recharge to the aquifer by irrigation drainage, deteriorated sewage networks, and septic tanks. The deuterium and oxygen-18 compositions of the groundwater are depleted compared to Nile River water, which is the main source of aquifer recharge. This less isotopically enriched water probably represents older Nile water recharge that flooded the region before construction of the Aswan High Dam in 1963, or it is a mixture of a young water and originally deposited paleowater that was in deeper horizons at a time of cooler and more humid climate. Intensive pumping has moved the paleowater higher in the aquifer. Groundwater in the Shobra El-Khima area has higher residence time, based on the tritium concentration, than groundwater in the Imbaba area. The percentage of the isotopically depleted water equals 75% in the Shobra El-Khima and 35% in Imbaba, and the thickness of the clay cap above the aquifer is 38 m in Shobra El-Khima and 20 m in Imbaba. These factors are indicative of the rate of recharge to the aquifer and were used to evaluate the pollution vulnerability in the two areas. Electronic Publication     

Adjoint formulation and constraint handling for gradient-based optimization of compositional reservoir flow

An adjoint formulation for the gradient-based optimization of oil–gas compositional reservoir simulation problems is presented. The method is implemented within an automatic differentiation-based compositional flow simulator (Stanford’s Automatic Differentiation-based General Purpose Research Simulator, AD-GPRS). The development of adjoint procedures for general compositional problems is much more challenging than for oil–water problems due to the increased complexity of the code and the underlying physics. The treatment of nonlinear constraints, an example of which is a maximum gas rate specification in injection or production wells, when the control variables are well bottom-hole pressures, poses a particular challenge. Two approaches for handling these constraints are presented—a formal treatment within the optimizer and a simpler heuristic treatment in the forward model. The relationship between discrete and continuous adjoint formulations is also elucidated. Results for four example cases of increasing complexity are presented. Improvements in the objective function (cumulative oil produced) relative to reference solutions range from 4.2 to 11.6 %. The heuristic treatment of nonlinear constraints is shown to offer a cost-effective means for obtaining feasible solutions, which are, in some cases, better than those obtained using the formal constraint handling procedure.