Industrial development in the Kingdom of Saudi Arabia: Achievements and potential critical success factors     

Mirghani  Mohamed Ali 《GeoJournal》1986,13(3):261-268

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A Hydrologic Budget Analysis for the Nile Valley in Egypt   总被引：3，自引：0，他引：3  

Fatma A. R. Attia  Mohamed N. Allam  Abdel Wahab Amer 《Ground water》1986,24(4):453-459

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Kriging of water levels in the Souss aquifer,Morocco   总被引：2，自引：0，他引：2  

Mohamed Aboufirassi  Miguel A. Mariño 《Mathematical Geosciences》1983,15(4):537-551

Universal kriging is applied to water table data from the Souss aquifer in central Morocco. The procedure accounts for the spatial variability of the phenomenon to be mapped. With the use of measured elevations of the water table, an experimental variogram is constructed that characterizes the spatial variability of the measured water levels. Spherical and Gaussian variogram models are alternatively used to fit the experimental variogram. The models are used to develop contour maps of water table elevations and corresponding estimation variances. The estimation variances express the reliability of the kriged water table elevation maps. Universal kriging also provides a contour map of the expected elevation of the water table (drift). The differences between the expected and measured water table elevations are called residuals from the drift. Residuals from the drift are compared with residuals obtained by more traditional least-squares analysis.  相似文献   

Jurassic radiolarian-bearing series of Tunisia: biostratigraphy and significance to western Tethys correlations     

Mabrouk Boughdiri  Fabrice Cordey  Houaïda Sallouhi  Kamel Maâlaoui  Amara Masrouhi  Mohamed Soussi 《Swiss Journal of Geoscience》2007,100(3):431-441

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Evaluating some factors that affect feasility of using ground penetrating radar for landmine detection     

Mohamed Metwaly　Ahmed Ismail　Jun Matsushima 《应用地球物理》2007,4(3):221-230

Ground penetrating radar （GPR） is one of the promising technologies that can be used to detect landmines. Many factors may affect the ability of GPR to detect landmines. Among those factors are： 1） the type of landmine material （metallic or plastic）, 2） conditions of the host soil （soil texture and soil moisture）, and 3） the radar frequency utilized. The impact of these factors on the ability of GPR to detect landmines is investigated by studying their effect on the dielectric permittivity contrast between the landmine and the host soil, as well as on the attenuation of the radar waves. The impact of each factor was theoretically reviewed and modeled using the Matlab and Mathcad software packages. Results of the computer modeling were correlated with GPR data acquired for metallic and plastic landmine types. It was found that the ability of GPR to detect landmines depends to a great extent on the landmine type, water content of the host soil, utilized radar frequency, and soil texture. The landmines are much easier to detect than plastic landmines for any soil conditions and any radar frequency. Increasing the soil＇s moisture content, regardless of soil texture, eases the detection of the plastic landmine and worsens the detection of the metallic mines. Increasing the percentage of clay in the soil causes the same effect as the moisture content. However, higher radar frequency delivers better results for landmine detection as long as the percentage of clay and the moisture content in the soil remains low. The results of this study are expected to help in selecting optimum radar antennae and data acquisition parameters depending on the landmine type and environmental conditions.  相似文献   

Tectonic Evolution and Hydrogeological Characteristics of the Khanaser Valley,Northern Syria,Derived from the Interpretation of Vertical Electrical Soundings     

J. Asfahani  Y. Radwan 《Pure and Applied Geophysics》2007,164(11):2291-2311

The Khanaser Valley was geoelectrically thoroughly surveyed through a grid which consisted of twelve VES profiles. The tectonically-oriented Pichgin and Habibullaev method was enhanced to be applicable in areas of rugged relief and topography. The enhanced profiles were tectonically interpreted and subsurface structures within the Khanaser Valley were delineated. Accordingly, a tectonic evolutional scenario of the valley was established and its hydrogeological characteristics were derived. An approach for groundwater exploration in areas of prominent relief and topography in dry areas such as the Khanaser Valley was established and its validity was estimated.  相似文献   

Local geoid determination combining gravity disturbances and GPS/levelling: a case study in the Lake Nasser area, Aswan, Egypt   总被引：1，自引：0，他引：1  

C. C. Tscherning  Awar Radwan  A. A. Tealeb  S. M. Mahmoud  M. Abd El-Monum  Ramdan Hassan  I. El-Syaed  K. Saker 《Journal of Geodesy》2001,75(7-8):343-348

 The use of GPS for height control in an area with existing levelling data requires the determination of a local geoid and the bias between the local levelling datum and the one implicitly defined when computing the local geoid. If only scarse gravity data are available, the heights of new data may be collected rapidly by determining the ellipsoidal height by GPS and not using orthometric heights. Hence the geoid determination has to be based on gravity disturbances contingently combined with gravity anomalies. Furthermore, existing GPS/levelling data may also be used in the geoid determination if a suitable general gravity field modelling method (such as least-squares collocation, LSC) is applied. A comparison has been made in the Aswan Dam area between geoids determined using fast Fourier transform (FFT) with gravity disturbances exclusively and LSC using only the gravity disturbances and the disturbances combined with GPS/levelling data. The EGM96 spherical harmonic model was in all cases used in a remove–restore mode. A total of 198 gravity disturbances spaced approximately 3 km apart were used, as well as 35 GPS/levelling points in the vicinity and on the Aswan Dam. No data on the Nasser Lake were available. This gave difficulties when using FFT, which requires the use of gridded data. When using exclusively the gravity disturbances, the agreement between the GPS/levelling data were 0.71 ± 0.17 m for FFT and 0.63 ± 0.15 for LSC. When combining gravity disturbances and GPS/levelling, the LSC error estimate was ±0.10 m. In the latter case two bias parameters had to be introduced to account for a possible levelling datum difference between the levelling on the dam and that on the adjacent roads. Received: 14 August 2000 / Accepted: 28 February 2001  相似文献   

Textural attributes, mineralogy and provenance of sand dune fields in the greater Al Ain area, United Arab Emirates     

Mohamed M. Abu-Zeid  Ashraf R. Baghdady  Hassan A. El-Etr 《Journal of Arid Environments》2001,48(4):475

Sand dunes and interdune sediments around Al Ain city have markedly high carbonate contents which increase towards Jabal Hafit mountain and the Arabian Gulf coast. The dunes are composed predominantly of well-sorted fine sands, consisting of unstrained quartz and carbonate grains together with minor proportions of chert and feldspars. Scanning electron microscope (SEM) examination reveals that quartz grains display various mechanically- and chemically-formed surface textures. The heavy minerals are dominated by opaques and pyroxenes with minor tourmaline, garnet, rutile, epidote, monazite, zircon, hornblende and staurolite.Interdune sediments consist of fine and very fine, poorly- to extremely poorly-sorted sands together with small concentrations of gravel, silt and clay. The light sand fractions compositionally resemble those of dunes but contain, in addition, gypsum, anhydrite, halite and celestite. Percentages of pyroxenes are higher whereas those of zircon, tourmaline and rutile are lower than in dunes. X-ray diffractometry reveals that the clay fractions consist solely of palygorskite. Generally, interdune sediments are much less mature texturally and mineralogically than dune sands; the maturity of both types of sediments decreases toward the NE of the study area.Sand dunes in the various districts of the greater Al Ain area are genetically related. Also, there is a partial genetic relationship between the dunes and interdune sediments; both are mainly multicyclic. Their major parts were brought mainly by the dominant north-west (El Shamal) winds from older dune fields in other localities in U.A.E., Qatar and El-Rub El-Khali. Local contributions to the dune fields from Jabal Hafit mountain, the Oman Mountains and the calcareous coast of the Arabian Gulf were, in cases, significant. Also, authigenesis by groundwater under highly evaporitic conditions played a major role in the formation of interdune sediments through the genesis of the clay and some nonclay minerals.  相似文献   

Drought assessment in a south Mediterranean transboundary catchment     

Khouloud Gader  Ahlem Gara  Marnik Vanclooster  Slaheddine Khlifi  Mohamed Slimani 《水文科学杂志》2020,65(8):1300-1315

ABSTRACT

Predicting the impacts of climate change on water resources remains a challenging task and requires a good understanding of the dynamics of the forcing terms in the past. In this study, the variability of precipitation and drought patterns is studied over the Mediterranean catchment of the Medjerda in Tunisia based on an observed rainfall dataset collected at 41 raingauges during the period 1973–2012. The standardized precipitation index and the aridity index were used to characterize drought variability. Multivariate and geostatistical techniques were further employed to identify the spatial variability of annual rainfall. The results show that the Medjerda is marked by a significant spatio-temporal variability of drought, with varying extreme wet and dry events. Four regions with distinct rainfall regimes are identified by utilizing the K-means cluster analysis. A principal component analysis identifies the variables that are responsible for the relationships between precipitation and drought variability.  相似文献   

Neoproterozoic magmatism in NW Sinai,Egypt: magma source and evolution of collision-related intracrustal anatectic leucogranite     

Mohamed?M.?El-SayedEmail author 《International Journal of Earth Sciences》2003,92(2):145-164

The present study deals with tectonomagmatic evolution of the collision-related leucogranite located near the northwest corner of exposed basement in Sinai, Egypt. The area is composed of: (1) a gabbroic complex; (2) amphibolite; (3) post-orogenic leucogranite; (4) Feiran gneisses. The amphibolite and gabbroic suites, generated in an island arc environment, have a high Fe-tholeiitic affinity and were derived from two independent magmas. On the basis of rare earth element (REE) patterns, the gabbroic melts could have been generated from a garnet- and amphibole-bearing, enriched mantle, and were subsequently modified by fractional crystallization of pyroxene and amphibole with minor plagioclase, whereas the amphibolite melts could be derived from garnet-free depleted mantle.The leucogranite has high Al₂O₃ content (>13 wt%), alumina saturation index (ASI) mostly >1, and normative corundum, indicating a peraluminous nature. Chondrite-normalized REE patterns for the leucogranite show light REE enrichment (La/Sm_N=2.7–4.86), general flattening of the heavy REE (Gd/Lu_N=1.2–2), and negative europium (Eu) anomalies (Eu/Eu*=0.24–0.47). The peraluminous nature and enrichment of the incompatible elements (K, Rb, Ba and Th) in the leucogranite strongly suggest derivation from a crustal source. The most probable source for the leucogranite magmas is represented by the adjacent Feiran gneisses, which could have generated the leucogranite by dehydration melting under water-undersaturated conditions. It appears likely that the restite unmixing model is responsible for the chemical variations within the leucogranite. In accordance with this model, the chemical variation of the leucogranite can be attributed to varying degrees of separation of restitic material from the melt during its emplacement and solidification and fractional crystallization could have played a minor role during magma ascent through the crust.  相似文献