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41.
Neveen B. Abd El Mageed Amgad S. El Ansary Ashraf M. Ghanem Gamal H. Elsaeed 《Environmental Geology》2009,57(1):195-202
The Egyptian government is replacing the existing Naga Hammadi barrage, located across the Nile River some 450 km south of
Cairo, with the New Naga Hammadi barrage (NNHB) to incorporate a hydropower plant and to improve conditions for river traffic.
The new structure will lead to an increase in river water levels, both locally near the new barrage and upstream. The rise
in river water levels will in turn result in changes in groundwater levels in the aquifer system up and downstream of the
barrages. In this paper, an area is chosen, which is expected to suffer from a high groundwater table after the construction
of the NNHB, to investigate the problem and propose alternatives for lowering the groundwater levels. The study area is a
village called Bakhaness, with an area of 588 ha. It is located some 1.5 km upstream of the NNHB. A computer model (MicroFEM)
has been used to simulate the groundwater conditions before and after construction of the NNHB. Alternatives for lowering
the groundwater table are proposed, simulated and evaluated. The systems, which are assessed are a municipal sewer system,
a system of perforated pipes in urban areas, and tile drainage with different values of efficiency in agricultural areas. 相似文献
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Siwa oasis is located in the extreme western part of the Egyptian western desert. There are several archaeological sites in
the oasis; the most distinct ones are Alexander the Great temple at Aghormi hill and the Gebel El Mota tomb excavations. They
have suffered due to deterioration and cracks of different kinds and some parts are getting worse as rock falls occur. From
field inspection and lab analysis, it is clear that lithology plays an important role on the extent of damage. Alexander the
Great temple was built over the northern edge of Aghormi hill, which consists of two distinct beds—an upper limestone bed
and a lower shale one. From field survey and laboratory analysis, the shale is considered as a high expanded bed and weak
in its bearing capacity, as its clay content (mainly smectite) experienced swelling due to wetting from the ground water spring
underneath. Consequently, the upper limestone bed suffered from map cracking associated with rock falls due to the differential
settlement of the swelled lower shale one. The temple was threatened by slope instability and had experienced many cracks.
At Gabal El Mota tomb excavations, it was noticed that a comparison of tombs of the same opening size revealed that those
that excavated on shale beds had cracked much more than those that excavated on limestone. This may be attributed to the low
bearing capacity of excavated shale walls. The remedial measures suggested to overcome the stability problems on these archaeological
sites are grouting or construction of retaining walls. 相似文献
46.
Abdel Galil A. Hewaidy Gamal M. El Qot El Sayed M. Moneer 《Arabian Journal of Geosciences》2018,11(24):781
The Campanian-Lower Paleogene successions exposed at the Kharga Oasis contain well-preserved gastropods. Nineteen gastropod species are identified and described in detail. Two new species are established: Gisortia khargaensis from the lower Eocene El Rufuf Formation and Ornopsis? barisensis from the lower Paleocene Kurkur Formation. In addition to, Turritella (Torquesia) derbesi Coquand is recorded herein for the first time from Egypt. The studied gastropods belonging to four clades: Sorbeoconcha (Metacerithium abictiforme (Wanner), Mesalia hofana Mayer-Eymar, Mesalia sp., Turritella (Torquesia) derbesi Coquand, Turritella (Torquesia) forgemoli Coquand, Turritella kaserensis Hewaidy and Azab, Turritella sp.), Littorinimorpha (Cypraedia bullina Oppenheim, Gisortia khargaensis nov. sp., Natica farafrensis Wanner, Aporrhais schweinfurthi (Quaas), Drepanocheilus bicarinatus Abbass, Drepanocheilus? sp., Anchura? unicarinatus (Abbass), Epitonium sp.), Neogastropoda (Ornopsis? barisensis nov. sp., Rostellana daniensis (Quaas), Vouta sp.), and Heterobranchia (Avellana cretacea Quaas). 相似文献
47.
Ahmed Zaki Ahmed Hamdi Mansi Mohamed Selim Mostafa Rabah Gamal El-Fiky 《Marine Geodesy》2018,41(3):258-269
The determination of high-resolution geoid for marine regions requires the integration of gravity data provided by different sources, e.g. global geopotential models, satellite altimetry, and shipborne gravimetric observations. Shipborne gravity data, acquired over a long time, comprises the short-wavelengths gravitation signal. This paper aims to produce a consistent gravity field over the Red Sea region to be used for geoid modelling. Both, the leave-one-out cross-validation and Kriging prediction techniques were chosen to ensure that the observed shipborne gravity data are consistent as well as free of gross-errors. A confidence level equivalent to 95.4% was decided to filter the observed shipborne data, while the cross-validation algorithm was repeatedly applied until the standard deviation of the residuals between the observed and estimated values are less than 1.5 mGal, which led to the elimination of about 17.7% of the shipborne gravity dataset. A comparison between the shipborne gravity data with DTU13 and SSv23.1 satellite altimetry-derived gravity models is done and reported. The corresponding results revealed that altimetry models almost have identical data content when compared one another, where the DTU13 gave better results with a mean and standard deviation of ?2.40 and 8.71 mGal, respectively. A statistical comparison has been made between different global geopotential models (GGMs) and shipborne gravity data. The Spectral Enhancement Method was applied to overcome the existing spectral gap between the GGMs and shipborne gravity data. EGM2008 manifested the best results with differences characterised with a mean of 1.35 mGal and a standard deviation of 11.11 mGal. Finally, the least-squares collocation (LSC) was implemented to combine the shipborne gravity data with DTU13 in order to create a unique and consistent gravity field over the Red Sea with no data voids. The combined data were independently tested using a total number of 95 randomly chosen shipborne gravity stations. The comparison between the extracted shipborne gravity data and DTU13 altimetry anomalies before and after applying the LSC revealed that a significant improvement is procurable from the combined dataset, in which the mean and standard deviation of the differences dropped from ?3.60 and 9.31 mGal to ?0.39 and 2.04 mGal, respectively. 相似文献