Determination of Hydraulic Conductivity from Complete Grain-Size Distribution Curves   总被引：13，自引：0，他引：13  

Mahmoud S. Alyamani  Zekâi &#;en 《Ground water》1993,31(4):551-555

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Effect of sewage effluent on the sediments of Nordåsvatnet (a land-locked fjord), Norway     

Mahmoud Kh. El-Sayed 《Marine pollution bulletin》1982,13(3):85-88

Nordåsvatnet is a land-locked anoxic fjord along the west coast of Norway which is used as a natural recipient of untreated domestic sewage. The study of four core sediments collected from the heavily polluted basin of the fjord reflects the enrichment of surface sediments by Fe, Mn, Cu, Zn and organic matter. This surface enrichment is entirely attributed to the anthropogenic input.  相似文献   

Total dissolved and particulate lead in the Western Harbor of Alexandria,a Mediterranean basin under stress     

Saad MA  Beltagy AI  Mahmoud WM 《Marine pollution bulletin》2003,47(1-6):52-58

The Western Harbor of Alexandria, the largest harbor of Egypt on the Mediterranean Sea, receives different internal and external untreated pollutants affecting dramatically its water, sediments and biota. Surface and bottom water samples were collected bimonthly from this harbor for studying vertical, regional and monthly distributions of total suspended matter (TSM), total dissolved lead (TDPb) and total particulate lead (TPPb). The high surface TSM values coincided with air-borne dust, organic aggregates, plankton productivity and discharged wastes. The high TSM averages in winter resulted mainly from turbulence of the water column by wind action. The highest averages of TDPb in the petroleum and coal basins in the Western Harbor reflect their effects on the water column, while the lowest averages of TDPb and TPPb were found at a location far away from pollution sources. For the water column, the maximum and minimum monthly averages of TPPb and TDPb respectively in June reflect the increase in the rate of lead uptake by phytoplankton abundant in summer, favored by temperature elevation. The annual mean concentration of TPPb was nearly double that of TDPb, indicating that lead was transported to the Western Harbor mainly in particulate form. This reflects the high TSM content in the harbor water onto which a considerable part of lead was adsorbed.  相似文献   

Responses of Ras El Bar seafloor characteristics to the protective engineering structures, Nile delta, Egypt     

Mahmoud M. El Banna 《Environmental Geology》2006,49(5):645-652

Bathymetry of the seafloor in the area in front of Ras El Bar coast, the characters of the seafloor sediments and the effects of protective structures on seafloor bathymetry were examined. Seafloor depths in front of Ras El Bar seawall ranged between 2 and 4 m. These depths, coupled with wave climate, result in waves breaking directly onto the wall and exerting high, dynamic pressures on the area at the structure’s toe. The sandy seafloor in front of the wall has been scoured. Sea water has undermined the wall causing removal of sediment, destabilization of its slope and the whole face of the wall has slipped. Toe protection in the form of a rocky apron is required to prevent such damage. West of the seawall, the constructed breakwater system has affected the bathymetry of the seafloor in the area. Shoaling and submerged spits have been formed in the shadow of each breakwater unit. The gaps between the breakwater units have attained deep depths and steep slopes. Scours and steep slopes adjacent to the head of the breakwater units have been recorded. Seaward of the breakwater system, deeper depths and gentle slopes characterize the seafloor. Offshore–onshore current and sediment movements toward the northeast is inferred from the configuration of the bottom contour lines.  相似文献   

Application of the single point measurement in discharge estimation     

Mahmoud F. Maghrebi 《Advances in water resources》2006

The fluid flow system can be described by an equivalent electromagnetic system. In this paper a successful application of the Biot–Savart law in hydraulics is presented. Similarity between the magnetic field of a current wire and the isovel contours in a channel cross-section is used to derive the isovel patterns in an open or closed channel. Having obtained the normalized isovel contours, one can easily obtain the discharge using a single point of velocity measurement at the conduit cross-section. The estimated discharge, based on measured points and the predicted isovels on the upper half of the flow depth away from the boundaries was within ±5% of the measured and much better in comparison to the prediction of one- and two-point methods. Furthermore, the model was applied to real life channels. The prediction of the water surface velocity for the River Unon in Japan and depth-averaged velocity for the Severn River in UK show a good agreement with the measured data and analytical results.  相似文献   

Distribution and Influence of Iron Phases on the Physico—Chemical Properties of Phyllosilicates     

MERVATSAIDHASSAN SAYEDMAHMOUDSALEM 《中国地球化学学报》2002,21(1):29-39

Clay minerals from different Cretaceous stratigraphic successions of Egypt were investigated using XRD,DTA,dissolution analysis(DCB),IR,Moessbauer and X-band Electron Spin Resonance(ESR) spectroscopies.The purity of the samples and the degree of structural order were determined by XRD.The location of Fe in the octahedral sheet is characterized by absorption bands at-875cm^-1 assigned as Al-OH-Fe which is present after chemical dissolution of free iron.The Moessbauer spectra of these clays sow two doublets with isomer shift and quadrupole splitting typical of octahedral coordinated Fe^3 ,in addition to third doubler with hyperfine parameter typical of Fe^2 in the spectra of Abu-Had kaolinite (H)sample.6-lines magnetic hyperfine components which are consistent with those of hematite are confirmed in the spectra of both Isel and Rish kaolinite samples.Goethite was confirmed by both IR and DTA.Multiple nature of ESR of these clays suggested structural Fe in distorted octaedral symmetry and as non-structural Fe.Little dispersion and low swelling indices as well as incomplete activaiton of investigated montmorillonite samples by NaCO3 appear to be due to incomplete disaggregation of montmorillonite particles.This can be explained by the ability of Fe-gel to aggregate the montmorillonite into pseudo-particles and retard the rigid-gel structure.However,extraction of this ferric amorphous compound by dithonite treatment recovers the surface properties of the montmorillonite samples.On the other hand,amounts and site occupation of Fe associated with kaolinite samples show a negative correlation with the parameters used to describe the degree of crystalline perfection,color,brightness and vitrification range of these kaolinite samples.  相似文献   

Les manifestations tectono-sédimentaires d'âge Campanien–Maastrichtien en Tunisie : implications sur l'évolution géodynamique de la marge Nord-AfricaineThe Campanian–Maastrichtian synsedimentary tectonic activity: implication in the geodynamic evolution of the North African Margin     

Mahmoud Dlala 《Comptes Rendus Geoscience》2002,334(2):135-140

The synsedimentary tectonic activity evidenced in central and northern Tunisia points out the fact that the Campanian–Maastrichtian deposits are associated with several NW–SE and east–west normal faults. These results suggest that the east–west transform fault of North African Margin is still active during this stage. These data allow us to discuss a new geodynamic model for the North African Margin. To cite this article: M. Dlala, C. R. Geoscience 334 (2002) 135–140.  相似文献   

Very short-term behaviour of the flare star EV Lac     

Farouk M. Mahmoud 《Astrophysics and Space Science》1993,208(2):205-215

Sinusoidal variations in Johnson'sB-band of the flare star EV Lac have been confirmed at its quiet state luminosity. The cycle lengths are more than one hour and less than two hours with amplitudes varying from 0 _. ^m 105 to 0 _. ^m 306. These registered cycles have agreed with cycles detected by Mavridis and Varvoglis (1990) and Mavridis (1990). In the same time, the cycles have confirmed the light variation detection in Johnson'sV-band in the same flare star by Pettersen (1980) with a cyclic period equals about 4 _. ^d 378 and an amplitude of about 0 _. ^m 07. Our net results confirm, to some extent, the presence of active region(s) as an origin of stellar flare phenomenon of UV Ceti type flare stars. We can cautiously say that the solar and stellar flare phenomenon have a similar origin.  相似文献   

Erosion and accretion rates and their associated sediment characters along Ras El Bar coast,northeast Nile Delta,Egypt     

Mahmoud M. El Banna 《Environmental Geology》2007,52(1):41-49

Beach profile data, covering the coast of Ras El Bar, northeast Nile Delta, collected during the years from 1990 to 2002 combined with landsat images for the area and sedimentological investigation have been used to identify beach and nearshore seafloor sediment changes. Along the coast of Ras El Bar, two accretion sectors and one of erosion have been recognized. The first accretion sector is located west of Damietta harbour, where the harbour jetties have halted the littoral transport, while the second one is behind a system of detached breakwaters protecting Ras El Bar resort. Both the two sectors are characterized by growing shoreline with maximum rates ∼15 and 10 m/year, respectively. Also, they have maximum nearshore seafloor accretion rates of ∼18 and 22 cm/year, respectively. The erosion sector is located east of Damietta port and has a maximum rate of shoreline retreat ∼−10 m/year. Erosion of its nearshore seafloor is indicated recording a maximum rate of ∼−20 cm/year. The rate of net sediment volume change in the area indicates shifting of the accretion sector (II) westward, responding to installation of the new breakwaters unit. The two accretion sectors are characterized by dominance of moderately sorted fine sands in their shore area which change seaward into less sorting very fine sands. Beach sands of the eroded sector are poorly sorted medium grain size. The dominant constituents of heavy mineral species in beach and sea-bottom sands are the characteristic assemblages of the Nile deposits. The sands of the eroded zone are relatively enriched in monazite, zircon, tourmaline, garnet, and rutile.  相似文献   

Settlement of inhomogeneous consolidating soils—II: The symmetrically loaded mass     

M. S. Mahmoud  H. Deresiewicz 《国际地质力学数值与分析法杂志》1980,4(1):73-88

We continue our study of the consolidation of inhomogeneous clay soils with an analysis of the response of a soil mass, whose shear modulus increases linearly with depth, to axially symmetric pressure on its surface. This extends the work reported in Part I on the corresponding one-dimensional problem of a clay column, and generalizes researches of Gibson and coworkers on the elastic model of the soil (i.e., the initial response). Because of great mathematical complexity when Poisson's ratio is allowed to assume arbitrary values, we have confined ourselves (as did Gibson in several of his papers) to variations of the modulus from a zero surface value, this being in reasonable accord with published test results on London clay. The deflection of points within this region, the deflection relative to the central one (that is, the shape of the deformed loading area), as well as the absolute deflection of surface points exterior to the load.  相似文献