Evaluation of the crustal deformations in the northern region of Lake Nasser (Egypt) derived from 8 years of GPS campaign observations     

A. Rayan  R.M.S. Fernandes  H.A. Khalil  S. Mahmoud  J.M. Miranda  A. Tealab 《Journal of Geodynamics》2010,49(3-4):210-215

The proper evaluation of crustal deformations in the Aswan (Egypt) region is crucial due to the existence of one major artificial structure: the Aswan High Dam. This construction induced the creation of one of the major artificial lakes: Lake Nasser, which has a surface area of about 5200 km² with a maximum capacity of 165 km³. The lake is nearly 550 km long (more than 350 km within Egypt and the remainder in Sudan) and 35 km across at its widest point. Great attention has focused on this area after the November 14, 1981 earthquake (M_L = 5.7), with its epicenter southwest of the High Dam.In order to evaluate the present-day kinematics of the region, its relationship with increasing seismicity, and the possible influence of the Aswan High Dam operation, a network of 11 GPS sites was deployed in the area. This network has been reobserved every year since 2000 in campaign style. We present here the results of the analysis of the GPS campaign time-series. These time-series are already long enough to derive robust solutions for the motions of these stations. The computed trends are analyzed within the framework of the geophysical and geological settings of this region. We show that the observed displacements are significant, pointing to a coherent intraplate extensional deformation pattern, where some of the major faults (e.g., dextral strike-slip Kalabsha fault and normal Dabud fault) correspond to gradients of the surface deformation field. We also discuss the possible influence of the water load on the long-term deformation pattern.  相似文献   

Electrodialytic Defluoridation of Brackish Water: Effect of Process Parameters and Water Characteristics     

Mourad Ben Sik Ali  Bchir Hamrouni  Mahmoud Dhahbi 《洁净——土壤、空气、水》2010,38(7):623-629

The aim of this work is to study the removal of fluoride from brackish polluted water using electrodialysis. The influence of several parameters such as flow rate, initial feed concentration, co‐existing ions, and initial pH on process efficiency were studied. This efficiency is evaluated by the removal rate, demineralization rate, and power consumption. The defluoridation process showed to be independent of pH of feed solution. Although the remained studied parameters plays a significant role on the defluoridation efficiency and mainly on the specific power consumption. The defluoridation of a contaminated real water sample was investigated so as to improve the efficiency of the process. The fluoride concentration could be reduced from 2.9 to 0.4 mg L⁻¹ which was lower than World Health Organization (WHO) standard (1.5 mg L⁻¹). Moreover the concentrations of different species in the obtained treated water are below the amounts recommended by WHO for drinking water.  相似文献   

Comparison of LLNF,ANN, and COA-ANN Techniques in Modeling the Uniaxial Compressive Strength and Static Young’s Modulus of Limestone of the Dalan Formation     

Mokhtari  Maryam  Behnia  Mahmoud 《Natural Resources Research》2019,28(1):223-239

Natural Resources Research - The uniaxial compressive strength and static Young’s modulus are among the key design parameters typically used in geotechnical engineering projects. In this...  相似文献   

Design flood estimation in ungauged catchments and statistical characterization using principal components analysis: application of Gradex method in Upper Moulouya     

Mahmoud Zemzami  Lahcen Benaabidate  Badr Layan  Abdallah Dridri 《水文研究》2013,27(2):186-195

Design flood estimation in ungauged catchments is of great importance in hydrologic practice especially where there is no available data about streamflow. Except the watershed of Anseghmir who is equipped with a gauge station, all the other watersheds are ungauged catchments. The use of frequency analysis of series of rainfall and streamflow is very important for the characterization of the hydrologic resources of the Upper Moulouya. The region has a semiarid climate that requires a good knowledge of the watershed's potential water to assist policy makers in forecasting extreme events, managing water resources and decision making. The frequency analysis was used to determine the design flood of different return periods. The results obtained are used in Gradex method to estimate the hydrologic variables of each subcatchment of the Upper Moulouya. Once the hydrologic study is completed, a principal components analysis was made to highlight the affinities between the different subcatchments and to deduce the hydrologic and hydrographic parameters that better characterize them. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Spatial analysis of a historical phenomenon: using GIS to demonstrate the strategic placement of Umayyad desert palaces   总被引：1，自引：0，他引：1  

Mahmoud Bashir Alhasanat  Shahid Kabir  Wan Muhd Aminuddin Wan Hussin  Erin Addison 《GeoJournal》2012,77(3):343-359

The Umayyad qusour (desert palaces) are monumental structures built during the reign of the first caliphate of Islam. Usually dismissed as “pleasure palaces” or “hunting lodges,” some scholars are beginning to argue that these prominent structures were strategic interventions in the landscape. Until now, historians have relied mainly on textual, architectural and art-historical analyses of the qusour in order to understand Umayyad state architecture. This research proposes the use of spatial analysis through GIS to lend a new dimension to the discussion. The results of the analysis show that Umayyad qusour are carefully situated at routes of transhumance and water sources. The distribution pattern of the Umayyad qusour is clustered at the outlet of Wadi Sarhan, and there is actually line-of-sight communication between Azraq, Amra, Haranah, Muwaqqar, Umm al Walid, Mushatta, and Qastal. There is also a positive association between Umayyad qusour and their water sources. These results support the argument that the Umayyad qusour were built strategically at perennial water sources in order to monitor routes of transhumance amongst the socio-political centers of the period.  相似文献   

Delineation of potential sites for groundwater recharge using a GIS-based decision support system   总被引：2，自引：2，他引：0  

Shereif H. Mahmoud 《Environmental Earth Sciences》2014,72(9):3429-3442

In arid and semi-arid regions without perennial water sources such as rivers or lakes, almost all water supply needs are met by groundwater. Groundwater recharge (GWR) is critical to maintain the abundance of groundwater. This paper presents a methodology based on a decision support system (DSS) that combines remote sensing, field survey and geographic information system techniques to identify suitable GWR areas. The DSS was implemented to obtain suitability maps and to evaluate the existing GWR in the study area. The DSS inputs comprised maps of rainfall surplus, slope, potential runoff coefficient, land cover/use and soil texture. The spatial extents of GWR suitability areas were identified by a hierarchical process analysis that considered five layers. The model generated a GWR map with four categories of suitability: excellent, good, moderate and poor and unsuitable. The spatial distribution of these categories showed that 0.08 and 32.3 % of the study area was classified as excellent and good for GWR, respectively, while 63.2 and 4.42 % of the area was classified as moderate and poor and unsuitable, respectively. Most of the areas with excellent to good suitability have slopes of between 4 and 8 % and are intensively cultivated areas. The major soil type in the excellent to good areas is loam, followed by clay loam, and the rainfall in these areas ranges from 150 to 260 mm. Another suitability model, in which all criteria were assigned equal influence, generated a suitability map in which 0.1 % of the study area was rated as excellent, 10.9 % as good, 82 % as moderate and 7 % as poor and unsuitable. The locations of existing GWR dams were compared with the locations indicated on the generated suitability map using the proximity analysis tool in ArcGIS 10.1. Most (77 %) of the existing GWR structures that were categorised as successful were within the excellent and good areas, followed by moderately suitable (23 %).  相似文献   

Distribution patterns of some heavy metals in the surface sediment fractions at northern Safaga Bay, Red Sea, Egypt   总被引：2，自引：0，他引：2  

Mahmoud A. Dar 《Arabian Journal of Geosciences》2014,7(1):55-67

The distribution patterns, the index of geo-accumulations (MI_geo), and the enrichment ratios (ER _n ) of the contaminant metals: Fe, Mn, Zn, Cu, Pb, and Ni were studied in gravel, sand, mud, coarse, medium, and fine sediment fractions of the uppermost layer of the bottom sediments collected from 12 stations covering the northern part of Safaga Bay. The distribution levels of these metals were increasing with grain size decreasing toward the central axis of the bay that extends NE–SW and southward to Safaga Harbour indicating that these metals concentrated mainly in the fine, very fine, and particulate fractions of sediments and to many anthropogenic sources. The geo-accumulation factor of Zn was more significant (MI_geo?≈?0.62–4.23) relative to the other metals. The bay was classified as moderately to strongly polluted by Zn while it is unpolluted to moderately polluted with the other metals with accumulation sequence of: Zn>Ni>Cu>Mn≥Pb. Zn and Ni recorded the highest enrichment ratios (average ER_Zn?≈?3.07 to 8.89; average ER_Ni?≈?0.84 to 3.63) in the different sediment fractions relative the other metals. These enrichment ratios classified the bay as minimal enrichment, suggestive of no or minimal pollution, to significant enrichment, suggestive of a significant pollution signals with metals sequence of: Zn>Ni>Cu>Pb>Mn.  相似文献   

Upgrading of the inverse slope method for quantitative interpretation of earth resistivity measurements     

Haby S. Mohamed  Mahmoud M. Senosy  Gamal Z. Abdel Aal 《Arabian Journal of Geosciences》2014,7(10):4059-4077

The present study is an attempt to upgrade the previously used semi-analytical inverse slope method. The upgrade method was applied to the interpretation of VES’s measured with different electrode arrays in two and three layers laboratory tank model. Then the method was applied on VES’s measured at different sites of different geologic conditions. The study showed that the inverse slope method is a quick method for obtaining depths to interfaces. The method can be implemented on a hand-held calculator or more efficiently on a small microcomputer where the data can be processed at a faster rate than that of conventional data acquisition systems. This allows the method to be potent tools for infield data analysis and more cost effective to assess the success of a sounding on-the-spot and modify the experimental set-up as appropriate. The comparison between the results obtained from this method and the traditional digital computerized methods indicated that the geoelectrical models derived from inverse slope method have a good correlation with the actual model. Also, when applying the method on VES’s measured by using Schlumberger and Wenner arrays at areas of different geologic setting, gave results in comfortable with the actual lithology obtained from the lithologic data of the neighboring wells. The results obtained from the lab experiment and field survey indicated that the inverse slope method has the potential to be applied on VES data collected with any electrode array, the advantage that is not available with all the traditional interpretation methods available nowadays.  相似文献   

Investigation of a relation between radiogenic heat production and kinetic surface temperature from multispectral ASTER-TIR data: a case study on Elmissikat-Eleridiya granites,Central Eastern Desert,Egypt     

Mahmoud Elsaid  Hatem Aboelkhair  Ahmed Dardier  Elsayed Hermas 《Arabian Journal of Geosciences》2014,7(11):4615-4628

In this paper, an attempt was tried to study the relation between radiogenic heat production rate (RHPR) that derived from gamma-ray spectrometric data and the kinetic surface temperature KST, which was calculated from the thermal emission and reflection radiometer-thermal infrared (ASTER-TIR) imagery applied on Elmissikat-Eleridiya district. This area is considered one of the most important uranium localities in the Central Eastern Desert of Egypt. The gamma-ray spectrometric data including both airborne data and in situ measurements concurrent with the collection of 20 rock samples were used to determine the rock density. The ground gamma-ray spectrometry has been conducted using GS-256 spectrometer at the same locations of rock samples. The gamma-ray spectrometric data (airborne and ground) beside rock density data were used for calculating RHPR. Alongside, pairs of daytime and nighttime ASTER-TIR images were collected and surface kinetic temperature for both day (daytime kinetic surface temperature (DKST)) and night (nighttime kinetic surface temperature (NKST)) were derived by using reference channel emissivity technique. The study showed a relative higher RHPR within syenogranite (4.2 up to 6 μW/m³) than other rock units. Besides, the KST of syenogranite ranged from 33 to 48 °C in daytime and between 7 and 17 °C at night. Comparing all results, no clear relation between RHPR and KST is evident. This is due to the very weak RHPR that is not sufficient to affect the surface heat temperature, which can be remotely sensed by ASTER satellite TIR data. This factor in addition to other factors such as: structural elements, topography, geographic locations, shading and scattering, rock moisture and density, can strongly affect the surface temperature. In conclusion, these results could be improved in areas of very high radioelement concentrations, especially ²³⁵U and through the use of the enhanced spatial resolution of future satellite TIR imaging instruments.  相似文献   

Survival of Vibrio alginolyticus in seawater and retention of virulence of its starved cells     

Ben Kahla-Nakbi A  Besbes A  Chaieb K  Rouabhia M  Bakhrouf A 《Marine environmental research》2007,64(4):469-478

The aim of this study was to evaluate the survival responses of four strains of Vibrio alginolyticus in seawater under starvation conditions. We used microcosms containing sterilised seawater and incubated at ambient temperature (22-25 degrees C). V. alginolyticus maintained its culturability for at least nine months. Long-term-starved cells showed an absence or a decrease in their enzymatic activities. Resuscitation assays of viable but non-culturable (VBNC) cells were conducted and the recovery of these cells was achieved after the addition of nutrients. Amplified 16S ribosomal DNA (rDNA) restriction analysis (ARDRA) was used to confirm that the same strain of V. alginolyticus persisted in all microcosms during a long period of time. Starved cells maintained their infectivity for gilt head sea bream (Sparus aurata) and sea bass (Dicentrachus labrax) as determined by intraperitoneal challenges.  相似文献