Alexandria-Nile Delta coast,Egypt: update and future projection of relative sea-level rise   总被引：1，自引：1，他引：0  

Omran El Sayed Frihy  Essam A. Deabes  Samy M. Shereet  Farid A. Abdalla 《Environmental Earth Sciences》2010,61(2):253-273

Previous studies have indicated that the Nile River deltaic plain is vulnerable to a number of aspects, including beach erosion, inundation, and relatively high rates of land subsidence. This issue motivates an update and analysis of new tide-gauge records, from which relative sea-level changes can be obtained. Estimated rates from five tide gauges are variable in terms of magnitude and temporal trend of rising sea level. Analysis of historical records obtained from tide gauges at Alexandria, Rosetta, Burullus, Damietta, and Port Said show a continuous rise in mean sea level fluctuating between 1.8 and 4.9 mm/year; the smaller rate occurs at the Alexandria harbor, while the higher one at the Rosetta promontory. These uneven spatial and temporal trends of the estimated relative sea-level rise (RSLR) are interpreted with reference to local geological factors. In particular, Holocene sediment thickness, subsidence rate and tectonism are correlated with the estimated rates of relative sea-level change. From the relatively weak correlation between them, we presume that tectonic setting and earthquakes, both recent and historical ones, contribute more to accelerated RSLR than that of dewatering and compression/dewatering of Holocene mud underlying the Nile Delta plain. As a result, large areas of the coastal plain have been subsided, but some sectors have been uplifted in response to tectonic activities of thick underlying older strata. Projection of averaged sea-level rise trend reveals that not all the coastal plain of the Nile Delta and Alexandria is vulnerable to accelerated sea-level rise at the same level due to wide variability of the land topography, that includes low-lying areas, high-elevated coastal ridges and sand dunes, accretionary beaches, and artificially protective structures. Interaction of all aspects (tectonic regime, topography, geomorphology, erosion rate, and RSLR rate) permitted to define risk areas much vulnerable to impacts of sea incursion due to accelerated sea-level rise.  相似文献   

Rogue waves for Kadomstev-Petviashvili equation in electron-positron-ion plasma     

S. A. El-Wakil  Essam M. Abulwafa  A. Elhanbaly  E. K. El-Shewy 《Astrophysics and Space Science》2014,353(2):501-506

The nonlinear ion-acoustic waves in plasma having excess super-thermal electrons and positrons have been investigated. Reductive perturbation method is used to obtain a Kadomstev-Petviashvili equation describing the system. The dynamics of the modulationally unstable wave packets described by the Kadomstev-Petviashvili equation gives rise to the formation of rogue excitation that is described by a nonlinear Schrödinger equation. The dependence of rogue waves profiles on the system parameters investigated numerically. The result of the present investigation may be applicable to some plasma environments, such as galactic clusters, interstellar medium.  相似文献   

Gravity data analysis of Ungaran Volcano, Indonesia     

Hakim Saibi  Essam Aboud  Agus Setyawan  Sachio Ehara  Jun Nishijima 《Arabian Journal of Geosciences》2011,5(5):1047-1054

Mount Ungaran is a Quaternary volcano located in the province of Central Java, Indonesia. The study area was covered by a gravity survey in order to delineate the subsurface structure and its relation to the hot springs that are spread throughout the area. The gravity data were analyzed using gravity gradient interpretation techniques, such as the horizontal gradient and Euler deconvolution methods, and many faults were detected. The results of the present study suggest that the hot springs around Ungaran Volcano are structurally controlled and have depths ranging from 1 to 3 km. The results of the present study lead to an understanding of the relationships between the interpreted faults and the locations of hot springs and may aid in future geothermal exploration of the area.  相似文献   

New times of the minima and light elements of SW Lacertae     

A. Essam  H. A. Mahdy  M. A. Hamdy 《Astrophysics and Space Science》1992,188(1):117-126

SW Lacertae is a short-period variable star of the W UMa-type. A total of 261 photoelectric observations for eachU, B, andV filter were obtained in 1986 while 522 photoelectric observations for eachB andV filter were obtained in 1987. All these observations were transformed to theU, B, andV colours of theUBV standard system. Nine light curves for primary and secondary eclipses were obtained, their times of minima were determined and a new linear ephemeris was obtained. The period changes of the system were also discussed.  相似文献   

Turbulent dynamo in asymptotic giant branch stars     

Noam Soker  Essam Zoabi 《Monthly notices of the Royal Astronomical Society》2002,329(1):204-208

Using recent results on the operation of turbulent dynamos, we show that a turbulent dynamo may amplify a large-scale magnetic field in the envelopes of asymptotic giant branch (AGB) stars. We propose that a slow rotation of the AGB envelope can fix the symmetry axis, leading to the formation of an axisymmetric magnetic field structure. Unlike solar-type αω dynamos, the rotation has only a small role in amplifying the toroidal component of the magnetic field; instead of an αω dynamo we propose an α ² ω . The magnetic field may reach a value of     , where B _e is the equipartition (between the turbulent and magnetic energy densities) magnetic field. The large-scale magnetic field is strong enough for the formation of magnetic cool spots on the AGB stellar surface. The spots may regulate dust formation, and hence the mass-loss rate, leading to axisymmetric mass loss and the formation of elliptical planetary nebulae (PNe). Despite its role in forming cool spots, the large-scale magnetic field is too weak to play a dynamic role and directly influence the wind from the AGB star, as required by some models. We discuss other possible problems in models where the magnetic field plays a dynamic role in shaping the AGB winds, and argue that they cannot explain the formation of non-spherical PNe.  相似文献   

A local geoid determination based on ellipsoid approximation in Western China     

Essam Ghanem  LI Jiancheng 《地球空间信息科学学报》2013,16(3):6-10

A new methodology for precise geoid determination with finest local details based on ellipsoidal approximation is presented. This methodology is formulated through the “fixed-free two-boundary value problem” based on the observable of the type modulus of gravity intensity, gravity acceleration and gravity potential at the GPS positioned stations, with support of the known geoid's potential value, W0.  相似文献   

Optical and near-infrared photometric study of NGC 6724     

Reda Bendary  Ashraf Tadross  Priya Hasan  Anas Osman  Ahmed Essam 《天文和天体物理学研究(英文版)》2018,(2)

BVRI CCD photometry of the poorly studied open cluster NGC 6724 has been carried out down to a limiting magnitude of V ～20 mag. The stars of the cluster have been observed using the Newtonian focus(f/4.84) of the 74-inch telescope at Kottamia Astronomical Observatory in Egypt.Also, the 2 MASS-JHK system is used to confirm the results we obtained. The main photometric parameters have been estimated for the present object; the diameter is found to be 6 arcmin, the distance is 1530±60 pc from the Sun and the age is 900±50 Myr. The optical reddening E(B-V) = 0.65 mag,while the infrared reddening is E(J-H) = 0.20 mag. The slope of the mass function distribution and the relaxation time estimations indicate that cluster NGC 6724 is dynamically relaxed.  相似文献   

Finite difference time domain simulation of radar wave propagation through comet nuclei dielectric models     

Ruth A. CARLEY  Essam HEGGY 《Meteoritics & planetary science》2008,43(6):1085-1095

Abstract— The 90 MHz radar‐wave experiment, Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT), on board the Rosetta mission (ESA, 2004) is expected to probe the nucleus of the comet 67P/Churyumov‐Gerasimenko (67P/C‐G) to reveal information on its physical properties, chemical composition, and internal structure. This investigation assesses the potential to recognize lithological structure in the comet nucleus with a radar experiment such as CONSERT. Radar simulations at 90 MHz were performed with a finite difference time domain (FDTD) method. The amplitude and losses of the transmitted and reflected electric field components of an incident radar pulse were evaluated as a function of time. Seven different dielectric models of sections of a hypothetical comet nucleus were used, representative of existing theories of comet nuclei. Values of dielectric constant assigned to these models are based on mixing laws for a porous mixture of ice and meteoritic dust, employing laboratory measured values of relative permittivity for mainly chondritic meteorites. Our results confirm that structural differences such as layers or inclusions are discernable from transmitted and reflected radar signals at 90 MHz, the central frequency of the CONSERT instrument. Such simulations help to constrain the ambiguities that might exist in future radar data associated with the nature of the comet nuclei, whether conglomerate or layered in nature.  相似文献   

Geo-environmental evaluation of Wadi El Raiyan Lakes,Egypt, using remote sensing and trace element techniques     

Hend S. Abu Salem  Atef Abu Khatita  Mamdouh M. Abdeen  Essam A. Mohamed  Ahmed M. El Kammar 《Arabian Journal of Geosciences》2017,10(10):224

Wadi El Raiyan depression represents a discharge area of excess wastewater from the Faiyum province. It comprises two lakes: the upper lake connects the lower one through a channel. The intensive agriculture in the area hazardously affects both lakes. To assess the status of these lakes, this work studies the change detection using image classification and post-classification comparison, physicochemical parameters, concentration of trace elements, and microbiological contents. The classified images indicate a maintained constant area of the upper lake from 1990 to 2012 and decreased by 1.6% in 2014. The lower lake area increased by 4.8% between 1990 and 2001, then decreased till 2014 and increased again by 8.4% in 2015. The change detection concluded that the lake could be disappeared by 2019 if the exploitation of water from the upper lake continues, or the lake could be rebounded if the government planned to increase the recharge. The factor analysis implies that the total Fe, Mn, Ni, Ba, and As are controlled by pH–Eh relationship, Cu by TDS, Pb by temperature, while Cd is attributed to anthropogenic factor. The upper and lower lake samples exhibit biological oxygen demand (BOD) and chemical oxygen demand (COD) values lower than fish farm samples. The high BOD and COD values were coupled by high nitrate contents in the studied water samples. The cultivated land drains and the fish farms samples have total coliform (TC) and fecal coliform (FC) higher than the samples collected from the upper lake.  相似文献   

Editors     

Essam El-Hinnawi 《Global Change & Human Health》2001,2(1):2-2

Editorial Introduction

Editors  相似文献