Identification of sinkhole development mechanism based on a combined geophysical study in Nahal Hever South area (Dead Sea coast of Israel)   总被引：2，自引：0，他引：2  

Michael Ezersky  Anatoly Legchenko  Christian Camerlynck  Abdallah Al-Zoubi 《Environmental Geology》2009,58(5):1123-1141

Seismic refraction, magnetic resonance sounding (MRS), and the transient electromagnetic (TEM) method were applied to investigate the geological and hydrogeological conditions in the Nahal Hever South sinkhole development area at the Dead Sea (DS) coast of Israel. Microgravity and MRS results reliably reveal large karst cavity in the central part of investigated area. The map of the seismic velocity shows that sinkholes in Nahal Hever can be divided into two major groups: sinkholes close to the salt edge and sinkholes over compact salt formations between a few tens to a hundred meters from the major cavern. The present study shows that the formation of sinkholes of the first group is caused by soil collapsing into the cavern. In the area occupied by sinkholes of the second group, karst was not detected either by MRS or by seismic diffraction methods. TEM results reveal shallow clay layer saturated with DS brine underlain sinkholes of this group. It allows suggestion that the water drainage and intensive water circulation during rain events wash out fine rock particles from the unsaturated zone into the pre-existing cavern, initiating the formation of sinkholes of the second group. Karst development takes place at a very low bulk resistivity (<1 Ω m) of the DS aquifer, attesting to the fact that pores are filled with a highly saline solution. Refilling of the karstic cavities with collapsing and flushed soil slows down sinkhole development in the area. The sinkhole formation cycle at the site is estimated at 10 years. Sinkhole development throughout the studied area is triggered by a drop in the level of the DS, which reduces the head of the confined aquifer and the strength of the overlain sediments.

Abdallah Al-ZoubiEmail:

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Geochemical and Environmental Evaluation of Um Shashoba Gold Mine Area,Southeastern Desert,Egypt     

Mohamed Abdallah Gad DARWISH 《《地质学报》英文版》2011,85(4):881-898

A suite of elements(Ag,Au,Ba,Bi,Cd,Co,Cr,Cu,Ga,Hf,Hg,Mn,Mo,Ni,Pb,Rb,Sb,Se, Sr,Te and Zn),total organic carbon(TOC)and pH were analyzed in stream sediment and tailing samples from Um Shashoba area,in order to evaluate Au placer and the sediments being impacted by old mining activities.Analytical results were examined using statistical,graphical and mapping methods.In spite of the results revealing that Au and most of the elements in sediments were in general significantly lower than those in tailing,Au wa...  相似文献   

Flash flood risk estimation along the St. Katherine road,southern Sinai,Egypt using GIS based morphometry and satellite imagery   总被引：7，自引：4，他引：3  

Ahmed M. Youssef  Biswajeet Pradhan  Abdallah Mohamed Hassan 《Environmental Earth Sciences》2011,62(3):611-623

Flash floods are considered to be one of the worst weather-related natural disasters. They are dangerous because they are sudden and are highly unpredictable following brief spells of heavy rain. Several qualitative methods exist in the literature for the estimations of the risk level of flash flood hazard within a watershed. This paper presents the utilization of remote sensing data such as enhanced Thematic Mapper Plus (ETM+), Shuttle Radar Topography Mission (SRTM), coupled with geological, geomorphological, and field data in a GIS environment for the estimation of the flash flood risk along the Feiran–Katherine road, southern Sinai, Egypt. This road is a vital corridor for the tourists visiting here for religious purposes (St. Katherine monastery) and is subjected to frequent flash floods, causing heavy damage to man-made features. In this paper, morphometric analyses have been used to estimate the flash flood risk levels of sub-watersheds within the Wadi Feiran basin. First, drainage characteristics are captured by a set of parameters relevant to the flash flood risk. Further, comparison between the effectiveness of the sub-basins has been performed in order to understand the active ones. A detailed geomorphological map for the most hazardous sub-basins is presented. In addition, a map identifying sensitive sections is constructed for the Feiran–Katherine road. Finally, the most influenced factors for both flash flood hazard and critical sensitive zones have been discussed. The results of this study can initiate appropriate measures to mitigate the probable hazards in the area.  相似文献   

Evaluation and rehabilitation of dam seepage problems. A case study: Kafrein dam   总被引：1，自引：0，他引：1  

Abdallah I. Husein Malkawi  Mohanned Al-Sheriadeh 《Engineering Geology》2000,56(3-4):335-345

The intention of this study is to locate the probable sources of the Kafrein dam seepage problem. A methodology known as excitation-response analysis will be considered. Analytical expressions, depicting the groundwater level response in the underlying aquifer as a result of changes in the reservoir water level, were derived from a linearized groundwater flow equation for one-dimensional semi-infinite, isotropic and homogeneous porous media. The results revealed that a large proportion of the seepage water originates from a site at a distance about 1 km from the observation point M1 and streamlines along the existing faults. Emphasis in this work was also placed on controling and mitigating the seepage problem.  相似文献   

An historical account of Brazilian public policy on fisheries subsidies     

Patrízia R. Abdallah  Ussif R. Sumaila 《Marine Policy》2007

This paper presents a historical account of Brazilian public policy on fisheries subsidies, and a discussion of problems and limitations resulting from such policy. From the 1960s to the mid-1980s, public policies led to a great increase in fisheries catch without appropriate consideration for the long-term sustainability of the resources, resulting in declining catches over the years. The goals of current Brazilian public policy on fisheries will not help in reducing overexploitation. This is because these policies are too optimistic about the abundance of fish in Brazil's EEZ, and are not accompanied by a fisheries management plan that is likely to work.  相似文献   

Biocontrol of Meloidogyne javanica on Tomato Plants by Hypocrea lixii (the Teleomorph of Trichoderma harzianum)          下载免费PDF全文

Abdallah M. Elgorban  Mohamed A. Abdel‐Wahab  Ali H. Bahkali  Basheer A. Al‐Sum 《洁净——土壤、空气、水》2014,42(10):1464-1469

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Biocontrol of Meloidogyne javanica on Tomato Plants by Hypocrea lixii (the Teleomorph of Trichoderma harzianum)          下载免费PDF全文

Abdallah M. Elgorban  Mohamed A. Abdel‐Wahab  Ali H. Bahkali  Basheer A. Al‐Sum 《洁净——土壤、空气、水》2014,42(11):1660-1660

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Application of time–frequency representation in the study of the cyclical behavior of wind speed in Algeria: wavelet transform     

Farouk Chellali  Abdallah Khellaf  Adel Belouchrani 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(8):1233-1239

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The origin of dolomite associated with salt diapirs in central Tunisia: Preliminary investigations of field relationships and geochemistry     

Ihsan S. Al-Aasm  Hassen Abdallah   《Journal of Geochemical Exploration》2006,89(1-3):5

Black and white dolomite crystals (mm to cm width) of different isotopic composition are associated with Triassic diapirism in central Tunisia, as well as with evaporite minerals and clays. The white dolomites occur mostly in the Jabal Hadifa diapir near the contact with Cretaceous limestones, whereas the smaller black dolomites occur in the Jabal Hamra diapir. The former dolomite has a narrow range of δ¹⁸O and δ¹³C values (− 3.83‰ to − 6.60‰ VPDB for δ¹⁸O; − 2.11‰ to − 2.83‰ VPDB for δ¹³C), whereas the latter dolomite has a wider range and more depleted values (− 4.92‰ to − 9.97‰ for δ¹⁸O; − 0.55‰ to − 6.08‰ for δ¹³C). However, the ⁸⁷Sr / ⁸⁶Sr ratios of most of the samples are near Triassic seawater values. Dolomite formation is due to at least two different fluids. The main fluid originated from deeper hydrothermal or basinal sources related to the Triassic saliferous rocks and ascended through faults during the diapiric intrusion. The second, less important fluid source is related to meteoric water originating from Cretaceous rocks.  相似文献   

Petrogenesis,Geodynamics and Radioactivity of the Granitic Rocks of the Nugrus Weakness Zone,South Eastern Desert,Egypt     

Soliman ABU ELATTA Abdallah Mahmou  Gehad M.R. MANSOUR 《《地质学报》英文版》2021,95(4):1183-1198

The studied granitic bodies belong to the south Eastern Desert of Egypt. They extend in a NNW–SSE trend along the same strike of the Nugrus weakness zone by which they are structurally controlled. These rocks are composed of biotite and biotite-muscovite monzogranites to syenogranites. Geochemically, a higher abundance of Ba and Rb in biotite granites with a relatively low abundance in biotite-muscovite granites as well as the diversity of Th, U, Nb, Ta, Zr, and REE reflects their origin from different sources and geodynamic settings. The biotite granites are predominantly metaluminous to low peraluminous whereas the biotite-muscovite granites have a peraluminous nature. Potassium enrichment at the expense of calcium in these rocks reflects a derivation from crustal sources by partial melting in the presence of a volatile system. Radiometric investigation showed high abundances of U(up to 38 ppm) and Th(up to 26 ppm) in biotite-muscovite granites relative to biotite granites(up to 5 ppm U and 18 ppm Th). Radioactive anomalies furthermore have been recorded in parts of biotite-muscovite granites that were affected by the faults(up to 116 ppm eU and 97 ppm eTh). Consequently, biotite-muscovite granites form a potentially fertile source for uranium mineralization.  相似文献