Assessment of crushed shales for use as compacted landfill liners     

Yahia E.-A. Mohamedzein  Amer A. Al-Rawas  Mohammed Y. Al-Aghbari  Ahmed Qatan  Abdul-Hamid Al-Rawas 《Engineering Geology》2005,80(3-4):271-281

The possibility of using crushed shales as landfill liners is investigated in this study. Two types of shales were studied by performing the following laboratory tests: hydraulic conductivity, compaction, swelling, consolidation, X-ray diffraction (XRD), scanning electron microscope (SEM) and chemical analysis. For both compacted shales, the hydraulic conductivity was in order of 10^− 7 cm/s or less which satisfies the specifications for landfill liners. The results of XRD and SEM support the low values of the hydraulic conductivity. Because of the dominant presence of low-activity kaolinite, there was no significant change in the hydraulic conductivity when the compacted shales are exposed to calcium chloride solution. The compressibility of the compacted clay was low and no serious post-construction settlement is expected. The shear strength of the compacted shales was within the usual expected range for earthen liners and, therefore, should pose no challenges with respect to shear strength. The crushed shales also satisfy the other criteria related to Atterberg limits and grain size.  相似文献   

Soil detachment and transport on field‐ and laboratory‐scale interrill areas: erosion processes and the size‐selectivity of eroded sediment     

O. Malam Issa  Y. Le Bissonnais  O. Planchon  David Favis‐Mortlock  Norbert Silvera  John Wainwright 《地球表面变化过程与地形》2006,31(8):929-939

Field‐ and laboratory‐scale rainfall simulation experiments were carried out in an investigation of the temporal variability of erosion processes on interrill areas, and the effects of such variation upon sediment size characteristics. Poorly aggregated sandy soils from the semi‐arid environment of Senegal, West Africa, were used on both a 40 m² field plot and a 0·25 m² laboratory plot; rainfall intensity for all experiments was 70 mm h^?1 with a duration of 1 to 2 hours. Time‐series measurements were made of the quantity and the size distribution of eroded material: these permitted an estimate of the changing temporal balance between the main erosion processes (splash and wash). Results from both spatial scales showed a similar temporal pattern of runoff generation and sediment concentration. For both spatial scales, the dominant erosional process was detachment by raindrops; this resulted in a dynamic evolution of the soil surface under raindrop impact, with the rapid formation of a sieving crust followed by an erosion crust. However, a clear difference was observed between the two scales regarding the size of particles detached by both splash and wash. While all measured values were lower than the mean weight diameter (MWD) value of the original soil (mean 0·32 mm), demonstrating the size‐selective nature of wash and splash processes, the MWD values of washed and splashed particles at the field scale ranged from 0·08 to 0·16 mm and from 0·12 to 0·30 mm respectively, whereas the MWD values of washed and splashed particles at the laboratory scale ranged from 0·13 to 0·29 mm and from 0·21 to 0·32 mm respectively. Thus only at the field scale were the soil particles detached by splash notably coarser than those transported by wash. This suggests a transport‐limited erosion process at the field scale. Differences were also observed between the dynamics of the soil loss by wash at the two scales, since results showed wider scatter in the field compared to the laboratory experiments. This scatter is probably related to the change in soil surface characteristics due to the size‐selectivity of the erosion processes at this spatial scale. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Seismic structural analysis at Abu Darag area,Gulf of Suez,Egypt     

Prof. Dr. M. A. El-Hefnawy  Dr. M. A. Amer 《GeoJournal》1989,18(4):393-397

This study is an attempt to clarify the subsurface geological settings at Abu Darag area in the N part of the Gulf of Suez through the analysis of the available seismic data. The time contour maps of three different reflectors (Top Kareem, Within Rudeis and Top Nukhul) present in this area were constructed and several structures were detected. Generally, the area is considered as a tilted fault block dipping in NE-SW direction and it is dissected by different faults. Major and minor NW-SE faults are the strongest trend in the area while other fault trends are with very weak magnitude and limited extent. All these fault trends restrict between them some high and low areas. Also, two geo-seismic sections were built to confirm the structural prospects on Top Nukhul time contour map.  相似文献   

Soil–vegetation relationships in a coastal desert plain of southern Sinai, Egypt     

Monier M. Abd El-Ghani  Wafaa M. Amer 《Journal of Arid Environments》2003,55(4):607-628

The present study provides an analysis of soil, vegetation types as well as structure and species distribution in 19 sites in El-Qaa plain along the Gulf of Suez (south Sinai, Egypt), and focuses on the environmental factors that control the species distribution. A total of 203 species belonging to 39 families of the vascular plants are recorded. Asteraceae, Fabaceae, Chenopodiaceae and Poaceae are the largest families. Grasses constitute only 9% of the recorded species, while the woody perennials (shrubs and sub-shrubs) are highly dominated (46%). Therophytes and chamaephytes are the most frequent, denoting a typical desert life-form spectrum. Floristic composition in the different geomorphologic landscape units showed differences in species richness. The highest mean species richness of 19.7±1.7 is recorded in the wadi channels. The lowest species richness values are recorded in the coastal shore and playas (6.0±1.4) and in the alluvial fans (mean of 8.4±1.6 species). Chorological analysis revealed that 46% of the studied species are uniregional, being native to the Saharo-Arabian region. On the other hand, about 50% of the recorded species are biregional and pluriregional, extending their distribution all over the Saharo-Arabian, Sudano-Zambezian, Irano-Turanian and Mediterranean regions. Classification of the vegetation is analysed using two-way indicator species analysis (TWINSPAN) techniques resulted in the recognition of five vegetation groups, each of definite vegetation and soil characters, and could be linked to a specific geomorphologic unit. Capparis spinosa var. spinosa occupied the terraces, Cornulaca monacantha, Convolvulus lanatus and Deverra tortuosa inhabited the alluvial plains, Launaea nudicaulis and Artemisia judaica characterized the wadi channels, Acacia tortilis subsp. raddiana and Leptadenia pyrotechnica characterized the alluvial fans and Tamarix nilotica, Zygophyllum album and Nitraria retusa on the playas and the coastal shore. Ordination techniques as detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) are used to examine the relationship between the vegetation and studied soil parameters. Nine soil variables are included: electrical conductivity, pH, calcium carbonate, gypsum, organic matter, gravel, fine soil fractions and soil saturation percentage. Analysis with DCA gave results similar to CCA, suggesting that there is a relatively high correspondence between vegetation and soil factors. DCA axis 1 showed significant positive correlation with CaCO₃, pH, soil saturation and organic matter, and interpreted as a calcium carbonate—soil saturation gradient. DCA axis 2 showed significant correlation with pH, gypsum and electric conductivity, and interpreted as an electric conductivity—gypsum gradient. Application of CCA indicated that soil surface sediment, CaCO₃, soil saturation, pH and organic matter are the main operating edaphic gradients in the area. These gradients are related closely to the first three canonical axes, and accounted for 67% of the species–environment relationship among the sites.  相似文献   

Adsorption capacity and mineralogical and physico-chemical characteristics of Shuwaymiyah palygorskite (Oman)     

Ahmed Al-Futaisi  Ahmad Jamrah  Amer Al-Rawas  Saif Al-Hanai 《Environmental Geology》2007,51(8):1317-1327

In this paper, Shuwaymiyah palygorskite in the Sultanate of Oman has been characterized mineralogically by X-ray diffraction (XRD) and electron microscopy, chemically by oxide compositions, structural formulae, and cation exchange capacity (CEC), and physically by specific surface area and adsorption isotherms. Batch adsorption studies were performed to evaluate the adsorption performance of methylene blue (MB) basic dye on the local clay mineral. The quantitative XRD analysis indicates that the purity of some selected samples of palygorskite clay is very high (about 70% of the clay minerals are palygorskite and 30% kaolinite). The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images clearly support this conclusion. The adsorption equilibrium revealed that Shuwaymiyah palygorskite clay can uptake up to 51 mg of MB per 1 g mass of clay. MB adsorption is best fitted by Langmuir isotherm, and a pseudo-second-order kinetic model can be efficiently used to predict the kinetic of adsorption of MB by the palygorskite. The results obtained from these laboratory-scale adsorption tests indicate the promising adsorption capability of the Omani palygorskite.  相似文献   

One-dimensional steady state seawater intrusion in leaky aquifers     

Mohamed A. Hashish  Mohamed E. Rasmy  Abdelwahab M. Amer 《Advances in water resources》1981,4(1):34-42

An iterative technique is presented to compute the location and shape of the interior interface for the one-dimensional steady state seawater intrusion problem in a coastal leaky aquifer. Upper and lower bounds on the location of the top tip point of the interface are deduced based upon the aquifer geometry. Moreover, the dependency of the locations of the top tip point as well as the toe of the interface on the inland boundary condition are obtained through variational analysis of the governing equations. A considerable reduction in the computational effort is shown to be possible provided there is available information about whether the water hinge point lies on or outside the interface. Numerical results are furnished to indicate the efficiency of the proposed algorithm.  相似文献   

Variation of the solar atmospheric rotation over the 11 year cycle     

Mohamed El-Raey  R. Amer 《Solar physics》1975,45(2):533-542

The synodic rotation period and power spectra of solar microwave sources are investigated using accurate data in the interval 1956 to 1970. The variation of the approximate 27 day period is obtained over a complete solar cycle and is thought to be a result of the latitude change over the solar cycle of the origins of the radio emissions. High resolution power spectra have also been obtained and revealed the existence of a double peaked line near 160 day period. This line is attributed to changes in either the Eartn's heliographic latitudes or the Earth's inclination to the Earth-Sun line.  相似文献   

Egypt and the Nile Basin   总被引：1，自引：0，他引：1  

Magdy Hefny  Salah El-Din Amer 《Aquatic Sciences - Research Across Boundaries》2005,67(1):42-50

  相似文献   

Climate volatility and poverty vulnerability in Tanzania     

Syud Amer Ahmed  Noah S. Diffenbaugh  Thomas W. Hertel  David B. Lobell  Navin Ramankutty  Ana R. Rios  Pedram Rowhani 《Global Environmental Change》2011,21(1):46-55

Climate volatility could change in the future, with important implications for agricultural productivity. For Tanzania, where food production and prices are sensitive to climate, changes in climate volatility could have severe implications for poverty. This study uses climate model projections, statistical crop models, and general equilibrium economic simulations to determine how the vulnerability of Tanzania's population to impoverishment by climate variability could change between the late 20th Century and the early 21st Century. Under current climate volatility, there is potential for a range of possible poverty outcomes, although in the most extreme of circumstances, poverty could increase by as many as 650,000 people due to an extreme interannual decline in grain yield. However, scenarios of future climate from multiple climate models indicate no consensus on future changes in temperature or rainfall volatility, so that either an increase or decrease is plausible. Scenarios with the largest increases in climate volatility are projected to render Tanzanians increasingly vulnerable to poverty through impacts on staple grains production in agriculture, with as many as 90,000 additional people entering poverty on average. Under the scenario where precipitation volatility decreases, poverty vulnerability decreases, highlighting the possibility of climate changes that oppose the ensemble mean, leading to poverty impacts of opposite sign. The results suggest that evaluating potential changes in volatility and not just the mean climate state may be important for analyzing the poverty implications of climate change.  相似文献   

Middle paleolithic to neolithic cultural history of North Iraq     

Thamer Khazal Al-Ameri  Sahar Y. Jasim  Amer J. S. Al-Khafaji 《Arabian Journal of Geosciences》2011,4(5-6):945-972

Six sections of 1–2.7-m depth contain ten sediment samples, each collected from the caves of Shanidar, Hawdian, and Hazar Merd with the nearby river valley sites of Zawi-Chemi, Gawra River, and Barda Balka, respectively, in North Iraq. They have been analyzed palynologically for their climatic significance and vegetational cover during late Quaternary in northeastern Iraq. The main information gathered from these palynological analyses as well as stone tools is ancient open site settlements in Barda Balka of Paleolithic interglacial Acheuleon culture. During the last Ice Age (120,000–10,000 years before present (B.P.)) people refuged to cave settlements. Baradost Mountain as well as the Aqra and Piera Maqroon mountains cavemen of the Middle Paleolithic Period are related to steppe vegetation with cold climate and glacial storms. Those cavemen manufactured stone artifacts of Mousterian to Gravetian culture and have their own religious belief and funeral ceremony especially recorded in the Shanidar cave. They lived by hunting and food collecting from a nearby valley to each cave. During earliest Holocene time (10,000 years B.P.), changing climate to moderately warm climate with Quercus forests and poacean vegetation was recorded, and the cavemen evolved to Neolithic culture and hence moved to settle in plain areas and built the oldest villages of the world, viz., Zawi-Chemi and Jarmo with continuing temporarily living in the caves as well. Their habit changed from food collectors to farmers who cultivated the land with wheat, barley, fruits, olive, legumes, and flowers of brilliant colors, nice odor, and nectariferous as well as domesticated animals for their food resources. Clay tablets of the Sumerians, Babylonians, and Assyrians have documented (Arapha) Kirkuk as one of their cities since 5,500 years B.P. The stone writing records of Assyrian king Sennacherib (705–681 years B.C.) state of making irrigation canals flowing to the temple of Ishtar in Erbil. On the other hand, the similarity of Jarmo village in the present Kurdstan region of Iraq to ancient Tell Hassuna village, south of the present Mosul city (within ancient Nineva city), and the pottery of Jarmo villages to Nineva pottery could give evidence for Jarmo people as followers to the Babylonian–Assyrian cultures within their empire and to prove that people of North Iraq and South Iraq are interrelated cultures through the history within Mesopotamian cultures.  相似文献