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111.
Haoyuan Hong Seyed Amir Naghibi Mostafa Moradi Dashtpagerdi Hamid Reza Pourghasemi Wei Chen 《Arabian Journal of Geosciences》2017,10(7):167
Forest fire is known as an important natural hazard in many countries which causes financial damages and human losses; thus, it is necessary to investigate different aspects of this phenomenon. In this study, performance of four models of linear and quadratic discriminant analysis (LDA and QDA), frequency ratio (FR), and weights-of-evidence (WofE) was investigated to model forest fire susceptibility in the Yihuang area, China. For this purpose, firstly, a forest fire locations map was prepared implementing MODIS satellite images and field surveys. Then, it was classified into two groups including training (70%) and validation (30%) by a random algorithm. In addition, 13 forest fire effective factors were prepared and used such as slope degree, slope aspect, altitude, Topographic Wetness Index (TWI), plan curvature, land use, Normalized Difference Vegetation Index (NDVI), annual rainfall, distance from roads and rivers, wind effect, annual temperature, and soil texture. Using the training dataset and effective factors, LDA, QDA, FR, and WofE models were applied and forest fire susceptibility maps were prepared. Finally, area under the curve (AUC) of receiver operating characteristics (ROC) was implemented for investigating the performance of the models. The results depicted that WofE had the best performance (AUC = 82.2%), followed by FR (AUC = 80.9%), QDA (AUC = 78.3%), and LDA (AUC = 78%), respectively. The results of this study showed the high contribution of altitude, slope degree, and temperature. On the other hand, it was seen that slope aspect and soil had the lowest importance in forest fire susceptibility mapping. From the AUC results, it can be concluded that FR, WofE, LDA, and QDA had acceptable performance and could be used for forest fire susceptibility mapping at the regional scale. 相似文献
112.
Hend Ahmed Ibrahim Hussein Adam Ricka Tomas Kuchovsky Maged Mostafa El Osta 《Arabian Journal of Geosciences》2017,10(7):170
The demand for water is rapidly increasing in Egypt, because of high population and agriculture production growth rate, which makes research of water resources necessary. The regional multi-aquifer system of the Miocene–Pleistocene age is discharged in Wadi El Natrun area. Intensive aquifer overexploitation and agricultural development in the area are related to groundwater quality deterioration. Hydrochemical and hydrogeological data was evaluated to determine the groundwater origin and quality in the south-eastern part of wadi, which appears to be more significant for water supply owing to lower groundwater salinity. The dominance of the high mineralised Cl groundwater type was found; however, also less mineralised SO4 and HCO3 types were identified there. Based on the ion relations, halite and gypsum dissolution and ion exchange are the most important hydrochemical processes forming the groundwater chemical composition. The Cl dominated groundwater matches the discharge part of the regional hydrogeological system. Contrary, the presence of HCO3 and SO4 hydrochemical types corresponds to the infiltration and transferring parts of the hydrogeological system indicating the presence of zones conducting low mineralised groundwater. The discharge area of the over-pumped aquifer in Wadi El-Natrun lies 23 m beneath the sea level with the shoreline being at the distance of 100 km, thus there is a real risk of seawater intrusion. Using the hydrochemical facies evolution diagram, four samples in the centre of the discharge area indicate advanced seawater intrusion. The zones of the highest demand for groundwater quality protection were indicated based on a spatial pattern of hydrogeochemical composition. 相似文献
113.
Hicham Si Mhamdi Mohammed Raji Soufiane Maimouni Mostafa Oukassou 《Arabian Journal of Geosciences》2017,10(5):125
The Paleozoic massif of Tichka in the southern part of the Western High Atlas of Morocco constitutes a structural transition between the Meseta and the Anti-Atlas domains. It was affected by a complex network of fractures noticeable at different scales. Using Landsat ETM+ imagery permits detecting the main fracture directions. Various techniques of lineament’s extraction were applied, including the colored compositions, spectral band ratios, and directional filters applied to the principal component analysis. Lineament’s extraction is based on visual interpretation and completed by field observations. The resulted map allows recognizing at least four trending fracture system, with average N-S, NE-SW, E-W, and NW-SE orientations. The surrounding rocks of the granitic massif show a high fracture density. Tectonic indicators show that this massif is initially affected by NW-SE Variscan tectonic extension, followed by NW-SE Variscan compression. This regime is being maintained until the late Variscan period corresponding to the relaxation of the NW-SE major Variscan stress. A clockwise rotation of the latter stress, which became N-S to NNE-SSW, related to the late Variscan deformation, is responsible for reworking preexisting faults. 相似文献
114.
Back analysis of an excavated slope failure in highly fractured rock mass: the case study of Kargar slope failure (Iran) 总被引:2,自引:1,他引:1
Mostafa Sharifzadeh Mohsen Sharifi S. Mohammad Delbari 《Environmental Earth Sciences》2010,60(1):183-192
This paper examines the failure of Kargar cut slope located at the south part of Esfahan subway using analytical and numerical
back analysis methods. The excavated trench has 27 m depth with near vertical walls due to the space limitation around it.
The geology of the area comprises weathered and heavily jointed shale and sandstone overlaid by alluvium deposits. Despite
the slope being supported by shotcrete and fully grouted rock bolts, a catastrophic failure occurred at the east wall. Due
to the uncertainty about the causes of failure initiation, back analyses have been performed via both the limit equilibrium
and numerical method for considering various probable mechanisms. In the back analysis with limit equilibrium method, the
rock mass is assumed as an equivalent continuum and Hoek–Brown failure criterion and geological strength index (GSI) are applied
to calculate the shear strength parameters. The results show that GSI value was 33 in the failed mass. In the numerical back
analysis, the distinct element method is applied to study the contribution of rock joints to the failure and progressive rock
mass strength degradation until failure. The results show that threshold values of joint cohesion and friction were 0.2 MPa
and 30°, respectively. Also the modeled slip surface being step-shaped agrees with the observed one. 相似文献
115.
116.
Evidence of uranium biomineralization in sandstone-hosted roll-front uranium deposits, northwestern China 总被引:13,自引:0,他引:13
We show evidence that the primary uranium minerals, uraninite and coffinite, from high-grade ore samples (U3O8>0.3%) in the Wuyiyi, Wuyier, and Wuyisan sandstone-hosted roll-front uranium deposits, Xinjiang, northwestern China were biogenically precipitated and psuedomorphically replace fungi and bacteria. Uranium (VI), which was the sole electron acceptor, was likely to have been enzymically reduced. Post-mortem accumulation of uranium may have also occurred through physio-chemical interaction between uranium and negatively-charged cellular sites, and inorganic adsorption or precipitation reactions. These results suggest that microorganisms may have played a key role in formation of the sandstone- or roll-type uranium deposits, which are among the most economically significant uranium deposits in the world. 相似文献
117.
Driss Khattach Pierre Keating El Mostafa Mili Touria Chennouf Pierre Andrieux Abdellah Milhi 《Comptes Rendus Geoscience》2004,336(16):1427-1432
Various techniques (horizontal and vertical derivatives, upward continuation, Euler deconvolution) have been applied to the gravity data from the Triffa's plain and the north flank of the Beni-Snassen massif to delineate various major geological structures such as faults and basins. These results allow the production of a structural map showing the fault systems for the survey area. This map forms the basis for planning future hydrogeological research in this region. To cite this article: D. Khattach et al., C. R. Geoscience 336 (2004). 相似文献
118.
Abdel-Meguid Ahmed A. Fayed Laila A. Mostafa Mostafa E. Mostafa Mohamed S. 《Natural Hazards》1998,17(1):47-67
The plateau east of the Nile Valley at El Minia, Egypt, has been chosen for the siting of El Minia El Gedida city. Problems of underground caves suggested the need for integral geological, geotechnical and environmental hazard studies to examine the suitability of the area as a building site.Geologically, the area is formed of a thick sequence of Middle Eocene fossiliferous limestones and chalk with some layers of sandy, cherty and marly limestones. These rocks have heterogeneous physical and mechanical properties and fall within the weak to very weak range of limestones. Their mode of failure is almost of the brittle type developing extension, wedge and single shear type fractures. The mechanical properties are controlled by their physical, geological and mineralogical properties. They increase with density and dolomite content and decrease with porosity and calcite content. Empirical equations for some of these relations as well as the relation between field measures of rebound index and compressive strength are presented.Both regional and detailed structural analyses revealed the presence of major and minor normal faults and fractures trending in NW and NE directions. The NW faults are dominant. They define the topographic escarpments in the area. Most of the caves are aligned along major faults of this trend. Faults, fracture distribution and structural hazard maps of the area are presented. Paleostress tectonic analysis of these fractures suggests that the NW and NE faults are extensional due to tectonic stress which changes from normal to parallel to the Red Sea at different geologic times starting in post Middle Eocene. The similarity of this paleotectonic setting to present Red Sea tectonics points out the possibility of future rejuvenation of these faults.Topographically, the area lies in shallow surface drainage basins. The topographical risk is increased by fracturing and it should be considered if the area is subjected to a long period of heavy rainfall. Radiometrically, El Minia El Gedida city represents one of the lowest natural radioactivity areas within the safe limits recommended by the International Commission on Radiological Protection (ICRP). 相似文献
119.
João A. Hackerott Mostafa Bakhoday Paskyabi Joachim Reuder Amauri P. de Oliveira Stephan T. Kral Edson P. Marques Filho Michel dos Santos Mesquita Ricardo de Camargo 《Boundary-Layer Meteorology》2017,165(2):211-231
We discuss scalar similarities and dissimilarities based on analysis of the dissipation terms in the variance budget equations, considering the turbulent kinetic energy and the variances of temperature, specific humidity and specific CO\(_2\) content. For this purpose, 124 high-frequency sampled segments are selected from the Boundary Layer Late Afternoon and Sunset Turbulence experiment. The consequences of dissipation similarity in the variance transport are also discussed and quantified. The results show that, for the convective atmospheric surface layer, the non-dimensional dissipation terms can be expressed in the framework of Monin–Obukhov similarity theory and are independent of whether the variable is temperature or moisture. The scalar similarity in the dissipation term implies that the characteristic scales of the atmospheric surface layer can be estimated from the respective rate of variance dissipation, the characteristic scale of temperature, and the dissipation rate of temperature variance. 相似文献
120.
Mostafa Rabah Zaki Zedan Essam Ghanem Ahmed Awad Ahmed Sherif 《Arabian Journal of Geosciences》2016,9(13):613
Nowadays many continuously operating reference stations (CORS) network were established in Middle East to improve the surveying tasks. Establishing such geodetic control networks can be a costly business where multiple stations should be occupied simultaneously and post-processed with scientific software. Recently, precise point positioning (PPP) provides precise positioning values that may be an alternative to precise relative processing. The current research aims to investigate that PPP has a potential as a reliable absolute positioning technique operational simplicity as well as to investigate the capability of PPP approach to be a low cost alternative to the conventional positioning methods used in position determination of core networks stations. In comparison with common relative GPS techniques, the costs are reduced; because no base stations and no simultaneous observations are necessary, no need for control network maintenance which could be the most defective factors that Egypt HARN network suffered from. To see the feasibility study of using PPP for precise determination of the CORS, 14 days of GNSS data for the 14 Kuwait integrated with 27 IGS stations were processed by Bernese software to calculate the precise coordinates of Kuwaiti CORS network in the latest terrestrial geodetic frame. Three days of these data were processed by Trimble business center software and using PPP approach to calculate the precise coordinates of Kuwait network. In the current research, a comparable investigation was carried out between the coordinates obtained from Bernese software, Trimble business center, and PPP approach. The comparison proved high level of agreement between the coordinates which confirm that PPP approach can be applied for establishment of CORS network. 相似文献