A simplified three-dimensional shallow landslide susceptibility framework considering topography and seismicity     

Daniel M. Hess  Ben A. Leshchinsky  Michael Bunn  H. Benjamin Mason  Michael J. Olsen 《Landslides》2017,14(5):1677-1697

Shallow landslides are a prevalent concern in mountainous or hilly regions that can result in severe societal, economic, and environmental impacts. The challenge is further compounded as the size and location of a potential slide is often unknown. This study presents a generalized approach for the evaluation of regional shallow landslide susceptibility using an existing shallow landslide inventory, remote sensing data, and various geotechnical scenarios. The three-dimensional limit equilibrium model derived in this study uses a raster-based approach that uniquely integrates tree root reinforcement, earth pressure boundary forces, and pseudo-static seismic accelerations. Contributions of this methodology include the back-calculation of soil strength from a landslide inventory, sensitivity analyses regarding landslide size-pixel size relationships, and the determination of shallow landslide susceptibility for a landscape or infrastructure considering various root, water, and seismic conditions using lidar bare-earth DEMs as a topographic input. Using a distribution of inventoried landslide points and random points in non-landslide locales, the proposed methodology demonstrated reasonable correlation between regions of high landslide susceptibility and observed shallow landslides within a 150-km² region of the Oregon Coast Range when the water-height ratio was 0.5. The method may be improved by considering spatial hydrologic conditions and geology more explicitly.  相似文献   

Imaging of wastewater percolation in heterogeneous soil using electrical resistivity tomography (ERT): a case study at east of Tenth of Ramadan City,Egypt     

Khaled S. Gemail  Mohamed Attwa  Mohamed Eleraki  Sara Zamzam 《Environmental Earth Sciences》2017,76(19):666

The objective of this study is to evaluate the effectiveness of DC resistivity surveys for imaging the wastewater percolation around the stabilization ponds in the Tenth of Ramadan City, the desert fringes of East Nile Delta, Egypt. Detailed resistivity surveys, including DC soundings and electrical resistivity tomography (ERT), were carried out along several profiles. Furthermore, synthetic modeling of ERT was designed to optimize the survey configurations and interpretation of the results. A 2D modeling of smoothness-constrained least-squares inversion scheme was applied to delineate the possible wastewater infiltration zones from oxidation ponds. Because the geoelectrical interpretation has a degree of non-uniqueness, the resistivity inversion was constrained using borehole lithological information and soil sample laboratory measurements. The DC inversion results indicate decreasing resistivity down to a depth of 15 m around waste disposal sites. The inferred soil zone close to the oxidation ponds was a mixture of sand, silt and clay. Moreover, the clay minerals were characterized by moderate swelling that could have reduced the vertical infiltration speed, causing wastewater seepage, especially around unlined disposal sites and open surface drains. Accordingly, the medium-to-low resistivity values can be attributed to wastewater leakage in clayey sand soil. Because the area slopes generally toward the northeast, the surface seepage was dominant in the shallow impermeable sandy clay subsoil. Therefore, measuring soil parameters is a complementary method to optimize resistivity interpretation, with potential for mitigating environmental hazards from wastewater leakage around disposal ponds.  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   

Calcite and barite precipitation in CaCO<Subscript>3</Subscript>-BaSO<Subscript>4</Subscript>-NaCl and BaSO<Subscript>4</Subscript>-NaCl-CaCl<Subscript>2</Subscript> aqueous systems: kinetic and microstructural study     

Hanen Azaza  Lassaad Mechi  Amira Doggaz  Virgil Optasanu  Mohamed Tlili  Mohamed Ben Amor 《Arabian Journal of Geosciences》2017,10(10):220

During the production of hydrocarbons from subterranean reservoirs, scaling with calcium carbonate and barium sulfate causes flux decline and dangerous problems in production facilities. This work is intended to study the effect of calcium ions on the precipitation of barium sulfate (barite); then, the effect of the formed barite on calcium carbonate crystallization. The conductometric and pH methods were used to follow the progress of the precipitation reaction in aqueous medium. The obtained precipitates were characterized by FTIR, RAMAN, SEM, and XRD. It was shown that Ca²⁺ in the reaction media does not affect the microstructure of barite even for higher calcium–barium molar ratio. It influences the precipitation kinetics and the solubility of barite by the formation of CaSO₄° ion pairing as a predominant role of complex formation (CaSO4) and the increase of the ionic strength. In Ca(HCO₃)₂-BaSO₄-NaCl aqueous system, experiments have showed that added or formed barite in the reaction media accelerates calcite precipitation. No effect on the microstructure of heterogeneous formed calcite which remain calcite shape. However the presence of carbonate ions affects slightly the microstructure of barite.  相似文献   

Fractal dimension of pore space in carbonate samples from Tushka area (Egypt)     

Yi Ding  Andreas Weller  Zeyu Zhang  Mohamed Kassab 《Arabian Journal of Geosciences》2017,10(17):388

To investigate inhomogeneous and porous structures in nature, the concept of fractal dimension was established. This paper briefly introduces the definition and measurement methods of fractal dimension. Three different methods including mercury injection capillary pressure (MICP), nuclear magnetic resonance (NMR), and nitrogen adsorption (BET) were applied to determine the fractal dimensions of the pore space of eight carbonate rock samples taken from West Tushka area, Egypt. In the case of fractal behavior, the capillary pressure P _c and cumulative fraction V _c resulting from MICP are linearly related with a slope of D-3 in a double logarithmic plot with D being the value of fractal dimension. For NMR, the cumulative intensity fraction V _c and relaxation time T ₂ show a linear relation with a slope of 3-D in a double logarithmic plot. Fractal dimension can also be determined by the specific surface area S _por derived from nitrogen adsorption measurements and the effective hydraulic radius. The fractal dimension D shows a linear relation with the logarithm of S _por . The fractal dimension is also used in models of permeability prediction. To consider a more comprehensive data set, another 34 carbonate samples taken from the same study area were integrated in the discussion on BET method and permeability prediction. Most of the 42 rock samples show a good agreement between measured permeability and predicted permeability if the mean surface fractal dimension for each facies is used.  相似文献   

Lithologic mapping of Aja granitic batholiths,Ha’il,Saudi Arabia,using remote sensing     

Mohamed E. Hereher  Shehta E. Abdullah 《Arabian Journal of Geosciences》2017,10(14):313

In this study, remote sensing, field and petrographic investigation were integrated for lithological mapping of different granitic masses in Aja complex of Ha’il, Saudi Arabia. The Landsat-8 data were processed to spectrally discriminate variations within rock types using band combinations, band ratioing and principal component analysis (PCA) techniques. Results showed that band combination of the principal components could potentially distinguish the different rock units of Aja complex than any other transform. Field observations and petrographic identification were performed to validate remotely sensing data and to map different rock units. Alkali granites were accurately recorded on the peripheries of Aja Mountain. The present study demonstrates that remote sensing techniques could provide useful tools for mapping economic rock types, particularly in well-exposed arid regions.  相似文献   

EGY-HGM2016: an improved hybrid local geoid model for Egypt based on the combination of GOCE-based geopotential model with gravimetric and GNSS/levelling measurements     

Mohamed El-Ashquer  Basem Elsaka  Gamal El-Fiky 《Arabian Journal of Geosciences》2017,10(11):251

An improved hybrid gravimetric geoid model for Egypt, EGY-HGM2016, has been recently computed implementing the least-squares collocation (LSC) method through the remove-compute-restore (RCR) procedure. The computation of EGY-HGM2016 involves different datasets in terms of gravity anomalies determined from the GOCE (gravity field and steady-state ocean circulation explorer)-based global geopotential model (SPW-R4) up to d/o 200 and EGM2008 from d/o 201 to 720 combined with terrestrial gravity datasets in terms of 2140 gravity field anomalies and about 121,480 marine surface gravity anomalies. In addition, orthometric heights from 17 GPS/levelling measurements have been considered during the modelling process to improve the determination of the hybrid gravimetric geoid over the Egyptian region. The EGY-HGM2016 model estimated over Egypt provides geoid heights that are ranging from 7.677 to 21.095 m with a standard deviation (st. dev.) of about 2.534 m in the northwest of the country excluding the involvement of the orthometric heights from GPS/levelling measurements. When the later dataset is considered during the implementation of LSC process, hybrid residual height anomalies ranging from ?1.5 to +0.9 m, with a mean of 0.22 m and a st. dev. of 0.17 m, are obtained. Comparison of the predicted hybrid gravimetric geoid with the corresponding ones obtained from EGM2008, GOCE-based SPW R4 model, and GPS/levelling reveals considerable improvements of our EGY-HGM2016 model over Egypt.  相似文献   

Regionalisation of the “intensity-duration-frequency” curves in Northern Algeria     

Mohamed El Amine Khelfi  Bénina Touaibia  Enrico Guastaldi 《Arabian Journal of Geosciences》2017,10(20):441

The flood events observed during last years in the urban areas are subject of main interest for quantification of the hydro-climatic risks and climatic change to the regional scales. The establishment of a statistical relationship between the intensities of intense rains and the recurrence of these events allows us to determine the dimensions of the works according to a previously defined level of risk. They constitute today a leading tool for various users. This work concerns the study of the maximum annual rains, recorded at 49 stations in the northern Algeria. The objectives of this work are to determine the estimators who are the “intensity-duration-frequency” curves and to extract from these whole of information the b Montana climatic parameter to be regionalized for the calculating the river flow and for the dimensioning of the networks of cleansing in the event of insufficiency of data. Different durations going from 15 min to 24 h are studied. We utilised the collocated co-kriging as multivariate estimation method for interpolation in order to yield the space distribution maps of b Montana climatic parameter, with the benefit of using spatially correlated secondary variables, such as the digital elevation model and the distance from the coastline that are known at any localisation. All features led to choose the digital elevation model as covariate for interpolating b Montana values, yielding a better regionalisation of the studied climatic parameter. The geostatistical handling of b Montana values strictly related to auxiliary variables that constitute physical factors overcomes the data shortage in planning, managing and preventing the rain flood risk.  相似文献   

Imagery of the metamorphic bedrock roof of the Sahel active fault in the Sablettes (Algiers) reclaimed area by ambient vibration HVSR     

Mohamed Yacine Tebbouche  Djamel Machane  Souhila Chabane  El-Hadi Oubaiche  Aghiles Abdelghani Meziani  Dalila Ait Benamar  Hakim Moulouel  Ghani Cheikh Lounis  Rabah Bensalem  Abderrahmane Bendaoud 《Arabian Journal of Geosciences》2017,10(13):292

The Sablettes (Algiers) coastal reclaimed fringe region, located on the hanging wall of the Sahel active fault, is subject to different types of geological hazard such as flood and tsunami, coastal uplift, earthquake, liquefaction, landslide, and site effects. In this present work, we used ambient vibration HVSR for imaging the bedrock. The thickness of the sedimentary column under the backfill layer is unknown, and the coastal reclaimed areas are prone to strong amplification of seismic waves. The determination of the depth of the metamorphic base allowed us to establish a mapping of the bedrock roof surface. The 3D representation of this surface enabled us to present models of tectonic structures in this basement (i.e., fault, fold). This analysis will make it possible to make better evaluation of the amplification after having determined the depth of the metamorphic basement exceeding 240 m, which is supposed to have velocities close to those of the seismological basement, as well as the thicknesses of the different layers surmounting it.  相似文献   

Mineralogy, Chemical Characteristics and Upgrading of Beach Ilmenite of the Top Meter of Black Sand Deposits of the Kafr Al-Sheikh Governorate, Northern Egypt     

Abdel-Aal M.?ABDEL-KARIM  Mohamed I. MOUSTAFA  Adel H. El-AFANDY  Mohamed G. BARAKAT 《《地质学报》英文版》2017,91(4):1326-1338

Egyptian beach ilmenite occurs in a relatively high content in the naturally highly concentrated superficial black sand deposits at specific beach zones in the northern parts of the Nile Delta at Rosetta. Microscopic study shows that the ilmenite occurs as fresh homogeneous black or heterogeneous multicoloured altered grains and exhibits three types (homogeneous, exsolved and altered) of ilmenite varieties. XRD data of ilmenite indicates their association with minor hematite and quartz, whereas leucoxene shows its association with Nb‐rutile, pseudorutile and hematite. Grain size distribution suggests a very fine sand size of >89% and 80% and a fine sand size of 10.5% and 18.3% for fresh and altered ilmenites, respectively. The density of fresh, altered ilmenite and leucoxene concentrates varies from 2.70, 2.50 to 2.40 ton/m³, suggesting a gradual decrease from high grade fresh to leucoxene and consistent with variation in magnetic susceptibility as a consequence of the leaching of iron. Mass magnetic susceptibility reveals 97.6% of ilmenite and 92% of the altered form are obtained at 0.20 and 0.48 ampere. Fresh ilmenite exhibits variable TiO₂ (47.18%) and Fe₂O₃^T (46.10%) with minor MnO, MgO and Cr₂O₃ (1.22, 1.10 and 0.51%). The altered ilmenite is higher in TiO₂ (76.16%) and SiO₂ (4.68%) and lower in Fe₂O₃^T (14.45%), MnO, MgO and Cr₂O₃ (0.39, 0.52 and 0.11%) compared with the fresh form. Three concentrates of ilmenites (G1, G2 and G3) were prepared from crude ore using a Reading cross belt magnetic separator under different conditions, revealing a gradual increase of TiO₂, SiO₂, Al₂O₃ and CaO accompanied by a decrease of Fe₂O₃^T, MgO and Cr₂O₃ with repetition of the separation processes. Several ore dressing techniques were carried out to upgrade the ilmenite concentrate.  相似文献