Abstraction of informed virtual geographic environments     

Mehdi MEKNI 《地球空间信息科学学报》2012,15(1)

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On a damaging earthquake-induced landslide in the Algerian Alps: the March 20, 2006 Laâlam landslide (Babors chain,northeast Algeria), triggered by the Kherrata earthquake (<Emphasis Type="Italic">M</Emphasis><Subscript>w</Subscript> = 5.3)     

Mehdi A. Guemache  Djamel Machane  Hamoud Beldjoudi  Sofiane Gharbi  Leila Djadia  Sihem Benahmed  Hayet Ymmel 《Natural Hazards》2010,54(2):273-288

On March 20, 2006, an earthquake (M _w = 5.3; SED) struck the mountainous region of the Babors chain (Wilaya of Bejaia, northeast Algeria). The seismic epicenter was located near the Kherrata village. This earthquake was felt on a large area of the northeastern part of Algeria. It reached an intensity of VII (EMS scale) at the Laalam village, situated at about 20 km northeast of Kherrata. Here, many old and recent houses were damaged or collapsed totally, four people died and 68 were injured. Field investigations revealed that these casualties were caused by a landslide triggered by the earthquake. Many fissures were visible on ground throughout the site. They were generated by both sliding and settling phenomena. The Laalam site is prone to landslide, as revealed by some evidences on old instabilities. This is due to two main factors: local geomorphology and geology. These factors intervene synchronously for reducing the slope instability at the Laalam village. The March 20, 2006 Kherrata earthquake was the trigger that released the Laalam landslide.  相似文献   

Metal fluxes to the sediments of the Moulay Bousselham lagoon,Morocco   总被引：2，自引：0，他引：2  

Asmae Mhamdi Alaoui  Mohamed Choura  Mohamed Maanan  Bendahhou Zourarah  Marc Robin  Maria Freitas Conceição  César Andrade  Mehdi Khalid  Christian Carruesco 《Environmental Earth Sciences》2010,61(2):275-286

The metal content in surface sediments (0–2 cm, 26 samples), in a sediment core (120, 1 cm slices), taken from Moulay Bousselham (Morocco) was investigated. Concentrations of Al, Fe, Mn, Pb, Zn, Cu, Ni, Cr, Cd, As, and Hg were evaluated in surface and cored sediments of Moulay Bousselham lagoon. Significantly high concentrations in μg g⁻¹ dw of Pb (31.7–6.2), Zn (758.9–167), Cu (310.7–22), Ni (96–10.5), Cr (113–18.9), Cd (0.84–0.02), As (1–0.1), and Hg (0.61–0.02) were found in sediment samples from Moulay Bousselham lagoon. Calculated enrichment factors [EF_Me = (Me/Al)_sample/(Me/Al)_background], using Al as a normalizer, and correlation matrices showed that metal pollution in Merja Zerga of Moulay Bousselham lagoon was the product of anthropogenic sources, while the metal content in Merja Kehla was of natural origins. The results suggest that a major change in the sedimentary regime of the lagoon, associated with internal trapping and re-distribution of heavy metal, has been occurring in the past few decades. The cause would appear to be the construction of a Nador Canal at the lagoon. Probable effects concentrations (PEC) were often exceeded for heavy metals in the lagoon sediments, especially for Zn, Cu, Ni, and Cr, and four stations, stations MZ-11, MZ-12, MZ-13, MZ-14, MZ-16, and MZ-17, had multiple metals at presumptively toxic levels. These comparisons suggest that sediment metal levels in the river are clearly high and probably pose an environmental risk at some stations. The levels of most of the metals were not greatly enriched, a consideration that is of the utmost importance when contamination issues are at stake. Metal concentrations found in Moulay Bousselham lagoon were comparable to aquatic systems classified as contaminated from other regions of the world.  相似文献   

Evidence for an underground runoff and soil permeability at the Ouled Fayet (Algiers,Algeria) subsurface landfill pilot project from geophysical investigations   总被引：1，自引：1，他引：0  

Leila Djadia  Djamel Machane  Jean-Luc Chatelain  Abdesslam Abtout  Rabah Bensalem  Mehdi Amine Guemache  Bertrand Guillier  Amar Boudella  El-Hadi Oubaiche 《Environmental Earth Sciences》2010,59(5):1149-1158

Results from geophysical investigations (electrical resistivity, electromagnetic mapping and seismic refraction) on an excavated cell of the Ouled Fayet (Algiers, Algeria) pilot landfill indicated the presence of an underground runoff and permeable soil underneath the cell. These results contradict those obtained by a feasibility study, based, however, only on the analysis of seventy-six 10-m drilling cores. The 1D boreholes information has been proven to be insufficient and to give biased results. The presence of water at depth is evidenced by lower resistivity, high conductivity anomalies and increase of P-wave velocity. Thus, to the contrary of what is claimed in the feasibility study, a threat of leachate pollution is real. This study shows that landfill construction studies cannot give trustful results without geophysical investigations. More specifically, in Algeria, it is imperative to elaborate a landfill construction code, which should include mandatory geophysical prospecting and deeper drilling cores.  相似文献   

Erratum à la note Rôle de l&#x27;halocinèse dans l&#x27;évolution du bassin d&#x27;Essaouira (Sud-Ouest marocain) [C. R. Geoscience 336 (2004) 587–595]     

Khalid Mehdi  Roger Griboulard  Claude Bobier 《Comptes Rendus Geoscience》2005,337(9):880

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First Research on Marine and Nonmarine Sedimentary Sequences and Micropaleontologic Significance across Permian／Triassic Boundary in Iran （Isfahan and Abadeh）     

MehdiYazdi ManizhehShirani 《中国地质大学学报(英文版)》2002,13(2):T002-T006

Abundant ichthyoid remains, conodonts and holothurians sclerites were recovered near the Permian/Triassic boundary from a section south of Isfahan. Recovered ichthyoid remains include shark micro teeth and scales. The ichthyolith material is similar to a Fasanian ichthyolith from the Zakazane area in the Slovak karst of the Western Carpathians, which represents a subspecies of Acodina triassia. Conodont species are mostly neogondolellids. This fauna indicates that the sedimentary environment was marine, while to the north of localities near Isfahan and Zagross, terrestrial deposition was dominant at that time. Aluminasilicate and kaolin are present in a continental unit in Dopolan refractory main (Shahid Nilchian mine) and a section south of Chahriseh Village, north of Isfahan. Pisolitie, ironstone facies and bauxite clay are common near the Permian/Triassic boundary in the Chahriseh region.  相似文献   

Strong motion dataset of Turkey: data processing and site classification     

Mehdi Zar  Pierre-Yves Bard 《Soil Dynamics and Earthquake Engineering》2002,22(8)

Strong motion records of Turkey are studied in order to prepare a catalog to be used as a database for further studies (for instance empirical attenuation laws). The network started to be installed in 1973, and the first record was obtained in 1976. The instruments are of SMA-1 analog recorders and SIG SM-2 and GeoSys GSR-16 digital types. Out of a total of 426 records released on the web sites of the General Directorate of the Disaster Affairs and of Kandili Observatory, a set of 210 records was selected with a satisfactory quality, for which it was possible to associate correctly determined source parameters (source magnitudes and epicentral distances). Most of the records are obtained from around North and East Anatolian Fault zones, as well as from western and southwestern parts of Turkey. The main outcome of this paper is a strong motion catalog of Turkey, with the indication of site conditions, of the frequency band of the reliability of the records, peak values of acceleration, velocity and displacements, source parameters (magnitude, epicentral and macroseismic distances), intensity and finally the fault plane solutions whenever possible. The aim is to have, with other regional dataset, a homogenous and good quality dataset.  相似文献   

Inhomogeneous shearing related to rock composition: evidence from a major late-Panafrican shear zone in the Tuareg shield (Algeria)     

Bernard Henry  Mohamed E. M. Derder  Boualem Bayou  Mehdi A. Guemache  Omar Nouar  Aziouz Ouabadi  Hamou Djellit  Mohamed Amenna  Abderahmane Hemmi 《Swiss Journal of Geoscience》2008,101(2):453-464

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Dynamic Positioning System Design for A Marine Vessel with Unknown Dynamics Subject to External Disturbances Including Wave Effect     

Hosseinnajad  Alireza  Loueipour  Mehdi 《中国海洋工程》2020,34(5):651-663

China Ocean Engineering - In this paper, a new control system is proposed for dynamic positioning (DP) of marine vessels with unknown dynamics and subject to external disturbances. The control...  相似文献   

Composition and structure of species along altitude gradient in Moghan-Sabalan rangelands,Iran     

Sahar Ghafari  Ardavan Ghorbani  Mehdi Moameri  Raoof Mostafazadeh  Mahmood Bidarlord 《山地科学学报》2018,15(6):1209-1228

This study provides a checklist of species distributed at the altitude gradient of Moghan-Sabalan rangelands in Ardabili province, Northwest Iran. We evaluated the changes in species composition, growth types of species, Raunkiaer’s life forms, geographical distribution, threat and endemicity status, and palatability of species along two altitudinal gradients in the sampling plots, which were conducted in eleven sites/habitats with 300 meters above sea level (masl) altitude intervals (from 100 to 3300 masl). We assessed the plant species composition with special reference to the gradient analysis, and identified overall 396 species, which was comprising 44 families and 194 genera. Results showed that Asteraceae family is by far the most species-rich family, followed by Poaceae, Fabaceae, Caryophyllaceae and Brassicaceae. Among the genera, Astragalus is the most diverse genus, followed by Allium, Veronica and Bromus, Galium, Silene and Ranunculus. Results indicated that the number of species increased as the altitude increased to 1200–1500 masl, but then starts to decline to 3300 masl. Family-to-genera ratio was 1:4.4, the family-tospecies ratio was 1:9, and the genera-to-species ratio was 1:2.04. Growth type of species analysis shows that the frequency of perennial plants was higher in the study area followed by annual species while the lower group was biennial species. The number of annuals showed a decreasing trend towards higher altitude. Hemicryptophytes and therophytes were the most frequent life forms constituted each with (41.9%). Hemicryptophytes showed an increasing trend with altitude, while therophytes showed a decreasing trend with altitude increase, followed by geophytes, chamaephytes, and phanerophytes. Results showed more than half of the species of the study area belonged to Iran-Turanian region and these species showed an increasing trend with altitude. In contrast, Sahara-Sindian species comprise a minor component of the spectrum, with decreasing trend with altitude. The rare and endangered species out of the surveyed taxonomic groups comprised 53 species in total which 29 of them are considered lower risk (LR), 13 data deficient (DD), 5 vulnerable (Vu) and with 3 rare (R) and identified endemic plants comprised 24 species. Some 56.6% species were identified as class III, 22.6% were class I and 20.8% were class II as the palatability variation. Moghan-Sabalan rangelands require strong conservation management policies in case of species loss and changing natural communities due to the occurrence of conversion into cropland, over-grazing and other anthropogenic effects.  相似文献