Etude Mineralogique Des Fractions Sableuse Et Argileuse Du Remplissage Du Gisement De Montgaudier, Charente, France

The mineralogical investigation of sand fraction of different sectors of filling of Montgaudier deposit revealed that heavy minerals are mainly composed of amphiboles and disthene in all analyzed samples. The other mineralogical species encountered appear having only a secondary role in the composition of heavy mineral processions. These minerals are: Andalusite, brookite, chlorite, epidote, garnet, pyroxene, rutile, sillimanite and sphene. The opaque minerals are relatively numerous in all the studied samples which they are in different stages of alteration, associated with other minerals presenting a fresh appearance. The light minerals consist mainly of hyaline or translucent quartz grains and milky or opalescent grains. The study of clay minerals generally showed a predominance of kaolinite in all sectors, followed by illite and chlorite. Smectite comes in only fourth place. This cortege is complemented by interstratified smectite-chlorite, which are very poorly represented. The mineralogical study of the deposits at the different parts of the layers filling of the Montgaudier deposit and the sediments in the immediate vicinity permitted to determine the origin of these deposits. Their procession is largely influenced by the geological nature of the Tardoire watershed but also of the mineralogical composition of the surrounding rock in which this cave was

Etude Sedimentologique Et Stratigraphique Du Remplissage Du Grand Porche Du Gisement De Montgaudier, Charente, France

The sedimentological study of the deposits accumulated at the level of the two sectors of the Grand Porche of Montgaudier allowed establishing a stratigraphic synthesis of the deposits in this part of the filling of this deposit and the paleoclimatic conditions of the establishment of the different types of sediments. The systematic analyzes carried out on samples taken from the two sectors I and II revealed their origins: allochthonous and autochthonous. The data from these sedimentological analyzes of this filling also revealed the conditions and the factors which led to the establishment of these deposits. Finally, these stratigraphic studies allowed establishing a chronological framework relative to the chronology of the deposits of the adjacent loci, 8 and 6, attributed to the old würm and the Riss-würm

Cartographie De L’erosion Qualitative Des Sols Du Bassin Versant De L’aoudour (Rif-Maroc)

The Aoudour watershed located in the northwest of Morocco and spreads over an area of approximately 1000 km2, and occupying the northeastern part of the Ouergha basin contently experiencing the effects of severe water erosion caused by the interaction of several natural factors such as the amount and aggressiveness of rainfall, plenty of steep slopes, low vegetation density and also the dominance of friable land. The Aoudour watershed also undergoes a human action that makes it very vulnerable to environment erosion, the degradation of the vegetation cover in recent decades and also by poor farming techniques. PAP / RAC is a method of qualitative study of water erosion that can prioritize the surface of a watershed in separate units according to its vulnerability to erosion. The method consists of a descriptive and predictive mapping in relation to the identification; evaluation and integration of basic physical factors such as slope, lithology and / or soils and vegetation cover, with the aim of establish initial assumptions about the risk of erosion. The use of remote sensing and GIS tools enabled us creating and overlying of thematic maps, executing speedily the cartographic works and, processing of databases

Etude Géotechnique Des Sols Compressibles : Caractérisation, Mécanisme Et Recommandation (Cas Des Régions De Berrechid Et Kenitra, Maroc)

Les constructions sur sols compressibles causent des dommages importants (stabilité, tassement, déformation, etc.) à court et à long terme partout dans le monde. Au Maroc, les zones dont les sols montrent une forte compressibilité correspondent le plus souvent à des plaines côtières récentes, comme celle de Berrechid et celle de Gharb. Les essais géotechniques réalisés au laboratoire permettent d’identifier et de savoir le comportement mécanique des sols étudiés. Parmi les tests effectués dans le cadre de ce travail : l’analyse granulométrique, le test par le bleu de méthylène, les essais des limites d’Atterberg et les essais œdométriques. D’après les résultats des essais d’identification, les deux sols sont de nature limono-argileuse dont la fraction argileuse correspond à une kaolinite, avec une granulométrie inférieure à 80 µm, une valeur de bleu de méthylène entre 1,5 et 2,5 ; et un indice de plasticité (IP) d’une valeur de 7 pour le sol de Berrechid et de 24 pour le sol du Gharb. Les coefficients de compressibilité, obtenus grâce aux essais œdométriques, indiquent que les sols de Berrechid sont moyennement compressibles avec Cc = 0,156, et les sols du Gharb sont assez fortement compressibles avec Cc = 0,252. Le choix de solution d’amélioration des sols vient après l’interprétation des résultats des essais. Dans notre cas, le renforcement recommandé, afin de corriger les problèmes de déformation et de tassement, est de réaliser des colonnes ballastés et des inclusions rigides ; tout dépend du type d’ouvrage élevé sur ces sols compressibles. Constructions on compressible soils cause significant damage (stability, compaction, deformation) in the short and long term in the world. In Morocco, the areas whose soils show high compressibility correspond most often to recent coastal plains, like that of Berrechid and that of Gharb. Geotechnical tests carried out in the laboratory allow to identify and know the mechanical behavior of the studied soils. Among the tests carried out in the context of this work: particle size analysis, the methylene blue test, the Atterberg limit tests and the oedometric tests. According to the results of identification tests, both soils are silty-clay nature, the clay fraction corresponds to a kaolinite, with a granulometry less than 80 µm, a methylene bleu value between 1,5 and 2,5 ; and a plasticity index (PI) of a value of 7 for Berrechid’s soil and 24 for Gharb’s soil. The compressibility coefficients, obtained by the odometric tests, indicate that Berrechid’s soils are moderately compressible with Cc = 0.156, and the Gharb’s soils are quite highly compressibles with Cc = 0.252. The choice of the soil improvement solution comes after the interpretation of the test results. In our case, the reinforcement recommended in ordre to correct the problems of deformation and compaction, is to make ballasted columns and rigid inclusions ; it all depends on the type of structure raised on these compressible soils

Etude Sedimentologique Et Stratigraphique Du Remplissage Du Premier Etage Du Gisement De Montgaudier, Charente, France

The study of the deposits accumulated over time in the first stage of the Montgaudier site, at the level of the two sectors, confirmed that these sediments were non-native and were put in place by runoff. Concretion processes have transformed the sandy sediments from the western part of this filling into a sandy bank. The detailed granulometric analyzes of these deposits have made it possible to establish the palaeoclimatic factors, rather temperate and humid, which presided over them. These factors were defined by the shiny bluntness of the quartz grains of these sediments. Finally, the sediment stratigraphy of the two sectors and their correlation with the deposits of the Gaudry shelter allowed the establishment of a relative chronology of this filling

Modélisation hydraulique du système Sebou-Fouarat, ville de Kenitra, Maroc - Cas des inondations de 2010

The city of Kenitra, located in the extreme downstream of the Sebou basin, is threatened by floods caused by the overflowing of the Oued Sebou and the rise of Oued Fouarat. The hydraulic modeling study of the Sebou Fouarat system in transient mode is carried out by the HEC-RAS software and has implicated the two rivers. Two geometric models were constructed on the basis of a digital terrain model (DTM) using the Arc-GIS and HECGeoRAS softwares after processing the collected topographic data. The first model, of which the areas of Merja Fouarat and Al Assam have been represented by cross-section, is one-dimensional. The second one is also onedimensional in which the two areas of Merja Fouarat and Al Assam are introduced as water storage zones. The components of these models are the stream sections, lateral links, storage areas and junctions between the branches of each model. The flood hydrographs of the Sebou and Fouarat rivers are introduced as conditions at the upstream limits of the models while the tidal is introduced as a downstream condition. After the stability and calibration of the models, the results of the consulted hydraulic simulations are the variations of the water levels as well as the temporal variations of the flow rates for each section, the maximum flow velocities and the propagation times of the flood waves. The analysis and comparisons of these results strongly suggest using the second model for the treatment of the flood issues as a decision-making tool helping to manage floods during times of crisis

Apport De La Stratigraphie Sequentielle Dans L’evolution Jurassique Du Moyen Atlas Central (Maroc)

The Jurassic evolution of the central Middle Atlas is governed by various factors (climate and eustatism). The use of the concepts of sequential stratigraphy in the regions of Tagnamas and Boulemane allowed to interpret the geometry and the vertical sequence of sedimentary sets. Twelve sequences are identified and delimited by sedimentary discontinuities. The lithostratigraphic division adopted in this study is synchronous with the coastal aggradation charter of Haq & al. (1987 & 1988) and Rioult & al. (1991). The correlations on a regional scale, between different Jurassic lithostratigraphic units is possible, whose the major factors controlling the evolution of intraplate basins are climate and eustatism

INTEGRATION OF GIS AND HEC-RAS IN FLOODS MODELING OF THE OUERGHA RIVER, NORTHERN MOROCCO

In recent years, hydrological hazards continue to worsen due to climate changes affecting the whole world. In Morocco, after a long period of severe drought that has ravaged the country since the eighties, the last years were exceptionally rainy. Records have been exceeded in terms of rainfall and flooding that affected many parts of the country. The Ouergha River, contributing with 50% of total water yield of the Sebou basin which is one of the most important watersheds in Northern Morocco, broke all records in 2009/2010 providing an exceptional amount of water of 7,4 109 m3. In this study, one-dimensional hydraulic modeling with HEC-RAS®, allowed to calculate the water flow profiles for some flood events that occurred downstream of Al Wahda dam. The exploitation of obtained results led to establish flood extension maps for each calculated profile, which made it possible to evaluate the management of the dam by the Sebou hydraulic Basin Agency. This type of results acquired from the hydraulic simulation and geographic information system, can significantly contribute in flood management interventions against overflows that persist despite the existence of a large dam (Al Wahda), because of extreme climatic and hydrologic events observed in recent years

Etude Sédimentologique Et Stratigraphique Des Dépôts Des Abris GAUDRY Et LARTET Du Gisement De Montgaudier, Charente, France

The sedimentological and stratigraphic study of the two shelters: Gaudry and Lartet of the Montgaudier deposit made it possible to characterize the large sedimentary assemblages and to describe within each of the discontinuities revealed by the granulometric characteristics that have subdivided them into distinct layers. Moreover, the detailed sedimentological analyzes of these two shelters have led to the conclusion that the sediments are deposited under the cold climatic conditions alternated by the temperate episodes. On the other hand, the stratigraphic lithostratigraphic arguments allowed us to establish a stratigraphic relationship between the two shelters. From a chronological point of view, the deposits of the shelter Lartet appear to a Mousterian Charentian type contemporary to the old würm. As for the Gaudry shelter, layers 1 and 2 are contemporary with Magdalenian and layer 5 is attributed to the aurignacian. This is confirmed by an absolute date

Landslide susceptibility mapping using GIS Matrix Method and Frequency Ratio, application in the marly context of Moulay Yacoub Region, Morocco

In the recent decades, the growth of population, man-made facilities, infrastructures, and lifelines at the expense of landslides-prone areas has been responsible for an exponential increase in human and economic losses in many parts of the world. In the Moulay Yacoub region, where marly hills dominate, the interaction of the semi-urban and rural socioeconomic development and landslides significantly increases, which urges identifying and prioritizing areas of risk in order to maximize harm reduction and to avoid the disastrous outcomes as is the case of Moulay Yacoub town. This paper aims to develop a landslide susceptibility map in a highly affected sector of the province, where no previous landslide data have been produced, and to find the most predisposing parameters. This goal is attained using two robust methods for landslide susceptibility mapping, the Frequency Ratio and the GIS Matrix Method. Before that, the correlation of 11 predisposing factors was tested. The results show that the anthropogenic factors, particularly the agricultural practices, were highly involved, and the field investigations proved that cereal farming slopes are the most affected. The success rate was about 0.75 (75%) for both models showing good quality results for the two susceptibility maps. Therefore, the two models could be efficiently used, and the new agricultural projects located in landslide-prone areas of the province must include such reliable methods of landslide hazard analysis to minimize the risk, which would put human lives, ecosystems, food production, and infrastructure in threat