Etude De La Vulnerabilite Aux Risques D’inondations Dans La Ville De Meknes. Apport Des Sig, Du Mnt Et Des Modeles Empiriques

The present study aims to assess, identify and map the risk of flooding urban in the aim of protecting the city of Meknes (center of northern Morocco) from the flooding of the Oued Boufekrane which runs along the city from the south to the north. It is carried out using the tools modeling, of empirical formulae and functions integrated into the software dedicated to the systems of Geographic Information System (GIS) and by exploiting the climate data, hydrological, topographical, geological, etc. The slopes of the watershed of the Oued Boufekrane vary approximately between 1 and 19%. They allow determining the areas and neighborhoods vulnerable to the risk of flooding with slopes not exceeding the 6%. The vulnerability to the risk of flooding which requires a priority intervention affects mainly the neighborhoods located in the southwest of the agglomeration of Meknes and along the valley of the Oued Boufekrane

Apport des isotopes de la molécule d'eau à la détermination de l'altitude de recharge des principales sources du Moyen Atlas calcaire (Maroc).

International audienceLa présente étude est menée au Maroc sur le Moyen Atlas calcaire à caractère karstique. Son objectif est de contribuer à la caractérisation des aquifères moyens atlasique et à la détermination des altitudes de recharge des principales sources issues des calcaires dolomitiques liasiques afin d'aider à la détermination de leurs zones d'alimentation pour leur protection. La méthodologie utilisée est basée sur l'utilisation des isotopes stables de la molécule d'eau. La caractérisation chimique des eaux de ces sources montre que leur composition est le reflet de celle des roches-réservoirs qu'elles drainent d'une part et de l'évolution qu'elles subissent au cours de leur transit au sein de ces réservoirs d'autre part. L'analyse de l'évolution du deutérium en fonction de l'oxygène 18 permet de tracer une droite locale similaire à celle des pluies analysées au sein de la station de Fès, ce qui montre que les aquifères concernés se rechargent par une infiltration rapide, sans évaporation notable des eaux de pluie. Le gradient altimétrique pour l'oxygène 18 est établi à -0.27‰ par 100m. L'application de ce gradient aux teneurs isotopiques des autres sources analysées permet de remonter aux altitudes de recharge de ces sources. La confrontation de ces résultats aux données hydrogéologiques locales et régionales montre une concordance notable pour les sources dont les bassins versants étaient connus, et une orientation précieuse pour les sources dont les bassins étaient mal connus, avec des altitudes de recharge qui peuvent être 1090m plus élevées que les zones d'émergence. Ces résultats aident d'une manière certaine à déterminer les zones de recharge des sources, et donc à définir une stratégie de protection de cette ressource. The present study contributes to the characterisation of Middle Atlas limestone karst aquifers by implementing water stable isotopic techniques to determine the recharge altitudes of major springs issuing from Liassic dolomitic limestone, helping to delineate protection areas for the springs. Chemical analyses of spring waters show a composition that reflects both reservoir lithology and a chemical evolution over the course of flow within the reservoir. Analysis of the evolution of deuterium as a function of oxygen-18 suggests a local water line similar to that derived for rainwater at a station in Fez, indicating that the aquifers in question are recharged through rapid infiltration, without appreciable evaporation of the rainwater. Application of the established -0.27‰ per 100m altimetric gradient for oxygen 18 to the isotopic signatures of other analyzed sources allows us to backtrack recharge altitudes for these springs. Comparison of these results with local and regional hydrogeologic data shows a notable agreement among springs for which the drainage basin is known, and allows for more precise localization of springs for which the drainage basin is poorly known, with recharge altitudes reaching 1090m higher than emergence zones. To a certain extent, these results help to determine recharge zones for Middle Atlas springs and thus aid in strategizing protection for this resource

Utilisation Des Indices De Qualité Et De Pollution Organique Dans L’évaluation De La Qualité PhysicoChimique Des Eaux Superficielles Des Oueds Moulouya et Ansegmir (Haute Moulouya, NE Du Maroc)

Surface water is subject to strong anthropogenic pressures caused by the development and extension of agricultural activities and also by industrial and domestic activities. Pollution is a serious problem for the environment due to discharges dumped into rivers and excessive use of agricultural fertilizers and discharges from urban and industrial sources. The objective of this study is to assess the quality and state of organic pollution in surface water in Upper Moulouya based on the water quality index (WQI) and the organic pollution index (IPO) during three sampling campaigns carried out between March and August of 2014. Ten stations were studied along the Moulouya and Ansegmir wadis up to the Hassan II dam. The results are visualized through the use of GIS through the production of thematic maps. They revealed that the majority of stations indicate excellent water quality and show no organic pollution with the exception of Boumia (M5) and Zaida (M6) stations which respectively have poor quality water and low pollution. at Boumia and non-drinking water with strong organic pollution at Zaida. This anthropogenic environmental degradation recorded downstream of the two urban communes would come from the use of nitrogen and phosphate agricultural fertilizers and above all from the discharge of untreated domestic and industrial wastewater from these two communes. The seasonal variation remains discreet and reflects a slight tendency towards degradation of the waters of the Upper Moulouya during the low waters of the summer period Les eaux superficielles sont soumises à de fortes pressions anthropiques suscitées par le développement et l’extension des activités agricoles et également par les activités industrielles et domestiques. La pollution est un grand problème pour l’environnement en raison des rejets déversés dans les rivières et de l’utilisation excessive des fertilisants agricoles et des rejets d’origine urbaine et industrielle. L’objectif de cette étude est d’évaluer la qualité et l'état de la pollution organique des eaux superficielles la Haut Moulouya en se basant sur l’indice de qualité de l’eau (IQE) et l’indice de pollution organique (IPO) durant trois campagnes de prélèvement effectuées  entre les mois de mars et août de l’année 2014. Dix stations ont été étudiées le entre les mois de mars et août de l’année 2014. Dix stations ont été étudiées le long des oueds Moulouya et Ansegmir jusqu’à l’amont du barrage Hassan II. Les résultats sont visualisés par l’utilisation des SIG via la réalisation de cartes thématiques. Ils ont révélé que la majorité des stations indiquent une excellente qualité d’eau et ne présentent aucune pollution organique à l’exception des stations de Boumia (M5) et de Zaida (M6) qui présentent respectivement des eaux de mauvaise qualité et une faible pollution au niveau de Boumia et des eaux non potables avec forte pollution organique au niveau de Zaida. Cette dégradation environnementale anthropique enregistrée en aval des deux communes urbaines proviendrait de l’utilisation d'engrais agricoles azotés et phosphatés et surtout des rejets d’eaux usées domestiques et industrielles non traitées de ces deux communes. La variation saisonnière reste discrète et traduit une légère tendance à la dégradation des eaux de la Haute Moulouya pendant les basses eaux de la période estivale

Contexto tectónico de los diapiros triásicos del frente de deformación de la cordillera del Rif, Norte de Marruecos

Located at the front of the external Pre-Rif, northern Morocco, at the edge between the Rif cordillera and the Saiss neogen basin, Triassic diapirs constitute one of the main features of this area, occurring within the Meso-Cenozoic allochthonous formations. In order to understand their geological setting and evolution during the Meso-Cenozoic times, we carry out a geological study based on structural analysis and fracturing field investigations. The obtained results are completed by previous geophysical and seismic works. The rising salt bodies (halite, anhydrite and gypsum) in those diapirs was controlled by the two NW-SE and NE-SW system faults from the Mesozoic to the Quaternary. The contacts between the Triassic material and the Miocene sedimentary marls are discussed. Some mapped tectonic contacts, considered as thrusting faults are in fact stratigraphic limits, which are characterized by polygenic conglomerates. These arguments allow us to review the whole history of these salt walls and to discuss their current geometryLa zona de estudio se ubica en el frente del Pre-Rif externo (norte de Marruecos), en el límite entre la cordillera del Rif y la cuenca neógena del Saiss, y se caracteriza por presentar diapiros triásicos dentro de las formaciones alóctonas Meso-cenozoicas. Para comprender su contexto geológico y su evolución durante el Meso-Cenozoico, realizamos un análisis estructural basado en medidas de fracturación en los materiales que rodean estos diapiros. Los resultados obtenidos se completan con trabajos geofísicos y sísmicos previos. El ascenso de material diapírico (halita, anhidrita y yeso Triásicos) fuo controlado por un sistema de fallas de dirección NW-SE y NE-SW desde el Mesozoico al Cuaternario. El análisis de los contactos entre el material del Triásico y las margas sedimentarias del Mioceno ha revelado que algunos de los contactos tectónicos cartografiados como fallas son en realidad límites estratigráficos caracterizados por conglomerados poligénicos. Este trabajo supone una revisión de la evolución de estos diapiros y un análisis de su geometría actua

Diachronic mapping and evaluation of soil erosion rates using RUSLE in the Bouregreg River Watershed, Morocco

Soil erosion has been severely affecting soil and water resources in semi-arid areas like the Mediterranean. In Morocco, this natural process is accelerated by anthropogenic activities, such as unsustainable soil management, overgrazing, and deforestation. With a drainage area of 395,600 ha, the Bouregreg River Watershed extends from the Middle Atlas Range (Jebel Mtourzgane) to the Sidi Mohamed Ben Abdellah (SMBA) dam reservoir south-east of Rabat. Its contrasted eco-geomorphological landscapes make it susceptible to unprecedented soil erosion due to climate change. Resulting changes in erosive dynamics led to huge amounts of solid loads transported to the catchment outlet and, thus, jeopardised the SMBA dam lifespan due to siltation. The research aims to quantify the average annual soil losses in this watershed using the Revised Universal Equation of Soil Losses (RUSLE) within a GIS environment. To highlight shifts in land use/land cover patterns and their effects on erosional severity, we have resorted to remote sensing through two Landsat 8 satellite images captured in 2004 and 2019. The C factor was combined with readily available local data regarding major erosion factors, e.g. rainfall aggressiveness (R), soil erodibility (K), topography (LS), and conservation practices (P). The helped to map the erosion hazard and determine erosion prone areas within the watershed where appropriate water and conservation measures are to be considered. Accordingly, from 2004 to 2019, average annual soil losses increased from 11.78 to 18.38 t∙ha-1∙y-1, as the watershed area affected by strong erosion (>30 t∙ha-1∙y-1) evolved from 13.57 to 39.39%

Groundwater potential of Middle Atlas plateaus, Morocco, using fuzzy logic approach, GIS and remote sensing

Groundwater is a most important resource in arid and semi-arid regions and is required for drinking, irrigation and industrialization. Assessing the potential zone of groundwater recharge is extremely crucial for the protection of water quality and the management of groundwater systems. To identify the groundwater potential zone in the study area, thematic layers of lithology, slope, karst degrees, land cover, lineament and drainage density were generated using topographic maps, thematic maps, field data and satellite image, and were prepared, classified, weighted and integrated in a geographic information system (GIS) environment by the means of fuzzy logic. The fuzzy membership values have been assigned to different thematic layers according to their classification on respect for their contribution and their occurrence in groundwater. Based on the generated groundwater potential map, it was found that about 8% of the investigation area was categorized as very high potential for groundwater recharge, 31% as high, 28% as moderate, 17% as low and 16% as very low potential for groundwater recharge. Finally, the results were verified using well-yield data. The highest recharge potential area is located towards the downstream regions related to more fractured and karstified limestone

Groundwater Hydrochemical and Isotopic Evolution from High Atlas Jurassic Limestones to Errachidia Cretaceous Basin (Southeastern Morocco)

International audienceThe objective of this research was to determine the recharge of the Cretaceous aquifers by the High Atlas, as well as the interaction and possible mixing phenomena between the waters of the different aquifers, by investigating the hydrochemical and isotopic evolution of groundwater flow paths from the limestone karst systems of the High Atlas to the Cretaceous basin of Errachidia. Geological techniques were used to investigate and confirm the chemical and isotopic characteristics of the waters. Although the Gibbs diagram shows that water–rock interaction is the dominant hydrochemical process, some water samples in the Cretaceous basin are influenced by both evaporation and water–rock interaction, indicating a mixture of rainfall and deep waters. A saturation index study indicated that limestone minerals were supersaturated in parts of the groundwater samples (calcite and dolomite). This result was confirmed by isotope data. Indeed, some Cretaceous basin samples show isotopic similarities to those from the Jurassic High Atlas. The geological cross-sections illustrate that the High Atlas Jurassic limestones are in direct contact with the Cretaceous basin’s permeable rocks, allowing groundwater to circulate from the High Atlas to Errachidia’s Cretaceous basin

Assessment of the risk of soil erosion using RUSLE method and SWAT model at the M’dez Watershed, Middle Atlas, Morocco

The preservation of soil resources is a primary global concern and a permanent challenge for all Mediterranean countries. In Morocco, the capacity of dam reservoirs continues to decline from one year to the next due to the rate of siltation, mainly due to the phenomenon of water erosion. Indeed, the origins of this erosion are generally related to land use planning, deforestation, agricultural practices and low vegetation cover. However, it is imperative to quantify soil erosion and its spatial distribution to achieve sustainable land use and governance of this resource. The SWAT hydro-agricultural model and the integrated RUSLE model were used to assess soil losses and characterize the degraded areas of the M’dez watershed, located in the upper Sebou, north of the Middle Atlas, and extend on an area of 3350 km2. The results obtained during this work show that the average soil losses estimated by the two models are consistent. For the SWAT model, the specific degradation of the watershed is estimated at 3.95 t/ha/year, whereas for the RUSLE model, the average loss of the basin is estimated at 2.94 t/ha/year). However, the use of these two models (SWAT and RUSLE), for the assessment and characterization of degraded areas at the level of Moroccan watersheds, has become a much sought-after approach for good soil conservation management

Application de la méthode DRASTIC à l'étude de la vulnérabilité à la pollution des aquifères dans la zone côtière d'Essaouira (Essaouira, Maroc)

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Application de la méthode DRASTIC à l'étude de la vulnérabilité à la pollution des aquifères dans la zone côtière d'Essaouira (Essaouira, Maroc)

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