43 research outputs found
Using the GPS Station to Study Wind and Coastal Morpho-dynamics in North-eastern Morocco
The purpose of this work is to evaluate the potential of Global Positioning System (GPS) measurements for the monitoring of aeolian and coastal dynamics. The studied sites are the Moulouya estuary, Bouarfaâs area and Tigri Chott. The study shows that GPS is used to determine the dune kinematics and the Moulouya estuary in 3-D with an annual temporal resolution and a sub-centimeter accuracy. The GPS measurements carried out between 2013 and 2021 have shown spatial and temporal variations of the dune kinematics and Moulouya estuary. The results presented here show that the GPS measurements have the capability of continuously surveying the geomorphological entitiesâ kinematics with small and slow displacements and thus, they could complement conventional topometric techniques in a warning system
Risque d'Ă©rosion hydrique entre fragilitĂ© des Ă©quilibres environnementaux et perspectives de durabilitĂ©: Cas du bassin dâOued El Abed (Maroc nord-est)
The objective of this work is to study water erosion phenomenon in El Abed watershed in North Eastern Morocco. With this in mind, we have analyzed the quantitative and qualitative information available on the one hand, and on the other hand, we have carried out field measurements by rain simulation (60 mm/h during 10 mn). Soil loss was estimated using the universal soil loss equation (USLE). The qualitative analysis based on the inventory of the various forms of water erosion showed a strong morphodynamic activity, characterized by diffuse and concentrated streaming, gullying and side extensions of valleys. The quantitative analysis of soil losses using USLE model made it possible to estimate that 4,7% of the watershed surface area are strongly eroded and that average specific degradation is estimated to be 6,4 t/ha/an. Measurements of rain simulation tests showed clear differences between the various land uses. Indeed, runoff coefficient is low on the vegetation covered plots of and the plots cultivated parallel to contour lines. On the other hand, runoff coefficient is high on steeply bare soils. The amount of detached soil varied from 0.014 t/ha for the covered plots to 2.9 t/ha for the steeply bare soils. It should be underlined that the extent of water erosion in El Abed watershed is due to its natural settings, but also to anthropic activities (cultivation and overgrazing).
Keywords: Water erosion, USLE, El Abed watershed, MoroccoL'Ă©rosion hydrique est lâun des risques inquiĂ©tants qui menacent le milieu physique et la stabilitĂ© humaine. Le bassin dâoued El Abed, est sujet Ă ce phĂ©nomĂšne depuis longtemps, ce qui a induit des mutations importantes et a touchĂ© divers domaines Ă©conomiques, sociaux et environnementaux. Ainsi, la problĂ©matique de cette Ă©tude est axĂ©e sur lâĂ©tude de lâĂ©rosion et son Ă©valuation dans ce bassin. Le bassin dâoued El Abed est situĂ© au sud-ouest de Taourirt, dans la partie ouest du couloir de Guercif-Oujda et comprend une partie de la plaine de Tafrata. Sa surface est de 317 kmÂČ Ă sa confluence avec oued Moulouya. Pour Ă©tudier l'Ă©rosion dans ce bassin, nous avons, dâune part analysĂ© les donnĂ©es quantitatives et qualitatives disponibles et, dâautre part, rĂ©alisĂ© des mesures sur le terrain par simulation de pluie (intensitĂ© de 60 mm/h durant 10 mn). L'estimation de la perte en sol a Ă©tĂ© faite en se basant sur l'Ă©quation universelle de perte en sol (USLE). L'inventaire des diverses manifestations et formes d'Ă©rosion hydrique dans le bassin de l'oued El-Abed montre clairement qu'il s'agit d'une forte activitĂ© morphodynamique caractĂ©risĂ©e par un ruissellement diffus et concentrĂ©, des ravinements, des extensions latĂ©rales des vallĂ©es. AprĂšs avoir calculĂ© les diffĂ©rents facteurs de lâUSLE, on a constatĂ© que 4,7% de la surface du bassin serait fortement Ă©rodĂ©e. La dĂ©gradation spĂ©cifique moyenne a Ă©tĂ© estimĂ©e Ă 6,4 tonnes/ha/an. Les mesures de simulation de pluie ont montrĂ© des diffĂ©rences nettes entre les utilisations des terres. En effet, les coefficients de ruissellement sont faibles dans les parcelles couvertes de vĂ©gĂ©tation et celles cultivĂ©es parallĂšlement aux courbes de niveau. Par contre, sur les sols nus et les pentes fortes, ce coefficient est Ă©levĂ©. Les quantitĂ©s de sols dĂ©tachĂ©es varient de 0,014 pour les parcelles couvertes Ă 2,9 t/ha pour celles nues et Ă forte pente. LâĂ©rosion dans le bassin dâEl Abed est due Ă sa fragilitĂ© naturelle mais surtout aux actions anthropiques (mise en culture, surpĂąturage).
Mots clĂ©s: Ărosion hydrique, USLE, Bassin dâoued El-Abed, Maroc nord-es
Study of the biomimetic oxidation reaction of phenols and diphenols by in situ prepared catalysts based on heterocycles and transition metals
The studies of the complexes reactivities of transition metals, as compound models to reproduce the catalytic activities of metalloenzymes, are particularly interesting for the development of bioinspired catalysts for oxidation reactions, in particular phenols oxidation in the air.In this manuscript, we estimated the potentialities of some complexes formed in situ to catalyse the oxidation reaction of catechols and phenols to corresponding o-quinones, with the aim of looking for good models to reproduce the catalytic activity of the enzymes « catĂ©cholase » and « tyrosinase » , in our works, we have used several types of ligands and various metallic salts as catalysts, the catalytic activity of the complexes formed in situ was estimated by UV-visible spectrophotometer by following the formation of the quinone according to time.To acheive our goal; we have studied the capacity of copper complexes formed in situ, in the oxidation of the catechol and phenol; and our research is concentrated on the use of the complexes arising from pyrazole, bidentate, benzyle, triazole, and schiff bases ligands and transition metals, and we noticed that all complexes catalyze the oxidation reaction of catechol, and some of them catalyzed the phenol oxidation to catechol, and oxidation of catechol to o-quinone at ambient conditions using the oxygen of atmosphere as oxidant. Our study indicates that the nature of ligand, the nature of the solvent, concentration of ligands, metallic salt, and nature of substrate, really affect on the catalytic activities of corresponding combinations.Finally, to illustrate the mechanism of the oxidation reaction of catechol and the relationship between the structure and the catalytic activity, we realized a theoretical study which allows us to form a quantitative structure - activity relationship QSAR.Les Ă©tudes des rĂ©activitĂ©s des complexes des mĂ©taux de transition , comme des composĂ©s modĂšles pour reproduire lâactivitĂ© catalytique des mĂ©talloenzymes, sont particuliĂšrement intĂ©ressantes pour le dĂ©veloppement de catalyseurs bioinspirĂ©s pour des rĂ©actions d'oxydation, en particulier lâoxydation Ă lâair des phĂ©nols.Dans ce manuscrit, Nous avons Ă©valuĂ© les potentialitĂ©s de certains complexes formĂ©s in-situ, pour catalyser la rĂ©action dâoxydation des catĂ©chols et des monophĂ©nols en o-quinones correspondants, dans le but de rechercher des bons modĂšles pour reproduire lâactivitĂ© catalytique de lâenzyme « catĂ©cholase » et lâenzyme « tyrosinase »; pour cela, nous avons focalisĂ© nos travaux sur lâutilisation de plusieurs types de ligands et des diffĂ©rents sels mĂ©talliques comme catalyseurs; lâactivitĂ© catalytique des complexes formĂ©s in-situ, a Ă©tĂ© Ă©valuĂ©e par spectrophotomĂ©trie UV-visible en suivant la formation de lâo-quinone en fonction du temps.Pour atteindre notre objectif, nous avons Ă©valuĂ© les propriĂ©tĂ©s catalytiques des complexes formĂ©s in-situ, pour la rĂ©action dâoxydation de la catĂ©chol et de phĂ©nol, et notre recherche est concentrĂ©e sur lâutilisation des complexes, formĂ©s in situ, par des dĂ©rivĂ©s de pyrazole, bases de Schiff benzylique ou triazolique, et des hĂ©tĂ©rocycles carbonylĂ©s avec des mĂ©taux de transition. Tous ces complexes ont montrĂ© une activitĂ© catalytique importante vis-Ă -vis lâoxydation de la catĂ©chol, et certains d'entre eux ont contribuĂ© Ă la catalyse dâoxydation de phĂ©nol en catĂ©chol, puis lâoxydation de ce dernier en o-quinone (activitĂ© tyrosinase), dans les conditions ambiantes, en utilisant lâoxygĂšne de lâair comme oxydant. Notre Ă©tude indique que la nature et la concentration de ligand et de substrat, la nature du solvant, et la nature du sel mĂ©tallique, affecte et influence l'efficacitĂ© et lâactivitĂ© catalytique de combinaisons correspondantes. Finalement, pour illustrer le mĂ©canisme de la rĂ©action dâoxydation de la catĂ©chol et la relation entre la structure et lâactivitĂ© catalytique, nous avons rĂ©alisĂ© une Ă©tude thĂ©orique qui nous permet dâĂ©tablir une relation quantitative entre la structure molĂ©culaire et lâactivitĂ© catalytique Ă lâaide de la mĂ©thode QSAR (quantitative structure â activity relationship)
Erosion hydrique et dynamique environnementale dans les bassins versants de Tlagh et El Abed (Maroc oriental). Approches géomatiques
Water erosion is one of the most natural hazards with obvious and detrimental damage to the surface of the land and a serious threat to the environmental balance, in particular in arid and semi-arid environments. It is also one of the important most challenges associated with basins and rural areas. Erosion leads to the transfer of solid materials to valleys, depressions and dams. The Taourirt-Guercif corridor has undergone significant spatial changes which have led to demographic challenges, environmental and spatial imbalances which have modified the characteristics of the geographical landscape. This is manifested by the dominance of forms of water erosion and the degradation of the vegetation. By addressing erosion quantitatively and qualitatively, the General Soil Loss Equation (USLE) showed that the average soil loss is 37.64 tonnes/ha/year for the Wadi Tlagh basin and 32.23 tonnes/ha/year for El-Abed wadi basin. It was also concluded through the PAP/RAC model that important areas recorded a high potential for erosion. Direct field measurements using a RAMP-type rain simulator showed that the average rate of sheet erosion in 37 experimental plots is 39.18 tonnes/ha/year. Topographic surveys to measure localized erosion, characteristic of some places, have shown that the average grubbing up in only three sites is 1349 tonnes/ha/year. The study of the hydrological behavior of several types of exploitation concluded that these surfaces have a different flow coefficient between them; and this difference can be useful for land use planning through the orientation of the exploitation modes. These measurements have shown the types of exploitation from which runoff can start quickly, and thus the farmer can be made aware of the modes of exploitation that can be followed to reduce the risk of erosion. The role of natural characteristics and spatial distribution in degradation aspects and in activating environmental dynamics has also been highlighted. The slope and orientation affect the nature of the runoff, and the drought contributes to the fragility of the land by preventing the natural growth of plants, thus becoming weak, more degraded and less intense. Faced with the degradation of this environmental space, the human factors activating this dynamic were diagnosed, and land use patterns as well as the role of state projects in the management of these resources were discussed. One of the results of this on environmental media is that changes in these exploitation methods have an impact and control degradation by accelerating its mechanisms. Given this situation of degraded areas threatened by continuous water erosion, and on the basis of the results obtained, it has become necessary to reconsider the forms of intervention in these fragile and paralyzed environments; and these precious resources that nature does not preserve by itself must be preserved by man giveb their fragility. Nature creates these ecological balances, but man helps break and violate them. âL'Ă©rosion hydrique est l'un des risques naturels les plus importants qui ont un impact Ă©vident sur la surface et menacent les Ă©quilibres environnementaux, en particulier dans les milieux arides et semi-arides, et c'est l'un des dĂ©fis les plus importants associĂ©s aux bassins et aux zones rurales. L'Ă©rosion hydrique conduit Ă l'Ă©rosion des sols et au transfert de matĂ©riaux solides vers les vallĂ©es, les dĂ©pressions et les barrages. Le couloir de Taourirt-Guercif a connu d'importantes mutations spatiales qui ont entraĂźnĂ© des dĂ©fis dĂ©mographiques et des dĂ©sĂ©quilibres environnementaux et spatiaux qui ont modifiĂ© les caractĂ©ristiques du paysage gĂ©ographique. Ceci se manifeste par la dominance des formes d'Ă©rosion hydrique et la dĂ©gradation du couvert vĂ©gĂ©tal. En abordant l'Ă©rosion quantitativement et qualitativement, l'Ă©quation gĂ©nĂ©rale de perte des sols (USLE) a montrĂ© que la perte moyenne de sol est de 37,64 tonnes/ha/an pour le bassin d'oued Tlagh et de 32,23 tonnes/ha/an pour le bassin d'oued El-Abed. Il a Ă©galement Ă©tĂ© conclu Ă travers le modĂšle PAP/CAR que des zones importantes ont enregistrĂ© un fort potentiel d'Ă©rosion. Des mesures directes sur le terrain Ă l'aide d'un simulateur de pluie de type RAMP ont montrĂ© que le taux moyen d'Ă©rosion en nappe dans 37 parcelles expĂ©rimentales est de 39,18 tonnes/ha/an. Les relevĂ©s topographiques pour mesurer l'Ă©rosion localisĂ©e, caractĂ©ristique de certains endroits, ont montrĂ© que l'arrachage moyen dans seulement trois sites est de 1349 tonnes/ha/an. L'Ă©tude du comportement hydrologique de plusieurs types d'exploitation a conclu que ces surfaces ont un coefficient d'Ă©coulement diffĂ©rent entre elles, et cette diffĂ©rence peut ĂȘtre utile pour lâamĂ©nagement du territoire Ă travers l'orientation des modes d'exploitation. Ces mesures ont montrĂ© les types d'exploitation Ă partir desquels le ruissellement peut dĂ©buter rapidement, et ainsi l'agriculteur peut ĂȘtre sensibilisĂ© aux modes d'exploitation qui peuvent ĂȘtre suivis pour rĂ©duire le risque d'Ă©rosion. Le rĂŽle des caractĂ©ristiques naturelles et de la rĂ©partition spatiale dans les aspects de dĂ©gradation et dans l'activation de la dynamique environnementale a Ă©galement Ă©tĂ© mis en Ă©vidence.La pente et l'orientation affectent la nature du ruissellement, et la sĂ©cheresse contribue Ă la fragilitĂ© du terrain en empĂȘchant la croissance naturelle des plantes, devenant ainsi faibles, plus dĂ©gradĂ©es et moins intense. Face Ă la dĂ©gradation de ce milieu environnemental, les facteurs humains activant cette dynamique ont Ă©tĂ© diagnostiquĂ©s, et les modes d'occupation des sols et le rĂŽle des projets de lâEtat dans la gestion de ces ressources ont Ă©tĂ© discutĂ©s. L'un des rĂ©sultats de ceci sur les milieux environnementaux est que les Ă©volutions de ces modes dâexploitation ont un impact et contrĂŽlent la dĂ©gradation en accĂ©lĂ©rant ses mĂ©canismes. Face Ă cette situation dominĂ©e par des zones dĂ©gradĂ©es menacĂ©es par l'Ă©rosion hydrique continue, et sur la base des rĂ©sultats obtenus, il est devenu nĂ©cessaire de reconsidĂ©rer les formes d'intervention dans ces milieux fragiles et paralysĂ©s, et ces prĂ©cieuses ressources que la nature ne conserve pas d'elle-mĂȘme doivent ĂȘtre prĂ©servĂ©es si l'homme n'a pas conscience de leur fragilitĂ©. La nature crĂ©e ces Ă©quilibres Ă©cologiques, mais l'homme en vient Ă opposer son veto et Ă les violer
Five naphthalene azo benzene ligands complexed with copper metals: An excellent in-situ catecholase catalyst
Catechol oxidase and Copper(I/II) Complexes Derived from Bipyrazol Ligand: Synthesis, Molecular Structure Investigation of New Biomimetic Functional Model and Mechanistic Study
Apport du GPS dans l'étude de la dynamique des dunes : exemples au Maroc oriental
The aim of this study is to add to the results already obtained in eastern Morocco, in the Bouarfa - Chott Tigri area, on the potential of GPS (Global Positioning System) to follow the movement of dunes. The measurements, carried out once a year from 2013 to 2023, were used to determine changes in four small dunes: movement in different directions, extension or retraction, fattening or degradation. The results obtained demonstrate the value of GPS as well as its limitations for studies of this type.Traduction réalisée par Deep