Mohamed Maanan - Academia.edu (original) (raw)

Papers by Mohamed Maanan

Dans le cadre des travaux menes par l'OR2C sur l'histoire des risques en Pays-de-la-Loire... more Dans le cadre des travaux menes par l'OR2C sur l'histoire des risques en Pays-de-la-Loire, le laboratoire LETG mene des analyses sedimentologiques pour detecter les tempetes passees. L'une d'entre elles, datee du 16 Novembre 1940, a laisse une marque importante dans les Traicts du Croisic ou des prelevements de terrain ont ete effectues. La concomitance entre parametres meteorologiques et oceanologiques intenses a provoque des submersions marines dans les zones basses cotieres, expliquant les depots marins detectes dans la lagune. Les impacts socio-economiques revelent que cet evenement a egalement marque les populations littorales de l'epoque.

E3S Web of Conferences, 2021

This study analyses the seasonal distribution in the superficial sediments of the Marchica waters... more This study analyses the seasonal distribution in the superficial sediments of the Marchica watershed of trace and major elements, grain size, and total organic carbon. Samples were taken during the wet and dry seasons of 2018 in the mainstream valleys carrying the discharges to the Marchica Lagoon. Ecotoxicological indices (Enrichment Factor, Contamination Factor, Pollution-Load Index) and sedimen-quality guidelines were used to evaluate the ecotoxicological risk. The results revealed during both wet and dry seasons contamination by lead in all stream valleys. The northwest stream valley, characterized by some industrial activities, and the stream valley crossing the abandoned mine were the most polluted by zinc and copper. Minimal pollution for Cr, Co, and Ba was found during both the wet and dry seasons. Despite the restoration actions achieved around the Ramsar site of Marchica lagoon during the last decades, the watershed continues to have a negative impact on this ecosystem. Th...

Diversity, 2021

Marchica Lagoon, a Ramsar site on the Mediterranean coast of Morocco, is experiencing the impacts... more Marchica Lagoon, a Ramsar site on the Mediterranean coast of Morocco, is experiencing the impacts of watershed pollution, which includes pollutants from the domestic, agricultural, industrial, and mining sectors. Restoration actions were undertaken around this lagoon during the last decade in order to protect its ecological value and to develop tourist activity. To conserve the biodiversity in the lagoon, it is important to assess the environmental state of this ecosystem. This study aims to evaluate the ecotoxicological state of sediments through the post restoration characterization of the trace elements Pb, Cu, Zn, Cr, Co, and Ba, as well as their correlation to the major elements, grain size, and total organic carbon, sampled during two campaigns (the wet and dry seasons of 2018) across a sampling network of thirteen stations. Multivariate analysis and ecotoxicological risk assessment of the trace elements using the sediment quality guidelines and five pollution indices (geoaccu...

ISPRS International Journal of Geo-Information, 2021

The dwarf eelgrass Zostera noltei Hornemann (Z. noltei) is the most dominant seagrass in semi-enc... more The dwarf eelgrass Zostera noltei Hornemann (Z. noltei) is the most dominant seagrass in semi-enclosed coastal systems of the Atlantic coast of Morocco. The species is experiencing a worldwide decline and monitoring the extent of its meadows would be a useful approach to estimate the impacts of natural and anthropogenic stressors. Here, we aimed to map the Z. noltei meadows in the Merja Zerga coastal lagoon (Atlantic coast of Morocco) using remote sensing. We used a random forest algorithm combined with field data to classify a SPOT 7 satellite image. Despite the difficulties related to the non-synchronization of the satellite images with the high tide coefficient, our results revealed, with an accuracy of 95%, that dwarf eelgrass beds can be discriminated successfully from other habitats in the lagoon. The estimated area was 160.76 ha when considering mixed beds (Z. noltei-associated macroalgae). The use of SPOT 7 satellite images seems to be satisfactory for long-term monitoring o...

Land degradation is a problem that increasingly affects large areas of territories and affects va... more Land degradation is a problem that increasingly affects large areas of territories and affects various ecosystem services provided by coastal wetlands. These marine ecosystems provide valuable benefits to the environment and to humans, including services such as coastal blue carbon sequestration (CBCS) the economic value of which is still poorly understood. This paper investigated land use/cover (LULC) changes in Moulay Bousselham lagoon (MBL) from 1971 to 2020 and their effects on CBCS variation. The transformation of LULC and their cumulative conversions in coastal wetlands were studied during the 1971-2010 and 2010-2020 periods based on LULC data. Then the InVEST model was used to quantify the carbon storage provided by coastal ecosystems in response to LULC changes. The results show that the overall area of strictly wetland habitats in the MBL has decreased by 8.83% since 1971. There were 94 types of LULC transformation over 1971-2020, with significant wetland losses marked by t...

Human and Ecological Risk Assessment: An International Journal, 2017

ABSTRACT The Oualidia lagoon provides important ecosystem services, such as fishing, aquaculture,... more ABSTRACT The Oualidia lagoon provides important ecosystem services, such as fishing, aquaculture, tourism and high biological and ecological productivity. Many indices have been developed to evaluate environmental risks and to estimate the anthropogenic contribution of potentially toxic elements (PTE) in surficial sediments. The results show that the concentrations of the PTE found in surface sediments due to the anthropogenic activities in the area (urban effluents, aquaculture and agricultural areas) are significantly higher than those from the local background and sediment quality guidelines (SQGs). The potential ecological and biological risk index present satisfactory results. However, the sites near to the areas where anthropogenic activities are developed present 49% probability of toxicity, while the rest of the lagoon, present 9% to 21% probability of toxicity and low potential ecological risk, except for Hg where the risk was considered to be considerable. The PTE are mainly originated from the anthropogenic activities; nevertheless, anthropogenic contributions represent up to 69% of the total sediment of content, but it depends on the PTE: Cd (16%), Ni (38%), Zn (41%), Cr (43%), Cu (56%), Hg (68%), Pb (69%). Compared with the Sub-basin soils, the PTE are higher than 80%, hence the sub-basin feeds the lagoon by these elements (PTE).

Journal for Nature Conservation, 2018

The natural conservation of coastal lagoons is important not only for their ecological importance... more The natural conservation of coastal lagoons is important not only for their ecological importance, but also because of the valuable ecosystem services they provide for human welfare and wellbeing. Coastal lagoons are shallow semi-enclosed systems that support important habitats such as wetlands, mangroves, salt-marshes and seagrass meadows, as well as a rich biodiversity. Coastal lagoons are also complex social-ecological systems with ecosystem services that provide livelihoods, wellbeing and welfare to humans. This study assessed, quantified and valued the ecosystem services of 32 coastal lagoons. The main findings of the study are: (i) the definitions of ecosystem services are still not generally accepted; (ii) the quantification of ecosystem services is made in many different ways, using different units; (iii) the evaluation in monetary terms of some ecosystem service is problematic, often relying on non-monetary evaluation methods; (iv) when ecosystem services are valued in monetary terms, this may represent very different human benefits; and, (v) different aspects of climate change, including increasing temperature, sea-level rise and changes in rainfall patterns threaten the valuable ecosystem services of coastal lagoons. sisting of "the functions and products of ecosystems that benefit humans, or

Environmental Monitoring and Assessment, 2015

Compte tenu des activites aquacoles importantes dans la baie de Bourgneuf, l'utilisation des ... more Compte tenu des activites aquacoles importantes dans la baie de Bourgneuf, l'utilisation des donnees sedimentaires couplee a des modeles hydrodynamiques est particulierement preconisee et interessante pour le suivi de l'evolution cotiere. L'objectif de cette communication est de montrer par l'exemple l'apport des modeles hydrosedimentaires pour le suivi des evolutions cotieres dans la baie de Bourgneuf. Cette region possede une frange littorale qui, soumise aux influences combinees des courants cotiers, de la houle, et du depot de sediments de l'estuaire de Loire, presente de tres fortes evolutions, liees aux deplacements d'importants bancs vaseux et des phenomenes d'erosion et d'accretion autour de Noirmoutier. Enfin, un bilan a court puis a long terme des evolutions est propose sur l'ensemble de la cote.

Dans le littoral d'El Jadida les processus hydrodynamiques entretiennent la mobilité des sédiment... more Dans le littoral d'El Jadida les processus hydrodynamiques entretiennent la mobilité des sédiments produits par l'érosion. Suite à leur action, les sédiments sont soit stockés soit transportés sur différentes zones côtières. Le suivi de l'évolution morphodynamique de la plage mésotidale au niveau de la baie d'El Haouzia, à court et à moyen terme, montre une forte variabilité morphologique. Les morphologies moyennées et volumes de la plage d'El Haouzia ont été calculés en termes de saisons et d'années. Les simulations du transport longshore, calculé à partir de la formule du CERC (1984), montrent de nombreuses similitudes dans les directions du transit avec les observations de terrain. Le transport total varie de 10 6 à 5.10 6 m 3 /an selon les secteurs de la baie. Le transport théorique résultant indique un point de divergence dans la partie centrale de la baie d'El Haouzia.

This study presents the results of the systematic analysis of heavy metals in surficial sediments... more This study presents the results of the systematic analysis of heavy metals in surficial sediments and marine molluscs from Oualidia and Sidi Moussa lagoons. The present field investigation determines baseline heavy metal conditions in two Atlantic lagoons for the purpose of prioritizing future lagoon remediation efforts. Heavy metal levels in the two lagoons were exceedingly high, but varied widely among sampling stations. PEC (probable effects concentrations) concentrations were often exceeded for heavy metals in the lagoon sediments, especially for Pb, Cd, As and Hg, and some stations had multiple metals at presumptively toxic levels. These comparisons suggest that sediment metal levels in the lagoons are clearly high and probably pose an environmental risk at some stations. Although a complete inventory of pollutant inputs has not been completed, major pollutant sources have been identified and they should be given first attention in remediation efforts. Therefore, a two-tiered remediation strategy is suggested: one tier aimed at source reduction by installing wastewater purification station at Oualidia lagoon and a second tier aimed at minimizing metal re-mobilization impacts, possibly via finer-sediment dredging, as water quality improves.

ABSTRACT poster à la 8ème conférence internationale des géomorphologues, Paris

XIIIèmes JNGCGC Dunkerque, 2014

par son caractère pérenne à constituer un véritable outil d'aide à la gestion prévisionnelle du t... more par son caractère pérenne à constituer un véritable outil d'aide à la gestion prévisionnelle du trait de côte. Il couvre un linéaire côtier sableux de 19 km allant de La-Barre-de-Monts (Fromentine) à Saint-Jean-de-Monts (plage des Demoiselles) en Vendée. Le coeur de l'observatoire est un système d'informations géographiques (SIG), qui intègre les données pertinentes issues d'un point sur les connaissances existantes, ainsi que les suivis de terrain (état initial, suivis réguliers et événementiels). Son intérêt pour appuyer la gestion durable du territoire est illustré à partir de l'exemple de l'érosion du trait de côte, avec la comparaison court terme (volume de sable exporté par Xynthia)/long terme (évolution du trait de côte sur 100 ans). Le bilan de la mise en place de l'observatoire, au bout de 5 ans, est (a) un SIG en cours de finalisation avant livraison à la collectivité, (b) des interprétations des observations et phénomènes en jeu et (c) des premières réponses aux questions de la collectivité ainsi que des premières mises en application de solutions (fils lisses, …).

Environmental Earth Sciences, 2010

The metal content in surface sediments (0–2 cm, 26 samples), in a sediment core (120, 1 cm slices... more 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),

The Science of the total environment, Jan 5, 2015

The present research presents the first large-scale analysis of heavy metal assessment in the Mor... more The present research presents the first large-scale analysis of heavy metal assessment in the Moroccan Atlantic shelf. This work provides scientific basis for future studies on environmental research and fills the gap in knowledge on the worldwide continental platforms. Metal distributions identified three different zones, mainly influenced by industrial and urban sewer (northern areas), agriculture runoffs (central zone), and estuarine discharges (southern areas), respectively. In the north part of the shelf, metal enrichments are observed near industrial and urban sewer mouths (Casablanca and Mohammedia cities). In the south and central areas, the probable absence of human impact on sediments is attributed to effective trapping in the estuary (Oum Er Rbia) and coastal zones, as well as dilution with less contaminated sediments and shelf sediments and removal with fine fractions due to estuary discharges.

Physio-Géo, 2014

ABSTRACT Coastal dunes raise a special problem to scientists because of the high dynamic nature o... more ABSTRACT Coastal dunes raise a special problem to scientists because of the high dynamic nature of most beach-dune systems. Coastal dunes can change shape quickly and frequently due to the violence of winds and waves during storms. This study analyses and interprets spatial and temporal patterns in sediment volume changes in a beach-dune system using different aeolian transport formulas. During the measurements (24 campaigns), traps allowed to collect particles transported by the wind in order to determine the grains size and the critical shear velocity. For the grains size, the mode varies between 160 and 250 μm. The critical shear velocity is 0.23 m.s-1. Measured wind velocities range from 7.45 to 13.13 m.s-1. The transport flow varies between 0.19 and 1.14 kg.m-1.min-1. The measured transport rates were compared with the predictions of different models. The BAGNOLD-equation, using roughness length (zo) of 0.1 mm (S.M. ARENS, 1997) and adjustment length (K = 1.2), proved to have the best predictive ability: for every trap, the predictions are in the 95 percent confidence interval of the measurements (Root Mean Square = 30 %). The amount and direction of annual net transport have been computed with the BAGNOLD-equation. On the El Haouzia beach there is a positive transport flux in the direction of the dune field. This causes an annual increase of the average dune height of several centimetres. The used sand traps were compared.

Numerical simulations of the sediment transport are useful tools for planning, design and managem... more Numerical simulations of the sediment transport are useful tools for planning, design and management. Sediment erosion results from hydrodynamic forcing, represented by the bottom shear stress, and from the erodability of the sediment, defined by the critical ...

Journal of Coastal Research, 2012

Abstract KALLOUL, S.; HAMID, W.; MAANAN, M.; ROBIN, M.; SAYOUTY, EH, and ZOURARAH, B., 2012. Sour... more Abstract KALLOUL, S.; HAMID, W.; MAANAN, M.; ROBIN, M.; SAYOUTY, EH, and ZOURARAH, B., 2012. Source contributions to heavy metal fluxes into the Loukous estuary (Moroccan Atlantic Coast). Aluminum, iron, mercury, lead, copper, cadmium, chromium, ...

International Journal of Sediment Research, 2014

ABSTRACT An integrated approach, involving land use patterns and heavy metal contents of the surf... more ABSTRACT An integrated approach, involving land use patterns and heavy metal contents of the surficial and cored sediment, was proposed to detect the characteristic spatial and temporal scale of point and non-point source human disturbances on the Oualidia lagoon in Morocco. Identification and description of the temporal and spatial distributions of the main contamination sources of heavy metals are analyzed using statistics and GIS methods. The results show that surficial sediments are highly enriched in heavy metals compared to their preindustrial background levels. Land-use types affected lagoon sediment pollution in different ways: 1) agricultural areas had the highest potential for sediment contamination by heavy metals, particularly Pb, Cu and Hg, 2) Ni and Cr are the main pollutants originating from urban sewage and 3) oyster farming and traditional land uses such as salt flats, pastures showed low levels of others metals. The enrichment factors (normalized by Al) obtained from the sediment cores indicated that the lagoon is (strongly/moderately) polluted by all metals which were attributed to agricultural activities and wastewater discharges from urbanized areas.

Environmental Toxicology, 2007