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The Aguelmam Sidi Ali is the largest natural lake in the Middle Atlas, both in size and depth. During the last four decades, the lake has experienced very marked fluctuations in its water level, and its general trend is tending to shrink. It is the manifestation of increased climatic drought. In this context and with the aim of studying the hydroclimatic variability, a bathymetric record was made during 2017 which seems to be an arid year, in order to make comparisons with those of the hydrological year 1975/1976 when the lake reached its maximum level. We also correlated between the lake level and the climatic parameters influencing its water balance. The data analyzed reflects changes in lake level and reflects the weight of climate variability in the area and its impact on the lake's water supply. The results obtained confirm a continuous decrease in the lake's limnimmetry. The lake's extent is considerably reduced, its maximum depth was of the order of 40 m instead of 43.5 m in 1975, and the water balance (P- PET1) records a deficit of 242 mm/year throughout the observation period (1975/76 - /2016/17).

ABSTRACTSalinity is an important parameter influencing the water quality of estuaries, and can constitute a serious problem to society due to the need for freshwater for industry and agriculture. Therefore, the determination of salt intrusion length in estuaries is a challenge for managers as well as scientists in this field. The managers tend to use simple and reliable tools for salinity variation. Although 2-D and 3-D numerical models are common tools for the prediction of salinity intrusion now, analytical models of salinity variation are much more efficient, and also require minimal sets of river data. In this paper, two analytical solutions, Brockway and Savenije used worldwide to assess longitudinal salinity variation in alluvial estuaries, are applied to the Moroccan Atlantic semi-closed estuaries, i.e., Sebou and Loukkos. The solutions are derived from salt convection-dispersion equations, with different assumptions for the dispersion coefficient. The estuaries' bathymetry is described by an expon...

Climate changes are the main motivation for alteration of ecosystems; in fact the effects of these changes on biodiversity and ecosystems are considered as the most challenging cases in present century. Therefore, since the lakes are the most important services and functions of ecosystems, the effect of climate change on water level fluctuations of Aguelmam Sidi Ali Lake (Morocco) was analyzed as a natural ecosystem in this essay. The regular observations from the lake have found that a very sensitive withdrawal of their water level during the dry years. Therefore, a hydrodynamic model has been used to simulate the condition of Aguelmam Sidi Ali Lake, with observed field data (model has been set up to run annually for a total 35 year data,i.e., precipitation, evaporation, runoff discharges and water-level which are available for the last 35 years) being used for model calibration and validation. Additionally, the model validation process showed that the model results fit the observed data fairly well (R2 = 0.70−0.74, root mean square error [RMSE] = 1.63−1.71 m). On the other hand, different hydrological conditions regarding lake input and output data were tested and water depth was calculated using bathymetry to predict water-level fluctuations in the future. The results predict that the water-level will decrease continuously (In 2044, the water level will reach to 6.20 m). The water level decrease due to the climate change in both scenarios (dry and very dry) is dramatic and a profound adverse impact on the environmental balance is predicted in the region. Additionally, the lake will be dried up in about 20 years if very dry conditions continue in the region. This reveals the importance of this type of approach for obtaining a first-order estimate of water-level variations in Sidi Ali Lake, affected by climate change.

Abstract The dam of Takerkoust, located at the outlet side of N'fis Basin (Western High Atlas of Morocco), is one of the strategic reservoirs in Morocco facing a serious problem of siltation due to soil erosion. A paleo-hydrology approach combining chronological and sedimentological analyses is conducted to understand the evolution of the depositional sediment history of the Takerkoust reservoir between 1988 and 2016. First, a series of 8 bathymetric surveys in the Takerkoust reservoir was used to determine the chronology of flood event deposits. Second, grain size distribution, clay mineralogy (XRD) and organic matter content were analyzed in 2 cores drilled in the Takerkoust reservoir and the newly build Ouirgane reservoir in upstream (from which 46 samples were taken). Third, Soils samples collected from the uppermost soil horizons (First 5 cm) of different localities of the N’fis watershed were also analyzed to identify sediments origins. Eleven couplets with different textures and thickness are identified in the Takerkoust reservoir corresponding to the period 1988–2016. The highest correlation is observed between instantaneous maximum flow and thickness of the sandy component of the couplets. The variation of the siltation rate allows highlighting two distinct periods: the oldest period (1988–1999) characterized by a high sediment yield SY (908.6 t·km−2·yr−1) and a youngest one (1999–2016) characterized by a low SY (203.9 t·km−2·yr−1). The newly built Ouirgane dam, seems to be responsible for the decreasing siltation rate and change of the clay assemblages of the sedimentary series in Takerkoust reservoir.

Since the Miocene, the thinned continental crust below the Alboran Sea and its overlying sedimentary cover have been undergoing deformation caused by both convergence of Eurasia and Africa and by deep processes related to the Tethyan slab retreat. Part of this deformation is recorded at the Xauen and Tofiño banks in the southern Alboran Sea. Using swath bathymetry and multichannel seismic reflection data, we identified different stages and styles of deformation. The South Alboran Basin is made up of Early Miocene to Pliocene sedimentary layers that correlate with the West Alboran Basin depocenter and are dominated by E‐W trending folds and thrusts. The Xauen and Tofiño Banks first recorded the phase of extension and strike‐slip movement during the slab retreat, followed by the phase of compressional inversion since the Tortonian and are now structured by tight folds, thrusts, and mud bodies. This study proposes that the Banks were located on the southern‐inherited Subduction Tear Edge Propagator (STEP) fault related to the westward migration of the Alboran domain during the Miocene. The STEP fault zone, acting as a boundary between the African block and the Alboran block, was located along the onshore Jebha‐Nekor fault and the offshore Alboran Ridge and the Yusuf fault zone. Thick‐skinned and thin‐skinned shortening occurred when slab retreat stopped, and inversion began. The present‐day style of the deformation seems to be linked to a decollement level made of undercompacted shale on top of the Ghomaride complex This work was funded by the French program Actions Marges, the ALBAMAR JCJC ANR‐17‐CE03‐0004, the EUROFLEETS program (FP7/2007‐2013; 228344), and project FICTS‐2011‐03‐01. [...] This work also benefited from the DAMAGE (AEI/FEDER CGL2016‐80687‐R) and Fauces (Ref CTM2015‐65461‐C2‐R; MINCIU/FEDER) Projects financed by “Ministerio de Economía y Competitividad y al Fondo Europeo de Desarrollo Regional” (FEDER). 25 pages, 14 figures, 1 table.-- Seismic reflection and bathymetric data collected during the MARLBORO and SARAS cruises are stored at SISMER and Seanoe (SEA scieNtific Open data Edition) (https://doi.org/10.17600/11480100, https://doi.org/10.17600/12450090, and https://campagnes.flotteoceanographique.fr/campagnes/12000010) With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

This study provides a first estimate of the offshore wind power potential along the Moroccan Atlantic shelf based on remotely sensed data. An in-depth knowledge of wind potential characteristics allows assessment of the offshore wind energy project. Based on consistent daily satellite data retrieved from the Advanced Scatterometer (ASCAT) spanning the period from 2008 to 2017, the seasonal wind characteristics were statistically analyzed using the climatological Weibull distribution functions and an assessment of the Moroccan potential coastal wind energy resources was qualitatively analyzed across a range of sites likely to be suitable for possible exploitation. Also, an atlas of wind power density (WPD) at a height of 80 m was provided for the whole Moroccan coast. An examination of the bathymetrical conditions of the study area was carried out since bathymetry is among the primary factors that need to be examined with the wind potential during offshore wind project planning. The results were presented based on the average wind intensity and the prevailing direction, and also the wind power density was shown at monthly, seasonal and interannual time scale. The analysis indicated that the coastal wind regime of the southern area of Morocco has the greatest energy potential, with an average power density which can reach in some places a value around 450 W/m2 at heights of 10 m and 80 m above sea level (a.s.l) (wind turbine hub height) more particularly in the south of the country.

In active basins, tectonics can segment the continental shelf and control its stratigraphic architecture and physiography. Segmentation can explain the local evolution and morphology of the continental shelf because of sea-level variations, local tectonic segmentation and hydrodynamic processes. Here we investigate the tectonically active Morocco continental margin (southern Alboran Sea) using high-resolution seismic profiles and multibeam bathymetric data. The active faults bounding the transtensive Nekor basin triggered the segmentation of the shelf into three sectors showing different subsidence rates: a western sector corresponding to an extensive fault relay, a central sector corresponding to the subsiding Al-Hoceima Bay and an eastern sector corresponding to the footwall of the Trougout senestral normal fault. Results show that the staircase morphology of the shelf corresponds to successive submarine terraces at the shelf edge (ST1), mid-shelf (ST2) and inner-shelf (ST3) around −110 m,-80 m, and −40 to −20 m deep, respectively. The terraces correspond to the top of prograding wedges seaward and are erosive landward. They are correlated with stillstand from the Last Glacial Maximum to the Holocene highstand. Above the terraces, sub-aqueous dune fields are interpreted as degraded and deposited during the post-glacial transgression. In the central sector, typical delta front seafloor undulations on the shelf and crescent shaped bedforms at the head of marine incisions on the upper slope denote a fluvial influence during the Holocene. Seismic stratigraphy analysis revealed the preservation of six seismic units bounded by polygenic regional unconformities (S1, S2, S3, S4 and S5). Based on comparison with other Mediterranean margins, S1 to S5 are attributed to 4th order maximum regressive surface. We discuss the local preservation of the system tracts as a function of the vertical motion and the physiography of this tectonically active domain. This study provides useful clues for future local paleo-seismic analysis and to advance our understanding of sedimentary processes in active areas This work was funded by the French program Actions Marges, the EUROFLEETS program (FP7/2007-2013; n°228344), project FICTS-2011-03-01. Seismic reflection data were processed using the Seismic UNIX SU and Geovecteur software. [...]. This work also benefited from a State Grant from the French Agence Nationale de la Recherche (ANR) in the Program « Investissements d'avenir » reference ANR-10-LABX-19-01, Labex Mer and from the Fauces Project (Ref CTM2015-65461-C2-R; MINCIU/FEDER) financed by "Ministerio de Economía y Competitividad y al Fondo Europeo de Desarrollo Regional" (FEDER) 20 pages, 14 figures, 1 table Peer Reviewed

Cette étude s’intéresse à une portion de la marge Ouest Africaine, à la jonction entre deux segments largement étudiés, situés au large de Dakhla et de la Mauritanie, caractérisés par une morphologie globale de type destructif avec de larges glissements. Entre ces deux segments, celui de Dakhla est généralement décrit comme une portion de marge de type constructif. Durant la mission océanographique Dakhla (Décembre 2002), au large de Dakhla, de nouvelles données de sismique haute résolution, de bathymétrie et d’imagerie ont été acquises autour de la latitude 23oN. Ce nouveau jeu de données révèle l’existence de différentes morphostructures du fond telles qu’un canyon, des dépressions plus ou moins circulaires (pockmarks), différents types de rides et des escarpements, structures interprétées comme autant de témoignages de processus de transferts sédimentaires et de rupture de pente. This study explores a portion of the West African margin at the junction between two well- known segments offshore Dakhla and offshore Mauritania with destructional architecture characterized by giant slides. In between these two segments, the Dakhla segment has historically been described as a constructional section. During an oceanographic Dakhla cruise (2002), high resolution seismic data, swath bathymetry and imagery were acquired around latitude 23° N, offshore Dakhla,. This new data set reveals the existence of varied and complex morphologies on the continental slope, interpreted as a "shallot-shaped" canyon, seafloor depressions or pockmarks, ridges and scarps. These morphologies are interpreted as clues of sedimentary transfers and rupture processes. A scenario is proposed for the development of these different sedimentary morphologies.