Simulation du bilan hydro–sédimentaire d’un barrage collinaire en zone marneuse méditerranéenne (Cas du barrage Saboun, Maroc)

La présente étude a pour objectif de suivre et de simuler les apports en eau et en sédiments dans un barrage collinaire, en utilisant un modèle hydrologique de type physique distribué permettant le calcul de l’écoulement et de l’érosion des petits bassins versants marneux.Le modèle utilisé est le modèle « Mina », transposé dans cette étude au bassin versant marneux de Saboun situé au nord-ouest du Maroc, équipé d’un petit barrage en son exutoire et d’un très petit lac collinaire dans sa partie amont. La simulation est basée sur un découpage du bassin versant en unités hydrologiques homogènes dont les valeurs des paramètres de l’infiltration sont déduites d’expérimentations de simulation de pluies à l’échelle du mètre carré. Le calage et la validation du modèle sont effectués par confrontation des sorties du modèle aux mesures hydrologiques et bathymétriques réalisées au niveau de la retenue aval entre 1997 et 1999.Cette confrontation a montré que le modèle « Mina » sous-estime l’écoulement pour des sols très humides et le surestime pour des sols secs. Cette surestimation est expliquée par la fissuration des sols marneux à l’état sec. La sous-estimation s’explique par le colmatage rapide des sols marneux à l’état humide. Pour réduire ce biais, une augmentation de la perméabilité initiale doit être appliquée pour les sols secs à faible indice d’humidité IK et une diminution de la perméabilité finale doit être appliquée pour les sols humides à fort indice d’humidité IK. Ces rectifications ont permis l’amélioration de l’estimation des volumes simulés et une meilleure estimation de l’envasement de la retenue du barrage Saboun.The objective of the present study was to monitor and simulate the water and sediment balance in a small dam, by using a distributed physical hydrological model to estimate the outflow and the erosion rate of a small marl watershed.The “Mina” model was applied to the Saboun watershed, which is located in north-western Morocco and contains a small dam at its outlet. The simulation was based on the partitioning of the watershed into homogeneous hydrological units, and on infiltration and humidity parameter values deduced from rainfall simulation experiments. The model was validated by comparing the simulated data to hydrological and sedimentation data measured between 1997 and 1999.The analysis of this comparison showed that the model underestimated the watershed outflows for rainfall events that had a high antecedent humidity index (IK > 15 mm), and overestimated the outflows for rainfall events that had a low antecedent humidity index 0 < IK < 15 mm. This observation is explained by the hydrodynamic behaviour of the marl soils, which crack under dry conditions and fill up quickly during wet conditions. To reduce this variability, the initial permeability values were decreased or increased, respectively, for the rainfall events with low and high antecedent humidity indexes. This resulted in the improvement of simulated volumes by about 80% and a better prediction of the water balance and accumulation of silt in the reservoir upstream from the Saboun dam

CIRCULATION MARINE DE LA LAGUNE DE NADOR (MAROC) PAR MODELISATION HYDRODYNAMIQUE

The marine circulation of Nador lagoon (Morocco) have been studied from April to July 2011 by hydrodynamic 3D model, under the new configuration of its new inlet which is operational from 2011. This study aims to understand the new mode of hydrodynamic functioning of this lagoon. The circulation in the lagoon is wind driven circulation, as the wind is contributing to mixing internally the lagoon waters. During the neap tides, the surface currents are very strong in the new inlet (&gt; 1 m.s-1), less than 0.5 m.s-1 in the centre and 0.3 m.s-1 near the continental sides of the lagoon. The bottom currents are in the opposite direction from the surface currents and less than 0.2 m.s-1

Circulation Marine de la Baie de Cintra (Sud du Maroc) par Modèle Hydrodynamique 2D

The marine circulation of Cintra bay located at Dakhla Oued Eddahab area (south of Morocco 23°08’N-16°20’W) has been studied from October to November 2016 by 2D hydrodynamic model. This study aims to understand the marine circulation of this bay and its hydrodynamic functioning. Mainly governed by wind and semidiurnal M2 tides, currents are generally strong in intensity (mainly &gt; 0.5 m.s-1 ) outside the bay. Inside the bay, their intensity are less than 0.3 m.s-1 and generally oriented to the south of the bay due to the influence of the trade winds (NE). Due sometimes to the influence of W and/or SW winds, the coastal circulation of the bay is oriented from the south to the north, impacting its northern part

Ecological risk analysis in marine fish farming: a case study of a seabass (

The present study aimed at studying ecological interaction between a fish farm cages located in M’diq bay, in western Moroccan Mediterranean coast, and its local environment. It was carried out in 2013 and 2016 through seabed analysis in terms of organic matter and some nutrients parameters such as Nitrogen and Phosphorus, as well as through monitoring macro-fauna assemblages. The results showed recorded values relatively stable in three years’ interval and have a well-integrated fish farming activity within its ecosystem. Sediment was sandy to sandy shelly types and macro-benthic fauna were composed of six groups, Gastropods, Bivalves, Scaphopoda, Amphipods, Nematoda and Polychaeta. Organic matter and Total Organic Carbon were respectively less than 3.2% and 1.87% and very low comparing with others Mediterranean fish farms sites. Estimation of Nitrogen, Phosphorus and Carbon potential releases of M’diq fish farm gave low data related to its production capacity not exceeding 200 tons by year. Influenced with open sea location and high current state, dispersion pattern of these fish farm discharges seemed to play a key role in keeping lower values. ANOVA analysis showed no significant difference between studied parameters in the five sampling stations comparing with the reference station both on geographical and temporal levels (seasons and years)