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EN
The Bouregreg valley, located on the Atlantic coast of Morocco, has been subject to several anthropogenic and natural impacts that disturb the proper functioning of the estuary’s ecosystem. Important dredging operations influenced by both tides and freshwater inflows have created a significant variation of estuary’s morphology characterized by a sand bar developed at the mouth. The main objective of this study is to investigate the Morphodynamic processes of the estuary and in particular the impact of dredging operations using a two-dimensional horizontal numerical (2DH) modeling approach based on the shallow water equations. Several numerical tests have been carried out to calibrate the model and to investigate the hydrodynamic and morphological aspects of the estuary. For this technical solution, the modelling simulations show that in addition to the quantities of sand that will be dredged initially, the maintenance of the channel will facilitate a better water circulation between the Bouregreg valley and the Atlantic Ocean and improve the stability of the civil engineering structures and the neighbouring monuments. In addition, this water circulation will guide the river flow in the ebb phase of the tide. The model results show a reduction of about 30% in the impact of erosion, observed before the digging of the canal.
EN
Water erosion caused by rainfall and runoff, in the Morocco is the main threat of fertile agricultural soil losses causing important silting-up of dams. Most watersheds are characterized by excessive values of Soil Specific Degradation (Average annual soil loss per year and per km2), exceeding in many regions 2000 T/km2 /year. The main objective of this study is to investigate this phenomenon in the Tamdrost watershed located in northwestern Morocco. The methodology is based on integrating water erosion RUSLE model to Geographic Information System and satellite image processing. The aim of the study is to develop digital mapping for the main factors involved in the erosion processes as well as the variation of the average annual quantity of soil losses. The results outcome are: (i) the average value of the specific degradation is about 80 (T/ha/year), reaching a maximum value of 800 T/ha/year and a minimum value of 3 T/ha/year; (ii) The main factors that control water erosion by order of importance are successively: R, LS, K, and C factors. Finally, different maps representing erosion and the main factors involved, are be very helpful for decision makers to better assess this phenomenon and to implement antierosion measures in the threatened areas to support and control the water erosion.
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