AGROFOR International Journal, Vol. 2, Issue No. 1, 2017 99 Original Scientific paper 10.7251/AGRENG1701099S UDC 551.435.1(64) MODELLING RESERVOIR SEDIMENTATION AT BIN EL OUIDANE DAM, MOROCCO El Mouatassime SABRI 1* , Ahmed BOUKDIR 1 , Rachid El MASLOUHI 2 , Mustapha MABROUKI 1 , Abdellah EL MAHBOUL 3 , Vivien Romaric EKOUELE MBAKI 1 , Abdelhamid ZITOUNI 1 , Wissal BAITE 1 , Zhour ECHAKRAOUI 1 1 Department of industrial engineering, Faculty of sciences and technical, University of sultan Moulay Slimane, Beni Mellal, Morocco 2 Oum Er B’IA Hidrological basin Agency, Beni Mellal, Morocco 3 The Delegate Ministry in Charge of Water, Morocco *Corresponding author: sabri.elmouatassime@gmail. com ABSTRACT This study was conducted in the Oued El Abid watershed upstream of the Bin El Ouidane dam, in Tadla-Azilal province (Morocco) to quantify the dam siltation rates. To assess the annual soil erosion and the sediment yield the universal soil loss equation (USLE) was used. A geographic information system (GIS) was used to generate and integrate maps of the USLE factors. A spatial distribution of soil erosion in the Oued El Abid watershed was obtained. The soil erosion was determined for each rural commune in order to identify the soil erosion hotspot and estimate the amount of soil that has been transported downstream (Bin El Ouidane Dam). Soil erosion ranged from very limited values for flat and well covered areas to over 2100 t /ha/y in mountainous areas with sparse vegetation. The total annual soil loss within the watershed is estimated at 19. 6 million tons per year. An equation of sediment delivery ratio (SDR) based on river gradient was calculated. It was found that the value of SDR at the outlet of the watershed Oued El Abid was 0. 65 with a sediment yield of 12. 74 million tons per year which affect the durability of the dam. Keywords: soil, erosion, USLE, GIS, SDR. INTRODUCTION Soil erosion is a complex dynamic process by which productive soil particles are detached, transported and accumulated in a distant place. This results in exposure of subsurface soil and sedimentation in reservoirs(Jain et al., 2001). In Morocco, the dam siltation retained annually reduces the storage capacity of 75 million m, which represents 0. 005% of the annual water mobilization with a total shortfall of 1 billion dollars per year. Out of the total area of 710 850 Km² of Morocco, it is estimated that about 150 000 km is affected by serious water and wind erosion (Namr and Mrabet, 2004).