A 2-D Model Simulating Sediment Transport In Shallow-Wide Streams (SED-2) M.M. Elfiky 2 , A.M. Negm 1 , T.M. Owais 1 , M. Nassar 3 A 2-D mathematical model was developed simulating the sediment transport in alluvial shallow-wide streams in order to solve practical problems in the Nile River. The Finite Difference technique was used to solve the convection-diffusion equation of the suspended sediment in open channels. A 2-D hydrodynamic model (HYD-2) was used to describe the flow field solving the Reynolds form of the Navier-Stokes momentum equations in two dimensions in addition to the continuity equation. The developed 2-D mathematical model was verified using actually measured field data. The field data were collected from one of the main canals of irrigation network in Egypt called El-Naser main canal. Good agreement was observed between the model results and the field observations. The model could be applied for solving local hydraulic and navigation problems where some reaches of the Nile River suffering. Various proposals could be investigated and the optimal solution in each case could be reached. Introduction A fundamental phenomenon of non-equilibrium sediment transport is the continuous adjustment of the sediment transport to the sediment capacity, especially in environments with a predominant suspended load transport. The morphological processes can be simulated sufficiently accurately by 1-D or 2-D horizontal models based on equilibrium sediment formula. However, commercial mathematical models fail in many cases to simulate exactly the sediment transport in the rivers due to the employed extremely simplified assumptions and lack of calibration and validation processes. On the other hand, the available empirical sediment transport equations as those of (Bagnold, 1966, Engelund-Hansen, 1967, Van Rijn, 1984 a, b) produce total sediment load that deviates by more than 200% in some cases compared to the actual measured field data. Moreover, the physical models or laboratory experiments to predict the sediment transport are generally very time-consuming, costly and, for many practical problems, impossible (Guo, Jin, 1990). This highlights the importance of developing a mathematical model to solve the sedimentation problems in shallow wide streams as rivers, which is the main aim of the present paper. The sedimentation problems in the Nile River become more severe after the construction of the Aswan High Dam because of the sediment free flow has the ability to convey sediment from either the river bed or banks causing a bed degradation and bank erosion. As a result, the bed level was lowered and the canal intakes, the pumping stations intakes, the bank stability, foundation of the hydraulic structures, ground water levels and navigation paths could be affected. The developed 2-D sediment transport model can predict the locations of scouring and silting zones along the considered river reach. Proper solutions may be suggested and easily studied for 1 Associate Professors, Dept. of Water & Water Structures Eng., Faculty of Engineering, Zagazig University, Zagazig, Egypt, E-mail: amnegm85@hotmail.com 2 Professor of Civil Engineering, Dept. of Water & Water Structures Eng., Faculty of Engineering, Zagazig University, Zagazig, Egypt 3 Post graduated student, Demonstrator, Dept. of Water & Water Structures Eng.,Faculty of Engineering, Zagazig University, Zagazig, Egypt