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Bridges are one of the important structures across the Nile River; these bridges may be subjected to collapse if there is no monitoring or safety precaution for local scour during high floods. This research was commenced in order to evaluate the scour around bridge piers. 1-D and 2-D mathematical models were applied to Aswan and El Minia bridges, in the 1st and 4th reaches, respectively. The two bridges are considered two major bridges so their impacts should be studied. Total Scour (local, contraction and long-term degradation) was evaluated and the expected morphological changes were estimated. The local scour and contraction scour at Aswan Bridge is higher than El-Minia Bridge due to the big dimensions of piers. 2D model gives accurate results especially in the non-uniform cross sections. It was found that the smallest local scour was obtained in case of sharp nosed piers at normal flow to the piers. Keywords: Local scour, Bridge piers, HEC-RAS, CCHE-2D, Aswan bridge, El-Menia bridge

This paper is an attempt to predict the deposition in the Aswan High Dam Reservoir, in Egypt, in order to estimate the effective life span of the reservoir. A two dimensional numerical model (CCHE-2D) was implemented to simulate the sedimentation along a 150 km reach of the reservoir where most of the sediment deposits. During the course of this study, the calibration and validation of the model for flow and sediment deposition were executed during the period 2006–2007. A good agreement, between the observed and modeled results for the whole domain, was obvious. Confident with the obtained results, the model was further tooled to predict the sediment deposition in the reservoir during the period 2009–2014.