الفهرس 
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Abstract
Bridges are very important structures that could be considered as strategic structures. Local scour is the most common cause of bridge collapse. It is defined as the removing of bed particles from around bridge Supports due to many variables including continuous flow of water, mean velocity, flow depth, sediment particles size and the pier dimensions. In this case study, the cable stayed bridge of Rod el Farag corridor connects the east branch of Nile River to El Warraq island. This area is in the fourth reach of the River Nile. Water discharge is a main variable in boundary conditions that is required in the scour calculation for this area. The water flow is distributed around El Warraq island. A one-dimension mathematical model HEC-RAS was used to calculate the flow distribution ratio around the island. The same model was used in preparing a simulation for the bridge area and calculating both local and contraction scour. Both models were calibrated by using a velocity measured data of the research area. Finally, the bridge supports were affected by scouring especially local scour. The middle piers will have the greatest local scour. Many scour Countermeasure systems could be applied to resist the local scour in this area. Riprap countermeasure system was designed to resist the local scour around the bridge piers.