FLOOD EFFECTS ON LOCAL SCOUR AT IMBABA BRIDGE

Construction of Aswan High Dam (AHD) in 1968 has reserved and controlled the Nile River discharge to protect Egypt not only from floo ds but also from drought. During the past few years, Egypt has experienced high floo ds. Consequently, high inflows have to be passed to the river downstream the dam a ccording to dam operation rules. These inflows constitute risks to bridges and other structures on the Nile River especially in narrow river sections where general s cour is expected. Imbaba Bridge (km 934.70 downstream Aswan Dam) is located upstream Delta Barrage (km 954 from Aswan). It is considered one of the major brid ges across the Nile River. Some studies investigated local scour around Imbaba brid ge pier based on laboratory flume data analysis that suffer from scale effects. In th is study, HEC-RAS mathematical model was used to simulate the scour phenomenon around Imbaba bridge piers. The computation of bridge pier scour depth depends on f low velocity, flow depth, bed sediment characteristics and pier width. The main o bjective of this research paper is to predict, evaluate and analyze the future maximum excepted scour occurred on the Imbaba Bridge piers that would take place due to th e occurrence of high releases during a high flood period.