Assessment of hydro-morpho dynamics of the Nile River confluence scour

Abstract

ABSTRACT Confluences of rivers are important component of river systems. Confluence scour is significant geomorphologically because it is a node in a channel network that controls sediment distribution, thus controlling the formation of channel migration. Nile River confluences take various shapes, such as downstream islands. Due to the construction of Aswan High Dam, major changes in hydrological characteristics downstream of the dam have affected river morphology, including the formation of islands. The purpose of this study is to investigate the hydrodynamic and morphological parameters for the Nile River confluences to provide an appropriate formula to predict confluence scour depth. For the current study, six confluence areas were selected. A numerical model was used to calculate the hydraulic characteristics of the Nile River. Geometric, morphological, and hydrodynamic analyses of selected confluences were performed in different years. Five confluence scour equations were applied to compute scour depths for the selected confluences. The scour depths for the specified confluences were calculated using five confluence scour equations. Field observations were compared to the calculated scour depths. The selected confluence scour equations didn’t have a satisfying performance for estimating the confluence scour depth in the Nile River. A new dimensionless confluence scour equation has been established.