Mahgoub, M.; Hinkelmann, R., and La Rocca, M., 2015. Understanding the behaviour of gravity currents in tideless estuaries and considering the impact of sea level rise within the Nile Estuary.

Gravity currents are complex phenomena that occur in estuaries, and the complexity of these phenomena is even higher for tideless estuaries. To improve the process of understanding such phenomena, the three-dimensional TELEMAC3D modelling system was used to model the Nile estuary as an example of tideless estuaries. The nonhydrostatic simulation and the use of a complex turbulence model were necessary. The current mean flow conditions were modelled first; the results were then compared with three scenarios of sea level rise to study its impact. According to the model results, the salt wedge was not stagnant but fluctuated in cycle-like variations; the fluctuations were higher at the surface and smaller near the bottom, and at the end of the salt wedge, no fluctuations were noticed. The salt concentration and hence the density differs significantly throughout the salt wedge in the longitudinal direction as well as in the vertical direction. Changes in density in the lateral direction were also noticed; greater concentrations were at greater water depths for the same transverse section. The sea level rise caused greater saltwater intrusion inside the Nile and the greater the sea level rise, the more the intrusion increased. To maintain the current saltwater intrusion length without any increase, discharging additional water from the Edfina Barrage (the last barrage on Rosetta branch) could be used as a direct mitigation option; however, doing so, could have negative consequences on the water budget of the country.