Dynamics of wind setdown at Suez and the Eastern Nile Delta

Area of Science:

• Earth and Ocean Sciences
• Hydrodynamics
• Coastal Engineering

Background:

• Wind setdown is a phenomenon where sustained wind stress lowers water levels, exposing formerly submerged terrain.
• This hydrodynamic process has been hypothesized as an explanation for the biblical parting of the Red Sea.

Purpose of the Study:

• To analyze the hydrodynamic mechanism of wind setdown and the time required to reach a steady-state solution.
• To investigate wind setdown at a specific site in the eastern Nile delta (Lake of Tanis) using historical and geological data.
• To demonstrate a novel hydrodynamic mechanism for water body division under wind stress.

Main Methods:

• Conducting a satellite and modeling survey of the eastern Nile delta, incorporating ancient bathymetry and historical wind event data.
• Performing a suite of ocean model experiments to simulate wind setdown effects.
• Reconstructing topography and testing the model's behavior under specific wind forcing.

Main Results:

• A uniform 28 m/s easterly wind forcing in the reconstructed model basin exposed mud flats, forming a 3-4 km long and 5 km wide land bridge.
• The exposed land bridge remained open for approximately 4 hours.
• The study demonstrated a mechanism by which an angular body of water can divide under wind stress.

Conclusions:

• Wind setdown can create significant temporary land bridges in specific geographical and bathymetric conditions.
• The findings support the potential for wind setdown to explain historical accounts of water parting.
• The study highlights the impact of wind setdown on navigation in shallow-water harbors during strong offshore winds.