Numerical Simulations of Exchange Processes between the El Gouna Lagoons and the Red Sea, Egypt

The Red Sea is one of the most appealing areas in the whole MENA region, representing one of the top spots worldwide for tourism activities, especially because of its biodiversity, characterized by remarkable corals and marine life forms. It is also one of the fastest growing areas throughout the recent years concerning shipping and logistic industry mostly influenced by the Suez Canal, as well as for the increasing number of touristic resorts. This raises crucial research questions, such as: (1) which are the negative consequences on the Red Sea marine ecosystem and (2) is it possible to identify good management practices and smart water solutions to mitigate those negative impacts, ensuring a higher environmental and economic sustainability?

The study area is a touristic resort called El-Gouna, about 30 km from the city of Hurghada, on the Egyptian Red Sea eastern coast. El Gouna consists of islands and onshore areas, surrounded by various interconnected lagoon-like water bodies with several connections to the Red Sea. Especially in case of low wind conditions, the water quality in the lagoon becomes highly stressed through the high temperature, the sewage flows from the numerous hotels and marinas, the brine dumping from the desalination treatment plant and the long residence times.

A 2D (depth-averaged) approach for flow and transport simulations was set up to investigate the hydrodynamics and the interactions of the lagoons with the Red Sea, using the open TELEMAC-MASCARET modeling system. The simulations were conducted first on two simplified basin types (namely open and semi-enclosed) and, afterwards, on the real computational domain – including a part of the lagoons, in the surroundings of the desalination plant. A statistical analysis of the wind data was carried out, to identify mean and extreme values of wind, the measured mean tidal effect is about 60 cm. The water exchange processes between the lagoons and the Red Sea were assessed through the simplified basins, considering different wind and tidal scenarios and estimating the water residence times with an alternative numerical approach. In the real domain, the flow dynamics under such scenarios and the potential brine emissions from the desalination system were additionally analyzed.

This modeling study provides first results to respond to the above-mentioned challenges in the near future.