Hydrodynamic Modelling of Sharjah lagoons (UAE) under Climate Changes

A Master of Science thesis in Civil Engineering by Mohamed Nashaat Singer entitled, “Hydrodynamic Modelling of Sharjah lagoons (UAE) under Climate Changes”, submitted in April 2022. Thesis advisor is Dr. Serter Atabay and thesis co-advisor is Dr Georgenes Cavalcante. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).

Abstract

Global warming has become a growing issue, especially because it is causing a rise in sea level which in turn has contributed to increased inundation areas and flooding risks. More specifically, the sea level in the Arabian Gulf is predicted to continue rising during the 21st century, which will certainly intensify coastal hazards in lagoons located in the United Arab Emirates. Such a combination of natural and anthropogenic stressors is expected to affect the internal hydrodynamics of the system, modifying its efficiency in exchanging water and altering the spatial residency time; this may result in a noticeable degradation of the water quality of lagoons. In the Emirate of Sharjah, the lagoons of Al Khalid, Al Khan and Al Mamzar are among the most important natural assets because they play an essential role in the coastal socioeconomic environment and, more importantly, because the hydrodynamics of these lagoons in the context of climate change has never been studied. This thesis, therefore, focuses on developing a hydrodynamic model using the Delft 3-D FM (Flexible mesh) on Sharjah Lagoons to determine the water circulation and residence time variability under present and future projected 1 m sea level rise in the next 100 years. The results from the model show that a 1 m sea level rise increased the tidal range by around 35% and the current velocity inside the lagoon from 0.31 m/s (present) to 0.43 m/s (future), with maximum currents of 1.4 m/s occurring near the tidal inlet during the flood tide and 0.8 m/s during ebb tide. The increase in the water speed improves the water circulation, reducing the residence time significantly inside the lagoons. The inner areas of the lagoon experienced increased residence times compared to the outer regions of the lagoon which may impact water quality status for inner regions. Overall, the residence time was reduced from 27 days (present) to 14 days (future), reflecting a 50% reduction. In that sense, considering a 1m sea level rise in the new hydrodynamics will be more efficient in dispersing materials out of the lagoons.