Characterization of the water mass dynamic changes surrounding a seawater reverse osmosis desalination plant on the east coast of the Kingdom of Bahrain

Desalination in the Gulf Cooperation Council countries is essential in the provision of drinking water supply and in achieving the targets of the UN Sustainable Development Goals (SDGs), par-ticularly SDG6.1 aiming at achieving access for all to safe drinking water. On the other hand, desali-nation process is associated with several environmental externalities that have adverse impacts on the coastal and marine environments. The aim of this research is to assess the dynamic changes of the water mass quality parameters resulting from a seawater reverse osmosis (SWRO) desalina-tion plant located on the east coast of Bahrain, in relation to the tide cycle on seasonal basis. The evaluation is based on the spatial differences in water temperature and salinity in the surrounding areas of the plant outlet within about 2.5 km2. Water samples were collected at 42 locations for both surface and bottom waters over high and low tide cycle during winter and summer. The results revealed an extreme elevation in temperature (> 38 & DEG;C) and hypersaline waters (> 55%& DEG;) at locations nearby the discharge outlet as well as at bottom waters of depths > 3 m in both seasons with excep-tional levels in summer particularly during high tide cycle. Thermocline and halocline formations were noticeably occurred particularly during high tide in both seasons due to vertical differences in temperature (> 3 & DEG;C) and salinity (> 1%& DEG;) at several locations associated with depths more than 3 m. The thermocline and halocline formations indicate the path by which the thermal and hyper-saline water mass fluxed by the desalination plant sinking out towards the open water. The impacts of Al-Dur SWRO desalination need to be minimized to maintain the seagrass habitat around the coast to support the marine biodiversity, particularly the megafauna endangered species associated with seagrass, (dugongs, green turtles and dolphins) and other finfish and shellfish species.