The occurrence of salt wedge intrusion is a common phenomenon in microtidal Mediterranean river mouths, particularly during summer, when reduced river discharge occurs. In the Strymon River, upstream saltwater intrusion affects both the hydrodynamic functioning of the system and the estuarine ecosystem. This study investigates the integrated ecohydrological management of river mouths characterized by salt wedge intrusion, aiming to both limit upstream saltwater penetration and exploit the salinity gradient between seawater and river water for renewable energy production. The study examines the operation of a Salinity Gradient Energy power plant based on Pressure Retarded Osmosis (PRO) technology, with a nominal capacity of 1 MW, located at the Strymon River mouth. A dynamically coupled hydrodynamic and energy production model is developed to assess four operational scenarios with different seawater and freshwater intake locations along the river channel. The results show that, in all scenarios, salt wedge intrusion is restricted to a distance of less than 2000 m from the river mouth, while salt wedge salinity is reduced by up to 35% compared to reference conditions. At the same time, annual energy production exceeds 1.03 GWh in all scenarios, corresponding to the electricity demand of approximately 824 to 1045 households, depending on the operational configuration. Overall, the study demonstrates that salinity gradient energy exploitation can be effectively combined with ecological control of salt wedge intrusion, providing a novel and sustainable framework for the management of Mediterranean estuarine systems.
Zachopoulos et al. (Wed,) studied this question.