Nestos River plume dynamics under variable physical forcing

Περίληψη

The three-dimensional numerical model ELCOM was utilized to quantify the degree of influence of each physical forcing upon Nestos River plume. The model was calibrated and validated by a significant number of field samplings, collected during years 2006-2007. After the successful implementation and validation of the model, a series of scenarios were devised, isolating the impact of each physical force, such as wind speed and direction, tidal range, river discharge and coastal morphology. Further scenarios combined or altered forcing factors, aiming to distinguish the forces that play a primary role upon the plume dynamics. Results showed that Nestos River plume is mainly wind-driven, while its size depends on river discharge. The plume follows the direction of the wind having a small clockwise deflection. The wind speed is an important factor as it pushes the plume away from the mouth, while elevated wind speed enhances vertical mixing with the ambient water. Under low wind conditions, the Coriolis force becomes more dominant. Due to its narrowing, Thassos Passage also plays a special role on the western expansion and plumes shape and evolution. Surface waters within this strait gain extra speed and under high river discharge the plume enters Kavala Gulf. Tide has only a minor role on plumes evolution due to the microtidal nature of the area.