1. HYDRODYNAMIC SIMULATION, OF THE BRACKISH WATERS DISCHARGE FROM THE DARDANELLES STRAITS INTO THE NORTH AEGEAN SEA Kyriakos I. Kopasakis, Panagiotis B. Angelidis, Anastasios N. Georgoulas, Nikolaos E. Kotsovinos Laboratory of Hydraulics and Hydraulic Structures Democritus University of Thrace 67100 Xanthi, Greece 1

2. PRESENT ENVIRONMENTAL CONDITION OF THE BLACK SEA The ecosystem of the Black Sea is sufferred by excessive loads of nutrients and hazardous substances from the coastal countries as well as from various river discharges. Pollution inputs and other factors have rapidly changed Black Sea ecosystem since 1960 and have been seriously threatening biodiversity and the use of the sea for fishing and recreation. In addition to nutrient pollution, other pressures on the Black Sea ecosystems include organic pesticides, heavy metals and incidental and operational spills from oil vessels and ports. 2

3. ACCIDENTS IN DARDANELLES STRAITS: DECADE OF 1990-2000 In the Bosporus worst accident, on March 14, 1994, the 66,822-ton oil tanker Nassia collided with the Shipbroker at the Black Sea entrance to the Bosporus. In the conflagration that followed the vessel's port and center tanks containing over 20,000 tonnes of crude oil ruptured and polluted the Bosporus Straits. The channel was closed to shipping for a week, and the accident caused $1 billion in damages. Tankers more than four times as large as the Nassia now regularly travelling through the Bosporus and Dardanelles Straits. 3

4. WATER CIRCULATION IN DARDANELLES STRAITS The brackish water (salinity = 29.6ppt), that flows in the upper water sea layer (10m depth), with direction at the exit from the Sea of Marmara to the South Aegean Sea, has a mean volume of 1257km 3. At the same time, the saline water (with a salinity of 38.9ppt), that flows in the lower water sea layer, with direction from the North Aegean Sea to the Sea of Marmara appears to have a mean volume about 957Km 3. Thus, the annual water balance of the water inflow in the North Aegean Sea is 300Km 3, and the hydrodynamic behavior of the North Aegean Sea surface is affected by the water inflow of 1257Km 3 /year (40,000 m 3 /sec). 1257 km 3 /year 4

5. WATER CIRCULATION IN DARDANELLES STRAITS Ακρ. ΈλληBosporus Aegean Sea Black Sea 10m 50m 55m Water Inflow in the Aegean Sea = 300 km 3 /yr 5

6. WATER CIRCULATION IN DARDANELLES STRAITS The direct water exchange between the North Aegean Sea and the South Aegean Sea is not achieved, for depths greater than 250m, due to the bottom topography. Therefore, the accumulation of pollutants in the North Aegean Sea is further increased. 6

7. CORIOLIS FORCE The Coriolis force influence the direction of the water inflow from the Dardanelles Straits. 7

8. MODELLING THE NORTH AEGEAN  Horizontal Discretization: 2x2km 2  Vertical Discretization: 20 horizontal layers - 5m layer depth  Maximum Depth: 100m  Maximum number of computational cells: 500000 cells  Time Step: 5min  Computational time over the real time = 1/75  Maximum simulation time: 4 years  Climatological factors: air temperature, relative humidity, wind speed, wind direction, solar radiation, atmospheric pressure and rainfall 8

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10. INITIAL CONDITIONS BOUNDARY CONDITIONS Open Boundary Condition: South side of the grid Initial values for the North Aegean and the Open Boundary  Salinity S = 38.6ppt  Water Temperature Τ = 15.0 O C  Water Density ρ = 1028.75kg/m 3 Default values for the Inflow from Dardanelles  Seasonally Varied Discharge Qmax = 52732 m 3 / sec  Salinity S = 29.6ppt  Water Temperature T = 14.0 O C  Water Density ρ = 1022.0 kg/m 3  Inflow Width = 4000m  Maximum Inflow depth 10m 10

11. TRACERS TRACER_1 (Black Sea Pollutant-BSP): water inflow from the Dardanelles Strait, at the beginning of the simulation. TRACER_9: water inflow from the Dardanelles Strait, after 3 years of simulation. TRACER_10 (BSP3): inflow at the open boundary, at the beginning of the simulation 11

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21. Satelite image of the North Aegean Sea (June 2003) source: http//modis.gsfc.nasa.gov/) 21

22. FURTHER INVESTIGATION  Simulation with river outfows  model calibration and validation with field measurements or other computational models  Parallel execution of ELCOM with the environmental model CAEDYM. 22

23. 23 THANK YOU!!!