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

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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.

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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.

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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 1257km3. 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 957Km3. Thus, the annual water balance of the water inflow in the North Aegean Sea is 300Km3, and the hydrodynamic behavior of the North Aegean Sea surface is affected by the water inflow of 1257Km3/year (40,000 m3/sec).

1257 km3 /year

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WATER CIRCULATION IN DARDANELLES STRAITS

Ακρ. Έλλη Bosporus

Aegean Sea

Black Sea

10m

50m

55m

3866km yr

325km yr

3957km yr

3416km yr

31257km yr

3566km yr

Water Inflow in the Aegean Sea = 300 km3/yr

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WATER CIRCULATION IN DARDANELLES STRAITSThe 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.

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CORIOLIS FORCEThe Coriolis force influence the direction of the water inflow from the Dardanelles Straits.

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MODELLING THE NORTH AEGEAN

Horizontal Discretization: 2x2km2

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

rainfall8

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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 = 15.0OC Water Density ρ = 1028.75kg/m3

Default values for the Inflow from Dardanelles

Seasonally Varied Discharge Qmax = 52732 m3/ sec Salinity S = 29.6ppt Water Temperature T = 14.0OC Water Density ρ = 1022.0 kg/m3

Inflow Width = 4000m Maximum Inflow depth 10m

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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

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

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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.

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THANK YOU!!!