The role of episodic water level variations for the dynamics of Danube Delta coastal zone

Sebastian Dan1,2 and Adrian Stănică1

1. National Institute of Marine Geology and Geoecology — GeoEcoMar, Romania.

2. Delft University of Technology, Faculty of Civil Engineering and Geosciences, The Netherlands.

Outline:

1. Objective

2. Study zone

3. Methods - water level

variations - aerial beach

response

4. Results: - water level variations- aerial beach response

5. Conclusions

1. Objective

To identify the most vulnerable beach sectors to the water level variations induced by storm surges:

- water level - aerial beach response

2. Study zone

Turkey

Ukraine

Russia

BLACK SEABLACK SEA

DanubeDelta

Bulg

aria

Rom

ania

10 km

Sulina

Sf. Gheorghe

2. Study zone

PortiţaInlet

Canalul cu sondă

CâşlaVădanei

Zătoane

Periteaşca

-5m

-10m

Sahalin

advance5-10 m/year

erosionup to 20 m/year

migration> 20 m/year

erosion1 m/year

1 million m3/year

3. Methods

Water level variations:- numerical modelling.

Process-based numerical model Delft-3D: - SWAN module waves;

- FLOW module water level variations.

Ten storm scenarios based on 10 years of wind records:

- from north to south-west;

- from 15 to 40 m/s;- one extreme case.

3. Methods

Aerial beach response:- extension of flooding – 10 profiles, 3 years (1995 –

1997)

MSL

Aerial beach

Height0.67 – 2.52 m

Length13.6 – 93 m

4. ResultsWater level variations

Sulina

Sf. Gheorghe

x106

4.98

4.97

4.96

4.95

4.94

4.3 4.4 4.5 4.6 4.7 4.8 x105

x coordinate (m)

y co

ordi

nate

(m)

50

45

40

35

30

25

20

15

10

5

0

(m)

N

wind direction:

north

wind speed:40 m/s

Water levelvariation expressed in centimetres

4. Resultsy

coor

dina

te (m

)

Sulina

Sf. Gheorghe

4.3 4.4 4.5 4.6 4.7 4.8 x10 5

50

45

40

35

30

25

20

15

10

5

0

(m)x106

4.98

4.97

4.96

4.95

4.94

x coordinate (m)

wind direction:

south

wind speed:30 m/s

Water level variations

Water levelvariation expressed in centimetres

N

4. Results

Sulina

Sf. Gheorghe

c)y co

ordi

nate

(m)

x106

4.98

4.97

4.96

4.95

4.94

4.3 4.4 4.5 4.6 4.7 4.8 x10 5

50

45

40

35

30

25

20

15

10

5

0

(m)

x coordinate (m)

wind direction:

north-east

wind speed:40 m/s

Water level variations

Water levelvariation expressed in centimetres

N

4. ResultsAerial beach response

1995

-40

-20

0

20

40

60

80

100

P1 P2 P3 P4 P5 P6 P8 P9 P10

leng

th o

f the

flod

ed p

rofil

e (%

)

N40 NE28 NE40 E19 SE15 S30 SW19

4. ResultsAerial beach response

1996

-40

-20

0

20

40

60

80

100

P1 P2 P3 P4 P5 P6 P7 P8 P9 P10

leng

th o

f the

flod

ed p

rofil

e (%

)

N40 NE28 NE40 E19 SE15 S30 SW19

4. ResultsAerial beach response

1997

-40

-20

0

20

40

60

80

100

P1 P3 P4 P5 P6 P7 P8 P9 P10

leng

th o

f the

flod

ed p

rofil

e (%

)

N40 NE28 NE40 E19 SE15 S30 SW19

5. Conclusions

Variability of the water level variation along the Danube Delta coast due to change in the coast orientation.

Largest rates of flooding: Sulina – Sf. Gheorghe area, already vulnerable.

A catastrophic event (north-easterly wind, 40 m/s) would breach the dunes, with significant consequences:

- input of the salt water in a fresh water environment;- destruction of infrastructure; - potential flood of parts of the Sf. Gheorghe village.

The floodable inland areas are part of the DD Biosphere Reserve.

Need for rapid intervention on the most vulnerable parts of the Danube Delta coast.

Sulina

Sf. Gheorghe

Sahali

n

PortiţaInlet

-5m

-10m

Acknowledgements

EC FP6 no. 044122 project Concepts and Science for Coastal Erosion Management (CONSCIENCE) – numerical modeling.

Romanian National Research Core Programmes (1984 – present) the field measurements.