Variations of inherent optical properties in case

of harbour dredging in Estonian coastal sea

Liis Sipelgas

Tallinn University of Technology

Marine Systems Institute

Outline

• Study sites and collected IOP dataset at the time of dredging

• Examples of data

• Use of MERIS imagery for monitoring SPM distribution

• Plans for upcoming PECS project “Environmental monitoring of

harbour dredging”

18 19 20 21 22 23 24 25 26 27 28 29 30

57

57.5

58

58.5

59

59.5

60

60.5

EstoniaRussia

Latvia

Finland

Baltic Sea

Gulf of Finland

Gulf of Riga

Muuga harbour

Paldiski south harbour

Paldiski south harbour

•Harbours belong to the Port of Tallinn which is one of

three biggest cargo handlers in the Baltic Sea

•Maintenance of the harbours requires dredging of the

shipping channel and aquatory after every second year

Muuga harbour

The dataset of IOP-s have been collected during the monitoring of SPM

distribution at the time of port dredging. The data was used for detailed

description of SPM distribution near the dredging site for later evaluation of

environmental impact. The dataset contains:

•Vertical profiles of attenuation and absorption coefficient with WetLabs ac -

spectra

•Concentrations of SPM and Chlorophyll a

There are approximately 30 days of data from different sites collected during

years 2007-2010.

400 500 600 700wavelength, nm

0.5

1

1.5

2

2.5

3

3.5

sca

tte

rin

g c

oeff

icie

nt, m

-1

Graph 1St_1

St_2

St_3

St_4

St_5

St_6

St_7

St_8

St_9

St_10

St_11

St_12

St_13

Scattering coefficient 9_09_2009, Muuga Bay

24.8 24.85 24.9 24.95 25 25.05 25.1 25.15

Longitude

59.44

59.46

59.48

59.5

59.52

59.54

59.56

59.58

59.6

59.62

Latitu

de

S1

S2S3

S4

S5S6

S7

S8

S9

S10

0.3

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

2.1

dredging site

harbour

TSM mg/L

24.8 24.85 24.9 24.95 25 25.05 25.1

Longitude

59.46

59.48

59.5

59.52

59.54

59.56

59.58

59.6

59.62

Latitu

de

2.62

2.86

3.092.38

2.38

3.57

3.33

2.14

3.09

5.47

2.62

2

2.5

3

3.5

4

4.5

5

5.5

Chl mg/m-3

Dredging in Muuga 9_09_2009

400 500 600 700wavelength, nm

0

1

2

3

4

sce

cific

sca

tte

rin

g c

oe

ffic

ien

t, L

m-1m

g-1

Graph 1St_1

St_2

St_3

St_4

St_5

St_6

St_7

St_8

St_9

St_10

St_11

St_12

average

Fit 2: Power

Specific scattering coefficient, 9_09_2010, Muuga Bay

Fit 2: PowerEquation ln(Y) = -0.5281589405 * ln(X) + 3.927085499Alternate Y = pow(X,-0.5281589405) * 50.75882524

Coef of determination, R-squared = 0.887161

24.8 24.85 24.9 24.95 25 25.05 25.1

Longitude

59.46

59.48

59.5

59.52

59.54

59.56

59.58

59.6

59.62

La

titu

de

S1

S2

S3

S4

S5

S6

S7

S8

S9

S10

S11

S12

S13S14

S15

Sp

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

TSM mg/L

harbour dredging site

24.8 24.85 24.9 24.95 25 25.05 25.1

Longitude

59.46

59.48

59.5

59.52

59.54

59.56

59.58

59.6

59.62

Latitu

de

7.14

8.57

13.1

9.04

13.6

12.9

9.04

10.9

10.9

14

9.04

16.9

16.98.81

12.6

9.76

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

Chl mg/m3

400 500 600 700wavelength, nm

0.8

1.2

1.6

2

2.4

sca

tteri

ng c

oe

ffic

ien

t, m

-1

Graph 1S_1

S_2

S_3

S_4

S_5

S_6

S_7

S_8

S_9

S_10

S_11

S_12

S_13

S_14

S_15

Scattering coefficient 28_04_2010, Muuga Bay

Dredging at the time of spring

bloom in Muuga Bay

28_04_2010

400 500 600 700wavelength, nm

0.3

0.4

0.5

0.6

0.7

sp

ecific

scatt

erin

g c

oe

ffic

ien

t, L

m-1m

g-1

Graph 1S_1

S_2

S_3

S_4

S_5

S_6

S_7

S_8

S_9

S_10

S_11

S_12

S_13

S_14

S_15

average

Fit 3: Power

Specific scattering coefficient 28_04_2010, Muuga Bay

Fit 3: PowerEquation ln(Y) = 0.1596440467 * ln(X) - 1.728228851Alternate Y = pow(X,0.1596440467) * 0.1775986852Coef of determination, R-squared = 0.325869

0 1 2 3 4 5TSM (water samples), mg/L

0

1

2

3

4

TS

M (

ME

RIS

) m

g/L

2.084

3.039

0.65

0.38 0.4

1.17

0.414

0.710.62

0.78

1.718

1.455

1.7331.646

1.107

1.285

1.6881.6

2.315

1.7171.599

1.6931.789

1.509

1.666

1.439

Fit 1: Linear (for september)Equation Y = 1.368312343 * X - 0.09731612091Coef of determination, R-squared = 0.869024

Fit 1: Linear (for april)Equation Y = -0.1837222386 * X + 2.192029246Coef of determination, R-squared = 0.207206

28_04_2010

9_09_2009

Comparison of MERIS TSM

vs TSM water samples

• If the Chl content is low and

particles are mainly

resuspended MERIS TSM

product is reliable.

• In case of high Chl content the

MERIS TSM is underestimated.

23.94 23.98 24.02 24.06 24.1 24.14

Longitude

59.26

59.28

59.3

59.32

59.34

59.36

59.38

59.4

59.42

Latitu

de

2

6

910

12131416

17181920

222324

0.5

1.3

2.1

2.9

3.7

4.5

5.3

6.1

6.9

7.7

30

SPM, mg/L

23.94 23.98 24.02 24.06 24.1 24.14

Longitude

59.26

59.28

59.3

59.32

59.34

59.36

59.38

59.4

59.42

Latitu

de

5.5

5.5

6.213

6.714106

5.55.264

6.766.9

4

5.5

7

8.5

10

11.5

13

Chl mg m-3

Dredging Pakri Bay 5.09.2008

400 500 600 700wavelength, nm

0

0.5

1

1.5

2

2.5

3

sca

tteri

ng c

oeff

icie

nt, m

-1

16

18

20

22

24

26

sca

tte

rin

g c

oeffic

ien

t m

-1,

st

12

Graph 1St_2

St_6

St_9

St_10

St_12

St_13

St_14

St_16

St_17

St_18

St_19

St_20

St_22

St_23

St_24

Scattering coefficient 5_09_2008, Pakri Bay

400 500 600 700wavelength, nm

0

0.2

0.4

0.6

0.8

1

sp

ecific

sca

tte

rin

g c

oe

ffic

ien

t, L

m-1m

g-1

Graph 1St_2

St_6

St_9

St_10

St_12

St_13

St_14

St_16

St_17

St_18

St_19

St_20

St_22

St_23

St_24

average

Fit 2: Power

Specific scattering coefficient 5_09_2008, Pakri Bay

Fit 2: Power

Equation ln(Y) = -0.2774951811 * ln(X) + 0.7703492946Alternate Y = pow(X,-0.2774951811) * 2.16052078Coef of determination, R-squared = 0.712334

23.96 24 24.04 24.08 24.12

Longitude

59.26

59.28

59.3

59.32

59.34

59.36

59.38

59.4

59.42

Latitu

de

6.7

8.3

5.2

8.6119.5

2.63.851.7

3.33.87.9

0

3

5

6.5

8

9.5

11

12.5

Chl a, mg m-3

23.98 24.02 24.06 24.1

longitude

59.26

59.28

59.3

59.32

59.34

59.36

59.38

59.4

59.42

latitu

de

12

5

6

91011

12131415

181920

0.5

1.3

2.1

2.9

3.7

4.5

5.3

6.1

6.9

7.7

SPM, mg/L

400 500 600 700wavelength, nm

0.8

1.2

1.6

2

2.4

sca

tteri

ng c

oeff

icie

nt, m

-1

Graph 1St_2

St_5

St_6

St_9

St_10

St_11

St_12

St_13

St_14

St_15

St_18

St_19

St_20

Scattering coefficient 25_07_2008, Pakri Bay

Dredging Pakri Bay 25.07.2008

400 500 600 700wavelength, nm

0.3

0.4

0.5

0.6

0.7

0.8

sce

cific

sca

tte

rin

g c

oe

ffic

ient,

L m

-1m

g-1

Graph 1St_2

St_5

St_6

St_9

St_10

St_11

St_14

St_15

St_18

St_19

average

Fit 2: Power

Specific scattering coefficient 25_07_08, Pakri Bay

Fit 2: Power

Equation ln(Y) = -0.47227858 * ln(X) + 2.33238219Alternate Y = pow(X,-0.47227858) * 10.30245473Coef of determination, R-squared = 0.93384

Dredging Pakri Bay 21_11_2008

WN wind 8-10m/s,

very low phytoplancton content

chlorophyll a concentration less

than 0.3μg/L

400 500 600 700wavelength, nm

2

3

4

5

6

7

8

sca

tteri

ng c

oeff

icie

nt, m

-1

Graph 1St_1

St_2

St_3

St_4

St_5

St_6

St_7

St_8

St_9

Scattering coefficient 21_11_2008, Pakri Bay

23.96 24 24.04 24.08 24.12

longitude

59.25

59.3

59.35

59.4

latitu

de

12

345678

9

0.5

1.5

2.5

3.5

4.5

5.5

6.5

7.5

TSM, mg/L

400 500 600 700wavelength, nm

0.5

0.6

0.7

0.8

0.9

1

sp

ecific

sca

tteri

ng c

oeff

icie

nt, L

m-1 m

g-1

Graph 1St_1

St_2

St_3

St_4

St_5

St_6

St_7

St_8

St_9

Average

Fit 2: Power

specific scattering coefficient 21_11_2008, Pakri Bay

Fit 2: PowerEquation ln(Y) = -0.6391894809 * ln(X) + 3.657421566Alternate Y = pow(X,-0.6391894809) * 38.76127054Coef of determination, R-squared = 0.9911883

0 1 2 3 4 5TSM(water samples), mg/L

0.8

1.2

1.6

2

2.4

2.8

Sca

tteri

ng c

oeff

icie

nt 5

55n

m, m

-1

1.759

2.713

1.063

0.9453

1.041

1.424

1.146

0.9361

1.0371.047

1.353

2.278

1.476

1.5991.66

1.414

2.306

1.691

1.346

1.417

1.521

1.637

1.411

1.586

1.779

1.316

1.439

Muuga Bay

Fit 1: Linear (september)Equation Y = 0.8259146341 * X + 0.5969433537Coef of determination, R-squared = 0.877689

Fit 1: LinearEquation Y = 0.3135433218 * X + 0.6032899913Coef of determination, R-squared = 0.729111

400 500 600 700wavelength, nm

0.5

0.6

0.7

0.8

0.9

1

coe

rre

letio

n c

oe

ffic

ient,

R

Graph 1R_Muuga 9_09_09

R_Pakri_5_09_08

R_Pakri_21_11_08

R_Muuga_28_04_10

R_Pakri_25_07_08

TSM(water samples) vs scattering coefficient (402-730nm)0 2 4 6 8 10TSM (water samples) mg/L

0

2

4

6

8sca

tte

rin

g c

oeff

icie

nt 5

55n

m,

m-1

1.426

1.7381.688

1.328

1.9781.747

1.5261.441

1.1031.177

1.6221.696

0.40250.4148

2.189

1.365

0.969

0.69070.63540.60790.57040.61990.56020.46760.50180.5018

3.414

4.09

4.983

5.255

5.612

6.334

5.86

4.969

3.703

Pakri Bay

Fit 1: Linear

Equation Y = 0.277384589 * X + 0.7808843179Coef of determination, R-squared = 0.42306

Fit 1: Linear

Equation Y = 0.4049322394 * X - 0.06595408231Coef of determination, R-squared = 0.86091

Fit 1: Linear

Equation Y = 0.577706255 * X + 0.7795352423Coef of determination, R-squared = 0.943193

MERIS case-2 processor products are reliable for describing the SPM

distribution in case when dominant particles in water are resuspended

particles.

In PECS project “Environmental monitoring of harbour dredging” are

planed:

1. Analysis of SPM distribution in two largest harbours in Estonia using

entire MERIS mission data (from CoastColour database) for detection of

long term changes. Relating the data to ship traffic intensity and dredging

activities.

Interesting datasets:

- SPM maps for cloud free days

- If possible some estimate of particles size distribution would be very

interesting for the environmental impact evaluation.

2. Interactive software tool for harbour authorities with dataset from:

(1)MERIS, (2) in situ measurements and (3) hyrdodynamical model for

monitoring SPM distribution during dredging operations.