modelling the drift of marine litter in the bay of...
TRANSCRIPT
AZTI-Marine Research, Herrera Kaia, Portualdea z/g, 20110 Pasaia, Spain
MODELLING THE DRIFT OF MARINE LITTER IN THE BAY OF BISCAY
L. FERRER O.C. BASURKOI. GRANADO
I. RUIZ A. RUBIOJ. MADER
M. NOGUES I. EPELDE P. LIRIA
I. DE SANTIAGOJ.L. ASENSIO
A. CABALLERO A. DEL CAMPO
1 DEFINITION OF THE PROBLEM TO BE SOLVED: DRIFT OF MACROPLASTICS
1 DEFINITION OF THE PROBLEM TO BE SOLVED: DRIFT OF MACROPLASTICS
1 DEFINITION OF THE PROBLEM TO BE SOLVED: DRIFT OF MACROPLASTICS
PLASTIC
BOTTLES:
DRY
WEIGHT
RANGE
0.33-0.5 L~
15 g
………….
1.5 L~
33 g
1 DEFINITION OF THE PROBLEM TO BE SOLVED: DRIFT OF MACROPLASTICS
THEY HAVE AN
IMPORTANT
EMERGED
PART
BUT
IT DEPENDS
ON EACH
SPECIFIC
OBJECT AND
ITS STATE OF
DEGRADATION
1 DEFINITION OF THE PROBLEM TO BE SOLVED: DRIFT OF MACROPLASTICS
THE BIG QUESTION:
HOW DO THESE FLOATING OBJECTS DRIFT?
COMPLEX ANWSER, TAKING INTO ACCOUNT THAT THE DATA WE USE
TO ESTIMATE THE REAL DRIFT COME FROM NUMERICAL MODELS AND
THERE IS AN IMPORTANT PROPAGATION OF ERRORS FROM THE
ATMOSPHERIC MODEL TO THE WAVE AND OCEAN CURRENT MODELS
2 METHODOLOGY: MODEL
THE SOLUTION SEEMS TO BE HERE:
CLOSER TO A WIND MODEL THAN AN
EKMAN MODEL AND SEEMS TO DEPEND
ON THE WIND VELOCITY, THEN WE
ASSUME THAT THE DRIFT VELOCITY IS AS
SIMPLE AS FOLLOWS:
U_drift = C_d * U_wind_c
C_d = DRAG COEFFICIENT
U_wind_c = WIND VELOCITY CORRECTED
WITH A DEFLECTION ANGLE
2 METHODOLOGY: MODEL
WRF (WEATHER RESEARCH AND FORECASTING MODEL) WINDS WITH
A RESOLUTION OF 12 km (MODEL RUN BY METEOGALICIA)
NUMERICAL SIMULATIONS
(FOR DRIFTERS WITH A DRY WEIGHT < 1 kg):
C_d = 0.01, 0.011, 0.012,…, 0.068, 0.069, 0.07
DEFLECTION ANGLE (MINUS: TO THE RIGHT) = 0, -5, -10,…, -35, -40, -45
TOTAL: 610 COMBINATIONS
2 METHODOLOGY: SMALL WOODEN BUOYS
DIFFERENT WEIGHTS (g): 800 – 1,200
HEIGHTS (cm): 7 – 8
2 METHODOLOGY: DRIFTING BUOYS
WEIGHTS (g):
184, 293, 377, 513
VOLUMES (mL): 775
HEIGHTS (cm): 9.3
WEIGHTS (g):
350, 561, 724, 975
VOLUMES (mL): 1,308
HEIGHTS (cm): 15.7
3 RESULTS
3 RESULTS
3 RESULTS
3 RESULTS
3 RESULTS
THE BEST RESULTS (TO IMPROVE):
C_d: [0.015 – 0.030]
Deflection angle: [0º – 25º]
3
3
THE BEST RESULTS (TO IMPROVE):
C_d: [0.045 – 0.06]
Deflection angle: [0º – 25º]
3
FROM THE ORIA RIVER MOUTH
(NOT STILL SIMULATED)
CALM WEATHER LOW VELOCITIES
SHORT TRAJECTORIES AND A POSSIBLE
PROBLEM: MARINE LITTER GROUPING
3 RESULTS
MARINE
LITTER
GROUPING
PHOTO FROM IRATI’S HOUSE (ZARAUTZ)
3 RESULTSNEAR
ZARAUTZ
15 APRIL 2018
13:00 GMT
KOSTASystem
(WWW.KOSTASYSTEM.COM)
3 RESULTSNEAR
ZARAUTZ
15 APRIL 2018
14:00 GMT
KOSTASystem
(WWW.KOSTASYSTEM.COM)
3 RESULTSNEAR
ZARAUTZ
15 APRIL 2018
15:00 GMT
KOSTASystem
(WWW.KOSTASYSTEM.COM)
3 RESULTS
ZARAUTZ
BEACH
8 MAY 2018
16:00 GMT
KOSTASystem
(WWW.KOSTASYSTEM.COM)
2 RESULTS
LA CONCHA
BEACH
5 JUNE 2018
18:42 GMT
4 CONCLUSIONS
-MORE THAN 95% OF THE BOATS AND BUOYS DRIFTED, ON AVERAGE, TOWARDS THE EAST, DEPENDING MORE ON THE CYCLONIC CONDITIONS (HIGHER VELOCITIES) THAN ON THE ANTICYCLONIC ONES (LOWER VELOCITIES).
-WE FOUND THAT IT IS A DIFFICULT TASK FOR MARINE LITTER (IN MANY CASES DRIFTING IN GROUPS: “MARINE LITTER GROUPING”) TO ENTER OR LEAVE THE BAY OF BISCAY, SUGGESTING THAT THE SOURCES OF LITTER ARE IN THE BAY.
-A SIMPLE AND DIRECT RELATIONSHIP BETWEEN THE WIND AND DRIFT VELOCITIES IS APPLIED, WHICH REASONABLY REPRODUCES THE DRIFT OF THE BOATS AFTER ADJUSTING WIND PARAMETERS. IN THE CASE OF THE BUOYS, IT IS MORE COMPLEX TO OBATIN A SATISFACTORY RESULT (TO CONTINUE THE SIMULATIONS).
5 FUTURE WORKS
-WE WILL INCORPORATE THE EFFECTS OF WAVES AND SURFACE OCEAN CURRENTS (OUTPUTS FROM NUMERICAL MODELS AND HIGH-FREQUENCY RADAR) AND OTHERS TERMS SUCH AS THE TURBULENT DIFUSSION.
-BUT AS THESE DATA DEPEND ON THE WIND, IT IS VERY POSSIBLE THAT THE SOLUTION OBTAINED DOES NOT IMPROVE THE PRESENT RESULTS, BECAUSE THE WIND MODEL ERRORS PROPAGATE TO THE WAVE AND CURRENT MODELS.
-MOREOVER, THE MODEL OBTAINED MUST BE USED WITH FORECAST DATA INSTEAD OF THE BEST DATA OF THE PAST IN ORDER TO STUDY ITS ACCURACY IN FORECAST MODE, I.E. IT WILL BE MORE DIFFICULT FOR THE MODEL TO WORK WITH GUARANTEES.
-USE LOWER WEIGHT DRIFTERS SIMILAR TO EMPTY PLASTIC BOTTLES.
