Modeling extreme beach retreat and erosion volumes. A tool ... · PDF fileModeling extreme...
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Modeling extreme beach retreat and erosion volumes. A tool for susceptibility analysis Modeling extreme beach retreat and erosion volumes. A tool for susceptibility analysis Jorge Trindade * & Ana Ramos-Pereira * [email protected] [email protected] * Centre of Geographical Studies (IGOT/UL) Edifício da Faculdade de Letras, Universidade de Lisboa Alameda da Universidade, 1600-214 Lisboa, Portugal European Geosciences Union General Assembly 2012 Vienna | Austria | 22 – 27 April 2012 slif.info.ul.pt 1.Introduction Introduction Beaches are among the most dynamic systems in the coastal zone. This is due to the great variability in the main triggering factors that contribute to morphological change. Dramatic coast line retreat can occur in a short period of time due to episodic extreme wave events endangering people and property and therefore defining the local susceptibility to erosion. This research aims to determinate beach recession and volume erosion due to sediment loss during extreme wave events in non artificialized beaches of the Portuguese west coast, for susceptibilityanalysis. 2.Study Studyarea area The central west coast of Portugal is a wave dominated high energetic coastal environment. Storm frequency and magnitude are very important features on the definition of the annual local sediment budget and on the anthropogenic elements exposure to the direct action of waves through momentary or permanent coastline retreat. Hydrodynamic Hydrodynamicreference referencevalues values 5 6 7 8 9 10 11 12 13 14 s Tz Início →16.02.2006 (Sn) Direcção modal = NW 0 1 2 3 4 5 6 7 0 20 40 60 80 100 m horas Hs (0m - zh) Mr (0m - nmm) 6,28 5 6 7 8 9 10 11 s Início →23.10.2006 (Le) Direcção modal = W 0 1 2 3 4 5 6 7 8 0 20 40 m horas 7,34 5 6 7 8 9 10 11 12 13 14 15 16 17 s Início →13.02.2006 (Sn) Direcção modal = WNW 0 1 2 3 4 5 6 0 10 20 30 m horas 5,34 5 6 7 8 9 10 11 s Início →03.03.2006 (Sn) Direcção modal = WNW 0 1 2 3 4 5 0 20 40 60 80 m horas 4,29 5 6 7 8 9 10 11 12 13 14 s Início →16.02.2006 (Sn) Direcção modal = NW 0 1 2 3 4 5 6 7 0 20 40 60 80 100 m horas 6,28 5 6 7 8 9 10 11 s Início →03.03.2006 (Sn) Direcção modal = WNW 0 1 2 3 4 5 0 20 40 60 80 m horas 4,29 0m (msl) 0m recession [Dissipative profile] 3m recession [Dissipative profile] R² = 0,93 0 500 1000 1500 2000 2500 3000 3500 0 1000 2000 3000 m 3 /m m 3 /m Previsto Medido Predicted Measured -3 -2 -1 0 1 2 3 4 5 6 7 8 90 110 130 150 170 190 210 m m P5 pnmr↑ -3 -2 -1 0 1 2 3 4 5 6 7 8 m P4 pnmr↑ -3 -2 -1 0 1 2 3 4 5 6 7 8 m P3 ↑pnmr -3 -2 -1 0 1 2 3 4 5 6 7 8 m P2 -3 -2 -1 0 1 2 3 4 5 6 7 8 m a b c P1 ↑pnmr nmm -3 -2 -1 0 1 2 3 4 5 6 7 8 m P1 ↑pnmr -3 -2 -1 0 1 2 3 4 5 6 7 8 m P2 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P3 pnmr↑ -3 -2 -1 0 1 2 3 4 5 6 7 8 m P4 pnmr↑ -3 -2 -1 0 1 2 3 4 5 6 7 8 90 110 130 150 170 190 210 m m P5 ↑pnmr -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P2 ↑ pnmr -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m a b c P1 ↑ pnmr nmm -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P3 ↑pnmr -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P4 ↑pnmr -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P5 ↑pnmr -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 40 60 80 100 120 140 m m P6 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P2 ↑ pnmr -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P3 ↑ pnmr -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P4 ↑pnmr -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P1 ↑pnmr -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P5 ↑pnmr -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 40 60 80 100 120 140 m m P6 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P2 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P4 -3 -2 -1 0 1 2 3 4 5 6 7 8 0 50 100 150 m m P5 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P1 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P3 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P4 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 0 50 100 150 200 m m P5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P2 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m P3 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 m a b c P1 nmm Model Modelcalibration calibration Successive adjustment of the K (transport rate term) and Є (slope dependent term) for P1 in each beach system and on the first storm event to best fit measured results. In the worst case scenario themodelexplainsover89%ofthemeasuredprofile. Model Modelvalidation validation K and Є calibrated values where then applied to the rest of the 29 profiles in the three beach systems to access model performance and results validation. In most cases the model explains more than 90% (20 in 32 cases) of the measured changes due to storm events. The maximum relativedifferencevalue is -39,7%. SBEACH SBEACH Modeling Modeling Larson & Kraus, 1989; Wiseet al., 1996 Model Model calibration calibration K e e Є empirical empirical ajustment ajustment (P1) P1) Validation Validationof ofthe the volumetric volumetricbudget budget (P2 (P2, P3, P4, P5 e P6) , P3, P4, P5 e P6) Morphodynamic Morphodynamic reference referencevalues values Hydrodynamic Hydrodynamicreference referencevalues values coastline retreat. Winter offshore mean significant wave values reach 2.5m and waveswitha5yearrecurrenceperiodcanbehigherthan9m. 3. Methodology Methodology: (i)Morphodynamicdata – 3 yr of beach profilling(2004 – 2007); (ii)Sediment sampling in the most active sector of the beach profileandlab treatmentefor granulometricanalysis; (iii)Offshorewavedataprocessing; (iv)Stormsurgevalues determination; (v)Extreme volumetric predicted values (H s R100 ) based on SBEACHmodelling. 4.Parametrization Parametrization (i)H s ; (ii)Springtidemeanlevel; (iii)Stormsurge; (iv)Geometricpropertiesofthemeasuredbeachprofiles; (v)Sedimentpropertiesofthebeachprofiles. Morphodynamic Morphodynamicreference referencevalues values Days Profile Vol. budget (m 3 /m) SR 15.02.2006 01.03.2006 P1 -26,5 P2 -16,8 P3 -20,3 P4 -15,9 P5 +14,2 14.06.2006 28.11.2006 P1 -27,9 P2 -16,3 P3 -20,5 P4 -0,9 P5 -5,0 Days Profile Vol. budget (m 3 /m) AZ 31.01.2006 14.02.2006 P1 -19,0 P2 -22,1 P3 -25,2 P4 -18,7 P5 -16,9 P6 -47,7 28.02.2006 14.03.2006 P1 -6,7 P2 -22,6 P3 -11,7 P4 -7,2 P5 -3,8 P6 -23,6 Days Profile Vol. budget (m 3 /m) LZ 13.02.2006 02.03.2006 P1 -10,6 P2 -20,5 P3 -13,6 P4 -52,5 P5 -52,2 02.03.2006 15.03.2006 P1 -73,6 P2 -70,7 P3 -84,3 P4 -47,6 P5 -34,8 SR (P1) AZ (P1) LZ (P1) Measured pre-stormvolume (m 3 /m) 173,9 (15.02.2006) 90,6 (31.01.2006) 340,1 (13.01.2006) Measured post-stormvolume (a) (m 3 /m) 147,4 (01.03.2006) 71,6 (14.02.2006) 329,5 (02.03.2006) K (m 4 /N) 2,50*10 -7 2,50*10 -7 2,50*10 -7 Є (m 2 /s) 0,005 0,005 0,005 Predicted post-stormvolume (b) (m 3 /m) 131,4 69,9 301,6 Relative volume difference (a and b) (%) -10,9 -2,3 -8,5 Empirical Empiricalcalibration calibration 0 100 200 50 Meters 0 150 300 75 Meters 0 100 200 50 Meters S ta . Rita beach Azulbeach Fozdo Lizandro beach 0m (msl) System boundary 0m recession [Dissipative profile] 0m recession [Reflective profile] 3m recession [Dissipative profile] 3m recession [Reflective profile] References: BLOTT,S.& PYE,K.(2006)–Particlesizedistributionanalysisofsand-sizedparticlesbylaserdiffraction:anexperimentalinvestigationofinstrumentsensitivityandtheeffectsofparticleshape.Sedimentology,53,p.671–685; COSTA,M.(1994)–Agitaçãomarítimanacostaportuguesa.AnaisdoInstitutoHidrográfico,13,p.35–40; GAMA,C.;DIAS,J.;FERREIRA,Ó.&TABORDA,R.(1994)–AnalysisofstormsurgeinPortugal,betweenJune1986andMay1988.ProccedingsofLittoral94,Lisboa, p.26–29p.; LARSON,M.&KRAUS,N.(1998)–Numericalmodelforsimulatingstorminducedbeachchange.Report5:Representationofnonerodible(hard)Bottoms.TechnicalReportCERC-89-9,U.S.ArmyCorpsofEngineers,Vicksburg,U.S.A.,47p.; LARSON,M.;KRAUS,N.&BYRNES,M.(1990)–Numericalmodelforsimulatingstorminducedbeachchange.Report2:Numericalformulationandmodeltests.TechnicalReportCERC-89-9,U.S.ArmyCorpsofEngineers,Vicksburg,U.S.A.,120p.; OLIVEIRAPIRES,H.;PESSANHA,L.E.(1982)–CaracterísticasdireccionaisdaagitaçãomarítimanaregiãodeSines.InstitutoNacionaldeMeteorologiaeGeofísica,12p+fig.; ROSATI,J.;WISE,R.;KRAUS,N.&LARSON,M.(1993)–Numericalmodelforsimulatingstorminducedbeachchange.Report3:User’sManual.TechnicalReportCERC-93-2,U.S.ArmyCorpsofEngineers,Vicksburg,U.S.A.,64p.; STOCKDON,H.;HOLMAN,R.;HOWD,P.& SALLENGERJR.,A.(2006)–Empiricalparameterizationofsetup,swash,andrunp.CoastalEngineering,53,p.573–588; TABORDA,R.&DIAS,J.A.(1992)–AnálisedasobreelevaçãodomardeorigemmeteorológicaduranteostemporaisdeFevereiro/Marçode1978eDezembrode1981.Geonovas,1,p.89–97; Trindade,J.;Pereira,A.R.;Neves,M.;Borges,B.& Paixão,R.,2007.Monitorizaçãoda morfodinâmicadepraiascom dGPSeEstaçãoTotal.Comparaçãoderesultados.PublicaçõesdaAssociaçãoPortuguesadeGeomorfólogosVol. V,p.293-301 WISE, R.; SMITH, S.& LARSON, M. (1996) – SBEACH: Numericalmodel for simulating storm-induced beach change. Report4: Cross-shore transportunder random wavesand model validation with SUPERTANK and field data. Technical Report CERC-89-9,USArmyCorpsofEngineers,Vicksburg,260p.;
Transcript of Modeling extreme beach retreat and erosion volumes. A tool ... · PDF fileModeling extreme...
Modeling extreme beach retreat and erosion volumes. A tool for susceptibility analysisModeling extreme beach retreat and erosion volumes. A tool for susceptibility analysisJorge Trindade* & Ana Ramos-Pereira *
[email protected] [email protected]
* Centre of Geographical Studies (IGOT/UL)Edifício da Faculdade de Letras, Universidade de Lisboa
Alameda da Universidade, 1600-214 Lisboa, Portugal
European Geosciences Union
General Assembly 2012
Vienna | Austria | 22 – 27 April 2012
slif.info.ul.pt
11.. IntroductionIntroduction
Beaches are among the most dynamic systems in the coastal
zone. This is due to the great variability in the main triggering
factors that contribute to morphological change. Dramatic coast
line retreat can occur in a short period of time due to episodic
extreme wave events endangering people and property and
therefore defining the local susceptibility to erosion. This
research aims to determinate beach recession and volume
erosion due to sediment loss during extreme wave events in non
artificialized beaches of the Portuguese west coast, for
susceptibility analysis.
22.. StudyStudy areaarea
The central west coast of Portugal is a wave dominated high
energetic coastal environment. Storm frequency and magnitude
are very important features on the definition of the annual local
sediment budget and on the anthropogenic elements exposure
to the direct action of waves through momentary or permanent
coastline retreat.
HydrodynamicHydrodynamic referencereference valuesvalues
5
6
7
8
9
10
11
12
13
14
s
Tz
Início → 16.02.2006 (Sn)
Direcção modal = NW
0
1
2
3
4
5
6
7
0 20 40 60 80 100
m
horas
Hs (0m - zh)
Mr (0m - nmm)6,28
5
6
7
8
9
10
11
s
Início → 23.10.2006 (Le)
Direcção modal = W
0
1
2
3
4
5
6
7
8
0 20 40
m
horas
7,34
56789
1011121314151617
s
Início → 13.02.2006 (Sn)
Direcção modal = WNW
0
1
2
3
4
5
6
0 10 20 30
m
horas
5,34
5
6
7
8
9
10
11
s
Início → 03.03.2006 (Sn)
Direcção modal = WNW
0
1
2
3
4
5
0 20 40 60 80
m
horas
4,29
5
6
7
8
9
10
11
12
13
14
s
Início → 16.02.2006 (Sn)
Direcção modal = NW
0
1
2
3
4
5
6
7
0 20 40 60 80 100
m
horas
6,28
5
6
7
8
9
10
11
s
Início → 03.03.2006 (Sn)
Direcção modal = WNW
0
1
2
3
4
5
0 20 40 60 80
m
horas
4,29
0m (msl) 0m recession [Dissipative profile] 3m recession [Dissipative profile]
R² = 0,930
500
1000
1500
2000
2500
3000
3500
0 1000 2000 3000
m3/
m
m3/m
Pr
ev
isto
Medido
Pr
ed
icte
d
Measured
-3
-2
-1
0
1
2
3
4
5
6
7
8
90 110 130 150 170 190 210
m
m
P5
pnmr↑
-3
-2
-1
0
1
2
3
4
5
6
7
8
m
P4
pnmr↑
-3
-2
-1
0
1
2
3
4
5
6
7
8
m
P3
↑ pnmr-3
-2
-1
0
1
2
3
4
5
6
7
8
m
P2
-3
-2
-1
0
1
2
3
4
5
6
7
8
m
a
b
c
P1
↑ pnmr
nmm
-3
-2
-1
0
1
2
3
4
5
6
7
8
m
P1
↑ pnmr
-3
-2
-1
0
1
2
3
4
5
6
7
8
m
P2
-3
-2
-1
0
1
2
3
4
5
6
7
8
m
P3
pnmr↑
-3
-2
-1
0
1
2
3
4
5
6
7
8
m
P4
pnmr↑
-3
-2
-1
0
1
2
3
4
5
6
7
8
90 110 130 150 170 190 210
m
m
P5
↑ pnmr
-4
-3-2
-10
12
34
56
78
m
P2
↑ pnmr
-4
-3-2
-10
12
34
56
78
m
a
b
c
P1
↑ pnmr
nmm
-4
-3-2
-10
12
34
56
78
m
P3
↑ pnmr
-4-3
-2-1
01
23
45
67
8
m
P4
↑ pnmr
-4-3
-2-1
01
23
45
67
8
m
P5
↑ pnmr
-4-3
-2-1
01
23
45
67
8
40 60 80 100 120 140
m
m
P6
-4
-3-2
-101
23
45
67
8
m
P2
↑ pnmr
-4
-3-2
-10
12
34
56
78
m
P3
↑ pnmr
-4-3
-2-1
01
23
45
67
8
m
P4
↑ pnmr
-4
-3-2
-10
12
34
56
78
m
P1
↑ pnmr
-4
-3-2
-10
12
34
56
78
m
P5
↑ pnmr
-4-3
-2-1
01
23
45
67
8
40 60 80 100 120 140
m
m
P6
-3
-2
-1
0
1
2
3
4
5
6
7
8
m
P2
-3
-2
-1
0
1
2
3
4
5
6
7
8
m
P4
-3
-2
-1
0
1
2
3
4
5
6
7
8
0 50 100 150
m
m
P5
-3
-2
-1
0
1
2
3
4
5
6
7
8
m
P1
-3
-2
-1
0
1
2
3
4
5
6
7
8
m
P3
-4-3
-2-10
123
45
678
m
P4
-4-3
-2-10
12
345
67
8
0 50 100 150 200
m
m
P5
-4
-3-2
-101
23
456
78
m
P2
-4-3-2
-10
123
45
678
m
P3-4
-3-2-1
01
234
56
78
m
a
b
c
P1
nmm
ModelModel calibrationcalibrationSuccessive adjustment of the K (transport rate term) and Є (slope dependent term) for P1 in eachbeach system and on the first storm event to best fit measured results. In the worst case scenariothe model explains over 89% of the measured profile.
ModelModel validationvalidationK and Є calibrated values where then applied to the rest of the 29 profiles in the three beachsystems to access model performance and results validation. In most cases the model explainsmore than 90% (20 in 32 cases) of the measured changes due to storm events. The maximumrelative difference value is -39,7%.
SBEACHSBEACH
ModelingModelingLarson & Kraus, 1989;
Wise et al., 1996
ModelModelcalibrationcalibration
KK e e ЄЄ empiricalempirical ajustmentajustment
((P1)P1)
ValidationValidation ofof thethevolumetricvolumetric budgetbudget(P2(P2, P3, P4, P5 e P6), P3, P4, P5 e P6)
Morphodynamic Morphodynamic referencereference valuesvalues
HydrodynamicHydrodynamic referencereference valuesvalues
coastline retreat.
Winter offshore mean significant wave values reach 2.5m and
waves with a 5 year recurrence period can be higher than 9m.
33.. MethodologyMethodology::
(i)Morphodynamic data – 3 yr of beach profilling (2004 – 2007);
(ii)Sediment sampling in the most active sector of the beach
profile and lab treatmente for granulometric analysis;
(iii)Offshore wave data processing;
(iv)Storm surge values determination;
(v)Extreme volumetric predicted values (HsR100) based on
SBEACH modelling.
44.. ParametrizationParametrization(i) Hs ;(ii) Spring tide mean level;(iii) Storm surge;(iv) Geometric properties of the measured beach profiles;(v) Sediment properties of the beach profiles.
MorphodynamicMorphodynamic referencereference valuesvalues
Days ProfileVol . budget
(m3/m)
SR
15.02.2006����
01.03.2006
P1 -26,5P2 -16,8P3 -20,3P4 -15,9P5 +14,2
14.06.2006����
28.11.2006
P1 -27,9P2 -16,3P3 -20,5P4 -0,9P5 -5,0
Days ProfileVol . budget
(m3/m)
AZ
31.01.2006����
14.02.2006
P1 -19,0P2 -22,1P3 -25,2P4 -18,7P5 -16,9P6 -47,7
28.02.2006����
14.03.2006
P1 -6,7P2 -22,6P3 -11,7P4 -7,2P5 -3,8P6 -23,6
Days ProfileVol . budget
(m3/m)
LZ
13.02.2006����
02.03.2006
P1 -10,6P2 -20,5P3 -13,6P4 -52,5P5 -52,2
02.03.2006����
15.03.2006
P1 -73,6P2 -70,7P3 -84,3P4 -47,6P5 -34,8
SR (P1) AZ (P1) LZ (P1)Measured pre-storm volume (m3/m) 173,9 (15.02.2006) 90,6 (31.01.2006) 340,1 (13.01.2006)
Measured post-storm volume (a) (m3/m) 147,4 (01.03.2006) 71,6 (14.02.2006) 329,5 (02.03.2006)
K (m4/N) 2,50*10-7 2,50*10-7 2,50*10-7
Є (m2/s) 0,005 0,005 0,005
Predicted post-storm volume (b) (m3/m) 131,4 69,9 301,6
Relative volume difference (a and b) (%) -10,9 -2,3 -8,5
EmpiricalEmpirical calibrationcalibration
0 100 20050 Meters 0 150 30075 Meters 0 100 20050 Meters
Sta. Rita beach Azul beach
Foz do Lizandrobeach
0m (msl)
System boundary
0m recession [Dissipative profile]
0m recession [Reflective profile]
3m recession [Dissipative profile]
3m recession [Reflective profile]
References:BLOTT, S. & PYE, K. (2006) – Particle size distribution analysis of sand-sized particles by laser diffraction: an experimental investigation of instrument sensitivity and the effects of particle shape. Sedimentology, 53, p.671 – 685;COSTA, M. (1994) – Agitação marítima na costa portuguesa. Anais do Instituto Hidrográfico, 13, p.35 – 40;GAMA, C.; DIAS, J.; FERREIRA, Ó. & TABORDA, R. (1994) – Analysis of storm surge in Portugal, between June 1986 and May 1988. Proccedings of Littoral 94, Lisboa, p.26 – 29p.;LARSON, M. & KRAUS, N. (1998) – Numerical model for simulating storm induced beach change. Report 5: Representation of nonerodible(hard) Bottoms. Technical Report CERC-89-9, U.S. Army Corps of Engineers, Vicksburg, U.S.A., 47p.;LARSON, M.; KRAUS, N. & BYRNES, M. (1990) – Numerical model for simulating storm induced beach change. Report 2: Numerical formulation and model tests. Technical Report CERC-89-9, U.S. Army Corps of Engineers, Vicksburg, U.S.A., 120p.;OLIVEIRA PIRES, H.; PESSANHA, L. E. (1982) – Características direccionais da agitação marítima na região de Sines. Instituto Nacional de Meteorologia e Geofísica, 12p + fig.;
ROSATI, J.; WISE, R.; KRAUS, N. & LARSON, M. (1993) – Numerical model for simulating storm induced beach change. Report 3: User’s Manual. Technical Report CERC-93-2, U.S. Army Corps of Engineers, Vicksburg, U.S.A., 64p.;STOCKDON, H.; HOLMAN, R.; HOWD, P. & SALLENGER JR., A. (2006) – Empirical parameterization of setup, swash, and runp. Coastal Engineering, 53, p.573 – 588;TABORDA, R. & DIAS, J. A. (1992) – Análise da sobreelevação do mar de origem meteorológica durante os temporais de Fevereiro/Março de 1978 e Dezembro de 1981. Geonovas, 1, p.89 – 97;Trindade, J.; Pereira, A. R.; Neves, M.; Borges, B. & Paixão, R., 2007. Monitorização da morfodinâmica de praias com dGPS e Estação Total. Comparação de resultados. Publicações da Associação Portuguesa de Geomorfólogos Vol. V, p. 293 - 301WISE, R.; SMITH, S. & LARSON, M. (1996) – SBEACH: Numerical model for simulating storm-induced beach change. Report 4: Cross-shore transport under random waves and model validation with SUPERTANK and field data. Technical ReportCERC-89-9, US Army Corps of Engineers, Vicksburg, 260p.;
