transporte transversaltransporte transversalcuando es relevante? impacto de tormentas evolución de...

[email protected] – DINAMICA COSTERA

Transporte TransversalTransporte Transversal José A. Jiménezj ji @ [email protected]

Laboratori d’Enginyeria MarítimaETSECCPB

Universitat Politècnica de Catalunya

TRANSPORTE TRANSVERSAL


TRANSPORTETRANSVERSAL

CAMBIOS EN PERFILCAMBIOS ESTACIONALES (reversibles nat.)CORTO PLAZOTRANSVERSAL

UNDERTOW + otros

TRANSPORTELONGITUDINAL

CAMBIOS EN PLANTACAMBIOS PERMANENTES (irreversibles nat.)MEDIO-LARGO PLAZO

CORRIENTE LONGITUDINAL



CUANDO ES RELEVANTE?

Impacto de tormentasEvolución de rellenosCambios estacionalesEfecto SLREfecto del rebase del oleajeEfecto del rebase del oleajeEvolución frente a estructurasBypass de material en groins



Cambios en el perfil

Profile A Profile A –– Beach shaped byBeach shaped bynormal wave actionnormal wave action

t = horast = horas--diasdiasPerfil de erosión(impacto de temporales)

Profile B Profile B –– Storm wave Storm wave attackattack

Profile C Profile C –– After storm, normal After storm, normal wave action rebuildswave action rebuildsnew bermnew berm

t = semanast = semanas--mesesmesesPerfil de acumulación new bermnew bermPerfil de acumulación(oleaje baja energía)

TRANSPORTE TRANSVERSALProfile D Profile D –– Under normal wave Under normal wave action beach returnsaction beach returnsto berm profileto berm profile


Hazaki Oceanographical Research Station (HORS)


SeawardSeaward

Shoreline position changeShoreline position change


Tipologías básicas

Barra litoral

“Filtro energético”“Almacén” de material



December 11 2005: 12:00

December 13 2005: 9:00

January 7 2006: 8:00January 7 2006: 8:00

January 8 2006: 8:00January 8 2006: 8:00

January 9 2006: 9:00

January 10 2006: 9:00

TRANSPORTE TRANSVERSAL January 25 2006: 12:00


AGENTES IMPULSORESAGENTES IMPULSORES



Procesos que determinan el transporte transversal

BBCC

AABB



Asiim

etriaa

2

2

cosh 4 ( ) /( )

2 sinh (2 / )z d LH CU z

L d L

Mean drift velocity:


2 sinh (2 / )L d L


2/1 Transporte fuera de zona de rompientes

2/17 mcm Watanabe, 1982)

3

2/122 uu

Φ tasa de transporte adimensionalizadoΨm magnitud del parámetro de ShieldsΨc parámetro de Shields crítico

3u

Ψc parámetro de Shields crítico



No linealidad de las olas

HL

PeralteLdL

Profundidad relativa

//

LH L Hd L d

Altura de ola relativa

2 2

/d L dL H HLU Número de Ursell

3RUd d d



FUERA DE ZONA DE ROMPIENTES

Transporte hacia tierra

Depende de la asimetría del campo de velocidades oscilatorio

Aumenta con la no linealidad del oleajeAumenta con la no-linealidad del oleaje



Procesos que determinan el transporte transversal

BBCC

AABB



Undertow - Corriente de retorno



Undertow

(distribución vertical del tensor de radiación &

(distribución vertical de la

tensor de radiación & gradiente de presión)

velocidadxxdSdgd

dx dx

dx dx

0.08 0.010 gd (cerca del Undertow current ≈


gfondo)


(a) (b)


Qov

Qdw = Qup - Qov

Qup


Corrientes transversales

t t d•• transporte de masa• streaming

(boundary layer)• undertow

Transporte de masa (onshore)

Undertow (offshore)Streaming (onshore)



DENTRO DE ZONA DE ROMPIENTES

Transporte hacia mar

Depende de la intensidad del undertow

Decrece en las inmediaciones del punto de roturaDecrece en las inmediaciones del punto de rotura



Olas no rotas - onshore

Rompientes - offshore

Bajo tormentas – barra externa se mueve hacia tierra y la barra interna se achata

Barras múltiples si se reforman las olas en rotura

Barra externa se forma por las olas más energéticas

Barra interna se forma por las olas menos energéticas


PROCESS-BASED MODEL

2/17 mcm Watanabe, 1982)

Φ is the dimensionless transport rate, Ψm is the magnitude of the instantaneous Shields parameter and Ψc is the critical Shields parameterand Ψc is the critical Shields parameter

Note the massive scatter (log-log plot) and variations in the coefficients.


Predictores del cambio en el perfil de playa


3o oH HM berm

L T

LWT datos

3o

o o

L wT

H HM bar

o

M barL wT

0.00070M

datos de

(altura de ola media para oleaje irregular)

campo


Parámetro de Dean

• Annual berm-bar cycle.critical conditioncritical condition

aTw

Ho

> di t ff h (b )

Twf

• > a – sediment moves offshore (bar)• < a – sediment moves onshore (berm)

2 5 ( f)• a ≈ 2.5 (ag prof)• a ≈ 4 (rotura)


Perfil de equilibrio

Perfil de playa está en equilibrio con el oleaje incidente.

P fil d l di i d f if l fl j d í d lPerfil de playa disipa de forma uniforme el flujo de energía del oleaje incidente.

)tan(xh Línea de orilla y zona de swash

2

3/2Axh Perfil sumergido

)(25.22

gwA


)t (h

28.050

32.050

5094.0

50

4010)(230

104.0,)(23.0

4.0,)(41.0

mmddA

mmddA

mmddA

)tan(

2

3/2Axhxh

5011.0

50

5050

40,)(46.0

4010,)(23.0

dmmdA

mmddA

)(25.2

2

gwA


Perfil de equilibrio generalizado

Zona de rompientes

, 0mbh Ax x x (Dean profile m=2/3)

Offshore

bn

bn

b xxxxBhh ,)(/1


0

4

8

)

measured profile

lsq-fitted EBPs

-2

-1

Prof

ile E

leva

tion

(m)

-4

0

Prof

ile E

leva

tion

(m) lsq fitted EBPs

-3

2P

measured profile

lsq-fitted EBPs

-12

-8

P

180 200 220 240 260Cross-Shore Distance (m) 0 200 400 600 800

Cross-Shore Distance (m)

GWK (laboratorio) Long IslandGWK (laboratorio) Long Island


167 /30.142 bB h

12

3)

measured

empirical formula

8

amet

er (m

^7/3

4Shap

e Pa

ra

0

0 2 4 6 8Depth at Breaking (m)


2.a Equilibrium beach profile erosion model (Dutch)2.a Equilibrium beach profile erosion model (Dutch)

B h fil i ilib i ith i id t li tB h fil i ilib i ith i id t li tBeach profile in equilibrium with incident wave climate.Beach profile in equilibrium with incident wave climate.

Model developed for storm conditionsModel developed for storm conditionsModel developed for storm conditions.Model developed for storm conditions.

Based on a set of experiments in laboratory (Large Wave flume)Based on a set of experiments in laboratory (Large Wave flume)p y ( g )p y ( g )Vellinga (1986) in NetherlandsVellinga (1986) in Netherlands


Profile measurements


0.51.28 0.567.6 7.60.4714 18 2.0

wy x

0 0

0.4714 18 2.00.0268s s

y xH H


••New equilibrium equation including Tp:New equilibrium equation including Tp:0.5

1.28 0.4 65 0.5

0 0

127.6 7.60.4714 18 2.0

0.0268T

wy x

H H

TTpp = 12 s = 12 s

0 0 ps s

storm surge levelstorm surge level

initial profileinitial profile

Longer wave periodLonger wave period


2.b Equilibrium beach profile erosion model (US)2.b Equilibrium beach profile erosion model (US)

K i b l & D (1993) USAK i b l & D (1993) USAKriebel & Dean (1993) USA Kriebel & Dean (1993) USA

Using equilibrium beach profilesUsing equilibrium beach profilesUsing equilibrium beach profiles.Using equilibrium beach profiles.

Model developed for storm conditions.Model developed for storm conditions.pp

Storm characterized by stormStorm characterized by storm--surge & wave conditions.surge & wave conditions.

Two cases depending on the initial beach profile.Two cases depending on the initial beach profile.


Solutions for sloping beachface (general) Solutions for sloping beachface (general)


3.a Beach profile response to RSLR3.a Beach profile response to RSLR

B l (1962)B l (1962)Bruun rule (1962)Bruun rule (1962)

Simple behaviour modelSimple behaviour modelSimple behaviour model.Simple behaviour model.

Forcing condition (RSLR).Forcing condition (RSLR).g ( )g ( )


Types of CrossTypes of Cross--Shore Transport ModelsShore Transport Models

•• energy dissipation models (Kriebelenergy dissipation models (Kriebel--Dean)Dean)

•• energetics models (Bailardenergetics models (Bailard Inman)Inman)•• energetics models (Bailardenergetics models (Bailard--Inman)Inman)

•• concentrationconcentration--velocity modelsvelocity models


SIMPLE ENGINEERING MODEL

D&D

Example, profile is too shallow (slope less than equilibrium), sediment transport should be onshore to steepen profile.

For this case, shallow profile indicates a D<D*. Waves will break further offshore and there will be less turbulence than the equilibrium profile case for each cross-shore location


Cross-Shore Transport Rate I

Kriebel and Dean (1985):Kriebel and Dean (1985):

c eqq K D D

5 3/ 2 2 3/ 2524eqD g A


Cross-Shore Transport Rate II

Larson and Kraus (1989):Larson and Kraus (1989):

Surf zone (breaking waves):Surf zone (breaking waves):

cs eqdhq K D D

K dx

Offshore zone (nonOffshore zone (non--breaking waves):breaking waves):

/

exp ( )co b bq q x x 1/ 2

5025 b

dH

b

transporte transversaltransporte transversalcuando es relevante? impacto de tormentas evolución de...

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