Coastal systems under changing

meteo & climate conditions Invited lecture

Prof. Agustín Sánchez-Arcilla (agustin.arcilla@upc.edu)

Maritime Engineering Laboratory (LIM/UPC) – Intl. Centre for Coastal Resources Res.

Catalonia University of Technology (UPC) in Barcelona

1.- The case study (CAT coast) 2.- The climatic (decadal) scale: long-term planning 3.- The storm (hourly) scale: risk management 4.- The mid-term (yearly) scale: engineering 5.- The way ahead

High geo- diversity

Coastal fringe width 500 m 6.9% total area CAT - 48% total population CAT

The CATALAN coast case ~ 700 km

Length ~ 700 km Sand beaches ~ 250 km Urban (pocket) beaches ~ 150 km Open beaches ~ 75 km

26 Dec 2008 storms

Limited no. of extremes

Sharp gradients (prediction challenges)

High meteo - diversity The CATALAN coast case ~ 700 km

Riu Ebre

High variability Management signal clearly observable

Cap Tortosa erosion > 1750 m in 43 years (40 m/y) 1957 1973

1984

1989 1993

1998

2000 image

1900 1925 1950 1975 2000tiempo (años)

0

200

400

600

800

1000

caud

al m

edio

anu

al (m

3 /s)

The CATALAN coast case ~ 700 km

Port Balís – Mataró (Nord platja Callao) Trabucador, Delta del Ebre

The CATALAN coast case ~ 700 km

Horizontal variability hindered (by shore rigidization)

Horizontal/Vertical erosion (sediment scarcity)

Decadal (climatic) scale drivers Observations Barcelona (1992-2007) & Valencia (1992-2006) harbours Observed trend: slight decrease of MSL (steadiness)

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007Year

-60

-40

-20

0

20

40

60

Sto

rm S

urge

Lev

el [c

m]

Storm Surges (Barcelona, 92-07)Storm SurgesLinear Fit

Linear FitY = -8.03E-006 * X - 0.05

BNA

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006Year

-60

-40

-20

0

20

40

60

Sto

rm S

urge

Lev

el [c

m]

Storm Surges (Valencia, 92-06)Storm SurgesLinear Fit

Linear FitY = -1.7E-005 * X + 1.68

VAL

Trends may vary with interval: MSL (from hind casting) decreases from 1956-1991 and for the whole period but increases for the last decade

Ebre delta

Decadal (climatic) scale drivers

Climatic projections (CIRCE) show a clear increase of SSH for the Spanish Med coast

Simulated SSH at the Catalan/Valencia coast. The continuous line is the average series based on different simulations (1950-2050 and 1950-2060)

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050

0

0.4

0.8

1.2

1.6

2

Sea

Leve

l Hei

ght

Decadal (climatic) scale drivers

Observed waves off Ebre delta (1990-2006) Slight decreasing trend for both Hmax & Hs

1991 1992 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006Year

0

200

400

600

800

1000

Hm

ax [c

m]

HmaxHmaxLinear Fit

Linear FitY = -0.005 * X + 311.51

1991 1992 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006Year

0

200

400

600

Hsi

g [c

m]

HsHsLinear Fit

Linear FitY = -0.002 * X + 145.57

Decadal (climatic) / yearly (eng) scale drivers

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006year

10

15

20

25

30

35

dura

tion

of s

torm

s [h

]

Mean duration of StormsHs=1.5Hs=2.0

Linear Fit for Hs=1.5mY = 0.01 * X + 0.75

Linear Fit for Hs=2.0Y = 0.25 * X - 484.11

Ave. duration is 20 hrs for Hs=1.5m & 19 hrs for Hs=2.0m Increasing trend for Hs=2.0m

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006year

20

40

60

80

100

120

140

dura

tion

of s

torm

s [h

]

Maximum duration of StormsHs=1.5Hs=2.0

Linear Fit for Hs=1.5mY = 0.92 * X - 1768.43

Linear Fit for Hs=2.0Y = -0.03 * X + 105.25

Max. duration is 73 hrs for Hs=1.5m & 39 hrs for Hs=2.0m Increasing trend for Hs=1.5m

Decadal (climatic) / yearly (eng) scale drivers

Estimated shore-line erosion rates (total horizontal meters) for last century (Recent Past), present decade (Present) and by 2100 (Near Future)

(Sanchez-Arcilla et al 2011)

0102030405060708090

100

Recent Past Present Near Future

Valencia w/No Sub Ebro w/Sub

0102030405060708090

100

Recent Past Present Near Future

Valencia w/No Sub Ebro w/Sub

Decadal scale morphodynamic response (erosion) SLR SLR + storm effects

Meteo Module WRF + ECMWF BCs

Hydrodynamic module SWAN + ROMS

Morphodynamic Module XBEACH + DEM

Indicators Module

PRE-MOS

pre - MOS

December 2008 storm

Storm (high τ) scale drivers

3 areas for calibration

Playa de S’Abanell (Blanes)

Playa del Pont del Petroli (Badalona)

Playa de la Porquerola (Mont-Roig del Camp)

N

Río Tordera

Posidonea

170 µm

700 µm

350 µm

Storm (high τ) scale drivers (2008 storm)

Flooding (water/sand) & damages to promenade

Flooding

No significant damage

Storm (high τ) scale drivers

Hydrodynamics: Hs

Storm (high τ) scale drivers

Morphodynamic module XBEACH Local meshes (grandma → mom → daughter → grand daughter)

Storm (high τ) scale response (2008 storm)

After the storm

Breaching fan deposits (simulated and observed) contribute to maintening the unit (link to longer term scales)

Before the storm

Storm (high τ) scale response (2001 storm)

Storm (high τ) scale response (2001 storm) N

Ave. mid-term shoreline evolution (m/y) for the period 1995-2004 Cell: Port d’ Arenys - Port de Blanes

1950 1960 1970 1980 1990 2000 2010Time (years)

-80

-60

-40

-20

0

20

shor

elin

e di

spla

cem

ent (

m)

Pomareda S

Pomareda N

Blanes

s'Abanell

1950 1960 1970 1980 1990 2000 2010Time (years)

-80

-60

-40

-20

0

20

shor

elin

e di

spla

cem

ent (

m)

Pineda

Pins

St Susana

Malgrat

1950 1960 1970 1980 1990 2000 2010Time (years)

-20

0

20

40

60

shor

elin

e di

spla

cem

ent (

m) Cavalló

Pla

Canet

Llibre Verd Costa Catalana

Mid-term (engineering) scale: observations

24.000 m3/y

10,500 m3/y

Net alongshore transport capacity (m3 / yr) Interval: 1995 / 2006 — Cell: Port d’ Arenys - Port de Blanes Total change: - 20,000 m3 / yr (loss)

5000 m3/y

56.000 m3/y

Llibre Verd Costa Catalana

Mid-term (engineering) scale: calculus

1983 2001

Roca de Gaià

Altafulla beach Tarragona, Spain

Loss > 200.000 m3 in 10 years

Mid-term (engineering) scale: modelling

1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000alongshore distance (m)

40

60

80

100

120

140

160

180

200

acro

ss-s

hore

dis

tanc

e (m

)

Rc / H = +1.25

Rc / H = 0.00

Rc / H = -1.25

300

Computed shoreline with a one-line numerical model (BEACH_1L) behind a detached low-crested breakwater. Salient development as a function of freeboard for oblique wave incidence.

Mid-term (engineering) scale: modelling

The way ahead: predict with uncertainties

Select the “right” time scale

Make explicit the uncertainties

0 50 100 150 200 250 300 350 400 450 500300

350

400

450

500

550

600

650

Z4Weibull.maximum likelihood

Return period (years)

Hs

(cm

)

300000 350000 400000 450000 500000 550000 600000

4500

000

4550

000

4600

000

4650

000

4700

000

20530442054044

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20560482057048

20580482059048

2060044

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2061044

20620492063049

2064044

2064047

20640492065049

20660502067051

2068044

2068048

2068051

20680522069052

2070052

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2072044

2072048

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20720532073053

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20760562076057

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2080044

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2080056

5 0 m

PDF from observed data

38.3

69.8

25.7

54.9

32.8

164.0

Net Sl capacity (m3 / any) For 1996 / 2006 Cell Port Arenys - Port BCN

Llibre Verd Costa Catalana

Potential transport ≠ Actual transport

Make explicit the uncertainties

The way ahead: predict with uncertainties

Sl in swash for reflect.beaches

Sl b.c.(s) at end points Sl by-pass b.c.(total/partial)

Uncertainties in BCs

As a function of t-scale

The way ahead: predict with uncertainties