Impactos costeros bajo climas futuros El proyecto RISES-AM-

Prof. A. Sanchez-Arcilla

1) Impactos y tipos de costa 2) Escala de décadas y de tormentas 3) Seguimiento 4) Niveles de riesgo (coste) 5) Sostenibilidad (?)

More than SLR !

Courtesy Univ. Southampton

Free-transport coast

Costal Development Potential Impacts

(General)

Vulnerability

Resilience

Coast Typology & Vulnerability. Present

Adaptation to o Available space (present conditions) o Storm impact range (future conditions)

Barcelona Beach (Wave Height [m])

Impounded transport coast

Potential Impacts (Local)

Costal Adaptation (+) Vulnerability

Resilience

Coast Typology & Vulnerability. Present

For a given “pressure” (Hs, MSL…) Impact = f(typology)

Different for present / future conditions Impact (damage) hotspots

P20

Med-type coast Semi-enclosed environments

Present

Sediment starvation Permanent bars (limited natural recovery) Only “active” 20% in a year Highly sensitive to storm features (other than Hs)

1 2 3 4 5 6 7 8 9 10 11 12

0

2

4

6

8

10

12

14

0.2

0.4

0.6

0.8

1.0

1.2

Hs2 (

m)

transporte

H2

Transport

H2

0 20 40 60 80 100 120 140 160duración (horas)

0

40

80

120

160

Vole

ros

(m3 /m

)H=4m

H=5 m

H=6 m

Long-term considers future scenarios (high-end with warming up to 4ºC) o Physical (MSL + waves + storm surges): RCP4.5 & RCP8.5 + upper limit SLR o Socio-economic: SSP5 + SSP3

SSP5 – Lower population SSP3 – “Fragmentation “

95% or “max” (Moore et al 2013)

GDP pc + population projections IIASA realisations

Likely range, 66% (SPM, 2013)

Future scenarios → Need to downscale (my beach, my harbour…) → Impact adjustment requires monitoring (pressures & impacts)

1970 1975 1980 1985 1990 1995 2000 2005 2010Year

14

15

16

17

18

19

20

Tem

pera

ture

ºC

Estartit Yearly Averaged Mean, Min and Max Temp.Yearly Averaged Mean TemperatureYearly Averaged Max TemperatureYearly Averaged Min Temperature

LT decisions require downscaling (Med – Observations)

Lionello et al

S.-Arcilla et al, data from J. Pascual

Results: Changes of directional frequencies in winter (5 GCM-RCM sets)

Projected changes in absolute value (relative values are higher, exceeding in some cases 100%)

Directions

N (less freq)

NE

E

SE (more freq)

LT decisions require downscaling (Med – AR 4 – Sierra et al 2013)

5-year Ʈ positive surges (cm) under present climate for the Med (simulations). (%) variation under future climates (thick lines indicate CC is significant). Black line is the ensemble mean.

Ʈ = 5

Δ Ʈ=5(%)

LT decisions require downscaling (Med – AR 4 – Lionello et al 2014)

-7.5 -5 -2.5 0 2.5 5 7.5shoreline rate of displacement (m/y)

0

25

50

75

100

125

150

beac

h w

idth

(m)

proj. width < 15 m15 m < proj. width < 35 m35 m < proj. width < 50 mproj. width > 50 m

Predictions – 10 years (Davos forum) Based on 1995-2004 data

o Aerial images o Wave climate o Longshore transport computations

Indicator: beach width and berm height (follow-up)

Example: Catalan coast. Future conditions A1B SRES, AR4 (Med, Black seas)

Projections – 50 to 100 years (SRES & RCPs) Based on 1971-2000 vs 2071-2100 comparison

o Several models (5 GCM-RCM for SRES) Indicators (follow-up):

o Beach width/height for tourism and protection o Harbour agitation for port exploitation

Characterising a coast (beaches and harbours) out of wave “equilibrium”

2050 63% beaches more vulnerable

Catalan coast. Future conditions A1B SRES, AR4 (Med, Black seas)

Overtopping vulnerability for 5 year storm in 2050

Economic cost: Function of risk level RISK = HAZARD X DAMAGES Exp. x Vuln. • Transient “pressures”

(wave storms, population...)

• Scarce territory with

reduced “natural” response

capacity

• High level of damages

(potential) and risks (present)

to get more acute in the future

Maresme by summer …and by winter

Among assessment cases: Deltas / Estuaries o Higher impact (vulnerability) o Natural Scale Integrators

(forewarning)

Novel interventions: promote vertical accretion (flooding “compensates” subsidence )

Holocene subsidence rates (Somoza et al 1998)

Sustainability: novel/sustainable “solutions” at local, regional and global scales

Nov 2001 storm

Sustainability under RSLR + storm events

Response time

Morphodynamic gradient

Natural Resilience

Long

shor

e di

stan

ce (m

)

Time

Flooding threshold

RSLR = 0.3 m (2mm/y SLR+ 1mm/y S)

Oct 2003, τ = 5y

Hinterland providing accomodation space Adaptation capacity ↑ Shoreline retreat – beach maintains

Hinterland with no accomodation space (anthropic) Without adaptation capacity Shoreline rigidization – beach dissapears

Sustainability paradox and dilemma: value of land vs value of beach (shoreline definition)

1-line CZ definition Conundrums By 2100 ICC image + projection

Sustainability paradox and dilemma: natural vs artificial shoreline assessment (setback line concept)

No accom. space (human) 62 %

No accom. space (natural) 5 %

Accom. space 33 %

Sustainability via adaptation: accommodation space needed

Demand for coastal protection Liquete et al 2013. Assessment of coastal protection as an ecosystem service in Europe.

Policy context • EU – ICZM • EU Blue Growth • Regional Shoreline Mgt

Sustainability via Policy objective: Demand for Safety

Conclusions

Efficient coastal responses to Climate Change must consider Scale requirements: trends + extremes Vulnerability hotspots (deltaic & urban coasts) Cost (initial + maintenance + impact) at short and long term scales Novel + conventional interventions (working with Nature) Performance in terms of risk and contribution to climate mitigation

North Carolina’s coast, after Sandy © Program for the Study of Developed Shorelines / WCU