iahr 2015 - coastal sustainability for ,sanchez-arcilla,30062015
TRANSCRIPT
COASTAL SUSTAINABILITY FOR UNCERTAIN FUTURES. A MEDITERRANEAN CASE FROM THE RISES-AM- PROJECT
A. SANCHEZ-ARCILLA, JP. SIERRA , V. GRACIA, M. GARCIALEON, JA. JIMENEZ, C. MOSSO & H. VALDEMORO
Year 1990 Year 2004 Year 2015 Year 2025 Year 2035 Year 2045
1) Coastal-scale climate change
2) Climate impact projection i. Deltaic beaches ii. Urban beaches
3) Coastal adaptation
4) Final remarks (3rd Catalan Rep. on Climate Change)
Contents
A
Climate Change Global sea level projections
(IPCC, 2013)
Likely range, 66%
Upper limit (95%, RCP8.5), 1.8m
AR-4
AR-5
o Increase in AR o Probabilistic characterization
Jevrejeva et al, 2014
• Change in wave conditions → studied with AR4 (AR5 waves in the “oven”) • Projections indicate
– Slight reduction of Hs & surges under future scenarios – Increase in MSL (smaller than for N Atlantic)
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
Lionello et al S.-Arcilla et al, data from J. Pascual
Ebro delta
Dam / barrages ~ 180
Regulated basin 82,300 km2 (96.4 %)
Climate Influence on CZ
Locally
Basin-wise
Impact projection (deltaic vulnerability hotspot) o Catchment basin analysis o Anthropic coastal disconnection (from river basin) o Increasing sediment starvation (risks)
Impact vs Natural Deltaic response(RSLR)
Feed-back: RSLR-vertical accretion
(marshes & full delta) Pulsing events (wave
storms/river floods) supply large sediment volumes naturally
(deltaic resilience to CC) Natural mechanisms
can be enhanced to reduce impact (controlled flooding…)
Natural resilience (present and future) → working with Natural processes (against) Reduced cost and risk (economic sustainability) Reduced impact (environmental and energetic sustainability) Favouring flexible adaptation (no rigid infrastructures)
Based on natural accretion
Novel interventions: o Promoting vertical
accretion o Flooding offsetting
subsidence
Courtesy MMA, Spain
Natural accretion
0 100 200 300 400 500 600 700cross-shore distance (m)
-6
-5
-4
-3
-2
-1
0
1
2
elev
atio
n (m
)
La Marquesa (P33)
La Marquesa beach
Zmax = 1.5 m Z min = 0.7 m Z med= 1.14 m
tan β = 0.019
Ru time series o Storm events o With overwash (Ru > Zbeach) 81 storms (1.84 events/year) 44 years (Nguyen et al 2006 transport model)
0.0
0.0
0.0
0.1
1.0
10.0
100.0
Qow
(m3 /m
/sto
rm e
vent
)
Estimations for storm events (Ru > Zbeach) for evolving profiles
Zmin Zmed Zmax
STUDY SITE
Impact projection – Urban beaches (vulnerability hotspot)
TEST CASES
PRESENT CLIMATE CHANGE SCENARIOS
(0m) RCP 4.5 (0.47m)
RCP 8.5 (0.88m)
High End (1.88m)
Beach Normal Wave
incidence
Tr=1 yr • • • • Tr=5 yr • • • •
Tr=50 yr • • • •
time (hours)
Hs (m)
0 24
Erosion before – after storm (erosion depth in m)
Flooding at t=12.5 hours (water depth in m – minimum 0.1m )
Coastal impacts as a function of storm shape
PRESENT CONDITIONS
EROSION BARCELONETA BEACH Tr=50 YEARS (present PDF)
EROSION BARCELONETA BEACH Tr=50 YEARS HIGH END LIMIT
FLOODING BARCELONETA BEACH Tr=50 YEARS HIGH-END
GENERAL ADAPTATION OPTIONS 1- ↑ sediment supply (vertical/horizontal accretion) 2- ↑ natural accretion mechanisms 3- ↓ sediment losses (bio filters…) 4- ↓ sediment mobility (vegetation…) 5- ↑ raising defences (locally, geotextiles…) 6- ↑ water pumping 7- ↑ whole unit synergies
DRIVERS (D) 1- RSLR (+ subsidence) 2- Change of wave climate (South) 3- T (ºC) ↑ (water consumption) 4- Decrease of freshwater (Ql) 7- Decrease of sed supply (Qs)
PRESSURES (P) 1- Flooding 2- Erosion 3- Reshaping 4- Salinization
IMPACTS (I) 1- Rice yield 2- Agro-Tourism 3- Industry 4- Habitats 5- Connectivity
N ^
Adaptation options = f (D, P, I)
Ebro delta case study MED Vulnerability Hotspot
Efficient coastal responses under Climate Change should consider Multiple scale pressures: combined riverine/marine factors (ave. trends + extremes) Multiple scale responses: full catchment basin (avoiding short term “mortgages”)
RIVER
COAS
TAL
FRIN
GE
COAS
TAL
SEA
ideal management scale
usual management scales
Final Remarks 1. Scales
Efficient coastal responses under Climate Change should consider Cost at short to long term scales (initial + maintenance + impact) Ranking with risk (vulnerability) (deltaic, urban & small islands coasts) Rising grounds (high end conditions)
Final Remarks 2. Ranking as function of risk/cost
Maldives Is. SOTON 2014
Courtesy IRTA
Efficient coastal responses under Climate Change should consider Cost at short to long term scales (initial + maintenance + impact) Ranking with risk (vulnerability) (deltaic, urban & small islands coasts) Rising grounds (high end conditions)
Maldives Is. SOTON 2014
Courtesy IRTA
Final Remarks 2. Ranking as function of risk/cost