Coastal Impact on barrier Islands: Application to Praia de Faro

Transcription

1 Coastal Impact on barrier Islands: Application to Praia de Faro Theocharis Plomaritis, Oscar Ferreira and Susana Costas RISCKIT Final Meeting This project has received funding from the European Union s Seventh Programme for Research, Technological Development and Demostration under Grant Agreement No This presentation reflects the views only of the authors, and the European Union cannot be considered liable for any use that may be made of the information contained therein.

2 Regional to Local: Hotspot Tool Transform offshore physical parameters into onshore hazard; Transform the hazard into impact for selected receptors; Surrogate the computationally expensive morphodynamic simulations within an EWS using a BN Incorporate into the tool DRR measures so it can be used by coastal managers as a DSS.

3 Study Site Praia de Faro Coastal lagoon system protected by a barrierisland, with sandy shores and dunes. Storms Hs > 3m; up to 6-7m Tidal range up to 3.5 m Storm surge < 1 m Reduced river input

4 EWS/DSS Early Warning and Decision Support System (EWS/DSS) for use on hot spots. 1. Traditional EWS incorporated in Delft-FEWS that includes Tides/Surges-Waves-Morphodynamics 2. Store results in Bayesian Network for immediate evaluation of event impact. 3. Evaluation of Disaster Risk Reduction measures (DRR)

5 Model Train for EWS Domain 2 Domain 1 Domain 3 Surrogated

6 FEWS EWS Regional and local

7 Study Site Praia de Faro Hazards and relevant model selection (XBeach) Overwash Car-park 1996 Car-park 1990 Camping 1991 C. Sector 1995 Road colapse 1990 Protection Works 1990 Coastal/Dune Erosion

8 The BN training Historic events Date Duration (hours) Wave height (Dir) Total Water elevation, MSL (m) Impact 15/02/ (SW) 1.8 Inlet opening at Praia de Faro (Ancao Peninsula) 12/01/ ( SW) 1.1 Major overwash of houses; opening of an inlet and shoreline retreat 11/2/ (SW) 1.3 Damages and house destruction at Praia de Faro 13-27/11/ (SW) 1.7 Destruction of houses and seawall 23/01/ (SW) 2.31 The entire seawall was damaged at Praia de Faro 02-08/02/ (SW) 1.7 Destruction of few houses at Praia de Faro 23-31/12/ (SW) 1.3/1.7 7 houses destroyed at Fuzeta 04/01/ (SW) houses destroyed at Fuzeta 15/02/ (SW) 1.56 Strong overwash and breaching (downdrift) 02/03/ (SW) houses destroyed at Praia de Faro

9 The BN training Synthetic events Hs vs. Tp Hs vs. Surge Hs vs. Duration Number of Events Data Interval Surge (m) Hs (m) Tp (s) Historic Synthetic Poelhekke et al., 2016 Coastal Engineering

10 The BN training Synthetic Event Schematisation 1 Simulation for each tidal stage 3x30 =90

11 DRR measures Three DRR measures have been selected for the Praia de Faro case study (Considering end-users input from interviews): Beach nourishment (T1) (hazard related, extra modelling) House removal (T2) (exposure related) Create and/or improve Communication Channels (T3) (vulnerability related)

12 DRR measures Beach nourishment (T1) (extra modelling ) Nourishment specification were adopted from regional authorities protection plan for Praia de Faro

13 DRR measures House removal (T2) Areas Selection: 4 areas based on exposure characteristics Receptos Type Houses Infrastructure

14 DRR measures Channels of Communication (T3) Non-primary measures based on two primary measures: Sandbags Constructions on Piles

15 Model Results Observed Hazard threshold Hs vs Tp: Good separation of hazard/no hazard event

16 Model Results Proxy selection for Praia de Faro: Overwash: Max water Flux (cross-shore) Erosion: Vertical Erosion in 3 areas

17 Bayesian Network Boundary Conditions Hazard Impact Measures Receptors

18 BN Results For Hs> 7m and Tp> 14.5sec (Tr 50 years)

19 BN Results : Current Conditions Tr 50 years

20 BN Results : Current Conditions Tr 50 years Erosion

21 BN Results : Beach Nourishment Tr 50 years - Overwash Current Conditions Nourishment

22 BN Results : Beach Nourishment Tr 50 years Erosion Current Conditions Nourishment

23 BN Results : House Removal Tr 50 years - Overwash Current Conditions House Removal

24 BN Results : House Removal Tr 50 years Erosion Current Conditions House Removal

25 BN Results : Channels of Communication Tr 50 years - Overwash Current Conditions Channels of Communication

26 BN Results : Channels of Communication Tr 50 years Erosion Current Conditions Channels of Communication

27 BN Results : Nourishment + House Removal Tr 50 years - Overwash Current Conditions Nourishment

28 BN Results : Nourishment + House Removal Tr 50 years Erosion Sem SA4 Com SA

29 Concluding remarks Nourishment is the most effective DRR in reducing the impact on the houses. The use of a BN in EWS could result in significant reduction of the computational effort. The method requires a large number of simulation for the initial setup but can result in a very useful tool the event scale protection measures. The inclusion of DRR measures makes the proposed tool useful also for long-term decision making process.

30 Thank you Any questions?

31 Consequences - Impact (C) From Hazard to Impact - Erosion From Hazard to Impact - Overwash Depth-Velocity Product - vd (m²/s) House Type >7 Wood-Framed: No Collapse Partial Collapse Total Collapse Unanchored Wood-Framed: No Collapse Partial Collapse Total Collapse Anchored Masonry, Total Collapse (if concrete and No Collapse Partial Collapse (if v is also 2 m²/s) v is also 2 m²/s) brick Sr-A >= Tp Tp <= Sr-A <=Tpm Tpm <= Sr-A <= Tl Tl <= Sr-A ErVI None Low probability of asset collapse: Disruption caused by preventive evacuation before and during the event Medium probability of asset collapse: Disruption caused by preventive evacuation as well as during and post event checking/monitoring by civil protection and coastal management institutions High probability of collapse: High disruption and total loss of asset