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. 603458. 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.
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.
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
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)
Model Train for EWS Domain 2 Domain 1 Domain 3 Surrogated
FEWS EWS Regional and local
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
The BN training Historic events Date Duration (hours) Wave height (Dir) Total Water elevation, MSL (m) Impact 15/02/1941 24 4.2(SW) 1.8 Inlet opening at Praia de Faro (Ancao Peninsula) 12/01/1969 15 4.3 ( SW) 1.1 Major overwash of houses; opening of an inlet and shoreline retreat 11/2/1979 35 7.1 (SW) 1.3 Damages and house destruction at Praia de Faro 13-27/11/1989 40 7 (SW) 1.7 Destruction of houses and seawall 23/01/1996 49 6.5 (SW) 2.31 The entire seawall was damaged at Praia de Faro 02-08/02/1998 28 5.6 (SW) 1.7 Destruction of few houses at Praia de Faro 23-31/12/2009 50 5.8 (SW) 1.3/1.7 7 houses destroyed at Fuzeta 04/01/2010 12 4.7 (SW) 1.6 11 houses destroyed at Fuzeta 15/02/2010 45 4 (SW) 1.56 Strong overwash and breaching (downdrift) 02/03/2010 23 5.2 (SW) 2.15 3 houses destroyed at Praia de Faro
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 10 0.31-0.58 4.5-7.1 9.6-13.5 Synthetic 30 0.15 0.66 3.0-7.9 8.1-17.4 Poelhekke et al., 2016 Coastal Engineering
The BN training Synthetic Event Schematisation 1 Simulation for each tidal stage 3x30 =90
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)
DRR measures Beach nourishment (T1) (extra modelling ) Nourishment specification were adopted from regional authorities protection plan for Praia de Faro
DRR measures House removal (T2) Areas Selection: 4 areas based on exposure characteristics Receptos Type Houses Infrastructure
DRR measures Channels of Communication (T3) Non-primary measures based on two primary measures: Sandbags Constructions on Piles
Model Results Observed Hazard threshold Hs vs Tp: Good separation of hazard/no hazard event
Model Results Proxy selection for Praia de Faro: Overwash: Max water Flux (cross-shore) Erosion: Vertical Erosion in 3 areas
Bayesian Network Boundary Conditions Hazard Impact Measures Receptors
BN Results For Hs> 7m and Tp> 14.5sec (Tr 50 years)
BN Results : Current Conditions Tr 50 years 18 3 79
BN Results : Current Conditions Tr 50 years Erosion 50 45 5
BN Results : Beach Nourishment Tr 50 years - Overwash Current Conditions Nourishment 18 3 8 0 79 92
BN Results : Beach Nourishment Tr 50 years Erosion Current Conditions Nourishment 50 45 0 2 5 98
BN Results : House Removal Tr 50 years - Overwash Current Conditions House Removal 18 3 12 1 79 87
BN Results : House Removal Tr 50 years Erosion Current Conditions House Removal 50 5 45 70 28 2
BN Results : Channels of Communication Tr 50 years - Overwash Current Conditions Channels of Communication 79 18 3 85 13 2
BN Results : Channels of Communication Tr 50 years Erosion Current Conditions Channels of Communication 50 5 45 54 5 41
BN Results : Nourishment + House Removal Tr 50 years - Overwash Current Conditions Nourishment 18 3 0 3 79 97
BN Results : Nourishment + House Removal Tr 50 years Erosion Sem SA4 Com SA4 50 45 1 0 5 99
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.
Thank you Any questions?
Consequences - Impact (C) From Hazard to Impact - Erosion From Hazard to Impact - Overwash Depth-Velocity Product - vd (m²/s) House Type 0 1 2 3 4 5 6 7 >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