This document discusses a study analyzing the impact of input bathymetry uncertainty on coastal early warning system forecasts in Emilia-Romagna, Italy. The study found that uncertainty from bathymetry inputs, such as outdated beach profiles, can be comparable to meteorological uncertainties. An ensemble system using different beach profiles showed similar spread to an ensemble of meteorological conditions. This suggests bathymetry uncertainty is also important to represent. Improving surveys of winter and summer beach profiles could help make forecasts more accurate.

1. THE INPUT BATHYMETRY AS A SOURCE OF UNCERTAINTY
OF A COASTAL EARLY WARNING SYSTEM:
THE CASE OF THE EMILIA-ROMAGNA REGION (ITALY)
Silvia Unguendoli, Andrea Valentini, Lidia Bressan & Tiziana Paccagnella
sunguendoli@arpae.it, Arpae SIMC Emilia-Romagna, Italy
XBEACH USER DAY 2018
Thursday, 15 November 2018, Delft

2. THE MICORE PROJECT
Morphological Impacts and COastal Risks induced by Extreme storm events
COASTAL EARLY WARNING SYSTEM
Hydro-Meteo-Climate Service of Arpae
Emilia-Romagna (Arpae-SIMC)
BACKGROUND
Prediction of MORPHOLOGICAL IMPACTS due
to marine storm events in support of civil
protection mitigation strategies.
www.micore.eu
ITALIAN
CASE-STUDY SITE

3. SWAN-MEDITARE
ADRIA-ROMS
OPERATIONAL EARLY WARNING SYSTEM
XBEACH
COSMO I7
7 km resolution
www.cosmo-model.org
25 km Mediterranean Sea
8 km Italian Region
800m Emilia-Romagna
Regular grid resolution of 2 km

4. THE MORPHOLOGICAL MODEL
XBEACH MODEL
Mono-dimensional
8 Sites
22 Cross-shore Sections
Coastal Storm Risk
Harley, M. D., Valentini, A., Armaroli, C., Perini, L., Calabrese, L., and
Ciavola, P.: Can an early-warning system help minimize the impacts of
coastal storms? A case study of the 2012 Halloween storm, northern
Italy, Nat. Hazards Earth Syst. Sci., 16, 209–222.
http://geo.regione.emilia-romagna.it/schede/micore/
THE MODEL
Daily 3-day forecast
of coastal storm hazard
FORECASTS

5. MODELING CHAIN UNCERTAINTIES
More frequently used
New approach
Uncertainty viewpoint
WHY NOT?
INPUT
DATA
ENSEMBLE FORECASTING

6. THE ISSUE
UP-TO-DATE SURVEY OF THE BEACH PROFILES
REGIONAL PLANNING
Complex planning
Not always easy to make
Measuring instruments
Resources

7. THE ER COASTAL TOPO-BATHYMETRICAL NETWORK
251 CROSS-SHORE SECTIONS
SURVEYS : 1984 > 1993 > 2000 > 2006 > 2012

8. For Morpho-Dynamical Modeling, to what extent does
THE UNCERTAINTY DUE TO THE INPUT BEACH
MORPHOLOGY AFFECT RESULTS considering that, in
general, the uncertainty of the meteorological
component is supposed to be predominant?
CAN A “NOT UP-TO-DATE” BEACH PROFILE AFFECT RESULTS?
THE SCOPE

9. METEOROLOGICAL ENSEMBLE SYSTEM
MORPHOLOGICAL ENSEMBLE SYSTEM
16 different METEOROLOGICAL CONDITIONS
COSMO-LEPS System (probabilistic forecast)
Same beach profile (2015) for all simulations
COSMO-
LEPS XBEACH
SWAN
ROMS
16 METEOROLOGICAL
CONDITIONS
16 members
16 runs
16 runs
16 runs
COSMO XBEACH
SWAN
ROMS
5 BEACH
PROFILES
Single run
Single run
Single run
5 runs
One Meteorological condition
Deterministic run of COSMO-LEPS
5 DIFFERENT BEACH PROFILES measured in
2006,2009,2010,2012,2015 (5 simulations)
MODEL SET-UP

10. Impulsive event
THE SELECTED STORMS
Date Max Wave Height (m) Max Sea Level (m) Energy (m2h) Wind
20 November 2015 3.30 0.58 120.45 North-East
27 February 2016 2.30 0.80 61.25 South-East
Moderate and “smooth” event

11. METEOROLOGICAL Ensemble System
MORPHOLOGICAL Ensemble System
SPREAD Comparison
RESULTS
(END OF THE SIMULATION)

12. SHORELINE EVOLUTION RUNUP ERODED VOLUMES
SHORELINE EVOLUTION RUNUP ERODED VOLUMES
METEOROLOGICAL Ensemble System
MORPHOLOGICAL Ensemble System
RESULTS
(TIME EVOLUTION)

13. CONCLUSIONS
The study case aims at investigating the forecasts uncertainty
related to the INPUT BATHYMETRY
The meteorological and morphological uncertainties are
COMPARABLE and then NOT NEGLIGIBLE to have a complete
description of the uncertainties that propagates in the entire
modeling chain
Results suggest that a WIDER INVESTIGATION is useful, to
extend the analysis to different beach profiles (e.g. steeper
profiles, protected beach)
FUTURE DEVELOPMENT: the possibility to improve the
forecasting system performance by introducing a
MORPHOLOGICAL ENSEMBLE based on the input bathymetry.
The survey of both WINTER and SUMMER BEACH PROFILE can
be a starting-point to a more accurate representation of the
bathymetry for the warning system

14. THANKS FOR YOUR ATTENTION
SILVIA UNGUENDOLI
sunguendoli@arpae.it

15. DIFFERENT MORPHOLOGICAL INPUT FOR XBEACH
THE EXCEPTION
BEACH PROFILE MEASURED IN 2009

16. ANOTHER BEACH PROFILE, SAME SITUATION

17. METEOROLOGICAL Ensemble System
MORPHOLOGICAL Ensemble System
SPREAD Comparison
RESULTS
(+96h)

18. SHORELINE EVOLUTION RUNUP ERODED VOLUMES
SHORELINE EVOLUTION RUNUP ERODED VOLUMES
METEOROLOGICAL Ensemble System
MORPHOLOGICAL Ensemble System
RESULTS
TIME EVOLUTION

19. 10m wind forecast of COSMO (03 utc 22/11/2015)

20. Daily 3-day forecast of coastal storm hazard
STORM IMPACT INDICATOR SII
THE EMILIA-ROMAGNA EARLY WARNING SYSTEM
SCW Safe Corridor Width
Measure of the amount of dry beach
available between the dune foot and
waterline for safe passage by beach users
BWD Building Waterline Distance
Measure of the amount of dry beach
available between the seaward edge of a
building and the model derived waterline
FORECASTS