14 Jul 2023
 | 14 Jul 2023

A new European coastal flood database for low-medium intensity events

Marine Le Gal, Tomás Fernández-Montblanc, Enrico Duo, Juan Montes Perez, Paulo Cabrita, Paola Souto Ceccon, Vera Gastal, Paolo Ciavola, and Clara Armaroli

Abstract. Coastal flooding is recognized as one of the most devastating natural disasters, resulting in significant economic losses. Therefore, hazard assessment is crucial to support preparedness and response to such disasters. Toward this, flood map databases and catalogues are essential for the analysis of flood scenarios, and furthermore can be integrated into disaster risk reduction studies. In this study and in the context of the ECFAS project (GA 101004211), which aimed to propose a European Copernicus Coastal Flood Awareness System, a catalogue of flood maps was produced. The flood maps were generated from flood models developed with LISFLOOD-FP for defined coastal sectors along the entire European coastline. For each coastal sector, fifteen synthetic scenarios were defined focusing on high-frequency events specific to the local area. These scenarios were constructed based on three distinct storm durations and five different Total Water Level (TWL) peaks incorporating tide, mean sea level, surge and wave set-up components. The flood model method was extensively validated against twelve test cases for which observed data were collated using satellite-derived flood maps and in situ flood markers. Half of the test-cases well represented the flooding with hit scores higher than 80 %. The synthetic scenario approach was assessed by comparing flood maps from real events and their closest identified scenarios, producing a good agreement and global skill scores higher than 70 %. Using the catalogue, flood scenarios across Europe were assessed, and the biggest flooding occurred in well-known low-lying areas. In addition, different sensitivities to the increase of the duration and TWL peak were noted. The storm duration impacts a few limited flood prone areas such as the Dutch coast for which the flooded area increases more than twice between a 12 h and 36 h storm scenarios. The influence of the TWL peak is more global, especially along the Mediterranean coast for which the relative difference between a 2- and 20-year return period storm is around 80 %. Finally, at a European scale, the expansion of flood areas in relation to increases in TWL (Total Water Level) peaks demonstrated both positive and negative correlations with the presence of urban and wetland areas, respectively. This observation supports the concept of storm flood mitigation by wetlands.

Marine Le Gal et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1157', Anonymous Referee #1, 21 Jul 2023
    • AC1: 'Reply on RC1', Marine Le Gal, 01 Aug 2023
  • RC2: 'Comment on egusphere-2023-1157', Anonymous Referee #2, 08 Aug 2023
    • AC2: 'Reply on RC2', Marine Le Gal, 18 Sep 2023
  • RC3: 'Comment on egusphere-2023-1157', Anonymous Referee #3, 18 Aug 2023
    • AC3: 'Reply on RC3', Marine Le Gal, 18 Sep 2023

Marine Le Gal et al.

Marine Le Gal et al.


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Short summary
Assessing coastal hazards is crucial to mitigate flooding disasters. In this regard, coastal flood databases are valuable tools. This paper describes a new coastal flood map catalogue covering the entire European coastline, as well as the methodology to build it and its accuracy. The catalogue focuses on frequent extreme events and relies on synthetic scenarios estimated from local storm conditions. Flood prone areas and regions sensitive to storm duration and water level peak were identified.