Event-based assessment of coastal flood damages under 100-year extreme sea-level scenarios in Spanish coastal hotspots

This study assesses coastal flood exposure and direct economic damages associated with 100-year return-period extreme sea-level events in five vulnerable Spanish coastal hotspots: the Ebro Delta, Alcudia Bay, the Albufera of Valencia, the Mar Menor and Doñana. The analysis considers two time horizons, 2050 and 2100, and two climate change scenarios, RCP 4.5 and RCP 8.5, using high-resolution geospatial flood layers, land-use information and projected land-use change scenarios.

The methodology combines GIS-based spatial analysis, land-use change modelling with MOLUSCE, and depth–damage functions adapted to Spanish land-use categories. Flooded areas were quantified by land use and study area, while direct economic damages were estimated for the modelled flood footprint of each 100-year extreme sea-level scenario. These estimates were calculated for both current land uses and future land-use projections. In addition, potentially developable urban land exposed to coastal flooding was identified to support territorial planning and adaptation strategies.

Results show a strong increase in exposure towards the end of the century. Total flooded area rises from 4,926 ha under RCP 4.5 in 2050 to 28,915.3 ha under RCP 8.5 in 2100. The most affected land uses are rice fields and coastal lagoons, followed by marshes, salt flats and beaches. Event-based direct economic damages for current land uses increase from €109.2 million in 2050 under RCP 4.5 to €808.8 million in 2100 under RCP 8.5, while future land-use projections raise potential damages to more than €1.0 billion in the most severe scenario. The Ebro Delta and the Albufera of Valencia concentrate the largest flooded areas, whereas urban and tourist-related land uses drive the highest estimated economic losses in the Mar Menor and Alcudia Bay, highlighting the key role of urban exposure in determining local economic vulnerability.

 

The authors gratefully acknowledge the support and funding received from project 22697/PI/24 (ISANMAR), funded by FSRM/10.13039/100007801. This work was also supported by the SHIELD project, funded through the EUniWell Well-Being Research Incubator Programme and Seed Funding Programme of the EUniWell Consortium (European Universities for Well-Being, https://www.euniwell.eu/), within the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 101035821.