Quantifying the effects of coastal erosion on flooding projections at the climate change scale

Coastal flooding and erosion threaten coastal communities and climate change boosts their effects to unprecedented levels. Even if coastal erosion has a direct effect on coastal flooding, their effects are normally studied in isolation due to the complex interplays among them, leading to potentially erroneous flood risk estimates (Toimil et al., 2022). To handle this challenge, an advanced shoreline evolution model enriched with observations (Álvarez-Cuesta et al., 2022) is coupled with a profile translation model to provide the boundary condition over which to run a 2D flood model. This suite of process and physics-based models enriched with observations is applied to a 40-km coastal stretch in the Spanish Mediterranean to develop erosion-enhanced flooding projections. In this study, the effects of neglecting erosion are studied at the storm scale and in the long term on two key flood magnitudes: the total water level and the flooded area. Additionally, the most relevant climate-related uncertainty sources are identified and their relative importance evaluated. At this particular coastal site where the suite is illustrated, results reveal that neglecting erosion has a more important effect on the flooded extent than the choice of the climate model and the sea level rise trajectory by the end of the century.  This application sets the basis for establishing general behavioural rules that may come to question the conclusions of erosion-uncoupled flooding studies.

 

Toimil, A., Álvarez-Cuesta, M., & Losada, I. J. (2023). Neglecting the effect of long-and short-term erosion can lead to spurious coastal flood risk projections and maladaptation. Coastal Engineering, 179, 104248.

 

Álvarez-Cuesta, M., Toimil, A., Losada, I.J. (2022). Modelling long-term shoreline evolution in highly anthropized coastal areas. Part 1: Model description and validation. Coastal Engineering, 169, 103960.