Generating inundation maps for a coastal lagoon: A case study in the Ria de Aveiro (Portugal)

Coastal flooding due to storm surges combined with high tides causes a growing concern, and recent legislation requires that European Union countries develop inundation maps for the areas at risk. This paper describes the methodology to generate inundation maps and its application to the Ria de Aveiro, a coastal lagoon exposed to Atlantic storm surges that can exceed 1 m. The maps are based on the application of the shallow water model SELFE, for different return periods and scenarios of sea level rise. A new approach to define the model boundary conditions for different return periods is developed based on the statistical analysis of time series from tidal gauges. This approach considers the effect of storm surges as well as tides and their 18.6 year cycle. The extreme levels obtained with this method converge for the 20 years of available data and are more accurate than the ones obtained with traditional approaches for this limited data set. In addition, the new method provides not only the extreme levels, but also the time series that include them, which are needed to force the hydrodynamic model. The results show that the storm surges affects the entire length of the Ria de Aveiro.

► New approach to determine extreme water levels for different return periods.
► The approach is simple, accurate and provides the associated time series.
► Inundation maps for the Ria de Aveiro are generated using a shallow water model.