Waves and sea-level rise induced flooding in the Maldives

The Maldives, located in the Indian Ocean, are the paradigm of low-lying coral-reef islands where adaptation to climate change is essential. Besides the mean sea level rise in this region, that is expected to be around 1 m by the end of the century according to the last IPCC report, these islands are exposed to one of the largest swells in terms of significant wave height and peak period. In this study we characterize, using the output of global wind-wave models forced by wind fields from the CMIP5 ensemble delivered by CSIRO, the present conditions and future projections of the waves around the Maldivian archipelago, as well as the return periods for the predominant swell directions. We then propagate extreme waves inside the domain using WaveWatch III model run onto a high-resolution grid (down to 500 m at the coast). Finally, we evaluate the coastal impacts of extreme swell waves in two strategic case study islands with different exposures and where land reclamation and different adaptation solutions have been/are being done. To do so, we propagate waves using SWASH model with rising mean sea level towards the shoreline and assess the flooding extend under different conditions. This kind of studies are essential to help the policy makers in defining the most accurate and appropriate adaptation strategies.