Estuarine margins vulnerability to floods for different sea level rise and human occupation scenarios

Abstract

Sea level rise (SLR) is increasing the risk of flooding in marginal low-lying estuarine areas. High water levels in estuaries are associated with the simultaneous occurrence of various phenomena ranging from high tidal levels to large fresh-water discharges. The intense and diverse human occupation of some of these marginal areas increases the flood vulnerability, endangering human lives and causing heavy economic and environmental losses. This issue becomes even more relevant since the European Floods Directive establishes mandatory guidelines to all member states regarding flood risk assessment, integrating flood maps with territorial characteristics. The present study aims to assess the vulnerability to floods of a specific area in Tagus estuary, by integrating hydrodynamic modelling results with land use cartography. Results suggest that about 16.1% of the estuarine marginal fringe could be flooded for the 2050 scenario, rising up to 23.7% for the 2100 scenario. Moreover, industrial and urban areas will be the most affected sites. Considering future development scenarios planned for that site, the results point to an increasing vulnerability of urban areas and therefore to the relevance of this knowledge in future planning and management guidelines as well as measures to adapt to SLR. The uncertainties and implications of the study are also discussed, and future research topics are indicated.