Will inundation hazard by storm surges change in the near-future? The upper Tagus estuary case

18:00 Tuesday 28 May




André B. Fortunato (Portugal) 1; Marta Rodrigues (Portugal) 1; Paula Freire (Portugal) 1; Edmund Meredith (Germany) 2; Xavier Bertin (France) 3; Juan Ferreira (Portugal) 4; Margarida L.R. Liberato (Portugal) 5

1 - National Laboratory for Civil Engineering; 2 - Institut fur Meteorologie; 3 - UMR 7266 LIENSs, CNRS - Université de La Rochelle; 4 - Escola de Ciências e Tecnologia, Universidade de Trás-os-Montes e Alto Douro; 5 - Escola de Ciências e Tecnologia, Universidade de Trás-os-Montes e Alto Douro, and Instituto Dom Luiz

Like in most large estuaries, the Tagus’ margins are intensively occupied, thus vulnerable to inundations due to extreme sea levels. The present inundation hazard in the Tagus estuary is assessed through numerical modelling of the water levels due to tides, surges and waves for the most severe storm of the 20th century (the February 15, 1941 storm). Several scenarios are simulated with an atmospheric model (WRF), a large-scale wave model (WW3), a regional tide-surge model (SCHISM) and a coupled circulation and wave model (SCHISM-WWM). Results reveal the overtopping of dykes and the extensive inundation of agricultural lands. Changes of the hazard from the ñpresentî (1980-2015) to the ‘near-future’ (2021-2024) are then evaluated by forcing the regional tide-surge model with atmospheric reanalyses (ERA-INTERIN) and decadal predictions (MIKLIP). Changes in storminess in this period are shown to be negligible in the Atlantic Iberian coast. As a result, the growth in extreme sea levels will be dominated by sea level rise.