THE VARIABILITY OF SEA LEVEL AND ITS IMPACT ON COASTAL FLOODING IN BAÍA DE TODOS SANTOS (13oS)

Resumo

This study uses 21 years (2004-2024) of water level measurements carried out by the IBGE's Brazilian Continuous Monitoring Network (RBMC), in association with the Global Level Observation Program (GLOOS), with the aim to quantify the temporal variability of the water level, identify long-term trends of the mean sea level and determine the present spatial extend of tidal inundation of the suburban areas of Salvador. Harmonic, statistical and spectral analyses, complemented by numerical modeling of the hydrodynamics, show that the sea level is rising at a rate of 2.15 mm/year and the inundation time is increasing. Important seasonal variability is observed, with higher mean sea levels occurring in May and April driven mainly by the wind shear, whose interannual variation also causes alternate interannual MSL trends. The data indicates an increase in the frequency and severity of extreme high sea level events, regularly associated with the transit of subtidal waves that have become higher and more frequent along the years. Numerical simulations showed that subtidal oscillations tend to be amplified inside the estuary, likely increasing the severity of inundation events. A suburban area of 496,513 m2 along the bay margin of Salvador, with poor infrastructure, is undergoing tidal inundation that has become more intense every 4 years.