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Abstract

Roughly 48 million people live along the Bangladesh coast, and they are threatened every year by floods due to storm surges and monsoons. Flooding events occurring during extreme sea levels (ESL) are expected to get worse due to the ongoing sea level rise (SLR) and emphasized by an increasing tidal range. However, the contribution of these different factors to ESL is not yet well understood in this region. The aim of this work is to understand the relative contribution of each factor to the current ESL along the Bangladesh coast, and to what extent their variations could influence ESL in the future. Hourly tide gauge records, combined with atmospheric data from the ERA5 reanalysis, have been used to evaluate ESL changes over the past decades, by applying percentile analysis and a specific analysis of meteorological and surge events. We observed the long-term evolution of ESL and the long-term changes of their principal components (SLR, tidal range, atmospheric pressure and wind speed). As observed worldwide, SLR is the dominant component of the long-term changes observed in ESL in this region. Finally, we also investigated and discussed the important effect of the changes in tidal range on the ESL, at seasonal, interannual and decadal time scales.