Recent Evolution of Surge-related Events in the Northern Adriatic Area
Keywords:Lagoon hydrodynamics, flooding, surges, global warming
The recent increase in the frequency of coastal flooding in Venice mainly depends on loss of land elevation (subsidence and eustasy) and man-induced hydrodynamic changes in the lagoon area, but can also be strengthened in the near future by changes in climate. In this paper, after a short review of recent changes in the relative mean and maximal levels of the sea and their causes, the main meteorological factors (atmospheric pressure and winds of sirocco and bora), which produce sea surges in the Gulf of Venice, are identified statistically. The recent evolution of these meteorological factors in the Adriatic area shows some favorable trends (the atmospheric pressure is increasing, thus provisionally masking eustatic sea-level rise, and bora is sharply lessening). However, the effects of sirocco, which is increasing in frequency in the mid-Adriatic, seem to be prevailing. On the whole, the frequency of sea surges ≥5cm to ≥30cm, which are the most frequent, is increasing in the North Adriatic and this implies more "moderately high tide levels", which are however liable to flood the lowest parts of the city of Venice. Such increase in frequency seems related to recent climatic changes (possibly related to global warming) and may therefore be expected to worsen in the near future.