Introduction to the special issue Venice flooding and sea level: past evolution, present issues and future projections

Venice is an iconic place and a paradigm of a huge historical and cultural value at risk. The frequency of flooding of the city centre has dramatically increased in recent decades and this threat is expected to continue to grow and even accelerate through this century. This special issue collects three review papers addressing different and complementary aspects of the hazards causing the flooding of Venice: (1) the relative sea level rise, (2) the occurrence of extreme sea levels, and (3) the flood prediction. It emerges that the effect of compound events poses critical challenges to the forecast of floods, particularly from the perspective of effectively operating the new MoSE mobile barriers. Two strands of research are needed in the future. Firstly, there is a need to better understand and reduce the uncertainty on the future evolution of relative sea level and its extremes at Venice. However, uncertainty might not be substantially reduced in the near future, reflecting uncertain anthropogenic emissions and structural model features. Hence, complementary adaptive planning strategies appropriate for conditions of uncertainty should be explored and developed in the future.