Many coastal cities are currently or will be exposed to the coastal disasters and ecosystem degradation, and there are still some essential knowledge gaps and efficient actions needed on the way to coastal defence and disaster risk reduction. Further efforts need to be made in the near future for the following research challenges.

·Generation theory of coastal disasters under the impact of sea level rise

·Mechanism of multi-resource flooding event in coastal cities

·Dynamic response and failure mechanism of newly-designed marine structures

·Evolution of aquatic ecosystem in coastal wetland

·Influences of multiple human activities on coastal system

·Disaster risk management and reduction strategies