Reconciling flood-risk reduction and wetland resilience behind coastal floodgates

Coastal urban areas face increasing hazards from sea-level rise and extreme weather events. Where population relocation is not feasible, hard-engineering defence measures are often adopted to mitigate flooding. However, the implications of such interventions for the surrounding tidal eco-geomorphic system remain poorly understood. Here, we explore the effects of the recently implemented Mo.S.E. storm-surge barrier system on hydrodynamics and wetland resilience within the Venice Lagoon—a highly anthropized environment that may presage the future of coastal cities more broadly. Our analysis demonstrates that while the floodgates successfully protect urban areas from flooding, current operational practices significantly limit the magnitude and duration of wetland flooding, thereby reducing sediment deposition vital for wetland resilience. By comparing current barrier operations with a modelled optimized scenario, we show that subtle adjustments to activation timing can substantially reduce the eco-geomorphological impacts of the barriers, promoting a more sustainable balance between urban protection and ecosystem integrity.