Cities manage flood risk using different types of adaptation and regulatory mechanisms . Built flood-control infrastructure, such as levees and stream channelisation, reduces the demand for nature-based flood impact reduction. Cities facing flood risk that do not currently have extensive grey flood-mitigation infrastructure may find NBS to be an appealing, lower cost solution . In cities where flood-control grey infrastructure already exists, there is less demand for NBS of flood protection, but NBS may provide important back up, especially in a changing climate that may increase flood hazards . Overall, city and basin-wide NBS for riverine flood impact reduction can reduce the generation of new hazards by making space for water which can reduce the potential for a false sense of security provided by traditional flood management approaches .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report