Advancing understanding of the complex nature of flood risks to inform comprehensive risk management: Findings from an urban region in Central Vietnam

Driven by rapid climate, socio-economic, environmental, and political change, flood risks in urban regions are on the rise. Given that cities and urban regions are highly complex and integrated systems comprising social, ecological and infrastructure domains, flood risks in urban regions are characterized by high levels of complexity, such as cascading effects, interconnected risks and interacting risk drivers. To ensure the effectiveness of risk management interventions, enhanced understanding and empirical evidence of the complex nature of urban flood risks is needed. Failing to understand how risks interact across systems, and not identifying interactions of underlying risk drivers and root causes can lead to maladaptation in planning. Addressing this, we use impact chains and impact webs, i.e. conceptual risk models that have been co-created and validated in a participatory manner, to break down and understand the complex nature of flood risks, using the highly flood-prone urban region of Hue in Central Vietnam as a case study. Results show that flood risks and impacts in Hue are deeply interconnected, with cascading effects across systems. Further, our analysis reveals that risks and impacts are induced by the same underlying risk drivers and root causes. The co-development of conceptual flood risk models in Hue provides a useful methodology to move from systemic flood risk analysis to systemic flood risk management.