Optimizing Flood Risk Mitigation under Uncertainty: Towards Bridging Theory and Practice

Flood risk management is undergoing a fundamental shift from a purely flood protection-based approach to a more comprehensive risk management strategy. This shift was promoted by the recognition that existing flood protection measures have proven insufficient in mitigating the severe consequences of recent flood events across Europe. Despite this growing awareness of the need for integrated flood risk management, practical implementation faces significant challenges. The complex interplay of local protection measures, downstream effects, potential flood protection failures and inherent uncertainties complicates the assessment of the long-term impact of individual decisions on overall flood risk.

In practice, decisions on flood mitigation measures are often based on local expert judgment, political considerations, or general guidelines, rather than a coordinated, catchment-wide evaluation. This fragmented approach, which focuses on local effectiveness, overlooks the large-scale, interconnected dynamics of flood risk, leading to suboptimal outcomes at larger scales. To address these challenges, we develop a flood risk model capable of identifying globally optimal solutions for flood mitigation strategies. However, the direct application of these optimal solutions to real-world contexts is not straightforward. In countries such as Germany, persistent challenges remain in the context of political, stakeholder, and institutional dynamics. The hierarchical decision-making structures in these countries complicate the integration of global optimization solutions into practice.

In this contribution, we present the current state of our proposed flood risk model as well as a simplified optimization example, providing a foundation for discussions on how to translate these insights into the hierarchical structures of flood risk management practice.