Dikes, diseases, and disasters: a risk-based comparison of floods and pandemics
Cross-hazard lessons for managing low-probability, high-impact disasters
M.N.M. Schuiling (TU Delft - Technology, Policy and Management)
P.H.A.J.M. van Gelder – Mentor (TU Delft - Safety and Security Science)
S. Hinrichs-Krapels – Graduation committee member (TU Delft - Policy Analysis)
Dorien Lugt – Mentor (HKV Lijn in Water)
B. Kolen – Graduation committee member (HKV Lijn in Water)
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Abstract
This study demonstrates the value of a structured, risk-based comparison between floods and pandemics - two disasters that, despite their fundamentally different origins, share a common risk profile as low-probability, high-impact, threat-driven events. Both hazards challenge societies due to their rarity and large-scale consequences, yet also allow for early intervention because of their forecastable nature. Despite extensive disaster literature, cross-hazard comparisons remain limited. The research question guiding this thesis is: What can be learned from a structured risk-based comparison of floods and pandemics?
To answer this, the study adopts a semi-qualitative, multi-method approach integrating literature reviews, expert consultations, and case analyses, structured around three sub-questions: comparing risk mechanisms, case timelines, and intervention effects.
The analysis reveals both fundamental differences and actionable overlaps. Flood and pandemic risk mechanisms differ at the source: floods stem from physical and meteorological causes, while pandemics arise from complex biological, ecological, and socio-behavioral factors. This greater causal complexity results in deeper uncertainty, making prevention, prediction, and early action more difficult for pandemics - even though swift intervention remains critical. Floods, in contrast, are more predictable, often allowing for threshold-based decisions and scenario planning. Prevention is the most effective risk reduction strategy for both, but less reliable for pandemics, meaning residual risk remains higher even with high effort.
Cross-hazard learning proves valuable in both directions: flood management offers lessons on structured planning and preparedness, while pandemic response underscores the need for adaptability, real-time data, and societal resilience. Ultimately, residual risk is inevitable - neither hazard can be fully prevented or contained. Defining acceptable risk levels, an established principle in flood governance but still largely absent in pandemic contexts, is important for transparent and effective disaster risk management.