Do Bad Things Come in Threes?
The Importance and Challenge of Multi-Hazard Planning
Catastrophic risks are often plural rather than singular. Think of extreme heat, drought and wildfire. Like an unexpected house guest showing up when you have a big project due and an empty refrigerator, these risks often arrive together (“compound risks”).
Or think about wildfire, flooding and landslides. By denuding the landscape of vegetation and changing soil chemistry, wildfires can increase the possibility of flash floods, which can in turn increase the risk of landslides (“cascading risks”).
Flash flooding in Ruidoso, New Mexico after the 2024 South Fork Fire (Credit: Jeremy Klass/Emergency Operations Center, Ruidoso, N.M).
The complex, interdependent nature of catastrophic risks leads many to conclude that they are best approached from a “multi-hazard perspective” (Tilloy, et al., 2019; UNDRR 2021).
Yet single-hazard management approaches are far more prevalent because it is challenging to analyze and plan for multiple hazards (Kappes et al., 2012; Wang, He and Weng, 2020; Trogrlić et al., 2024).
Based on international experience, De Angeli et al. (2022, 10-16) outline a five-step multi-hazard assessment strategy:
Step 1: identify all hazards that affect a region and map their possible interactions;
Step 2: develop multi-hazard modeling based on the information collected in step 1;
Step 3: develop an impact assessment based on how hazards might develop across space and time;
Step 4: investigate how these hazards might interact and overlap spatially and temporally; and
Step 5: assess the impacts of these interacting hazards.
Similar strategies have been developed by other researchers (Hochrainer-Stigler et al. 2023).
These strategies are useful, but it is important to recognize that multi-hazard planning requires a lot from communities (Gallegos Reina and Perles Roselló, 2021). As Boyd et al. (2015, S156) observe in their study of regional water governance in Sweden, there is a “strong demand for reductionist approaches” that simplify complexity. Nor do our often siloed risk management arrangments make multi-hazard planning easy (Trogrlić et al., 2024).
While the challenges are very real, the complex and interdependent nature of catastrophic risks make multi-hazard planning more important than ever.
Chris Ansell
References
Boyd, E., Nykvist, B., Borgström, S., & Stacewicz, I. A. (2015). Anticipatory governance for social-ecological resilience. Ambio, 44(Suppl 1), 149-161.
De Angeli, S., Malamud, B. D., Rossi, L., Taylor, F. E., Trasforini, E., & Rudari, R. (2022). A multi-hazard framework for spatial-temporal impact analysis. International Journal of Disaster Risk Reduction, 73, 102829.
Gallegos Reina, A., & Perles Roselló, M. J. (2021). Relationships between peri-urbanization processes and multi-hazard increases: compared diachronic analysis in basins of the Mediterranean Coast. ISPRS International Journal of Geo-Information, 10(11), 759.
Hochrainer-Stigler, S., Trogrlić, R. Š., Reiter, K., Ward, P. J., de Ruiter, M. C., Duncan, M. J., ... & Gottardo, S. (2023). Toward a framework for systemic multi-hazard and multi-risk assessment and management. IScience, 26(5).
Kappes, M. S., Keiler, M., von Elverfeldt, K., & Glade, T. (2012). Challenges of analyzing multi-hazard risk: a review. Natural Hazards, 64, 1925-1958.
Tilloy, A., Malamud, B. D., Winter, H., & Joly-Laugel, A. (2019). A review of quantification methodologies for multi-hazard interrelationships. Earth-Science Reviews, 196, 102881.
Trogrlić, R. Š., Reiter, K., Ciurean, R. L., Gottardo, S., Torresan, S., Daloz, A. S., ... & Ward, P. J. (2024). Challenges in assessing and managing multi-hazard risks: A European stakeholders perspective. Environmental Science & Policy, 157, 103774.
UNDRR. (2021). Increasing global resilience to systemic risk: Emerging lessons from the COVID19 pandemic. Geneva: United Nations Office for Disaster Risk Reduction.
Wang, J., He, Z., & Weng, W. (2020). A review of the research into the relations between hazards in multi-hazard risk analysis. Natural Hazards, 104(3), 2003-2026.