145 Dynamics of Natural and Built Environments (Posters)

Our communities, economies and infrastructure depend on interactions between the natural and built environments. Engineered systems (e.g. earthworks, structures, utilities) must be resilient to evolving natural forcings, and similarly engineered systems must also minimize negative effects on the natural environment.

Monday, 20 October 2025
8:00 AM - 5:30 PM
HBGCC, Hall 1

Assessing postfire flow hazards before a fire begins: Challenges and opportunities

Paper number: 145-1
Program: Technical Sessions
Time: 8:00 AM – 8:00 AM

Authors

Abstract

Wildfire can amplify flood and debris-flow hazards by enhancing runoff and erosion during rainstorms. Hazards associated with these postfire flows include loss of life, damage to infrastructure, reductions in water quality, and negative effects on aquatic habitat. Strategies to mitigate postfire flow hazards include fuel reduction treatments, improvements to flow conveyance, construction of sediment and flood retention basins, and public outreach and education. Since approximately 25% of postfire debris flows occur within the first 60 days after a fire ignites there is limited time to evaluate and implement mitigation strategies after a fire begins. Prefire assessments of postfire flow hazards can therefore be a valuable tool for hazard mitigation because they allow for additional time to evaluate and implement mitigation strategies. Here, we report on preliminary findings from a workshop that brought together practitioners from regional flood control districts and consulting firms as well as scientists from local, state, and federal agencies throughout Arizona in April 2025 to discuss successes, barriers and opportunities for assessing postfire flow hazards before a fire ignites. Funding, interagency coordination, and technical challenges were highlighted as barriers while data sharing, interagency coordination, closing common knowledge gaps, creating reproducible workflows for flow hazard assessments, and quantifying benefits of preemptive hazard mitigation and risk reduction actions were discussed as promising opportunities. Overcoming technical challenges could benefit prefire assessments by quantifying and reducing uncertainty in flow modeling, providing a better foundation for quantifying the costs and benefits of mitigation strategies, and assessing the effects of land management on postfire flow outcomes.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-413170

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