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New research conducted by USGS, University of Alaska Fairbanks, and NOAA points to the escalating threat of flooding to coastal communities in Alaska, driven by climate change and rising sea levels. Published in Scientific Reports, the study employs innovative approaches to estimate flood elevations, crucial for planning and safeguarding Alaska’s many coastal communities.

Map of highest storm-driven flood impact category in 63 Alaska coastal communities for flood events from 1887 to 2022
Map of highest storm-driven flood impact category in 63 Alaska coastal communities for flood events from 1887 to 2022.

Coastal communities worldwide face intensifying flood hazards due to the dual impacts of climate change and sea level rise. To identify risk areas for effective planning, experts traditionally rely on metrics like the 100-year floodplain or record flood elevations. However, remote communities often lack precise flood elevation measurements, requiring new methodologies to calculate flood exposure.

In the study, researchers leveraged observation-based techniques to estimate record flood elevations in 46 Alaskan communities. Their findings, compared against elevation models, infrastructure distributions, and sea level rise projections, offer a comprehensive view of flood exposure in the region.

The results show that approximately 22% of structures in the analyzed communities are currently located within the record floodplain. However, with projections of sea level rise, this figure is expected to rise to 30–37% by the year 2100, should these structures remain in their present locations. Notably, the highest flood exposure is concentrated in western Alaska, with projections indicating that northern Alaska will confront similar levels of vulnerability by the end of the century.

"This evaluation of record flood height, category, and history provides vital context for coastal flood exposure, essential for informed decision-making," said Richard Buzard, USGS Research Geologist and lead author of the study. By identifying current and projected hazardous zones, communities can avoid unintentional development in floodplains and implement long-term safety measures.

The study's methodology offers promise beyond Alaska, with its transferability to other regions facing similar mapping challenges. As coastal regions worldwide confront escalating flood risks, innovative approaches like those employed in this study are key to enhancing resilience and mitigating the impacts of climate change-induced flooding.

This research is part of a larger effort to map Alaska’s floodplains and prepare communities for sea level rise and changing storm climatology. The USGS, with funding from the Climate Adaptation Science Center and Disaster Supplemental funding in the wake of typhoon Merbok, is adapting the Coastal Storm Modeling System (CoSMoS) to Alaska’s unique climate in order to map flood risk for several rural communities in western and northern Alaska.

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