Making Flood Inundation Mapping (FIM) Work for Multiple Users: Improving the Design of FIM for Decision Support

Abstract

Visualizing and communicating flood inundation depth and extent can be valuable for informing decisions related to flood preparedness and disaster response. In the United States, several different types of flood inundation mapping (FIM) exist and a new National Water Model (NWM) FIM product is being rolled out across the country (expected to be fully deployed by the end of 2026). A mixed-methods social science research study investigated how select FIM products are used for decision support, what barriers exist to using their information, and what improvements to design and delivery could improve their usefulness. Professional and residential participants in scenario-based focus groups and surveys in the Mid-Atlantic and West Gulf River Forecast Center regions provided feedback on FIM use and design that was incorporated into redesigned versions. These revised FIM products were tested in a follow-up online survey with professionals gathering more detailed feedback on what elements of the maps and design were most helpful for their needs. Many of the proposed changes were reviewed positively, including color transparency, localization (labeling/geographic context), delineation of the ordinary high-water channel, and inclusion of critical infrastructure and evacuation routes. Findings also describe user needs for FIM products to offer historical context, probabilistic information, and mobile accessibility. Overall, the study highlights the value of flood inundation mapping to decision-making and the desire for this type of information for both professional and public audiences and provides actionable design-related recommendations to improve the usefulness and accessibility of these products.