Comparing Flood Inundation Map Features and Diagnosing Decision Support Design Challenges

ABSTRACT The increasing frequency and intensity of hydrometeorological events such as floods driven by climate change necessitates reliable, spatially explicit decision support tools like Flood Inundation Maps (FIMs). Developing effective FIMs is challenging, as varying data complexities need to be managed whilst effectively communicating forecasts and uncertainties to diverse audiences. Visualisation literature offers some empirical evidence for designing effective user‐controlled decision support tools such as FIMs. Still, research and operational gaps persist, particularly with respect to whether FIMs are appropriately designed, communicated, translated, and interpreted to support effective near‐term flood response decisions. Our study draws from research in visualisation and user‐centred design literature to conduct a structured diagnostic assessment of eight (inter)national FIM forecast visualisations using independent task‐based usability questionnaires and guided workshops. We identified challenges such as unclear key messages, inconsistent colour schemes, ambiguous symbols, unclear legends, and inefficient interface layouts, likely reducing the usability and decision support value of these eight FIMs. We recommend identifying product key messages; designing user interfaces around those key messages; ensuring that visual features such as colours aid heuristic decision‐making and cognitive processing; and incorporating dynamic, user‐controlled features to enhance usability and decision‐making for technical and non‐technical audiences. Finally, we provide evidence‐informed design considerations that will improve the accessibility, interpretability, and effectiveness of FIMs as decision support tools, ultimately improving the process and outcomes of flood response decisions.