A new study published in Science Advances presents a detailed flood risk analysis across the U.S. Gulf and Atlantic coasts, using machine learning models trained on historical FEMA damage data. The research separates flood risk into two categories: general flood damage, which includes all levels of property damage, and extreme flood damage, which focuses on total losses. This distinction is critical for claims adjusters who must evaluate both frequency and severity of losses.
The findings show that a relatively small geographic footprint accounts for a disproportionate share of exposure. For example, just 1.1% of the study area falls into the highest risk category under general damage, yet it contains over 16% of the population. This concentration of exposure signals a high potential for claim clustering, particularly in urban coastal environments where insured values are dense.
Eight cities stand out as having the highest flood risk: New York, Norfolk, Charleston, Jacksonville, Miami, Mobile, New Orleans, and Houston. New York leads in total exposed population, with approximately 4.75 million people at risk under general damage scenarios. New Orleans shows the highest relative exposure, with nearly 99% of its population and buildings located in high-risk zones. For adjusters, this highlights two distinct risk profiles: high-frequency, high-severity urban exposure in large metros, and near-total exposure in smaller but highly vulnerable markets.
The study also identifies key drivers of flood losses. Low elevation, high drainage density, and population density are the most influential factors. In extreme damage scenarios, drainage density becomes the dominant factor, indicating that areas with rapid water runoff and overwhelmed infrastructure are more likely to experience total losses. This has direct implications for claims severity, particularly in urban areas with extensive impervious surfaces and aging drainage systems.
From a claims perspective, the research reinforces the importance of location-specific risk assessment. High-risk zones are not evenly distributed, and exposure is heavily tied to urban development patterns. The findings suggest that adjusters should anticipate higher claim volumes and larger losses in densely populated coastal cities, especially where infrastructure limitations and social vulnerability intersect.
The study also points to future challenges. Sea level rise and increased storm intensity are expected to expand flood exposure, potentially increasing both claim frequency and severity. For adjusters, this means greater demand for catastrophe readiness, improved loss estimation tools, and closer coordination with underwriting and risk management teams.
