WASHINGTON (AP) – An extensive and meticulously detailed investigation into flood susceptibility reveals that over 17 million individuals residing along the United States’ Atlantic and Gulf coastlines face the most substantial peril from inundation. Notably, New York and New Orleans have emerged as particular focal points of concern, according to the findings of one of the most exhaustive examinations of flood risk ever conducted.
A team of researchers from the University of Alabama meticulously analyzed sixteen distinct variables. These encompassed inherent geographic vulnerabilities, the density of population and critical infrastructure situated in at-risk zones, and the inherent fragility of resident communities.
Subsequently, historical damage data procured from the Federal Emergency Management Agency’s (FEMA) comprehensive archives were integrated. The application of three distinct artificial intelligence methodologies enabled the precise determination of flood risks spanning from Texas to Maine. The analysis projected that 17.5 million people are categorized as being at “very high” risk, with an additional 17 million identified as being at “high” risk, representing the subsequent severity level.
The study’s authors considered flooding incidents of all magnitudes. Furthermore, a separate evaluation was conducted focusing on what FEMA designates as the most egregious events, specifically the top 1% of occurrences in terms of severity.
The research indicated that 4.3 million coastal inhabitants are exposed to the most severe category of extreme flooding, while 20.5 million individuals are positioned at high risk, marking the second most elevated tier.
A significant prevalence of vulnerabilities was identified. The study specifically underscored eight urban centers of concern, ranging from Houston, which experienced substantial flooding during the aftermath of 2017’s Hurricane Harvey, to New York, which was profoundly impacted by Superstorm Sandy in 2012.
Although the absolute number of individuals exposed in New Orleans is considerably lower at approximately 380,000, this figure represents an astonishing 99% of the city’s entire populace.
Wanyun Shao, a climate scientist at the University of Alabama and co-author of the study, clarified that this statistic does not imply that 99% of residents will be inundated during any given storm. Rather, it signifies their potential susceptibility, contingent upon the specific trajectory of the weather system and its associated precipitation patterns.
“The sheer scale of these figures is both astounding and deeply concerning,” Shao remarked.
Shao further articulated, “When the next substantial storm targets New York City, or when a hurricane akin to Hurricane Katrina makes landfall in New Orleans, lives will be endangered, particularly impacting those segments of the population that are most socially disadvantaged,” referencing categories such as low-income individuals, the elderly, children, and those with limited educational attainment.
Both Shao and external specialists expressed surprise at the findings, notwithstanding their awareness of the escalating consequences of global climate change.
Alex de Sherbinin, a geographer at Columbia University unaffiliated with the study, commented, “New York’s known susceptibility to flooding, coupled with its substantial population, is a well-recognized factor. However, the finding that New York harbors an exposed population almost an order of magnitude larger than any other city is indeed unexpected.”
The study posits that the increasing frequency of flood-related challenges in New York and New Orleans can be attributed to anthropogenic climate change. Nevertheless, other metropolitan areas are also facing significant threats.
Jacksonville reports 679,000 residents at high or very high risk of flooding, with Houston closely following with just under 600,000. Additional municipalities identified as being at elevated risk include Miami, Norfolk in Virginia, Charleston in South Carolina, and Mobile in Alabama.
Shao and the external experts concur that the paramount distinction of this research lies in its unparalleled comprehensiveness, integrating an extensive array of influencing elements. These encompass land subsidence and the prevalence of impervious surfaces that impede water infiltration, alongside the incorporation of socio-economic factors such as poverty levels and demographic age profiles.
Venkataraman Lakshmi, a professor of engineering at the University of Virginia and head of the hydrology section at the American Geophysical Union, suggested the potential applicability of this methodology to other global regions, citing Manila, the capital of the Philippines, as an example. Lakshmi, who was not involved in the study, affirmed that the flood perils highlighted will likely escalate in both frequency and intensity due to human-induced climate change.
Marco Tedesco from Columbia University, also an independent reviewer of the research, stated, “This study powerfully reinforces the fundamental understanding that future flood catastrophes are not solely a function of water levels; they are intrinsically linked to where people reside, the methodologies employed in urban development, and the stratification of protection afforded to different populations.”
De Sherbinin further elaborated, “The meticulous analysis of flood risk determinants holds considerable value for municipal planners, emergency management professionals, and even those responsible for infrastructure maintenance, such as highway departments and utility providers. While the elevated risk associated with low-lying areas is generally acknowledged, the data compiled in this study offers profound new insights into flood susceptibility, particularly concerning flash flood events.”
Hemal Dey, the lead author of the study and a geospatial scientist, expressed his aspiration that local authorities will consider implementing a broader range of solutions beyond conventional structural measures like dams and levees. He advocated for the integration of natural infrastructure components, such as wetlands, grasslands, rain gardens, and estuaries.
Craig Fugate, a former FEMA director who did not participate in the research, commented, “This investigation provides robust validation for concerns that emergency managers have articulated for numerous years. The more challenging question, however, remains the commitment to concrete actions and their effective implementation.”
