A comprehensive study on the development of floodplains across the country has revealed that over two million acres have been developed in the last twenty years in the United States, with Florida being home to approximately half of all newly constructed floodplain housing.
Research conducted by scientists at the University of Miami’s Rosenstiel School of Marine, Atmospheric, and Earth Science offers fresh insights into floodplain development patterns, which could pose risks to populations and areas, particularly in the Southeastern U.S., where flooding is a frequent occurrence.
The new research integrated geospatial data on land use, impervious surfaces, and housing alongside digitized regulatory floodplain maps to evaluate new floodplain development across various U.S. communities. The findings, published in the journal Earth’s Future, indicate that more than 840,000 new residential properties have been constructed in floodplains nationwide, with around 398,000 of these in Florida—this accounts for 21 percent of all new housing in the state, marking it as the highest total among all states.
Lead author Armen Agopian, a Ph.D. candidate in the Abess graduate program at the Rosenstiel School, commented, “Considering the extensive size of floodplains and the overall housing growth, these numbers are actually much smaller than expected.”
The researchers further observed that if new housing construction had been distributed according to the proportion of floodplain land in Florida, around 40% of the new housing would have been located in these areas.
Moreover, they discovered that 74% of U.S. communities have imposed restrictions on new developments in floodplains, and 87% have limited new housing in floodplains through local regulations and practices. Additionally, the study found that coastal communities are more inclined to initiate new developments and housing projects in floodplains compared to their inland counterparts.
The analysis also highlighted that communities participating in FEMA’s Community Rating System, a voluntary program that incentivizes better flood management in exchange for discounted flood insurance rates, showed a higher tendency for floodplain development.
Agopian stated, “While communities with flood challenges may enroll in the program, mere participation is insufficient for fostering safer development patterns. It’s crucial for these communities to not only join but also enhance their floodplain management practices, as these are the communities that genuinely begin to restrict floodplain development.”
Developing in areas prone to flooding substantially contributes to rising flood-related damages, elevating both the chance of floods affecting individuals and infrastructure, as well as increasing the damage severity when floods do occur.
This research marks the first comprehensive dataset assessing floodplain development outcomes on a community-by-community basis across the nation. Until now, much of the research surrounding flood damages and corresponding actions has concentrated on regions that have faced significant floods resulting in destroyed homes and lost lives.
Senior author of the study, Katharine Mach, who serves as a professor and chair of the Department of Environmental Science and Policy at the Rosenstiel School, remarked, “Our findings reveal that numerous communities nationwide have proactively taken significant steps to avoid floodplain development, mitigating potential issues before they arise. There is much to learn from these often-unheralded communities that effectively prevent flood challenges from manifesting in the first place.”
The study was funded by grants from the National Science Foundation (# 2034308, # 2034239, and # 2033929), the Leonard and Jayne Abess Center for Ecosystem Science and Policy, as well as the Rosenstiel School of Marine, Atmospheric, and Earth Science.
