While the risk of coastal flooding from extreme storms and rising seas rightly attracts plenty of attention, Americans are being urged to look further inland for a similar threat receiving far less recognition: river flooding. New research conducted by the University of Bristol has revealed that as many as 41 million Americans are highly at risk from river floods – more than three times the number previously estimated – with real estate in areas such as Louisiana, Florida, Arizona and West Virginia found to be especially at threat.
For the first time, it has been possible to produce high-resolution flood risk maps that cover the entirety of the United States, whereas previous Federal Emergency Management Agency (FEMA) flood maps were capable of modelling no more than 60 per cent of the country. The fine details provided by these new maps also makes it possible to predict the impacts of flooding on many smaller streams than before, hence raising concerns about the significantly higher number of people potentially threatened.
‘We were all surprised by how many Americans we found are exposed to flooding from rivers,’ says Oliver Wing, from the University of Bristol’s School of Geographical Sciences. ‘It’s particularly worrisome considering that most of these people aren’t even aware of the risk they face.’
Additionally, there is the possibility that this lack of awareness means construction in high-risk river flooding areas will continue to rise, despite the threats. Estimates suggest that projected population growth, continued urbanisation trends, and the unpredictable threats posed by climate change will leave over 60 million Americans vulnerable to a 100-year flood by the middle of the century. ‘All of this highlights the critical need for comprehensive floodplain and flood risk management planning,’ adds Wing.
This was published in the April 2018 edition of Geographical magazine
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