Study offers flood warnings

The disastrous series of major hurricanes that hit last year — Harvey, Irma, and Maria — gave facility managers good reason to revisit their emergency response plans, with a particular eye on preparations for floods. A recent study from the University of Bristol in England offers more reason for concern: The risk of serious flooding across the United States is significantly greater than generally realized, according to Bristol researchers.

The gold standard of flood maps has been the ones from the Federal Emergency Management Agency. But according to the report, the FEMA maps have limitations that cause them to understate flood risks. The researchers say that FEMA maps focus on coastal areas, vary in quality, and don’t do a good job of covering smaller catchments — areas where precipitation collects and drains into a common outlet, like a stream.

The study used better spatial and population data to calculate flood risks across the contiguous 48 states. The results were sobering. According to the Bristol scientists, 41 million Americans live in an area with a 1-in-100-year flood risk. In other words, the study reports, 2.6 to 3.1 times as many Americans are exposed to serious flood risks as FEMA maps suggest.

What’s more, the number of Americans facing significant flood risks will almost certainly climb. One cause is population growth and the development that goes with it. The other reason is climate change. According to the 2014 National Climate Assessment, heavy downpours have been increasing in the United States, and so have floods in the Midwest and Northeast, which have seen the biggest increases in heavy rains. And rising sea levels triggered by the effects of changes in the climate — like melting glaciers and ice caps — pose an additional threat to facilities located in coastal communities.

A facility can’t prevent a flood. But it can be designed so that it survives and recovers from a flood or other disaster. The Bristol study is one more reason that resilience should be a priority for facility managers.