Researchers harnessed multiple types of data to come up with a new estimate
NEW ORLEANS — National flood maps are underestimating the risk for tens of millions of people in the United States. That’s the conclusion of researchers presenting a new study December 11 at the American Geophysical Union’s fall meeting.
The U.S. Federal Emergency Management Agency estimates that about 13 million people live in a “1-in-100-year” floodplain zone, a region that has a 1 percent chance of flooding in any given year. But the agency’s risk assessment largely focuses on larger streams and rivers, and lacks assessments of risk along smaller tributaries. FEMA’s calculations “miss a lot of the risk,” says Oliver Wing, a geographer at the University of Bristol in England.
Wing and his colleagues amassed a wealth of data, including the U.S. Geological Survey’s river gauge data, lidar measurements of land-surface elevation, rainfall data from the National Oceanic and Atmospheric