Northwestern University researchers in a recently completed study found that the intensity of rain, or how much precipitation fell during a period of rain, has increased over the past half-century throughout much of the U.S., increasing the risk of flooding events.

Researchers compared the rainfall data in 17 distinct climate regions in the U.S. between two climatologically distinct time periods: 1951-1980 and 1991-2020. Their observations showed an across-the-board shift towards more intense precipitation in the U.S., with particular increases in the East, South, and Midwest. Specifically, when it rained east of the Rocky Mountains in recent decades, about 5 percent more precipitation fell. The study not only found increasing precipitation intensity, but that intensities are becoming more variable as well, making water resource management even more challenging. The study’s results indicate that flooding events could become more common across much of the U.S. “You don’t need an extreme weather event to produce flooding,” said Northwestern’s Daniel Horton, the study’s senior author. “Sometimes you just need an intense rainstorm. And, if every time it rains, it rains a little bit more, then the risk of flooding goes up.” Access the original study here or read more at Northwestern Now.