Midwest Flooding Has Increased Over the Past 50 Years

Floods are becoming more frequent in the Midwest. Scientists have found that the U.S. Midwest and surrounding states have endured increasingly more frequently flood episodes over the past 50 years.

In order to see how flood episodes have changed over the years, the researchers examined daily records collected by the U.S. Geological Survey at 774 stream gauges in 14 states from 1962 to 2011. They found that 34 percent of the stations had an increase in frequency in the number of flood events. In contrast, only 9 percent of the stations showed a decrease.

"It's not that big floods are getting bigger, but that we have been experiencing a larger number of big floods," said Gabriele Villarini, one of the researchers, in a news release. "We related this increasing number of big floods to changes in rainfall and temperature. There was an overall good match between the areas with increasing frequency of flood events and areas experiencing increasing frequency of heavy rainfall events."

The researchers found that most of the flood peaks in the upper Midwest occur in the spring. In addition, these stem primarily from snow melt, rain falling on frozen ground and rain-on-snow events. In addition, spring also has the strongest increase in temperature over most of the northern part of the region studied.

The findings reveal that flooding is certainly increasing. These findings support the current thinking among climate scientists that global warming is impacting the hydrological cycle. As the atmosphere becomes warmer, it can hold more moisture and precipitation increases.

That said, the latest study doesn't make a connection between climate change and flooding; it just shows that flooding is increasing.

The findings are published in the journal Nature Climate Change.

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