Study shows Virginia at increased risk for flash floods and landslides
Extreme rainfall isn’t a distant possibility. It’s already been taking a toll on this country for decades. That’s the conclusion of a group called Climate Central which reviewed records dating back to 1970. You might expect to see great variation from one region to the next, but Andreas Prein at the National Center for Atmospheric Research, says that was not the case.
“What they found was very consistent across the United States – even Alaska," he says . "It doesn’t matter if you’re on the East Coast or in the Southwest where it’s very dry. All of the extreme rainfall increased very consistently across all the United States.”
And no wonder. Kevin Reed, an associate dean for research at Stonybrook University, says it’s getting warmer everywhere.
“As the atmosphere warms due to increases in greenhouse gases such as carbon dioxide, the amount of moisture that the atmosphere can hold increases. Not only has rainfall changed over the last 50 years, but it’s changing at a pretty alarming rate.”
Hurricanes and Nor’easters are known to cause flooding, and climate change has increased the intensity of precipitation during those storms. Prein recalls several in the recent past.
“West Virginia flooding in 2017, Hurricane Harvey in 2017 as well. You had Hurricane Matthew in North Carolina recently. Hurricane Ida that caused major flooding in New York last year, so we see this almost unprecedented rainfall extremes all over the place, and they can cause a lot of flash flooding.”
Here in Virginia, average hourly rainfall increased 24% in Norfolk, 15% in Lynchburg, 14% in Richmond and ten percent in Roanoke over the last 50 years, and the trend is likely to continue, so Reed says we should prepare to rebuild sewers, detention ponds, dams and other structures designed to protect us from flash floods.
“Those systems were often times designed decades ago, before this kind of large change in extreme rainfall that we’ve seen.”
And Prein warns people should be ready to leave on very short notice if the National Weather Service issues a warning for flash floods.
“You should know where to go and be prepared to evacuate. That’s very important, because in a situation where you have to, you have very little time to react.”
The Climate Central analysis also showed a third of flood damages since 1988 – costing $73 billion – were due to increases in rainfall.