When Hurricane Florence struck North Carolina in 2018, 11 people there died from freshwater flooding — all of them in cars.
This year, with hurricane season underway, a new advanced warning system will alert North Carolina officials in real time which specific roads and bridges are likely to flood soon, so the state can prepare and warn the public.
The network of river and stream gauges will, ideally, allow the Department of Transportation to prevent people from driving on flooded roads and help officials to respond more quickly and get roads reopened.
“The primary reason is to save lives. A lot of deaths occur because of drowning and flooding, rather than wind,” said Matt Lauffer, the transportation agency’s hydraulics design engineer. “The other part is to help the department prepare for, respond to and recover more rapidly from extreme events. We can get resources to places where roads are flooded.”
Nearly a dozen states are using such real-time monitoring to assess potential flooding at specific bridges or roads.
Although states and cities have used real-time flood gauge monitoring for years, the need for hyperlocal warnings will only grow.
Two states — Colorado and Maryland — are doing advance flood monitoring for roads because of environmental changes, said David Claman, a hydraulic engineer for the Federal Highway Administration.
In Colorado, wildfires have significantly increased the runoff and debris for streams, and in Maryland, coastal roads are at risk because of the rise in tides.
North Carolina’s system receives data from gauges at more than 400 sites that measure the water surface using radar or sonar every 15 minutes, according to the transportation agency’s Lauffer.
If water near or under a bridge is flooding, the system notifies officials, who in turn can notify the public.
So far, about 50 gauges, most east of I-95, are mapping about 2,700 miles of roadway, but those numbers are growing, Lauffer said. In a state with more than 80,000 miles of road and 40,000 miles of river, the potential for flooding is vast.
“Those gauges have been in a long time. But they didn’t tell us anything about the roadway network,” Lauffer said.
“What’s new this year is that we can analyze flooding on the roadways.”
Floods can be deadly.
Other than heat-related fatalities, more deaths occur from flooding than any other weather hazard, according to the National Weather Service.
The national 30-year average for flood deaths is 88 a year — higher than tornadoes or hurricanes. And drivers and passengers account for nearly half of all flash flood fatalities.
Jenni Bergal writes for Stateline, an initiative of The Pew Charitable Trusts. This story is distributed through the Tribune Content Agency.
About the Author
