ARI SHAPIRO, HOST:
Climate change is bringing more rain to many parts of the U.S. And that rain can cause devastating floods. NPR's Rebecca Hersher reports on the complicated and expensive problem for communities around the U.S.
REBECCA HERSHER, BYLINE: Ellicott City, Md., is old, 1772. And in the last 200 years, there have been about 20 floods in town. But two of the biggest ones were in 2016 and this year on Memorial Day weekend.
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UNIDENTIFIED PERSON #1: Hi, this is Howard County 911. We missed a call from you.
UNIDENTIFIED PERSON #2: Yes, I have a lady stuck in a building over here across the street (unintelligible) from me.
HERSHER: Thunderstorms dumped more than 8 inches of rain in three hours and turned the narrow main street into a raging river.
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UNIDENTIFIED PERSON #1: How much water is in the building now?
UNIDENTIFIED PERSON #2: It's going halfway up the inside of the building. She's screaming at the top of her lungs.
HERSHER: Both of these women survived. One man in town died. The restaurants and coffee shops in downtown Ellicott City had just reopened after the last flood. The repairs cost millions. Now some business owners say they don't know what they'll do.
Where was the water?
KEVIN BLOOM: Everywhere.
HERSHER: Kevin Bloom's family has run a commercial truck repair company at the west end of town since the 1920s. There's a boxy garage and a low-lying parking lot for vehicles waiting to be fixed or picked up. Until recently, Bloom only cleared out that parking lot in special situations like when the remnants of a hurricane made their way up the coast. Now...
BLOOM: Anytime there's a threat of a storm we just move things out of the way. That's how we have to operate. That's our new normal. So we have real estate that we can't use because of - there's certain times of the year it's always the threat of a storm, always threat. And it's not a tropical storm or a hurricane or - it's a - just the threat of a thunderstorm.
HERSHER: A few days after the storm, the parking lot is mostly empty. Too much rain is bad for business. Scientists say there are two reasons for flash floods like these. The first is more rain. Donald Boesch is the former director of the University of Maryland Center for Environmental Science. He explains that greenhouse gas emissions have led to more precipitation in some parts of the country.
DONALD BOESCH: As we increase the greenhouse gas concentration, the Earth is heating. The air warms up. The oceans warm up. More water vapor goes into the atmosphere. And if we can remember from, you know, fourth-grade water cycle, whatever goes up has to come down.
HERSHER: Rain storms are getting more frequent. And when the storms come, they dump more water. The second reason floods are getting worse is that that water has nowhere to go.
BOESCH: We have altered the watersheds so that the water runs off more rapidly - parking lots, roads and subdivisions and roofs.
HERSHER: For every new parking lot or wider road, communities should also build things like storm water retention ponds and larger storm drains. But many places big and small have not kept up with both development and climate change. A big example - Houston is scrambling to expand reservoirs and reinforce bayous after Hurricane Harvey. On a smaller scale, something similar is playing out in places like Ellicott City.
So how wide is this culvert?
BLOOM: So they measure this at 84 inches.
HERSHER: Kevin Bloom shows me a pipe across the street from his business. It was built decades ago to contain a stream that used to run alongside his family home where his grandmother was born. Making this pipe bigger is one of a handful of flood control measures the county is considering. Bloom thinks that's not enough.
BLOOM: The approach needs to change. Some homes may not be where they currently are because they need to give it back to the stream.
HERSHER: That includes his family's home. It's becoming clearer and clearer to him that if the floods are here to stay, the house will have to go. Rebecca Hersher, NPR News.
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