Harris County Flood Control District has been working with FEMA since 2018 on a total overhaul of the county's mapped floodplains, which are expected to grow significantly due to increasing rainfall and improved technology. Without the new maps, which were expected to be released two years ago, many residents still don't have an accurate idea of their property's flood risk as the region heads into another hurricane season.
While flooding can occur anywhere, floodplain maps designate the official boundaries of areas considered to be at heightened risk. They show whether a property could flood in a "100-year" storm — in which case, it's in the 100-year floodplain — or a "500-year" storm.
FEMA collaborates with local governments across the country — in Harris County, their partner is the flood control district — to create and update the maps. Harris County maps have not had a complete and comprehensive overhaul since 2007.
As of now, Harris County's new maps are being scrutinized in FEMA's extensive internal comment process, according to Larry Voice, senior engineer for risk analysis for FEMA Region 6.
"It's not that there are problems with the data as far as inaccuracies," Voice said. "It's all about how we show it."
The challenge, Voice said, is to "show the data in a way that makes sense to everybody so that everything's consistent and everything's very readable."
Voice said the process is taking longer than expected due to the sheer size of Harris County and the complexity of the cutting edge technology they're using. Some elements of the model are one dimensional, while others are two dimensional.
"We have been working through comments for a couple years now," Voice added, "so it has been a slower process than we would have liked."
In a statement, the flood control district said the project is "incredibly complex," and it appreciates the "thoughtful feedback" from FEMA.
"The Flood Control District has been in close collaboration with the FEMA team to ensure they have the needed data and materials from our team," it stated.
After significant flooding occurred outside the mapped floodplains during Hurricane Harvey in 2017, the new methodology is part of a major effort to capture a more comprehensive, accurate understanding of flood risk.
On the new maps, Harris County's 100-year floodplain is expected to increase from around 150,000 acres to 200,000 acres, Harris County Engineer Milton Rahman said last year.
With hurricane season around the corner, residents living in that expanded, heightened risk area may not know they need flood insurance since the maps haven't been released to the public.
Currently, many property owners are required to have flood insurance if they are located in the 100-year floodplain — but not if they're in the less risky 500-year floodplain.
Without the updated 100-year floodplain publicly available, Voice recommends that residents check whether they're in the current "500-year" floodplain to get a better idea of their risk.
"I would advise them to consider themselves at risk and get flood insurance," Voice said.
After the maps are released, it could take another two years before they go into effect. Property owners will have a 90-day appeal period to argue against their inclusion in the floodplain.
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