Focus on river gauges, data strengthens after Florence

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CONWAY, SC (WBTW) – September 2018 brought Horry County some of its darkest moments, as Hurricane Florence swept up the South Carolina coastline.

While the storm brought strong wind and rain to Horry County, most of its catastrophic damage is linked to the days of freshwater flooding that followed the storm.

The City of Conway was arguably one of the areas hardest hit.

“I don’t think you can look at a storm like Florence and say we were prepared with the floodwaters that came with it,” Conway City Administrator Adam Emrick remembered.

Emrick was fresh in his role as city administrator, and the only thing he had to compare the storm to was Hurricane Matthew in 2016.

“We scrambled to get ready before and give our residents as much notice as we could, but we were using Matthew as the benchmark, because it was the record,” he said. “We’ve never seen more than Matthew in our lifetime and we (saw) four feet higher.”

To this day, Emrick believes no one could prepare for a storm like Florence. The Waccamaw River reached a historic 21 feet due to freshwater flooding, water forced dozens of families out of their homes, and critical roadways like Highways 9 and 22 flooded out. SCDOT and the Army Corps of Engineers also had to construct a barrier down Highway 501 Bypass at Lake Busbee to keep flooding from taking over that road, as well.

Traffic issues in the days following Hurricane Florence caused upwards of 7.5 hour traffic backups in the City of Conway, as evacuees tried to re-access the coast.

Now two years later, Emrick says infrastructure and the area around Highway 501 Bypass is a critical issue still unmet.

“It was a priority, and it is still a priority for us, but we are not necessarily seeing it prioritized at the state level and we think it needs to be,” he explained. “This is clearly the problem. It is a damn now. It holds back water when it floods. We know. We measured it at the peak.”

We took Emrick’s concern to SCDOT and asked what — if anything — was being done to help improve the area around Highway 501 Bypass, specifically.

SCDOT told us it applied for a very competitive FEMA hazard mitigation grant after the storm. Officials say it would’ve paid for engineering work to help improve the approaches on 501. However, it found out late last year, it was not awarded the grant.

Since the state says an immediate fox isn’t in the works on Highway 501 Bypass, it’s turning its attention to the source of flooding. SCDOT and SCDNR both say improvements in measurements and data from river gauges could help governments better map high-risk flooding areas and anticipate water problems on critical roadways.

We talked to SCDNR Chief of Hydrology Scott Harder about it.

“It’s real time data they can see if conditions are worsening or changing, and tie those gauge heights to the severity of the flood or potential flood,” he explained.

Harder says SCDNR is working to improve its river gauge monitoring network and how local agencies interpret and use that information to protect its citizens. Harder says more than 100 different types of gauges are spread out across the state, funded by state agencies like SCDOT and SCDNR, public utilities, and private companies. The United States Geological Survey operates and maintains the sites.

Harder says SCDNR spends about $300,000 a year supporting about 15 gauges and plans to more than double its number by the end of 2021. Emrick says the City of Conway supports a river gauge under the Main Street Bridge on the Waccamaw.

“Of course, we had another pretty significant flood event in 2016,” Harder recalled. “So ever since that time, we’ve been looking at data gaps in our monitoring networks and have been coordinating with other agencies, including the department of transportation, who obviously needs information regarding evacuation routes and whether bridges are getting flooded out and things like that.”

Harder says SCDOT and SCDNR have both pursued and acquired additional funding to improve monitoring networks over the past four years — even before Hurricane Florence.

“A fair number have been put in by both our agencies and there are still more that are planning to be put in,” he explained. “There have been gauges added to the Pee Dee, added to the major tributaries. There’s been a few along the coast. All that being said, you can never have too much data. We’re always looking to add more gauges where and when we need them.”

SCDNR officials also told our team its updated its inundation mapping for potential large scale flood disasters. That information helps provide state and local governments critical information on what could possibly flood based on a forcasted event.

“The more detailed information that is input into the model should result in output information being more precise,” Maria Cox Lamm, SCDNR Flood Mitigation Program State Coordinator, said. “Inundation modeling is one tool of many that first responders and emergency managers can use to make decisions regarding flooding.”

Despite the progress made in recent years, Harder says some challenges still lie ahead in the effort. One of those includes getting the gauges all at the same datum or reference point for more accurate readings and data – helping local officials and citizens understand how to interpret and apply it – and a second is cost.

“Cost can be a challenge to people, but we’re trying to emphasize the importance of these networks — convince the decision makers this money is useful,” Harder explained.

Emrick argues it absolutely is, especially if infrastructure fixes aren’t in the immediate future.

“To have data that is measurable and predictable is the only way to do that service properly,” he said. “As a city we need it. As a county we need it. As a state we need it. Otherwise, we’re going to continuously flood, continuously find the same things we’ve found before.”

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