Debby flood map: Why storm’s biggest wallop in Georgia came days later

SAVANNAH — As Tropical Storm Debby approached Georgia, forecasters warned that some areas could be drenched by more than 2 feet of rain.

It was closer to 1 foot in the end. But that was more than enough to trigger significant inland flooding after the storm made landfall on Florida’s Gulf Coast and crossed South Georgia.

The hardest hit swath of the state was a roughly 70-mile corridor from north of Statesboro to near Savannah. Much of the flooding happened after Debby had left Georgia, unspooling over several days, carried by the overflowing Ogeechee River as it crossed several counties near South Carolina before emptying along Georgia’s coast.

The delayed flooding caught off guard many Georgians who thought they’d escaped the worst of the storm. Ten days after Debby reached Georgia on Aug. 5, some communities are still waiting for the floodwaters to fully recede.

The Georgia Emergency Management Agency and several affected counties say they are still assessing the damage after hundreds of people were evacuated and rescued as homes flooded and roads became impassable.

Chuck Watson, a Savannah-based researcher who specializes in natural hazards, expects that the storm’s economic impact in Georgia and South Carolina will surpass $1 billion, factoring in damage, disruptions and other recovery efforts.

One reason the flooding was so bad: Debby brought a lot of rain to a region that was already soaked.

“We had a lot of rain in July, so the system was saturated,” Watson said.

National Weather Service meteorologist Brian Haynes said the region’s geography can contribute to slow-moving floods, as the flat coastal plain takes longer to drain. He said floodwaters were expected to fully recede by this weekend.

The black-water Ogeechee River is more than 290 miles long, winding from near Crawfordville, between Athens and Augusta, southeast to the Atlantic coast near Ossabaw Island. The University of Georgia’s River Basin Center says it is one of the few remaining free-flowing rivers in the state.

As the Ogeechee flowed from its inland headwaters toward the coast, it funneled more and more rainfall, contributing to flooding in Screven, Bulloch, Effingham, Bryan, Chatham and Liberty counties.

Readings from the National Water Prediction Service showed that the Ogeechee reached its highest level in 22 years of recording at Rocky Ford in Screven County.

Rocky Ford got 10.1 inches of rain in July, about 4 more than normal, and another 13.2 from Debby. The river there was below 3 feet on July 19, but it had risen to almost 7 feet before the storm hit. On Aug. 8, three days after Debby reached Georgia, the river gauge topped 14 feet.

Debby also brought rainfall of 10 inches or more to several other counties in the Ogeechee’s path.

Record river levels flowed toward the coast over the next two days. The gauge near Eden in Effingham County peaked at 17.97 feet Saturday, more than double its height before the storm and its highest reading in nearly a century. Its flood stage was considered major from Aug. 8 to Monday.

Effingham emergency management director Clint Hodges said residents were asked to evacuate their homes on “a handful of roads” and that about 50 homes were damaged.

Officials were still waiting to learn this week whether the dams that burst in Bulloch County “may have contributed to some of the rise” of the Ogeechee, Hodges said. Bulloch officials reported last week that 75 people were rescued from flooding caused by several pond dam breaches.

Credit: GEMA

River gauges marked record highs closer to the coast as the weekend arrived. The Ogeechee peaked early Saturday near Ellabell in northern Bryan County, and then Saturday night at Richmond Hill in southern Bryan, near the river’s mouth.

The river peaked at 10.2 feet in Richmond Hill, about 20 miles southwest of Savannah, surpassing the 6.5 feet recorded in 2017 during Tropical Storm Irma, which also caused flooding. Parts of U.S. 17 were submerged between Richmond Hill and Savannah, and more than a dozen Richmond Hill roads were still closed Wednesday.

Across the Ogeechee River from Richmond Hill, several south Savannah neighborhoods flooded, and a temporary emergency road was installed. A Chatham County spokesperson said about 100 people had been rescued throughout the county.

Watson said flooding from the Canoochee River, an Ogeechee tributary, contributed to the flood levels in Chatham and Bryan. In nearby Liberty County, officials said record-high levels on the Canoochee and Ogeechee caused additional flooding there.

Credit: GEMA

The delayed flooding from Debby was a bit unusual for southeast Georgia. Many coastal residents, as Debby approached, were not focused on a river flowing from inland.

“Normally, when you think of a hurricane or tropical storm flooding, you’re thinking of (coastal) storm surge,” Watson said. “… That inland rain isn’t something you normally associate with a tropical system.”

But one thing that should not surprise residents, he said, is that lots of homes are vulnerable to flooding in Chatham, Bryan and Effingham counties.

Watson said he remembers the Ogeechee flooding when he was growing up in the 1970s, but few people were affected because there wasn’t a lot of development around the river. In the past few decades, many homes have been built in vulnerable areas, and drainage infrastructure has not kept up.

There are also more impervious surfaces, with large warehouses and parking lots springing up in all three counties over the years, much of it tied to Savannah’s growing port. Watson said that, as a pilot, he can see the new development from the air.

Impervious surfaces give rainfall less opportunity to be absorbed. That water can end up in rivers and make storm events worse.

“You get this surge of water that’s happening faster,” Watson said. “So, same amount of water, maybe, but it gets into the drainage, and it has nowhere to go because it’s already at capacity.”

Credit: Katelyn Myrick

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