The City of Valdosta partnered with the U.S. Army Corps of Engineers last year to study the local affects of regional flooding.

It has been said, many times, that Valdosta lies at the bottom of a large drainage basin. Mayor John Gayle has even describe Valdosta as being at the bottom of the bowl.

During a special presentation Tuesday to the Valdosta City Council, Dave Apple, P.E., chief of the watershed planning section, Army Corps of Engineers in the Jacksonville District, confirmed the original analysis.

“Valdosta is at the bottom of a 1,500-square-mile drainage basin. This is one of the largest river drainage basins in the United States,” Apple said. “But it is a small part of a much larger watershed. These problems are not just on the Georgia side. These problems are also on the Florida side, too.”

During the meeting, Apple explained a watershed as imagining a bowl-shaped leaf with the veins and mid-rib as creeks, streams, and rivers all flowing toward the base of the leaf. Valdosta is at the base of the leaf.

Although the names change, rivers do not recognize state lines. This means that what happens in the upper part of the basin affects the lower part of the basin, and vice-versa.

“The purpose of the Withlacoochee River and Sugar Creek Flooding Analysis Study is for the USACE to examine flooding in the portion of the city that was severely impacted during the 2009 and 2013 flood events,” said Valdosta’s Stormwater Manager Emily Davenport. “This report

provides an analysis of the flood impacts in the study area from 10-, 50-, and 100-year storm events using USACE methodology and existing data. Based on this analysis, possible flood risk management alternatives will be developed and evaluated.”

Hopefully because of this study, Valdosta’s flooding issues will gain federal interest, which would bring additional studies and federal support.

With data provided from the City of Valdosta, the USACE modeled existing conditions, and found that Valdosta’s flooding is caused by rising water in the Withlacoochee and Little rivers which backs into Sugar Creek and Two Mile Branch.

The modeling conclusion was confirmed anecdotally from observations during the 2009 and 2013 flood events, commonly called “sunny-day” flooding. This is flooding that occurs several days after an immediate rainfall.

To aid Valdosta in its flooding, the USACE developed seven alternative solutions. The first three were deemed too expensive. Options four through seven were expensive and had a large environmental impact. Alternative number seven, a flood-control levee and culvert system, was chosen as the city’s best option.

This levee and culvert system would be 3,950 feet long, 12 feet wide, and 24 feet high. It would run perpendicular through the north end of Sugar Creek, and adjacent to the Withlacoochee River.

The USACE and city officials say this plan would not prevent flooding but would reduce the depth and duration of flooding; the engineer’s models showed a reduction in water-surface elevation.

During a 10-year event, the water surface would be reduced by 0.1 feet; a 50-year event, a reduction of 1.7 feet; and a 100-year event would be reduced by 2.8 feet. This levee has the potential to lower water stages, but the results depend on home elevation.

The models show benefits, such as a reduction in flooding (also, the duration of flooding, in some cases, was reduced from days to a few hours); more time for homeowners and businesses to access property; and potentially less damage due to less standing water.

“The USACE stated that this is a regional watershed issue, one that cannot be solved by the city alone. This is important because the solutions must come from a full study of the Suwannee Basin which will require federal funding,” Davenport said. “The USACE modeling clearly shows that the flooding that occurred in the City of Valdosta is not due to any conveyance or structural issues within the city’s flood control system. The study recognizes a need for a regional solution; however, the scope of this project is limited to the flood-prone areas at the confluence of the Withlacoochee River, Sugar Creek, and Two Mile Branch.”

The estimated cost of this project is $3.85 million, but this does not include real estate, operation and maintenance, etc. Costs would increase if onsite material is not available; the price tag could reach $8 million.

More information: Contact the U.S. Army Corps of Engineers in the Jacksonville District’s public affairs office, (904) 232-2389; or the City of Valdosta’s public information office, (229) 259-3548.