The city of Jackson needs an estimated $2 million to stop flooding along Belhaven Creek.
Southern Consultants has nearly wrapped up design work on a project to alleviate drainage issues along Belhaven Creek south of Riverside Drive.
Recently, neighborhoods there were inundated by flood waters when a brief, but heavy storm came through the area.
Many streets, including St. Mary Street and St. Ann Street, were blocked off when the creek jumped its banks. Some individuals reported flooding in their yards, while at least one man had to dip water out of his vehicle.
Jackson Mayor Chokwe Antar Lumumba said addressing the problem was a top priority, and was planning to discuss how to fund the improvements with the city’s one-percent oversight commission.
“At this juncture, we’re looking for funding,” he said.
The commission asked the city to provide an update on all flood and drainage studies at its August meeting.
The one-cent commission meets on the second Wednesday of the month.
Last fall, Southern Consultants was awarded a $225,000 contract to design improvements for Belhaven Creek.
Recommendations, which were 95 percent complete at press time, call for replacing box culverts under Piedmont Street and St. Mary, and to re-channel portions of the creek to increase its capacity to handle runoff, according to city documents.
Between Piedmont and St. Ann, engineers are recommending building concrete walls along the creek banks, and adding rip rap along the bank from Laurel Street to Piedmont.
Engineers’ estimates show the plan would reduce flooding from a 25-year storm by four feet at St. Mary, between two and three feet at St. Ann, a little more than a foot at Lyncrest Drive and half a foot at Linden Place.
A 25-year storm, according to engineers, is a storm that has a four-percent chance of occurring once each year during a 25-year period.
The upgrades would alleviate nearly all of the flooding in the event of a storm similar to last month’s, which is considered a five-year-storm, James Stewart, Southern’s vice president and chief engineer, said.
“(Waters) shouldn’t top the road at St. Mary and St. Ann. There would still likely be some water on the street at Linden Place,” he said.
A five-year storm has a 20 percent chance of occurring each year during a five-year period.
Southern Consultants was initially brought on to draw up improvements for Belhaven Creek between Woodrow Wilson Avenue and Laurel Street.
Early recommendations included replacing six box culverts, making channel improvements from Laurel to Riverside, and purchasing several homes between Laurel and Linden Place to construct the improvements.
The work was expected to run around $10 million, and the plan was scaled back after talks with the city and the then one-percent program managers, IMS Engineers.
Southern also considered the building a retention pond north of Riverside to “delay flooding impacts downstream.” However, the stream would have had “no appreciable reduction of flooding … for rain events more intense than a 10-year storm.”
On the evening of Monday, July 10, a storm blew through the Belhaven and Fondren area, dumping between 2.5 and five inches of rain in less than an hour, according to revised experts’ estimates.
According to the National Weather Service (NWS), the creek didn’t flood just because of the rain, but because of the precipitation coupled with heavy runoff in the Belhaven Drainage Creek Basin.
“There was a pretty hefty event over that area,” NWS Hydrologist Marty Pope said. “The problem was the storm’s intensity and the fact that it didn’t fall over grassy areas.”
The Belhaven drainage basin runs basically from Glenway Drive and Lakeland Drive in the north to Pinehurst Street in the south. East to west, it stretches from Museum Boulevard to Veterans Memorial Stadium and Millsaps College.
It takes in the University of Mississippi Medical Center, the G.V. (Sonny) Montgomery VA Medical Center, Belhaven University and other development.
NWS statistics show more than 99 percent of the area is developed, while 41.58 percent of the area is impervious, such as parking lots, buildings and roofs, Pope explained.
Impervious areas do not soak up rain water, like natural ground, meaning the runoff has to go somewhere. That runoff quickly filled Belhaven Creek, leading to the flash flooding.
At Riverside, the creek rose from 3.16 feet to more than 13 feet between just before 7 p.m. and 7:30, and at Laurel Street, the creek went from 2.8 feet to 10.37 feet between 7 and 7:45, he said. The storm itself lasted about an hour.
While 2.5 inches fell in the Laurel Street area, Pope believes between three and five inches fell north of Riverside, which helped lead to the flooding.