Extreme storm events striking large municipalities often create challenges for quickly moving accumulated rainwater away from business and residential areas, as well as high-traffic thoroughfares.
Such was the case for Jonesboro, Ark., whose 300-plus miles of ditches often swelled to overflowing during heavy storms. To address the issue, city leaders began developing a storm water management plan with the help of Robert Kröger, an assistant professor at Mississippi State.
A new water management specialist in the university’s Forest and Wildlife Research Center, Kröger was asked earlier this year to assist in the evaluation of Federal Emergency Management Agency-designed drainage ditches for the largest city in northeastern Arkansas (Pop. 59,000).
"The goal of the project was to provide reliable information on the FEMA drainage ditches in need of urgent attention," said Kröger.
He was part of a team of scientists led by Jerry Farris, an Arkansas Biosciences Institute distinguished professor, and Matt Moore of the U.S. Department of Agriculture’s Agricultural Research Service office in Oxford [Miss]. Their recently concluded evaluation included a review of historical maintenance, as well as environmental forecasting and monitoring, among other areas.
"We spent a week evaluating more than 50 sites among the more than 300 miles of FEMA ditches within the Jonesboro city limits," Kröger said.
He said team members quickly noticed that many drainage canals had become heavily vegetated with water-loving wood species. While some could be properly maintained by city workers, other canals were too thickly congested with willows, sycamores and sweet gums, among others.
"By understanding what types of vegetation were in the ditches and their proportion compared to grasses, we developed a maintenance strategy for all the ditches," Kröger said.
Woody species often collapse into a drainage canal, where they create debris dams, Kröger explained. This, plus woody debris caught along the edges of drains and box culverts during deluges, are among the leading causes of municipal flooding problems.
"Our efforts, combined with planning by residents, city council members and other administrators, have contributed significantly to Jonesboro’s improved storm water management plan," Kröger said.
Jerry Farris of the ABI said the new comprehensive plan assigns rankings to the ditches: those suitable for drainage, those that have intermediate woody vegetation growth and those that require constant maintenance.
"The system allows planners to monitor and manage ditches that are prone to tree growth," Farris explained. "Integrated management of mechanical drainage controls, along with herbicide treatments that stabilize the growth of native plant species, should lead to a sustainable and achievable maintenance of drainage canals for Jonesboro."
Kröger and Farris agreed that the proven Arkansas plan can serve as an example for other municipalities interested in formulating similar strategies.