Spring floods and unplanted fields set the stage for a discussion on how to handle all that water Aug. 22 at Dakotafest in Mitchell.
Chuck Brandel, vice president of drainage consulting business ISG, and ISG civil engineer Mark Origer showed examples of dozens drainage systems.
Figuring out the best way to manage water while maintaining water quality is key to a successful operation, Brandel said. That’s especially true in southeastern South Dakota which was hit hard by wet conditions this spring. It has been the wettest 10 years on record for the whole country.
“We’re seeing more intense rainfalls,” Brandel said. “In the engineering world, we had to change what a 50- or 100-year event was because it just isn’t what it was 30 or 40 years ago.”
These intense systems have led ISG to design more complex drainage systems that take into account the wide impacts drainage can have on an operation.
“You need to design a system correctly and not just throw in whatever tile you can find,” Brandel said.
The overall capacity of a drainage system is typically represented as inches of water removed per 24 hour period.
“You can’t just pick a 6 or 8 inch tile and expect it to fix your system,” Origer said. “You have to hit the correct coefficient for your operation.”
It’s easy to ignore the area’s watershed, but it’s not a good idea, according to Origer. He’s seen operations with 500 acres of watershed flow into one drainage system that was designed for an 80-acre field.
“You may get drainage out of an 8 inch tile, but that drainage after a 4 inch rain isn’t going to help,” he said.
Rather than simply installing tile, operations are starting to want better control over managing drainage. Putting in gates along a drainage system, or at least having the ability to install gates later on, will give you drainage when it’s necessary and water when it’s needed late in the season, Bradel said.
“On a normal year, this will help regulate water for late in the season to increase yields,” he said. “Even if you aren’t going to do controlled drainage, at least set up so you could.”
The long-term investment of a drainage system can be daunting, Bradel admitted, but he and Origer mentioned cover crops as a way to increase water filtration and drainage in a system that is struggling with water, even if there is a drainage system in place.