Purdue researcher studies water runoff, climate change challenges

WEST LAFAYETTE, Ind. — Farmers’ actions in Indiana and the Midwest affect the entire country, and even the world, said Jane Frankenberger, professor of agricultural and biological engineering at Purdue University.

Frankenberger is an expert in water quality and watershed management, particularly in agricultural systems.

In celebration of World Water Day, she shared how she’s working on solutions to challenges at the intersection of water and climate change.

Frankenberger’s research has advanced water drainage design and management, watershed modeling of agricultural systems and soil and water conservation strategies.

“We have a network of what people call tile drains or drain tubing about three feet below the surface over most of our agricultural area,” she explained. “The strong majority of our water flows through those.

“It’s been found in the past 20 or 30 years that they carry a lot of nitrate with them, and nitrate causes problems downstream, both locally and especially in the Gulf of Mexico.”

Once the high nitrate water reaches salt water, it removes the limitation that stops algae from growing, she said.

As algae overgrows and then decomposes, oxygen is consumed — resulting in hypoxia, or low oxygen levels, in water.

Hypoxia kills fish, which depletes valuable fisheries and disrupts ecosystems.

“More recently I’ve really tried to think about how climate change is also affecting the same (nutrient runoff) problem,” Frankenberger said. “What’s really changing is the temperature, but also the precipitation. Our wetness is changing.

“We’ve always needed drainage, but there’s more water going through the drain tiles, especially in winter and spring, when our rainfall has already increased and is expected to increase even more.

“This just makes the problem more difficult to solve. It’s not a different problem. But there’s even more of the problem than we already have.”

Solutions to agricultural runoff challenges include controlled drainage or drainage water management.

Drainage water management is the practice of using a water control structure to raise the drainage outlet to various depths. This allows farmers to have more control over drainage.

“The idea there is that it forces the water to go through different pathways through the soil, or more of it will be transpired by the crops,” Frankenberger said.

“Therefore it lessens the flow and gives more opportunity for a process called denitrification — which is the best way to solve the nitrate problem in water.”

Frankenberger also researches a solution called drainage water recycling, in which farmers would capture water in a pond or a small reservoir and use that to irrigate crops later in the season.

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