River aficionado urges good soil for healthy waterways

Growing up on a northeast Kansas farm proved fruitful for Kari Bigham, but the payback wasn’t from being solely immersed in agriculture.

Her father, Dave Friedrichs, did most of the farming—raising corn, soybeans, grain sorghum, and pigs.

While Bigham pitched in—“I still had my chores,” she said—with brothers Kevin and Ryan and their mom, Betty, her passion was roaming bottom land along “Friedrichs Fork” of Raemer Creek near Herkimer, northwest of Marysville, Kansas.

It’s where Bigham began to marvel and wonder about rivers, streams and watersheds.

“Why does a river look the way it does and why does it act the way it does?” she wondered.

“I often found myself in the creek bottom,” Bigham told her audience Jan. 18 at the Soil Health U and Trade Show conference in Salina, Kansas. She married Dan, a farmer whose operation is in Jefferson County, east of Topeka.

Aside from family—they have a son and daughter—Kari’s professional focus is on rivers and streams.

Her presentation touched on natural surface water processes, understanding the water cycle and how soil health plays into river management.

An intense curiosity in those natural developments led her to Kansas State University, where she completed her doctorate in May 2022 in the study and understanding of how human pressures in a landscape, such as dams, urbanization, or agriculture, affect stream stability.

Bigham is a teaching assistant professor in the Carl and Melinda Helwig Department of Biological and Agricultural Engineering on the Manhattan campus.

Watersheds are areas where water drains to a common outlet, she said, and every one is different.

“A big one is the Mississippi River basin. A sub to that is the Missouri River basin,” Bigham said, comparing the systems to a Russian nesting doll.

What goes along for the water runoff ride depends on both natural phenomena and human actions, she said, such as farming, ranching, construction of buildings, roads, bridges, and other development.

“What we do here will have effects downstream,” she said, showing an artist’s depiction of a watershed.

“Rivers carry not only water, but also sediment, wood, and other organic matter,” Bigham said, and what floats along plays a role in the path rivers and streams take, as well as their size and dimensions.

“Many streams flow year-round, but even a mostly dry channel is still a river,” she said, showing a slide of a dusty section of the Arkansas River near Garden City in southwest Kansas.

Not all river channels are the same, Bigham said. “They vary in dimension.”

Waterways can rush or “meander,” and they cut different paths on their downstream journeys.

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“(Streams) do it to slow themselves down,” she said. “They go around bends, where there is the highest erosion, due to centrifugal force.”

The conversion of natural prairies into ag land increases water and sediment in rivers and streams which “results in aggradation, or the raising of the stream bed,” Bigham said.

Natural streams and watersheds that have avoided human influence present a healthy stream with room to handle occasional floods, having short banks with plenty of vegetative cover.

But farming practices that encroach and damage what nature built causes “degradation” of the waterway, she said.

Farmer Kendall Hodgson, of Little River, Kansas, in eastern Rice County, sat in on the presentation to learn how to have minimal impact on rivers, streams and channels.

“I would rather not erode anywhere,” he said. “We’re trying to keep the land where it is and the soil where it is. We want the nutrients and crop protection to stay on the land, and people downstream don’t want it in the water.”

Slowing the runoff is a big help, Hodgson said.

“If water goes straight down a hill, it erodes a ditch. If we put in a terrace and take the water on a slow grade, it won’t erode as much,” he said. “We want to walk the water off instead of running it off the field.”

Among challenges these days is figuring out “how to manage rivers that are ever-changing,” Bigham said.

Fixes are categorized as passive or active restoration using watershed-scale best management practices, also referred to as conservation practices.

“Treat the cause, not the symptom,” she said.

Active moves include physically changing the stream to a more stable form.

“Don’t throw Band-Aids on a streambank. Implement conservation practices in the watershed and design a channel that fits the conditions,” Bigham said.

Using Friedrichs Fork as an example through a recent watershed modeling assessment, she said, “We proposed conservation including cover crops, precision ag techniques, and filter strips. That was in addition to the conservation practices they were already doing within the watershed. Additional watershed conservation practices would further reduce water and sediment yields downstream.”

Those efforts would result in improvements to water quality as well.

“It is unreasonable to put the land back to perennial prairie,” Bigham said. “But we can increase the infiltration rate by selecting and incorporating proper BMPs.”

That means using cover crops, she said.

“If you’re looking to expedite downstream channel evolution, incorporating soil health practices are really going to help,” Bigham said. “Physically changing the stream costs a lot of money and takes a lot of expertise, and the buy-in is difficult. Streambank stabilization can do it, but you’ve got to understand the system before you start, and also make sure you get the right permits.”

Flooding is a big concern, she said, but better soil can help deter flooding by storing water and cutting back on runoff.

“Better infiltration is going to decrease runoff and adding year-round vegetative cover throughout a watershed is the most effective way in doing that.”

An audience member later asked Bigham about the role beavers play in curbing erosion.

“Fur trade and the removal of beaver dams has had an impact on stream stability.” she said, “We are currently assessing the use of man-made beaver dams in the Great Plains in reducing channel erosion.”

Bigham’s presentation snared good reviews.

“She gave me a lot of insight about the evolution of streams,” said Jeremy Holm, a farmer-rancher from Galva, Kansas, who serves on the McPherson County Conservation District Board.

“If you leave it alone, the river will flatten itself out,” he said. “The best practice over time is not farming up against a stream or river bank.”

Tim Unruh can be reached at [email protected].