IU students collecting sensors from a field after flood waters receded.
(Devan Ridgway/WTIU News)
It’s a sunny afternoon in a field just south of Columbus.
Students are out gathering sensors from the land. Master’s student Garret O’Hara is reading data being transmitted from a drone overhead.
The IU geology students are studying the impact of the recent heavy flooding, a so-called “50-year flood,” meaning the chances of it happening are 2 percent each year.
“This flood in particular helps us quantify exactly how a 50-year flood affects floodplains, and the deposition and erosion of sediment here, and exactly how much just the one flood affects this,” O’Hara said.
Typically, he studies how smaller floods affect floodplains over a decade at a time.
But this 50-year flood provided a rare opportunity.
“The area behind me on this floodplain, I'd say about a third of it has experienced over a foot of erosion in the past decade, and that's pretty significant,” he said. “And we're hoping to compare just the one flood event to see, you know, what kind of portion of that could be from one event?”
O'Hara stands in a field with freshly deposited sediment from the floods. A drone with a LIDAR scanner comes in for a landing behind him. (Devan Ridgway/WTIU News)
Just days before the waters rose, O’Hara and some undergraduate students rushed to this field to stake sensors in the ground for measuring water depth.
They also flew a drone with a sensor attached that measures ground elevation.
“Each of those pulses of light gives us an exact measurement to the ground and any point that it hits,” he said. “And with that data, we can make a lot of measurements. It's extremely valuable to a lot of different kinds of research.”
They’ll be able to use that data to determine if the flood eroded or deposited soil from the plain.
Right away, it was clear to the team that the floods brought a hefty layer of sand into the field. The lab’s head, Doug Edmonds, thinks that could be a good thing.
“That sediment can get worked back into the topsoil, restore some balance to the topsoil, maybe provide some nutrients,” he said. “That's certainly an interesting possibility.”
Edmonds said these floods are part of a historical trend that goes back to 1927.
“If you look at those trends over time, the annual maximum flow has been increasing pretty steadily,” he said. “Since then, it's been going up. And so the implication of that is that there are more frequent and bigger floods year after year.”
Doug Edmonds is the head of the lab looking at the effects of floods on soil. (Clayton Baumgarth/WTIU News)
This floodplain in particular is of interest to Edmonds because while there were clearly deposits from the White River, other areas of the field have been eroding.
“We're trying to tie this erosion back to its causes,” he said. “Is it related to increased flooding? Is it related to land use? Is it related to farmers’ planting habits or patterns? Ultimately, we want to try to help the farmers and the people of Indiana to try to conserve soil, because it's an important natural resource.”
Edmonds found in preliminary analysis that the floods caused more erosion than deposition, and 1 percent of the 650-acre study had more than 4 inches of erosion.
He is hoping to better inform farmers about utilizing floodplains across the state.
Though sediment deposits have the potential for creating more nutritious soil, scientists like Laura Bowling with Purdue’s Department of Agronomy said that isn’t always the case.
“There are some benefits from those sediments, if all of our waterways were perfectly clean and free of industrial chemicals and things like that,” she said. “There is a little bit of risk of water quality whenever you are dealing with flood waters.”
The field where students placed and collected their sensors from, just days before the waters receded. (Courtesy of Steve Scott)
This flood came at a good time for farmers; it’s still a bit too early to plant most crops in the southern portions of the state. But by the time major puddles and ponds dry out of fields, farmers will be left with a healthy, moist soil for their corn and soybeans.
“Those excessively wet conditions aren't healthy for the plants either,” she said. “So our corn and soybean crops really can't germinate under saturated conditions, and so you might have complete failure of seed emergence.”
For Bowling, this time of year isn’t when most farmers worry about their crop yields at harvest.
“Increasingly, we also worry about peak summer temperatures and the timing of pollination relative to when we have some of our hottest nighttime temperatures,” she said. “That can influence corn yields in particular.”
She said the increased amount of flooding Edmonds noted in his research, as well as the hot summers, all point to one big problem.
“That is the signal that we're seeing climate change,” she said.
