River research attempts to increase safety
Extensive research on the Le Sueur River, also known as the Minnesota River, is underway to develop a sediment budget and determine the cause of heavy sediment deposits in the river.
Patrick Belmont, USU assistant professor of watershed sciences, is studying what sort of potentially devastating effects that the deposit will have on nearby lands and inhabitants.
Belmont’s findings are reported routinely in national settings including the Geological Society of America and the American Geophysical Union. The final results of the project’s first leg is a continuation of a post-doctoral project Belmont began more than two years ago and will be submitted to the Pollution Control Agency in Minnesota in six to nine months.
The research is also part of a collaborative effort with the National Center for Earth-surface Dynamics, where Belmont studied before joining the Utah State staff.
Jack Schmidt, professor of the department of aquatic, watershed, and earth resources, said Belmont’s project has great value on a national scale.
“(The research) has national significance because they are trying a lot of innovative techniques to find sources of sediment yield, sources of eroding sediment, and ultimately how to control them,” Schmidt said.
Belmont himself said the extensive research itself involved a lot of time and energy, but it is for a great purpose.
“I have been studying erosion and sediment transport in the (Le Sueur) river, particularly trying to figure out where all the mud comes from, so we can determine the most effective way to restore the watershed and improve water quality,” Belmont said.
Belmont will be in Minnesota doing this research until Oct. 17. He said he will put in 14-hour days and routinely start field work at 7 a.m. He said his out-of-town, on-site research this week couldn’t have come at a better time.
“Last week, Southern Minnesota received 10 to 13 inches of rain in 24 hours and experienced the worst floods by far since we started tracking flows in the 1930s,” he said.
Due to the floods, the river has become very susceptible to testing, and tests can more easily be read as the water table rises.
Barbra Utley, a post-doctoral research fellow and Schmidt’s teaching assistant, said the reasons why the river is full of sediment are due to problems beginning 13,000 years ago at the end of the Ice Age.
A break in the glacier where south-central Minnesota now rests had a major slip that resulted in a large “nickpoint” or “headcut,” which are descriptions of rapid changes in elevation that propagate through a watershed. This nickpoint, and the location of much of the river, has caused the watershed to be 70 meters below the level of most of the landscape.
For this reason, the river is susceptible to erosion not just from the glacier, but from a second dilemma: the watershed lies below a surface that is routinely feeding into the river and other lakes further downstream.
“We care about water quality. We care about how it affects bio-industry. We care about how water is affected downstream, and the filling in of sediment, which effects (people),” Utley said, “There are really two different landscape processes occurring – how do you identify which one is the problem?”
Utley said that though the base of the watershed has since stabilized, the erosion problem remains. Belmont has taken the role of identifier, and is one of the reasons why the research garners attention, she said.
“That’s where (Belmont) comes in: to do a budget of where the sediment is coming from in this watershed. As this project is part of the Mississippi River, it gets a lot of publicity, (and) it gets a lot of money thrown at it,” Utley said.
“Are we wasting the money? Will the affects of the river be any different in five, 10, or 20 years? What scale are the changes occurring, and where is the watershed change coming from?
That’s part of what Patrick and others are trying to identify,” said Utley, a Virginia Tech and Georgia graduate.
The one currently assisting Belmont to identify those questions is Justin Stout, a watershed science major who is currently in his first semester of graduate school.
The eroding of the river can alter its course as well, and Utley said that’s where nearby residents and their lands could find themselves in the greatest potential peril. This will also affect the corn and soybean yield that grow in the rich soil of the Minnesota River Basin deposited by the Mississippi River.
“We have, as humans, changed the landscape and then have said, ‘we want to get more production out of these agriculture fields. So now we’re changing the hydrology in the headwaters of the river,'” Utley said.
She said drain tiles were installed 150 years ago to lessen the effects of the river’s altering course, but that hasn’t been enough to defer the river from being a danger and demanding the research to fix the problem.
“Instead of having the soils drain slowly so there’s a long retention time, it now permeates the soils and hits the drain tiles, and quickly makes it to the river. So it totally changes the landscape process,” Utley said.
Because of the quick drainage and possible change of course of the river, homes and life there today are potentially threatened.
“Residents are not worrying about flooding, but if the watershed started moving, and the river started moving toward the bluff, I would start caring about it a lot,” she said.
While human residents nearby the river are affected, potentially dangerous particles within the material, pesticides and other substances released into the surrounding area by humans and carried by the erosion also pose a threat to those living within the waters.
“On a larger scale, as all the sediment makes its way downstream, we as citizens care because we care that there are fish alive, that the fishing industries are maintained, that it costs less to clean water for drinking water, so there’s lots of reasons why we care about water quality,” Utley said. “That stuff can re-enter the water and can poison fish. It can poison us.”
–rhett.wilkinson@aggiemail.usu.edu