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Research indicates bank erosion creates sediment
By Fritz Busch
New Ulm Journal Staff Writer
(Second in a series on the Minnesota River)

NEW ULM -- Riverbank erosion is more of a factor than farm field erosion in polluting of the Minnesota River, according to two University of Minnesota professors and a U.S. Department of Agriculture Fellow who are using high-tech methods to study the river.

Using space-age technology that enables them to measure riverbank erosion more accurately, the researchers agree with farmers who think they are being unnecessarily asked by regulatory agencies to refrain from moldboard plowing in favor of conservation tillage techniques.

The group's research, printed in the December 2001 edition of Resource magazine, mentioned a farmer who said he lost 30 feet of his field to riverbank erosion over a 60-year period. His land borders the Blue Earth River.

The story also referred to a 10-year-old University of Minnesota study that said riverbank erosion contributed to between 50 and 65 percent of the Minnesota River's total sediment load.

Determining whether sediment comes from riverbanks or from farmland could help agencies direct resources for improving river water quality, the study said.

Satish Gupta and Marv Bauer, professors, and David Thoma, a Ph.D. candidate at the U of M, said conservation tillage techniques affect river sediment less than riverbank erosion.

Last spring, the researchers began using a helicopter-mounted laser scanner to construct a topographic model of 35 miles of the Blue Earth River between Amboy and the Rapidan Dam. The scanner produced 7,000 pulses per second with a 5-inch footprint.

The same area was scanned this spring to complete the project. Results will be known in the next few months, Gupta said.

The article said farmers are concerned that if conservation tillage with 30 percent residue cover has little impact on river water quality, regulating agencies will suggest no-till methods. These methods would affect high-clay and slow-draining fields adversely.

Gupta said the high-tech study showed little water quality differences between moldboard and chisel plowing. His study included testing conservation tillage techniques at the University of Minnesota Southwest Experiment Station at Lamberton.

"We aren't pointing fingers at people or telling them not to do conservation tillage, but that other strategies account for much more river sediment," Gupta said.

Sleepy Eye farmer Richard Wurtzberger praised the work of Gupta and his colleagues.

"These men are some of the few people willing to stand up to big government. I hope they continue to get funding," Wurtzberger said.

New Ulm conservation advocate Scott Sparlin of the Coalition for a Clean Minnesota River said recent research work on causes of river sediment is important and leads to other issues.

"Much of the river bank erosion is caused by excess water drainage caused by unnatural systems," Sparlin said.

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Last updated: February 1, 2006