River study goes high-tech

Research

indicates bank erosion creates sediment

Third in a series

By FRITZ BUSCH

Journal Staff Writer

NEW ULM -- Two University of Minnesota professors and a U.S. Department of Agriculture Fellow are using high-tech methods to gather evidence that indicates river bank erosion is more of a factor than farm field erosion in pollution of the Minnesota River.

Using space-age technology that enables them to more accurately measure river bank erosion, 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 was printed in the December 2001 edition of Resource magazine. The story mentioned a farmer, whose land borders the Blue Earth River, who said he lost 30 feet of his field to river bank erosion over a 60-year period.

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

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

Professors Satish Gupta and Marv Bauer and David Thoma, a Ph.D. candidate at the U of M, said conservation tillage techniques don't affect river sediment loads nearly as much as river bank erosion does.

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.

Another scan of the same area was made this spring to complete the project. Results will be known in the next few months, Gupta said.

The story 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. High-clay and slow-draining fields would be adversely affected by those methods.

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.

Gupta explained how to interpret the results of the study.

"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 the 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.

Friday's feature will center on issues and conditions that must be dealt with by the government and public if watershed and surface water restoration projects are to be completed.