Drain tiles that lead from farm fields into ditches and then into the Minnesota River contribute to the sediment now being deposited in Lake Pepin.

Peterson, Brian, Star Tribune

Commentary about sediment was unfair to researcher

  • Article by: CARL ROSEN
  • May 12, 2011 - 9:24 PM


As head of the Department of Soil, Water and Climate at the University of Minnesota, I strongly take exception to "Polluting the research pool" (May 6) by Lawrence Landherr and Willis Mattison.

I am actually surprised that opinion editors at the Star Tribune would even have published an article such as this, because it basically attacked the credibility of a scientist without first checking the facts.

Landherr and Mattison are upset with the research that Satish Gupta is conducting to determine the causes of sediment filling Lake Pepin. They claimed that Gupta has little expertise in the area, then accused the university of misusing academic freedom.

The facts are that Gupta, a professor in the Department of Soil, Water, and Climate, is a respected scientist, with more than 100 peer-reviewed publications on subjects related to soil and water resources.

He is a fellow of the Soil Science Society of America and the American Society of Agronomy, which are the highest recognitions given by these societies and reserved to only 0.3 percent of the respective society's active and emeritus members.

Further, he started the Larson-Allmaras Seminar Series in Soil and Water Issues, and his excellent reputation in the scientific community brings esteemed lecturers to the university each year to share their research on these topics.

Contrary to the prevailing theory in the 1990s, Gupta was among the first to show that bank erosion, not field erosion, was likely the major source of sediments in the Minnesota River.

Subsequently, in a peer-reviewed article, he and his student showed how airborne laser imagery could be used to measure bank erosion in a 35-mile section of the Blue Earth River. This pioneering research helped to change thinking about how sediment enters the Minnesota River.

In his recently completed project, Gupta used airborne laser imagery to quantify bank erosion from several rivers in Blue Earth County. His current research is concerned with identifying factors that may be causing increased rates of sedimentation in Lake Pepin.

He has identified the following factors as possible causes that need further research: increased sediment delivery from stream bank erosion due to natural soil seepage; bank destabilization from agricultural drainage; increased flow from increased precipitation; increased sediment transport due to channel modifications such as river dredging, straightening, and levee construction, and increased flow from impervious surfaces as a result of urbanization.

These are valid questions that deserve scientific scrutiny. I have heard Gupta give public seminars on these complex topics; he acknowledges that his hypotheses could be wrong but says they are worth pursuing.

This is part of the scientific method. It merits debate and review, and will take time to sort out.

Academic freedom is a core value of the University of Minnesota. It allows faculty "to explore all avenues of scholarship, research, and creative expression, and to speak or write on matters of public concern as well as on matters related to professional duties and the functioning of the University."

Unfortunately, Landherr and Mattison would like to cherry-pick what issues faculty can pursue and discuss, which is the antithesis of academic freedom.

Rather than writing scathing opinions in an attempt to discredit a respected scientist (only amplifying a polarized view of what is a credible scientific investigation), a more civil approach would be to focus on the science and the questions being asked.

Carl Rosen is head of the Department of Soil, Water and Climate at the University of Minnesota.

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