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Researchers Study Human Impact on Land

Posted on March 10th, 2014
Iowa's topsoil, so important to sustaining life worldwide, is part of the critical zone, which is the focus of a new five-year research project including the University of Iowa and IIHR.

Iowa’s topsoil, so important to sustaining life worldwide, is part of the critical zone, which is the focus of a new five-year research project including the University of Iowa and IIHR.

IIHR—Hydroscience & Engineering researchers at the University of Iowa are part of a $4.9 million, National Science Foundation-funded project to evaluate how more than 100 years of intensive agriculture have affected the Midwestern landscape.

Called the Critical Zone Observatory for Intensively Managed Landscapes (IML-CZO), the University of Illinois-led project includes the University of Iowa, four other Big Ten universities, and three other research institutions. It will focus on the Iowa landscape, as the state is especially reflective of changes that have taken place throughout the Midwest.

Iowa’s landscape is one of the most altered in North America. After the glaciers retreated, centuries of prairie plants created the layer of rich organic material that is now Iowa’s famously productive farmland. But after more than a century of intensive plowing, erosion, and drainage, the tallgrass prairie has been transformed into a checkerboard of farm fields, extensively drained by underground tiles discharging into straightened dredged ditches. Less than one-tenth of one percent of Iowa’s original tallgrass prairie is left untilled, ranking the state 50th in the nation in total uncultivated land remaining.

This transformation has made Iowa an agricultural leader, but it has had many other far-reaching effects as well, particularly for the “critical zone.” The critical zone is the region from the treetops into the bedrock aquifers, including Iowa’s layer of rich topsoil, where the atmosphere, biosphere, and geosphere interact to sustain life.

The majority of the research will focus on the Clear Creek Watershed near Iowa City, Iowa, and the Upper Sangamon River Basin in Illinois. These watersheds will be fundamental in analyzing, quantifying, and understanding critical zone processes that can then be extrapolated to other areas of the country.

Researchers will conduct experiments in the field and monitor baseline characteristics by placing sensors in the basins, while also collecting samples and data to understand how sediments, water, and nutrients flow through the system. Previously collected data will offer a historical context, particularly in the Clear Creek watershed, where more than a decade of information is already available. With this information, researchers will be able to build a very detailed and inclusive understanding of the processes at work in the system.

Praveen Kumar, project principal investigator, says the research offers a unique opportunity to understand the impact of humans on the critical zone. Kumar, a professor of civil and environmental engineering at the University of Illinois at Urbana-Champaign, says, “The observatory is aimed at understanding how natural processes happen together, how they co-evolve, and how human modification has altered that. What is the limit to these modifications and what do we need to do to recover many of the functions that originally made this land productive?”

IML-CZO co-principal investigator Thanos Papanicolaou, professor of civil and environmental engineering at the University of Tennessee-Knoxville, says that in the Midwest, we have a unique opportunity to study the critical zone in an intensely managed landscape. Papanicolaou says he wants to understand how much we have already degraded the critical zone resources. In addition, he hopes to learn:

  • How much time we have left before the system is exhausted, operating under current conditions.
  • How we can stabilize the critical zone.
  • What new science and engineering tools can be developed to return the system to a healthier state.

Researchers expect the project to be groundbreaking, says co-principal investigator Art Bettis, an IIHR associate research engineer and associate professor of earth and environmental sciences at the University of Iowa. Up until now, he says, researchers have not been able to study the critical zone holistically.

“It’s a system. The only way to understand a system is by looking at all of its parts, and the interconnections between them,” Bettis says.

By necessity, this effort is also highly interdisciplinary. The CZO research brings together researchers from a number of fields to cooperate and collaborate, and that can be a challenge in itself, Bettis says. “We benefit as much from that exercise as we do from a lot of the science,” he notes.

The IML-CZO project will continue for at least five years in order to foster experimentation and encourage the asking of complex and difficult questions. It also will encourage cooperation among researchers, as they learn to communicate and collaborate effectively across disciplinary boundaries.

IML-CZO researchers conduct deep, pure scientific research that could also have immediate practical applications. Team members will work with cooperative agencies, such as county conservation boards, that in turn will work with landowners and farmers to test new best-management practices. Many of these practices are already at work in the Clear Creek watershed, so scientists can monitor the effects of the practices to see how well they function in the real world.

The IML-CZO is unique among the CZO sites nationwide in that it focuses on agricultural and urban landscapes. Researchers here will be able to study the ag-urban transition zone in a new way.

“Human influence is the wildcard here,” Bettis says. “Particularly in the intensively managed landscapes of the Midwest, human activity has a disproportionate impact on the critical zone processes, and raises important issues not addressed at other observatories in the NSF-CZO network.”

Papanicolaou says the investment made by NSF to create the new IML-CZO indicates just how important it is to understand the system. “The ideal outcome would be for us to understand what actions we need to take as humans to sustain this environment,” he says.

In addition to Kumar, Bettis and Papanicolaou, other researchers include: Marian Muste, co-investigator and IIHR research engineer; Doug Schnoebelen, co-investigator and IIHR research scientist; Adam Ward, co-investigator and UI assistant professor of earth and environmental sciences; and Chris Wilson, UI Clear Creek Observatory site manager.

A full list of IML-CZO partners can be found at: For further details about the project, visit:

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