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Rediscovering the Pre-Lock and Dam Mississippi

IIHR graduate student Brice Stafne has developed a computer model that allows researchers to compare historic conditions on the Mississippi River to the river as it is today.

IIHR graduate student Brice Stafne has developed a computer model that allows researchers to compare historic conditions on the Mississippi River to the river as it is today.

When the first Europeans reached Iowa, they found a Mississippi River that must have looked like an almost endless series of pools, connected by shallow, narrow side channels — giving the river an almost “braided” appearance (Source: Iowa Department of Natural Resources). When engineers built the system of locks and dams in the 1930s to improve navigation, they forever changed the river as water levels rose in backwaters and side channels, and old islands were flooded.

The creation of the nine-foot navigation channel was a boon to interstate commerce, but it had many unexpected consequences. Plant and animals species lost valuable habitat when quiet backwaters disappeared. In recent years, researchers have begun working to restore habitat and ecosystems in the Mississippi River system, but a general lack of information about the river’s historic flow has hampered these efforts. An understanding of the hydrology is the key to the restoration, says IIHR graduate student Brice Stafne.

Working with his advisors Larry Weber and Doug Schnoebelen at IIHR’s Lucille A. Carver Mississippi Riverside Research Station (LACMRERS), Stafne has developed a tool to help researchers learn more about historic hydraulic conditions on the Mississippi River. Using an old topographic map from the 1890s provided by the U.S. Geological Survey and historic hydraulic data from the U.S. Army Corps of Engineers, he created a two-dimensional computer model for Pool 8 of the Upper Mississippi River, modeling the river’s flow before the lock-and-dam system was constructed. The model, which builds upon the research of several other former IIHR graduate students, allows Stafne to compare the historic conditions of the river to the current conditions, and to establish what he calls a “hydrodynamic reference condition.”

A comparison of velocities output from the model for current and historic conditions. Near the bottom note the “lower pool” area, which is the most changed by the construction of the locks and dams.

A comparison of velocities output from the model for current and historic conditions. Near the bottom note the “lower pool” area, which is the most changed by the construction of the locks and dams.

It’s a brand new field of research, Stafne says. “Nobody else is doing this type of work yet, but it has the potential to be a very useful tool for river managers,” he explains. “A need exists for understanding the natural hydraulic and hydrologic characteristics of the river if we hope to restore it to how it once was.”

A comparison of velocities output from the model for current and historic conditions. Near the bottom note the “lower pool” area, which is the most changed by the construction of the locks and dams.
Stafne took cross sections of the bed surface and interpolated them into a digital surface using a tool developed by a researcher at Purdue University. They are overlaid over the historic map from the 1890s.

Stafne took cross sections of the bed surface and interpolated them into a digital surface using a tool developed by a researcher at Purdue University. They are overlaid over the historic map from the 1890s.

Stafne took cross sections of the bed surface and interpolated them into a digital surface using a tool developed by a researcher at Purdue University. They are overlaid over the historic map from the 1890s.

Re-establishing islands allows river managers to disconnect some areas from the flow of the main channel, while still allowing hydraulic conditions in these areas to fluctuate naturally as river levels change. “The islands create low-velocity areas important to certain plant and animal species, and reduce the effects of wind by breaking up the expanses of open water,” Stafne says.

The project has an important potential economic consideration as well, Schnoebelen explains. Further development of the model will allow researchers to better assess the pros and cons of different restoration plans before undertaking expensive projects.

Making any change to the river is complicated. Many stakeholders have a vested interest, including state and federal government agencies, industry groups, environmental organizations, recreational users, and more. “It’s often a delicate balance to meet the differing needs of these groups,” Stafne says.

He’s grateful for the support he’s received at IIHR. “It’s a great atmosphere for graduate students,” Stafne says.  He will complete his master’s degree this month and then move on to a position as a professional consultant in Des Moines, but he plans to stay connected with Weber and Schnoebelen as they work to publish the research.

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Last modified on June 29th, 2015
Posted on September 6th, 2013

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