Flooding Could be Disastrous

Flooding could be disastrous

By Nicholas Pinter, Robert Criss and Timothy Kusky

This article ran in the St. Louis Post Dispatch on 03/04/2008.  Comments welcome!

There exists today a major threat to the St. Louis-Metro East river corridor. By describing this threat in detail, we hope we can open a dialogue with Col. Lewis F. Setliff III, the commander of the St. Louis district of the U.S. Army Corps of Engineers.

Three specific points — all involving the Corps — need to be discussed: the construction of river structures that magnify flooding; the failure of the Corps’ St. Louis district to address this issue in the design, planning and implementation process; and a long-term pattern of insularity and professional bias among the district’s technical staff.

Mainstream scientific and engineering research, some of it stretching back more than a century, documents that navigational structures in the Mississippi and Missouri Rivers have increased flood levels significantly. In the Corps’ Kansas City district, for example, a report dating from 1933 noted flood magnification because of “dikes and revetments used in shaping and controlling the stream for modern barge transportation.” A milestone paper in 1975 by Charles Belt of St. Louis University documented systematically higher flood stages over time, even with river flow rates that remained steady. Recent research has confirmed these links using hydrologic, statistical and numerical modeling techniques.

Sadly, the Corps’ St. Louis district has ignored this growing body of evidence as it continues to build structures in the Mississippi channel. It has constructed some of its latest inventions — arch-shaped chevrons — in the St. Louis harbor directly opposite Illinois levees that are in the procees of being decertified as viable flood protection structures.

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The district plans to build more chevrons, along with other large structures such as underwater walls called bendway weirs (another St. Louis district invention) and wing dikes, all of which will worsen a severe and growing problem. In terms of river water, these structures are the equivalent of loaded cannons pointed at St. Louis and East St. Louis, waiting to go off during the next large flood.

We fear that Col. Setliff may have been misled by staff engineers, some of whose statements are inconsistent with known scientific data. For example, through-the-looking-glass assertions that dikes lower river levels are flatly contradicted by more than a dozen peer-reviewed journal articles, as well as research by corps scientists outside the St. Louis district. These show clear and unequivocal data linking navigational structures to diminished channel conveyance and increased flood levels.

The National Science Foundation funded the compilation of a database at Southern Illinois University of more than 8 million hydrologic measurements and detailed construction histories for more than 2,500 miles of the Mississippi-Missouri River system. The pattern is clear: When and where dikes and levees were built, flood levels went up — and not by inches, but by five feet, 10 feet and more. Between 1990 and 1992 alone, the St. Louis district built 25,700 linear feet of bendway weirs and 14,700 feet of wing dikes on the Mississippi, contributing to the unprecedented water levels of the 1993 flood.

Part of the problem is that the St. Louis district uses so-called tabletop micromodels of the river to help design its navigational structures. Yet these micromodels have been criticized heavily in scientific circles.

In a 2006 article in the “Journal of Hydraulic

Engineering,” the Corps’ own engineers (notably, from outside the St. Louis district) concluded that the models’ use “should be limited to demonstration, education and communication.”

Such professionally reviewed published statements conclusively refute claims by St. Louis district engineers that the models can demonstrate what actually would happen in the river channel when their various structures are installed. In fact, the sandbox micromodels cannot even be run above flood stage and, thus, are useless in assessing the structures’ effects on flood levels.

The Corps provides invaluable services to St. Louis and to communities all along the Mississippi River. But in the case of these new chevrons between St. Louis and the crumbling levees protecting the Metro East area, some terrible error seems to have been made. How could these structures have been built without even addressing what impact they would have on flooding?

The consequences of this experiment going wrong simply are too great to ignore. We call for an independent scientific panel — preferably convened by the National Academy of Sciences — to assess the evidence linking navigational structures and flood levels. The time to ask these questions is now — not in the devasting aftermath of the next great flood.

Nicholas Pinter is a professor of geology, environmental resources and policy at Southern Illinois University-Carbondale. Robert Criss is a professor of earth and planetary science at Washington University in St. Louis. Timothy Kusky [is the PC Reinert Endowed Chair] of natural sciences and directs the Center for Environmental Sciences at St. Louis University.

[the position of T.Kusky is corrected from the original article)