Newspaper article St Louis Post-Dispatch (MO)

Putting Squeeze on River's Girth

Newspaper article St Louis Post-Dispatch (MO)

Putting Squeeze on River's Girth

Article excerpt

Like a straightjacket, levees squeeze the river to keep it in line. That helps navigation but pushes water higher in a flood.

Back in the 1840s, novelist Charles Dickens described the Mississippi River below St. Louis as "an enormous ditch, sometimes two or three miles wide, running liquid mud."

Old Man River has thinned down since then, shrinking from his old 4,200-foot width at St. Louis to today's slimmer 2,100-feet.

But what the Mississippi gave up in width over the last 150 years, he got back in height - mainly during big floods.

At the peak of the 1844 flood - which the record books say carried more water than the Flood of 1993 - the Mississippi crested at 41.3 feet at St. Louis. Last summer's floodwaters reached 49.58 feet.

What's to blame for that 8-foot difference in the river level?

Levees and flood walls in the St. Louis area are at least partly responsible for squeezing river heights. But experts disagree on the extent of the levee effect, and its impact on this year's flood. LEVEES AND FLOODS

In his new report, engineer Douglas T. Shaw estimates that river levels from the Arch to the River Des Peres would have been 1.6 feet to 2.2 feet higher at the 1993 flood's height if the Columbia and Harrisonville, Ill., levees had held back the peak flow.

But Shaw's analysis, which examined only a 34-mile segment of Mississippi from the Arch south, did not focus on the cumulative impact of all the region's levees and flood walls.

Charles B. Belt Jr., an associate professor of geology at St. Louis University, tried to estimate that cumulative impact for the 1973 flood. His conclusion: the 1973 crest would have been four or five feet lower if there were no levees in the St. Louis area.

Richard Sparks, the chief river researcher for the Illinois Natural History Survey, agrees that "flood heights are increasing" at St. Louis, partly because of levees and flood-plain development.

But Gary R. Dyhouse, chief hydrologic engineer for the Army Corps of Engineers in St. Louis, disputes Belt's analysis - and asserts that levees here prevent far more flood damage than they cause.

Using a concrete model of the Mississippi, Dyhouse compared recent flood flows and stages at St. Louis with similar flows before the region's levees and flood walls were built.

His conclusion: federal levees along the Mississippi near St. …

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