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Analysis of Land Cover Changes in Selected Side Channels of the Mississippi River

Human activities over the last 200 years have dramatically changed the composition and quality of floodplain habitats of the Upper Mississippi River.

In the undammed river reach between St. Louis, Missouri, and Cairo, Illinois, training structures were built to accommodate commercial navigation by ensuring deep water in the main channel. The structures have also starved side channels, many of which are now frequently left high and dry at low river discharges.

Recent advances in technology have made it possible to quantify such changes in detail if comparable images from the past are available.

In 2001, scientists at the Upper Midwest Environmental Sciences Center completed detailed analyses of habitat change at six side channel sites using images from four periods between 1950 and 1994.

Their results revealed how the process of channelizing the river altered natural successional processes to the point where habitats have shifted location or new habitats have been formed.

Four of the six sites lost their functional capacity to carry water at low river flows. Sediment (mud and sand) exposed above the river's low flow stage was rapidly colonized by forest. Extreme flooding in 1993 did not have the beneficial ecological effects it would have had if the high water had been allowed to reshape the floodplain template.

While these kinds of changes were generally known before the study, they had not been measured in spatial detail. The magnitude of the changes, made unambiguous by this study, will greatly enhance the river community's understanding of how much habitat restoration is required at the sites.

Project was completed in September 2001.

Principal Investigator: Ken Lubinski