WHY NATURALIZE DEVELOPED FLOODPLAINS?  AN INTEGRATED ANALYSIS AND RESPONSE

Richard E. Sparks

National Great Rivers Research & Education Center, Godfrey, IL 62035

      Why would anyone even consider undoing some development along floodplains 
of the Upper Mississippi River and its tributaries?  There are at least two 
answers: (1) the Great Flood of 1993 in the Upper Mississippi River Basin and 
the recent flooding of New Orleans along the lower Mississippi River reminded 
both the public and policy makers of the hazards of development in dynamic 
ecosystems characterized by periodic natural disturbances.  Although New Orleans 
was flooded this time by a hurricane-driven storm surge from the sea, the 
terrible consequences reminded everyone that New Orleans is also vulnerable to 
great floods from the Mississippi River.  (2) In addition to the desire to 
reduce the economic and human costs of repetitive natural disasters, there is 
growing public awareness of the services provided by natural systems and a 
growing desire to retain and recover these natural services.  Besides flood 
reduction and flood protection, natural services include maintenance of 
biodiversity, opportunities for outdoor recreation (fishing, hunting, viewing 
wildlife and scenery), and nutrient recycling and reduction (i.e., reduction of 
nutrient loading from the Upper Mississippi Basin to reduce eutrophication of 
the Gulf of Mexico).  
	There are several difficulties with proposals for naturalization.  First, 
there are significant economic consequences to making changes in land use, so it 
is important to predict, with some precision, the costs and benefits of various 
alternatives.  Second, location is also critical so that sites are chosen for 
reconnection that will have the greatest benefits for the costs and social 
disruptions caused by the change.  Finally, the man-made alterations to the 
watersheds (drainage of wetlands and channelization of streams) and to the 
rivers themselves (navigation dams) have changed the water and sediment regimes 
in the rivers, so simplistic approaches, such as just buying out some levee 
districts and breaching the levees could result in muddy lakes and barren 
mudflats that are unappealing to humans and wildlife alike. 
	Our project linked hydraulic and ecological models, and economic analyses, 
to evaluate alternatives for selective reconnection of the Illinois River and 
its floodplain.  The study focused on the La Grange Reach of the river, a 
section spanning 129 km south of Peoria, Illinois, but the approach is 
applicable to other developed reaches and rivers.  We learned that selective 
reconnection of portions of the floodplain could be done in a way that would not 
reduce the overall economic outputs of towns and counties along the river, but 
could even enhance them.  One of the important lessons from the project was that 
some adjustments in disciplinary approaches and interests were required to 
address issues that are important to stakeholders along the rivers and to 
contribute effectively to a multidisciplinary effort.  

Keywords:  decision support, predictive models, naturalization, restoration, 
economic impact, multidisciplinary, interdisciplinary, floodplain