HYDRODYNAMIC  MODELING  TO  CONSTRUCT   ARTIFICIAL   ISLANDS   WITH
DREDGED SEDIMENT: PEORIA LAKE ON THE ILLINOIS RIVER

Nani G. Bhowmik 1, R. Xia 2, David Soong 3, and John C. Marlin 4.  
1, 2, 3 Illinois State Water Survey, 2204 Griffith Drive, Champaign, IL 61820; and 4 
Waste Management and Research Center, Champaign, IL.

Restoration of a river reach, a stream, or a lake is not a simple undertaking.  All 
human-induced factors and natural processes within the watersheds and the main 
stems of the rivers have, in many cases, accelerated the morphological changes 
impacting appropriate use of the river system.  This paper will concentrate on the 
Illinois River and specifically on the Peoria Lake, the largest bottom lake along the 
Illinois River.  

The Illinois River is essentially contained within the State of Illinois, and has drainage 
area of about 75,000 square km.  Peoria Lake, a bottomland lake along the Illinois 
River, is about 32 km long and has a drainage area of about 36,000 square km, 
draining mostly agricultural lands.  Peoria Lake was formed by the deposition of 
tributary sediments at the delta mouths.  Sedimentation of Peoria Lake has also been 
accelerated due to the construction of navigation lock and dam.  Peoria Lake has the 
highest sedimentation rates in Illinois, and has lost more than 70 to 80 percent of its 
1903 capacity.  It has almost become an incised river with a deep navigation channel 
about 3.6 to 6m deep and about 1.5km wide on each side.  If no corrective measures 
are taken, this lake may lose 80 to 90 percent of its capacity in a few years and will 
no longer be useful as a wide deep lake.

Various alternative are under active consideration for Peoria Lake: create deep water 
habitats by selective dredging, build artificial islands with the dredge sediment, create 
artificial wetlands at or near the tributary mouths, stabilize steep bluff tributaries, and 
reduce bank erosion.  About 50 percent of the sediments to the lake are contributed 
by about 4 percent of the drainage areas draining the local tributaries.

A 2-D hydrodynamic model for Peoria Lake has been calibrated for the Peoria Lake.  A 
sediment transport model is also being calibrated to test the effects of various 
remedial alternatives such as those mentioned previously to determine the effects on 
the lake and river as far as the erosion, deposition, and channel alterations are 
concerned.  This is a joint effort by the State of Illinois and the Federal Government.

Keywords:  Illinois River, Peoria Lake, artificial islands, hydrodynamic models, dredged 
materials
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