Hydrologic and Hydraulic Modeling of the Cache River for Evaluating Alternative Restoration Measures

The Cache River basin, located in southern Illinois, has characteristics unique to the State of Illinois and nation, with diverse physical, chemical, and biological features that produced a great diversity of natural communities. Because of these unique characteristics, the Cache River basin contains some high quality bottomland hardwood forests and wetlands that have been recognized nationally and internationally. Changes in land-use practices and hydraulic modifications during the last century have significantly threatened the ecological integrity of some of these valuable habitats and wetlands. Therefore one of the key goals of resource managers working in the area is to restore the Cache River’s natural hydrologic character to a level that can sustain a viable ecology throughout the river corridor. An essential component of the restoration effort for the Cache River has been the development of detailed hydrologic and hydraulic models to determine water levels associated with proposed restoration measures. These models assist the Cache River Wetlands Joint Venture Partnership (JVP) in the decision-making process of selecting and implementing restoration projects that improve the hydrologic conditions for the natural ecosystem. Hydrologic and hydraulic modeling also allow the JVP to satisfy all regulatory requirements and ensure that natural, agricultural, and social resources are not damaged by flooding induced by modifications to the river system. Hydrologic and hydraulic models were developed by the Illinois State Water Survey for the Lower and Upper Cache River and are published in two reports (Demissie et al., 2008, 2010) located on the ISWS website http://www.isws.illinois.edu/pubs/search.asp (Contract Reports 2008-01 and 2010-06). This presentation summarizes the results for some of the modeling scenarios.