Planform change and stream power in the Kishwaukee River watershed, Illinois: Geomorphic assessment for environmental management
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Effective watershed-scale environmental management and restoration require a sound understanding of the dynamics of fluvial systems at the watershed-scale and the impact of humans on these dynamics. In Illinois, concern has arisen about the need to implement bank stabilization along meandering rivers, where bank erosion associated with lateral migration is often viewed as a sign of channel instability. Also, many rivers in the state are low-energy fluvial systems that exhibit limited responses to direct human modification such as channel straightening. From an ecological perspective, the lack of response is problematic owing to its potential long-term alteration of aquatic habitat.This study examines the spatial relationship between the planform dynamics of meandering rivers and stream power in the Kishwaukee River watershed in northern Illinois. The spatial extent of planform change at the scale of drainage network is quantified and related to spatial variations in the magnitude of stream power throughout the watershed. Historical channel change was determined using GIS-based analysis of aerial photography of several reaches scattered throughout the watershed. The results show that the amount of lateral migration per reach is greatest where stream power is highest, but that planform response to channelization is limited regardless of the magnitude of stream power. The findings from this historical analysis of channel change are useful for understanding both the fluvial dynamics of unmodified meandering rivers and the influence of human modification on these dynamics knowledge that can help guide environmental decision making about the need to implement channel stabilization or restoration measures.
