Catastrophic Human-Induced Change in Stream-Channel Planform and Geometry in an Agricultural Watershed, Illinois, USA

Abstract

The adverse effects of channelization on the environmental quality of streams and rivers at a global scale are well documented, but the magnitude of human-induced changes in river systems relative to the efficacy of geomorphological processes has yet to be ascertained quantitatively. Stream channelization is a common feature of the agricultural landscapes of the midwestern United States. This study shows that channelization in the Embarras River basin of east central Illinois has altered stream channel and planform geometries to an extent that exceeds background rates of change for unchannelized reaches by one to two orders of magnitude. The average rate of change in channel position resulting from stream responses to channelization also greatly exceeds the average rate of change for unchannelized reaches, yet the spatial extent of stream adjustments to channelization is limited, and most straightened or relocated channels persist in their altered state for decades following channelization.

Effects of geomorphology, habitat, and spatial location on fish assemblages in a watershed in Ohio, USA

“…Initial European settlement of the Midwestern USA started in the early 1800s, and by the end of the 19th century the landscape was radically transformed (Urban and Rhoads 2003). Part of this transformation involved channelization or "ditching" of streams to provide enhanced capacity for agricultural field drainage in the headwaters of many watersheds.…”

Accuracy assessment of georectified aerial photographs: Implications for measuring lateral channel movement in a GIS

“…While there is widespread recognition in the GIScience community of the sources, types, and implications of locational error in geospatial data sets (Chrisman, 1982(Chrisman, , 1992Goodchild and Gopal, 1989;Unwin, 1995;Leung and Yan, 1998), fluvial geomorphologists have generally ignored the magnitude of geospatial error in relation to geomorphic change or have used only Root Mean Square Error (RMSE) as a measure of this error (e.g., Urban and Rhoads, 2004). Only recently have fluvial geomorphologists begun to embrace geospatial error as an independent research topic (e.g., Mount and Louis, 2005).…”

Methods for Evaluating the Geomorphological Performance of Naturalized Rivers: Examples from the Chicago Metropolitan Area

“…The initial response often is threshold related with rapid recovery occurring only when straightening increases stream power above a critical value (Brookes, 1988). Systems below the threshold can remain straight for many decades (Rhoads and Urban, 1997;Urban and Rhoads, 2003) and may recover their sinuousity only over a period of centuries (Barnard and Melhorn, 1982).…”

“…Although major changes in channel position can be determined from simple visual inspection of a sequence of photos, a more sophisticated approach involves GIS-based analysis of a sequence of imagery (Rhoads and Urban, 1997;Urban and Rhoads, 2003). This type of analysis includes: scanning images to get them into a digital format; rectifying the digital images by georeferencing them to planimetric base images in a GIS environment; digitizing channel traces on the rectifi ed images; and plotting channel traces for different times on a single plot to illustrate patterns of channel change.…”