Characterizing Geomorphic Change from Anthropogenic Disturbances to Inform Restoration in the Upper Cache River, Illinois

Abstract

Over the past century, channelization, agricultural tiling, and land use changes have resulted in significant stream channel degradation of the Cache River in southern Illinois. With the increasing interest in restoration of the watershed's bottomland forests and swamps, we sought to characterize geomorphic change over the past 110 years to inform restoration and management. A previously surveyed stretch of river was resurveyed in the fall of 2011, following a record flood in the spring of that year. Results suggest that the slope of the channel in this section of the river has increased 345% between 1903 and 1972 (p < 0.01), but has not changed significantly since (p = 0.12). Within that same time period, bank heights increased between 1 and 7 m and bed elevation decreased between 1 and 5 m. Changes in resurveyed cross sections appear to be primarily due to recent flood scour. It appears as though early 20th Century stream channel modifications had immediate effects on the geomorphology of the channel; however, channel geometry is now at or near equilibrium. This case study of the Cache River watershed demonstrates how and why successful restoration will require integration of geomorphic processes of the system.

Process‐based assessment of success and failure in a constructed riffle‐pool river restoration project

“…Field assessments of project performance typically involve methods to evaluate the stability of the designs, such as measuring geomorphic change (Bouska & Stoebner, 2015;Rhoads et al, 2008) or monitoring the structural integrity of constructed features (Buchanan et al, 2014;Miller & Kochel, 2009;Roni et al, 2002). However, focusing on bed stability as a goal of river restoration is counter to geomorphic principles of dynamic equilibrium (Sear, 1994), leads to reduced long-term project success (Thompson, 2002), and ignores evidence that dynamic channels better support aquatic ecosystems (Beagle et al, 2015;Chin & Gregory, 2009;Clarke et al, 2003;Thorp et al, 2006).…”

Assessing the Performance of In-Stream Restoration Projects Using Radio Frequency Identification (RFID) Transponders

“…In the field, restoration success or failure is often assessed by measuring bed topography or geometry, for example by determining channel enlargement ratios [30], measuring local scour [28,31], or by assessing the structural integrity of restoration designs [10,[32][33][34]. Results are notoriously difficult to compare, however, due to the time it takes for "success" or "failure" to manifest [12] and the occurrence of both positive and negative consequences that may or may not have been part of the design [34].…”

Method for Rapidly Assessing the Overtopping Risk of Bridges Due to Flooding over a Large Geographic Region

“…Bridges are designed to accommodate a discharge with a given return period, but these designs are based on current conditions and estimates of future conditions when the bridge was built (VDOT, 2014). However, future conditions, including climate, land use, and stream patterns, may experience unanticipated changes (Loaiciga, 2001;Bonnin et al, 2011;Bouska and Stoebner, 2015). These changes can impact overtopping risk to bridges by affecting the drainage basin response to storm events of different return periods.…”

“…For example, the intensity and spatial distribution of storm events with certain return periods may change significantly as a result of climate change (Tucker and Slingerland, 1997;Yang et al, 2010;Khelifa et al, 2013). The watershed draining to the bridge may experience a higher rate of land development than anticipated, causing changes in the runoff characteristics including both the peak flow rate and the timing of the peak flow for a given storm event (Li et al, 2007;Bouska and Stoebner, 2015). Also, stream patterns change over time because of sediment transport and geomorphological processes, which could accelerate with more frequent extreme flooding events and human activities (Loaiciga, 2001;Yang et al, 2002;Hu et al, 2011).…”