Impact of Bank Stabilization Structures on Upstream and Downstream Bank Mobilization at Cedar River, Nebraska

Highlights Stabilization structures are only effective at stabilized segments. Erosion increased in two of the six segments post-stabilization period. Deposition decreased all Jetties reducing erosion but also prone to fail. Abstract . The effectiveness streambank stabilization is insufficiently quantified. Although such clearly reduce or eliminate local scale, little known about associated effects on unstabilized reaches immediately upstream and downstream. This study measured deposition stretches Cedar River, 1.5 meander wavelengths downstream from 24 that included jetties, rock vanes, root wads, gravel protection. We streambanks directly opposite locations. compared measurements pre-stabilization period (1993-2005) with those (2005-2018) using historical imagery ArcGIS. Upon completion this analysis, we were able reject an initial hypothesis adjacent segment rates would be significantly less after stabilization, greater locations stream Instead, differences pre- showed no statistical significance. Rather, our data indicated four was predominantly confined segment. Overall bank stabilization. In where wooden jetties installed, partial total failure common, further increases decreases more pronounced. conclude River location installation; there measurable effect reaches. Our results demonstrate need for improved monitoring practices better understanding how impacts entire river system. Such advances will enhance restoration design implementation, as well support future management efforts. Keywords: Adjacent reach, Deposition, Jetty, Erosion, Streambank