Spatial patterns of channel morphology and bed material texture at a chute cutoff

Authors: Abigail L. Knight*, Eastern Illinois University, James D. Riley, Eastern Illinois University
Topics: Geomorphology
Keywords: meander bends, chute cutoffs, fluvial geomorphology
Session Type: Poster
Day: 4/12/2018
Start / End Time: 1:20 PM / 3:00 PM
Room: Napoleon Foyer/Common St. Corridor, Sheraton, 3rd Floor
Presentation File: No File Uploaded

A chute cutoff has developed from a swale across the point bar of a meander bend on the Embarras River, south of Charleston, Illinois. The cutoff channel has been present for decades, but it has yet to capture the flow of the main channel. Instead, two channels exist at the bend separated by an island. The purpose of this field investigation is to document the channel morphology and bed material texture of the site to better understand the dynamics of cutoff development in a low-energy meandering river. Channel bathymetry was surveyed using a total station. A bar is located at the head of the island, on which a large pile of woody debris has previously accumulated and partially obstructed the entrance of the cutoff channel. Recent flow events have moved the pile and exposed the underlying bar. Pools associated with channel curvature at the bend are adjacent to this bar in the main channel. A region of bed scour confined to the base of the bank at the entrance of the cutoff channel, coupled with upper bank erosion and failure, occur on the opposite side of the mid-channel bar. A second bathymetric survey will follow a late winter high-flow event to document the response of channel morphology. Spatial patterns of bed material texture at this site will be discerned from sediment sampling and compared to morphologic features of the bed.

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