ASABE Technical Library - Abstract
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Meander Bend Restoration in an Incised River
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: Paper number 022238, 2002 ASAE Annual Meeting . (doi: 10.13031/2013.10432) @2002Authors: J.A. Magner
Keywords: River Restoration, Incised Channel, Point Bar, Geomorphic
Rahr Malting Company in negotiating their NPDES permit, piloted a point/nonpoint
source pollutant trade with the Minnesota Pollution Control Agency. One objective included
river restoration at an eroding bank/bluff. Geomorphic data was collected along a 200-m
meander bend of the incised Rush River near Henderson Minnesota. The data was used to
design and construct 10 J-hook rock vains tied to a 4-m wide floodplain bench along the
outside bank/bluff. The practice decreases near bank shear stress by moving the thalweg
away from the toe slope of the eroding bank/bluff. The floodplain bench provides velocity
reduction for flows larger than the 1-to-2-yr-recurrence interval. The curled end of the J
creates compressed accelerated flow into the thalweg to form a scour hole for fish habitat
and increased pool channel cross-sectional area.
After, 2 back-to-back 5-yr flood events in April 2001, the toe slope of the bank/bluff remained
stable. However, J-hook rock vains 7-10 sustained damage due to velocities in excess of
1.8 m/s. The damage was caused by inadequate point bar formation. The incised point bar
was not reshaped to accommodate the necessary bankfull channel width through the
meander bend. Several 1-m J-hook rocks were entrained and deposited 0.5-km
downstream. Continuous on-site inspection is necessary when working with contractors
unfamiliar with the geomorphic approach to river restoration.