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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Sediment management and morphodynamics : An experimental study on the bedrock re-exposure by sandbar formation and channel curvature
An experimental study on the bedrock re-exposure by sandbar formation and channel curvature
Author : TAKUYA INOUE (1), TOMOO USHIYAMA (2), KAZUTAKE ASAHI (3) & MITSUAKI YONEMOTO (4)
ABSTRACT
A weakly bedrock layer is partially exposed in the middle reaches of the Ishikari River (Hokkaido, Japan). Local bedrock
erosion has led to insufficient embedded depth of bridge piers and damage to revetments. As those problems are
becoming more serious, we are planning to be covered the bedrock by gravel in order to suppress the bedrock local
erosion. However, the formation of gravel bars often cause partial bedrock exposure. The purpose of this work is to
understand the mechanisms of the bedrock re-exposure using a large-scale flume experiment. We conducted an
experiment using 1/50-scale model of the Ishikari River. The flume bed was non-erodible mortar bed, and was covered
with sand of average diameter 1.1mm. The thickness of sand layer was 20mm. The experiment was bank-full flow with
discharge of 35.5L/s. Sediment feed rate was equal to the sediment transport capacity. The experimental results showed
that; 1) the bedrock was re-exposed by the bar formation near the flume banks; 2) in the straight channel zone, bedload
moves over the exposed bedrock patches; 3) in the meandering zone, the secondary flow prevents the intrusion of
bedload into the exposed bedrock patches.
File Size : 5,509,927 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Sediment management and morphodynamics
Date Published : 26/08/2015
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