Journal of Natural Disaster Science

Suppression Limit of Alternate Bar Migration through Sine-generated Meander Channels

Hajime Miwa
Faculty of Agriculture, Iwate University, Japan
and
Takeshi Nagayoshi
Sapporo Enginecring Vocational College, Japan

(Received 5 April, 1999 and in revised form 8 June, 1999)

Abstract

Alternate bars migrate downstream in a straight river channel and also migrate in weak meandering channels but do not move downstream through strong meander channels. We used different sine-generated meander channels to study the critical bend angle required to suppress bar migration. The critical bend angle becomes smaller as the meander channel wavelength lengthens. The relationship between the critical bend angle and meander channel wavelength was nearly the same under 3 hydraulic conditions in which the meander wavelength was 6 to 12 times as long as the channel width. These findings essentially agree with those reported by Kinoshita and Miwa for zigzag meander channels. A meander channel with a much longer wavelength, e.g., a 14-channel-width, gives different results. Alternate bars migrate easily as mobile short bars develop in the channels, and the critical bend angles become larger.

Key words

alternate bar,bar migration, meander channel, hydraulic experiment, critical bend angle