学会誌「自然災害科学」

実験蛇行水路における交互砂洲の移動抑止限界

Experimental Studies on the Suppression Limit of Alternate Bar Migrations Through Sine-Generated Meander Channels

三輪 弌*・永吉 武志**

Hajime MIWA* and Takeshi NAGAYOSHI**

Abstract

Alternate bars migrate downstream in straight river channels. They also migrate in weakly meandering channels, but do not move downstream through more strongly meander channels. We experimentally studied the critical bend angles to suppress bar migrations using various kinds of sine-generated meander channels. The critical bend angles are smaller as wavelengths of meander channels are longer. The relations between the critical bend angles and wavelengths of identical even in three different hydraulic conditions under which meander wavelengths are from six to twelve times as long as the channel width. These results are almost equal to those obtained in the previous study by Kinoshita and Miwa in their zigzag meander channels. In meander channels with much longer wavelengths, alternate bars migrate easily as mobile short bars develop in the channels. Therefore, the critical bend angles become larger.

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