Study on Suitable River Bed Condition for Spawning of Ayu

• ONITSUKA Kouki

  Dept. of Civil Eng., Kyushu Institute of Technology

• NAGAYA Takayuki

  CTI Engineering Co., Ltd.

• SHIRAISHI Yoshiki

  CTI Engineering Co., Ltd.

• HIGASHINO Makoto

  Dept. of Civil Eng., Oita Nat. College of Technology

• TAKAMI Tohru

  Dept. of Civil Eng., Oita Nat. College of Technology

• MATOBA Shinji

  Kyusyu Regional Development Bureau, Ministry of Land, Infrastructure and Transport

• AKIYAMA Juichiro

  Dept. of Civil Eng., Kyushu Institute of Technology

• OZEKI Hiroaki

  Toyota Production Engineering Corporation

• HATANAKA Hironori

  ACTIS Corporation

• NAKAGAWA Yumiko

  Miyako Town

Bibliographic Information

Other Title

• アユの産卵に適した浮き石状態の発生条件

Abstract

The ayu, Plecoglossus altivelis altivelis, spawns at the rapid in the lower reach of the rivers, because the velocity is high and also the bed condition is “soft bed”. The soft bed condition is defined by fishermen as that the bed materials move if someone walks on the spawning bed. Fishermen make their efforts to keep soft bed condition during the spawning season. However, it is quite difficult to keep soft bed condition, because they do not know how to make soft bed condition in detail. In this study, the soft bed condition is investigated quantitatively by the field survey. It was found that the soft bed condition is satisfied if the weight of the removed bed material by one step is larger than 0.1kg when someone walks on the river bed. Velocity measurements both in the water and under the bed in the flume were conducted. It was found that the soft bed condition is similar to the critical condition of sediment movement and also that the thickness of the mixing layer between the fixed bed material and moving one increase when the sift bed condition is satisfied.

Journal

• ENVIRONMENTAL ENGINEERING RESEARCH

  ENVIRONMENTAL ENGINEERING RESEARCH 44 59-66, 2007

  Japan Society of Civil Engineers

Keywords

• ayu
• spawning bed
• soft bed
• field survey

Details

• CRID: 1390282679088030848
• NII Article ID: 130003775869
• DOI: 10.11532/proes1992.44.59
• ISSN: 1884829X
• ISSN: 13415115
• Text Lang: ja
• Data Source:
  • JaLC
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed