本研究は国内外の河川において，aDcpを用いて測定されたデータ及び岸・黒木が提案したτ*-τ*’関係に着目して流水抵抗の分析を行う．初めに，姫川/山本地点及び千代田実験水路における観測データは既存のτ*-τ*’関係と良く整合した．また，信濃川/臼井橋地点では概ね整合するものの，τ*-τ*’関係の傾きが若干異なり，これは当該地点の相対水深が既存の水路実験のものより大きいことに起因すると推察された．一方，ジャムナ川及びメコン川下流域では既存のτ*-τ*’関係とは整合せず，これは当該地点の相対水深及び浮遊砂濃度が非常に高いためと考えられる．そこで，ジャムナ川及びメコン川下流域における抵抗予測を実施するために，観測データを用いて新たにτ*-τ*’関係を導出した結果，相対水深をτ*-τ*’関係の説明変数として導入することで粗度を良好に予測できた．
This study aims to analyze hydraulic resistance with field observation data obtained by acoustic Doppler current profilers. We focused on the τ*-τ*' relation proposed by Kishi & Kuroki, and compared it with the observed data. They showed a quite good agreement in the Hime river and the Chiyoda experimental channel. In addition, the τ*-τ*' relation and the observed data in the Shinano river also showed a reasonable agreement although they have a bit difference in terms of the slope of the τ*-τ*' relation. One of the reasons of the difference is likely to be the value of R/d in the field which is much higher than that of precedence researches. In contrast, observed data in the Jamuna river and the lower Mekong river showed a totally different tendency from the τ*-τ*' relation. It is inferred that high concentration of suspended sediment and high R/d value cause the difference. To conduct a prediction of roughness in the Jamuna river and the lower Mekong river, a new τ*-τ*' relation was derived with the observed data. It is showed that the new τ*-τ*' relation is capable to predict roughness coefficient reasonably by taking R/d into consideration.
実河川における流水抵抗の分析
JSCE_73_4_I769_I774.pdf
(1.6MB)
