Experiment and simulation of supersaturated total dissolved gas dissipation: Focus on the effect of confluence types

WATER RESEARCH

卷:155

Article

Shen, Xia^1,2  Li, Ran²  Hodges, Ben R.³  Feng, Jingjie²  Cai, Huanjie¹  Ma, Xiaoyi¹ 

[1] Northwest A&F Univ, Minist Educ, Key Lab Agr Soil & Water Engn Arid & Semiarid Are, Yangling 712100, Shaanxi, Peoples R China

[2] Sichuan Univ, State Key Lab Hydraul & Mt River Engn, Chengdu 610065, Sichuan, Peoples R China

[3] Univ Texas Austin, Ctr Water & Environm, Austin, TX 78712 USA

关键词: Confluence;    Total dissolved gas;    Supersaturation;    Separation zone;    Secondary flow;    Low-TDG-Saturation;   

DOI  :  10.1016/j.watres.2019.02.056

来源: Elsevier

【 摘 要 】

Total dissolved gas supersaturation (TDGS) downstream caused by spill discharge from high dams can easily cause fish to suffer from gas bubble disease (GBD). One potential approach to mitigate the impact of TDGS is at the confluence of a downstream tributary, where the introduction of low-TDG water might provide refuge space for fish. In this study, we carried out a series of flume experimental cases and established a three-dimensional TDGS model at confluences. The formula of the dissipation coefficient of TDGS had been obtained by parts of experiment cases. The other parts of experimental cases were carried out to validate the established TDGS model. The biggest relative error of TDG concentration between the experiment and simulation was -5.7%. The results show that the convergence of tributary water (TDG = 100%) can affect the mainstream water (TDG = 140% similar to 150%) significantly. The two most obvious features are the presence of the separation zone and secondary flow which become more significant as the flow rate increases. The separation zone area at the bottom is smaller than that at the surface. There are two secondary circulations on transversal planes which decrease as the longitudinal distance increases. In addition, the area below 110% and 120% of TDGS in different planes of different cases were compared in detail. This study can provide scientific basis for the utilization of the low-TDG-saturation region to protect fish from the damage of TDGS at confluences during high dam discharge. (C) 2019 Elsevier Ltd. All rights reserved.

【 授权许可】

Free