Feasibility Study for Evaluating Cumulative Exposure of Downstream Migrant Juvenile Salmonids to Total Dissolved Gas. Final Report 1996.

1997 ◽  
Author(s):  
C.Scott Abernethy ◽  
Dennis D. Dauble ◽  
Robert L. Johnson
Keyword(s):  
Feasibility Study ◽  
Cumulative Exposure ◽  
Final Report ◽  
Dissolved Gas ◽  
Total Dissolved Gas ◽  
Juvenile Salmonids ◽  
Downstream Migrant

Understanding gas bubble trauma in an era of hydropower expansion: how do fish compensate at depth?

2020 ◽  
Vol 77 (3) ◽  
pp. 556-563 ◽  
Author(s):  
Naomi K. Pleizier ◽  
Charlotte Nelson ◽  
Steven J. Cooke ◽  
Colin J. Brauner
Keyword(s):  
Bubble Growth ◽  
Gas Bubble ◽  
Hydroelectric Dams ◽  
Dissolved Gas ◽  
Empirical Relationships ◽  
Lethal Effects ◽  
Exposed Fish ◽  
Total Dissolved Gas ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
The Relationship

Hydrostatic pressure is known to protect fish from damage by total dissolved gas (TDG) supersaturation, but empirical relationships are lacking. In this study we demonstrate the relationship between depth, TDG, and gas bubble trauma (GBT). Hydroelectric dams generate TDG supersaturation that causes bubble growth in the tissues of aquatic animals, resulting in sublethal and lethal effects. We exposed fish to 100%, 115%, 120%, and 130% TDG at 16 and 63 cm of depth and recorded time to 50% loss of equilibrium and sublethal symptoms. Our linear model of the log-transformed time to 50% LOE (R2 = 0.94) was improved by including depth. Based on our model, a depth of 47 cm compensated for the effects of 4.1% (±1.3% SE) TDG supersaturation. Our experiment reveals that once the surface threshold for GBT from TDG supersaturation is known, depth protects rainbow trout (Oncorhynchus mykiss) from GBT by 9.7% TDG supersaturation per metre depth. Our results can be used to estimate the impacts of TDG on fish downstream of dams and to develop improved guidelines for TDG.

scholarly journals Energy dissipation efficiency as a new variable in the empirical correlation of total dissolved gas

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jingying Lu ◽  
Xiaolong Cheng ◽  
Zhenhua Wang ◽  
Ran Li ◽  
Jingjie Feng ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Standard Error ◽  
Air Entrainment ◽  
Empirical Equations ◽  
Generation Process ◽  
Field Observations ◽  
Dissolved Gas ◽  
Total Dissolved Gas ◽  
Future Work ◽  
Hydropower Stations

AbstractTotal dissolved gas (TDG) supersaturation, which occurs during dam spilling, may result in fish bubble disease and mortality. Many studies have been conducted to identify the factors pertaining to TDG generation, such as the spilling discharge and tailwater depth. Additionally, the energy dissipation efficiency should be considered due to its effect on the air entrainment, which influences the TDG generation process. According to the TDG field observations of 49 cases at Dagangshan and Xiluodu hydropower stations, the TDG was positively related to the energy dissipation efficiency, tailwater depth and discharge per unit width. A correlation between the generated TDG level and these factors was established. The empirical equations proposed by the USACE were calibrated, and the TDG level estimation performance was compared with the established correlation for 25 spillage cases at seven other dams. Among the considered cases, the standard error of the TDG estimation considering the energy dissipation efficiency was 5.7%, and those for the correlations obtained using the USACE equations were 13.0% and 10.0%. The findings indicated that the energy dissipation efficiency considerably influenced the TDG level, and its consideration helped enhance the precision of the TDG estimation. Finally, the generality of this approach and future work were discussed.

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