Model for Total Dissolved Gas Supersaturation from Plunging Jets in High Dams

Lu, Jingying; Li, Ran; Ma, Qian; Feng, Jingjie; Xu, Weilin; Zhang, Faxing; Tian, Zhilong

doi:10.1061/(asce)hy.1943-7900.0001550

Cited by 28 publications

(12 citation statements)

References 18 publications

(21 reference statements)

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“…The TDG saturation of the water in the stilling phase can be diluted by the TDG saturation level of the plunging jet. However, a shorter T r means greater turbulence, which promotes the gas-liquid mass transfer process (Lu et al, 2019). Both experimental and field monitoring results indicated a negative correlation between the T r and mass transfer coefficient.…”

Section: Discussionmentioning

confidence: 96%

Improved Model for Predicting Total Dissolved Gas Generation With the Residence Time of the Water in the Stilling Phase

Peng

Lin

Zeng

et al. 2022

Front. Environ. Sci.

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Quantitative predictions of total dissolved gas (TDG) super-saturation are essential for developing operation schemes for high dams. Most TDG generation prediction models have various shortcomings that affect the accuracy of TDG super-saturation estimation, such as oversimplification of influencing factors and uncertainty in parameter values. In this study, the TDG generation process was divided into three parts, gas-liquid mass transfer process in the stilling phase, dilution resulting from the water jet plunging into the stilling phase, and outflow of TDG–super-saturated water from the stilling phase, while considering the water body and bubbles in the stilling phase as a whole. The residence time of the water in the stilling phase (Tr) was introduced to estimate mass transfer time, along with dimensional analysis methods. The properties of TDG generation were evaluated experimentally under varying Tr values. Based on the theoretical analysis and experimental results, a basic water renewal model was proposed and was validated using experimental data. Furthermore, prediction results of this model were compared with those of a classical empirical model and mechanical model based on observed data from a field survey at Xiluodu Dam. The results show that the relative errors between the predicted and experimental measurements were all less than 5%, indicating that the developed prediction model has a good performance. Compared with the mechanism model, the developed model could reduce the standard error (SE), normalized mean error (NME), and error of maximum (REMAX) by 60, 96, and 15%, respectively. Meanwhile, the developed model could reduce the SE, NME, REMAX by 17.4, 36, and 23%, respectively, compared with the empirical model. Considering all the error indexes, it can be concluded that the prediction performance of the water renewal model is the best among the three models. The proposed model was also more generically versatile than the existing models. Prediction results of water regeneration model for TDG could aid the drafting of governing strategies to minimize the risk of super-saturated TDG.

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Section: Discussionmentioning

confidence: 96%

Improved Model for Predicting Total Dissolved Gas Generation With the Residence Time of the Water in the Stilling Phase

Peng

Lin

Zeng

et al. 2022

Front. Environ. Sci.

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“…In this situation, the TDG level generated by the spillage ( ) at this dam is obtained using Eq. ( 11 ) 11 . Moreover, the mixing level is also considered for the spillage cases listed in Table 2 .…”

Section: Methodsmentioning

confidence: 99%

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

Cheng

Wang

et al. 2021

Sci Rep

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Total 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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“…Fish mortality from GBD caused by TDG supersaturation from spill discharge has been reported in the Columbia River basin, USA, for a long time (Arntzen et al, 2009; Bragg & Johnston, 2015; Ham et al, 2009; McGrath, Dawley, & Geist, 2006; Weitkamp & Kate, 1980). When water is allowed to spill over a hydroelectric dam, air enters the deep‐plunge pool, which leads to the occurrence of TDG‐supersaturated water downstream of the dam (Hibbs & Gulliver, 1997; Li, Li, Li, Deng, & Feng, 2009; Lu et al, 2019). The supersaturated TDG in rivers cannot be effectively released over a long distance due to factors such as the flow rate and velocity (Feng, Li, Ma, & Wang, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…A previous study in the upper Yangtze River could only explain the characteristics of one species with specific size, and a consistent pattern that could be applied to all the resident fish was not established. While some scholars have developed mathematical models to predict TDG supersaturation downstream from a dam, mathematical models that can accurately predict fish behaviour in TDG‐supersaturated water are still rare (Li et al, 2009; Lu et al, 2019; Ma, Li, Feng, Lu, & Zhou, 2018; Xue et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Tolerance and avoidance mechanisms of the rare and endemic fish of the upper Yangtze River to total dissolved gas supersaturation by hydropower stations

Wang

Liang

et al. 2020

River Research & Apps

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Several superhigh dams (greater than 200 m in height) and many high dams have been built in the upper Yangtze River basin in recent years, and these dams have made total dissolved gas (TDG) supersaturation a serious environmental problem. A few studies have examined the tolerance and avoidance characteristics of rare and endemic fish in TDG‐supersaturated water in the upper Yangtze River over the past 10 years. These studies focused on specific species and specific sizes and did not identify a regular pattern that can be applied to all resident fish in the upper Yangtze River. However, elucidating this type of pattern is crucial for fishery management and dam operations in the upper Yangtze River. Data on the median lethal time (LT50), horizontal avoidance percentage, and vertical water depth of three rare and endemic species in the upper Yangtze River from previous studies were used in the current work. An exponential relationship was found between LT50 of fish and TDG supersaturation. The avoidance percentage of fish has a linear relationship with TDG supersaturation. Fish in the upper Yangtze River can use depth compensation to avoid the threat of TDG when the saturation is 130% or above but rarely avoid the threat of TDG when the saturation is less than 125%. We also described the tolerance and avoidance characteristics of fish in a TDG‐supersaturated river downstream from a super‐high dam. When the dam discharged a two‐year flood, the LT50 values of fish downstream ranged from 9.1 to 27.5 hr regardless of depth compensation. The avoidance percentage of resident fish ranged from 8.4 to 44.8%. The resident fish swam to a water depth of 2.43–3.33 m to avoid the threat of TDG.

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Model for Total Dissolved Gas Supersaturation from Plunging Jets in High Dams

Cited by 28 publications

References 18 publications

Improved Model for Predicting Total Dissolved Gas Generation With the Residence Time of the Water in the Stilling Phase

Improved Model for Predicting Total Dissolved Gas Generation With the Residence Time of the Water in the Stilling Phase

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

Tolerance and avoidance mechanisms of the rare and endemic fish of the upper Yangtze River to total dissolved gas supersaturation by hydropower stations

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