Factors Influencing Distribution Characteristics of Total Dissolved Gas Supersaturation at Confluences

Shen, Xia; Hodges, Ben R.; Li, R.; Li, Z.; Fan, Junliang; Cui, Ningbo; Cai, Huanjie

doi:10.1029/2020wr028760

Cited by 18 publications

(5 citation statements)

References 77 publications

(153 reference statements)

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“…In this study, ANSYS FLUENT 2021R2 was used to solve governing equations using the finite volume method. The RNG k‐ε turbulence model was selected for this study because of the strong turbulence and curved flow lines of the confluent flow (Shen et al., 2021). A mixed unstructured quadrilateral and a triangular grid was used to mesh the study area.…”

Section: Methodsmentioning

confidence: 99%

Hydrodynamic and dissolved oxygen–biochemical oxygen demand transport characteristics at the river confluence in China's largest alluvial plain—A modeling study

Shen,

Wang,

et al. 2023

J American Water Resour Assoc

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The Yellow River flows through multiple provinces in China, shaping the North China Plain, the largest alluvial plain in China. As the control node of basin ecological environment, the confluence of Weihe River and Yellow River is deemed as the gateway to North China Plain. In this study, a numerical simulation of the Weihe River–Yellow River confluence is conducted using a 2D hydrodynamic model and a coupled transport model for dissolved oxygen–biochemical oxygen demand. The results show that: (i) The typical flow field with multiple backflow areas is formed at the stagnant area where main stream and tributary converge and abrupt channel change area in different hydrological periods. The spur dike here mainly affects the velocity of the Weihe River outlet. (ii) There is an obvious concentration transition mixing zone downstream of the confluence, and the width of the mixing zone gradually linear increases with the direction of water flow. (iii) The self‐purification ability of the confluence is strongest in dry period, weaker in level period, and weakest in wet period. Water bodies have stronger self‐purification capacity on riverbanks than in the middle, and it is stronger in the upper reaches of Weihe River compared to Yellow River. Lower reaches also have a stronger self‐purification capacity than upper reaches. The study results can serve as a scientific reference for protecting the ecological environment of the Yellow River.

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Section: Methodsmentioning

confidence: 99%

Hydrodynamic and dissolved oxygen–biochemical oxygen demand transport characteristics at the river confluence in China's largest alluvial plain—A modeling study

Shen,

Wang,

et al. 2023

J American Water Resour Assoc

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“…When flow velocity and water depth were thoroughly analyzed, it was determined that the confluence location was suitable for shielding fish from TDG supersaturation. Based on this, Shen et al (2021) used the 3D simulation method to investigate the mechanism influencing the flow ratio and confluence angle on the distribution of TDG concentrations downstream of the confluence. It was discovered that the secondary flow's advection circulation caused higher concentrations of TDG to renew their surfaces more quickly, hastening the release of supersaturated TDG.…”

Section: Abatement Measures In the Release Stagementioning

confidence: 99%

“…Using a three‐dimensional hydrodynamic simulation method, Shen et al. (2021) investigated the impact of flow ratio and confluence angle on TDG release downstream of the confluence. The findings demonstrated that the main influences on the concentration distribution of TDG were inflow TDG, secondary flow, and turbulence intensity.…”

Section: Factors Influencing Tdg Supersaturationmentioning

confidence: 99%

Generation and Release Mechanism and Abatement Measures for Gas Supersaturation Downstream of Hydropower Dams: A Review

Zhang,

Fu,

et al. 2023

Water Resources Research

Self Cite

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Despite the considerable social and economic benefits of hydropower dams, they can cause total dissolved gas (TDG) supersaturation downstream of hydropower dams, which can harm fish through gas bubble trauma (GBT) and cause issues with aquatic ecology. This paper systematically reviewed the generation and release mechanism of TDG supersaturation, including three stages of TDG generation and release, to broaden the research ideas of TDG supersaturation and encourage the construction of environmentally friendly dams and other hydropower projects. The factors affecting the generation and release were summarized from the three stages of TDG generation and release, including temperature, momentum difference at the water‐air interface, and effective depth of bubble arrival. The research methods were introduced from four aspects: theoretical methods, field observations, experiments, and numerical simulations. The advantages, disadvantages, and application scopes of different research methods were outlined. Finally, the abatement measures in the three stages of TDG generation and release were introduced from the engineering and non‐engineering perspectives, and the future research directions were pointed out from the four aspects of TDG supersaturation generation and release mechanism, research methods, abatement measures, and management methods, including in‐depth study of whether gas‐liquid transfer through bubble surfaces or free surfaces dominates, consideration of bubble coalescence and rupture to improve the accuracy of numerical methods in TDG supersaturation prediction, the combination of engineering and non‐engineering measures to optimize TDG supersaturation abatement measures and consideration of artificial intelligence technology to improve hydropower project management methods.

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“…TDG super-saturation induces gas bubble disease in fish, thereby adversely impacting the local riverine eco-environment (Wang et al, 2020;Shen et al, 2021). Fish exposure to TDG supersaturated water can cause foam trauma and death-related injuries (Weitkamp and Katz, 1980).…”

Section: Introductionmentioning

confidence: 99%

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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Factors Influencing Distribution Characteristics of Total Dissolved Gas Supersaturation at Confluences

Cited by 18 publications

References 77 publications

Hydrodynamic and dissolved oxygen–biochemical oxygen demand transport characteristics at the river confluence in China's largest alluvial plain—A modeling study

Hydrodynamic and dissolved oxygen–biochemical oxygen demand transport characteristics at the river confluence in China's largest alluvial plain—A modeling study

Generation and Release Mechanism and Abatement Measures for Gas Supersaturation Downstream of Hydropower Dams: A Review

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

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