Journal of Hydroelectric Engineering

水力发电学报

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(vi)Chinese Academic Journals (CD).


2024 Vol. 43, No. 9 Published: 2024-09-25

	1	Simulations of influence of different water transfer methods on water quality in Chaohu Lake ^Hot!
		YI Yujun, WEI Zhen, GUO Yuming, LIU Hongxi, LIU Pei, XU Qiao
		DOI: 10.11660/slfdxb.20240901
		Water diversion projects are currently an important means to improve lake water quality. However, the water diversion route, incoming water volume, and incoming water quality are all crucial factors to achieve the improvement. This study develops a two-dimensional hydrodynamic water quality model to simulate the hydrodynamic conditions of a lake area, and applies it in a case study of the Yangtze-to-Chaohu Water Transfer Project. Based on the shallow lake characteristics, we consider that water flow diverted into Chaohu Lake not only improves directly the lake water quantity, but may cause changes in the hydrodynamic conditions in the lake area and endogenous releases. Thus, this model simulates the impacts on water quality improvement caused by different water diversion routes and different water volumes that change the lake’s hydrodynamic conditions, by different incoming water quality, and by strong release of nitrogen and phosphorus from endogenous sources. The results show that water diversion imposes weak disturbances to the lake flow in wet years and strong ones in dry years. A larger diversion flow rate affects more the lake water quality. The incoming water quality is the key to determining whether or not the lake water quality can be improved. Overall, the water transfer affects less the water quality in the western lake area. In contrast, water quality in the eastern lake area is an indicator of the changes in water quality across the entire lake. A water diversion plan should be formulated based on the lake's real water volume and water quality status, and take into account the flow rate and water quality of the water diversion project.
		2024 Vol. 43 (9): 1-12 [Abstract] ( 52 ) PDF (6487 KB) ( 89 )

	13	Progress in research of hydraulic characteristics of vertical pipe inlet-and-outlet
		GAO Xueping, YUAN Ye, ZHU Hongtao, LIU Yinzhu
		DOI: 10.11660/slfdxb.20240902
		A vertical pipe inlet-and-outlet is a common inlet-and-outlet type for controlling water flow at both ends of a pumped storage power station waterway system. It is a passage of bidirectional flows that undergoes two 90° turns (horizontal-vertical-horizontal) within a short distance. In such an inlet-an-outlet, flow direction changes drastically and its hydraulic conditions are complicated. For the design and construction of pumped storage power plants, it is of great significance to conduct an in-depth study of its hydraulic characteristics and to optimize its structure and shape. This paper first discusses the application background of the vertical pipe inlet-and-outlet and the characteristics of its channel shape, and examines the problems with its hydraulic characteristics. Then, we present a summary on the recent progress in the research on this device, the distribution of flow velocity in its trash rack section, the vortices and its head loss, etc. Finally, we sum up the research methods for its hydraulic characteristics, and suggest certain directions to focus on in the future research.
		2024 Vol. 43 (9): 13-26 [Abstract] ( 35 ) PDF (3032 KB) ( 89 )

	27	Effects of waves on migration and distribution of Microcystis colonies
		YANG Zhenhai, CAO Nana, YANG Fangyu, JIANG Weiquan, WANG Ping, ZENG Li
		DOI: 10.11660/slfdxb.20240903
		The migration and distribution of Microcystis colonies under waves are of great significance for understanding Microcystis blooms. This work experimentally investigates the trajectory, concentration distribution, and aggregation of Microcystis colonies under small amplitude waves. Results show that unlike the approximately vertical upward migration trajectory in still water, the Microcystis colonies show periodic motion in waves but still take an upward trend. The closer the Microcystis colonies are to the water surface, the greater the influence of water waves on them. The larger the wave height, the stronger the water carrying capacity caused by water waves. This leads to a more extensive range of periodic movement, and a more uniform profile of vertical concentration. When floating on the surface under large wave heights, the Microcystis colonies are prone to fragmentation and dispersion into the lower water layer by water waves. Large-scale Microcystis populations have a strong capability of vertical autonomous migration and tend to aggregate on the water surface, forming higher surface concentrations, while small-scale ones are weak in autonomous migration and are easily carried by water waves to the lower layer of water, with a relatively uniform vertical distribution.
		2024 Vol. 43 (9): 27-34 [Abstract] ( 31 ) PDF (4740 KB) ( 60 )

	35	Study on probabilistic forecasting of flash flood events based on critical rainfall uncertainty
		LIANG Fengming, WANG Jie, LIN Chengjie, LIU Miao, LI Jiao, CHEN Eyin
		DOI: 10.11660/slfdxb.20240904
		Hydrological modeling is an effective approach to flood forecasting and water resources management, significantly impacting the determination of critical rainfall in flash flood warnings. Focusing on three small watersheds in Hebei province, namely Liulin, Xitaiyu and Podi, this study examines the ranges of variations in the critical rainfalls under different sets of hydrological model parameters, using the Soil Conservation Service Curve Number (SCS-CN) hydrological model, a generalized likelihood uncertainty estimation method, and the Sobol method. A probability forecast method for flash flood events is developed. The results indicate this SCS-CN model performs well in three case studies, achieving an average Nash-Sutcliffe efficiency coefficient exceeding 0.7 and a relative error below 12% in its peak discharge calculations for most of the flood events. The uncertainty of critical rainfalls gradually increases with rainfall duration or warning level, especially under the conditions of low soil moisture. The curve number and the initial loss ratio in the hydrological model are two primary parameters that affect critical rainfall uncertainty and contribute 46.2% and 14.7% on average, respectively. Compared to the critical rainfall method, our probability forecast method enhances the comprehensive evaluation index by 9.8%, offering additional risk information for flash flood warnings.
		2024 Vol. 43 (9): 35-46 [Abstract] ( 42 ) PDF (4349 KB) ( 58 )

	47	Analysis of multi-scale spatial patterns and influencing factors of large- and medium-size reservoirs in China
		WANG Shichao, LI Peng, ZHU Jun, ZHAO Min, XIANG Huixuan
		DOI: 10.11660/slfdxb.20240905
		Large- and medium-size reservoirs are the key foundation for hydropower generation. Studying their spatial distribution is of great significance to water resource allocation and carbon emission reduction. Based on 4748 such reservoirs in China, the spatial pattern characteristics and influencing factors were deeply explored from multiple scales by using spatial analysis method. The results show that these reservoirs have a general spatial distribution structure of multi-core center and ring distribution. The global Moran index is 0.155, indicating the characteristics of obvious spatial correlation. Hunan, Guangdong and Hubei are the provinces with the largest number of large and medium-sized reservoirs, accounting for 24.3% of the national total. More than 50% are located in the third tier with annual rainfall above 800 mm, and the larger number of reservoirs are distributed over the mountain and hill topography and the Yangtze River Basin. The number on the southeast side to the Hu Huanyong's population dividing line accounts for 80.7%; the eastern, middle and western economic belts feature a distribution of more in west and less in east, gathering in east and scattered in west. The spatial pattern is mainly affected by the amount of water resources, relevant laws and regulations, fixed asset investment, and other factors.
		2024 Vol. 43 (9): 47-58 [Abstract] ( 34 ) PDF (3902 KB) ( 61 )

	59	Hydrological function of water tower on Tibetan Plateau and its regulation and storage mechanisms
		LI Mengyu, WENG Baisha, YAN Denghua, LI Mengling, WANG Hao
		DOI: 10.11660/slfdxb.20240906
		The Tibetan Plateau, known as the "Asian Water Tower," is essential in terms of hydrology, climate, and ecology. At the moment, our understanding of the hydrological functions of the water tower is mostly focused on its storage function, with little attention paid to its regulation function and mechanism. In terms of watershed preservation and regulation, this study describes the hydrological functions of the water tower’s water storage and regulation, and the hydrological functions and storage-regulation mechanism of multi-phase water towers. The Tibetan Plateau Water Tower not just has a powerful function of water storage, but plays other roles－redistributing precipitation over the water tower region; adjusting the runoff and its distribution within a year in the non-water tower regions, and regulating water resources such as precipitation, surface water, soil water, and groundwater in the basin. This study helps lay a basis for assessing the ecological and hydrological impact of the water tower on the upper and lower basins of the plateau, useful for protection and regulation of the water tower on the basins, so as to meet the production, living, and ecological water needs of this region and its surroundings through rational planning of water conservancy projects.
		2024 Vol. 43 (9): 59-69 [Abstract] ( 40 ) PDF (3352 KB) ( 83 )

	70	Intelligent inspection technology based on 5G technology and its fault diagnosis application at hydropower stations
		LI Changzhao, WANG Xiuyu, TAO Zhiyu, FANG Mingkun, ZHANG Yingling, SUN Zhiwei, TAO Ran
		DOI: 10.11660/slfdxb.20240907
		New hydropower energy has been faced with new opportunities and challenges against the backdrop of the strategic goal of peaking carbon emissions and achieving carbon neutrality proposed in the national 14th Five-Year Plan. As the scale of hydropower stations expands, traditional manual inspection combined with industrial monitoring often faces more problems such as inability to automatically identify and judge faults, and low sensitivity to information feedback. This paper describes a new method for applying variational mode decomposition and image grayscale processing techniques to an analysis of the operating data of hydropower plant units, through combining 5G technology and artificial intelligence. The results show that the fractal dimension of the images features two typical frequencies of 30 Hz and 85 Hz, with the corresponding amplitudes of 0.02 and 0.009 respectively, which are detected as the dominant and secondary frequencies, far stronger than other clutter frequencies. The VMD method successfully decomposes the signals of pressure pulsation at each monitoring point so as to obtain the characteristics of various modal functions in time and frequency domains. By examining the VMD decomposition results for two monitoring points at the tail water pipe, we have found that their frequency components are similar and consistent with those monitored inside the volute. This study would provide important support for construction of intelligent hydropower stations, along with an effective means for their operation and maintenance.
		2024 Vol. 43 (9): 70-81 [Abstract] ( 38 ) PDF (3662 KB) ( 93 )

	82	Study on effect of connecting column treatment on performances and internal flows in disc pumps
		HENG Yaguang, LUO Xipeng, CHEN Zhengsu, JIANG Qifeng, ZHANG Weibin, WANG Chuan, GE Jie
		DOI: 10.11660/slfdxb.20240908
		This paper presents a numerical simulation study on a disc pump in two different model scenarios of its connecting column region. The performance and the change in the flow inside the impeller under different flow conditions are examined and the calculations are verified with experimental measurements. Comparison of the calculations in the two schemes shows that in Scheme I, a significant low velocity region occurs on both sides of the connecting column, while in Scheme II, the local velocity is higher due to the set-up of near wall fluid. In the two schemes, local low-pressure areas occur on the blade suction surface, and the formed vortices also result in an increase in local energy dissipation. Therefore, most of the turbulent energy dissipation in the pump is concentrated on the blade suction surface, while energy dissipation near the pump inlet and outlet are weak. After the flow passes through the connecting column, its circumferential velocity and the circumferential component of its absolute velocity in Scheme II are smaller than those in Scheme I. This indicates that in pump operation, the energy loss generated by the blocking effect of the connecting column on the outlet flow is greater than the amount of energy brought by the column itself, resulting in a lift head lower in Scheme II than Scheme I. The calculations of the two schemes agree with the trends measured in the experiment, and the performance differences between them are rather small. Schemes I is simpler and efficient if only the rapid calculation of pump performance is considered; Scheme II is preferred if comprehensive and accurate information of internal flow is needed.
		2024 Vol. 43 (9): 82-93 [Abstract] ( 22 ) PDF (4109 KB) ( 63 )

	94	Influence of needle-shaped flake aggregate content on asphalt concrete aggregate gradation
		LI Yanlong, ZHAO Dong
		DOI: 10.11660/slfdxb.20240909
		This study examines the influence of needle flake aggregate content on the gradation of asphalt concrete aggregate, using a stepwise filling method and adopting skeletal stability as the sole criterion for assessing the quality of aggregate skeleton. A vertical vibration compaction device is used to prepare the specimens with needle flake contents of 0%, 20%, 25%, 30%, and 35%, respectively; Skeletal stability is evaluated comprehensively by combining the California bearing ratio (CBR) value, skeletal density, and porosity to determine the coarse aggregate gradation for different specimen sets. Aggregate gradation is designed using a composite gradation design method through blending coarse and fine fractions across the full-size range. The findings indicate that with an increasing content of needle-like aggregates, the stability of aggregate skeleton takes a trend of initial increase and then decrease. The optimal stability is observed at a needle flake content of 30%, while the least favorable is at the content of 35%.
		2024 Vol. 43 (9): 94-105 [Abstract] ( 31 ) PDF (3247 KB) ( 50 )

	106	Hybrid prediction model for dam seepage pressure based on STL decomposition and integrated learning
		WANG Xiaoling, WANG Cheng, WANG Jiajun, YU Jia, YU Hongling
		DOI: 10.11660/slfdxb.20240910
		Most of the previous studies on dam seepage pressure prediction did not distinguish the differences in the contributions of influencing factors to different characteristic components of seepage pressure, thereby reducing the interpretability of their models. Most of the previous prediction models in literature adopted a single algorithm and thus suffered such problem as a difficulty in exploring accurately the patterns of seepage pressure sequences with highly nonlinear, non-stationary mixed characteristics. This paper develops an interpretable hybrid prediction model for seepage pressure based on seasonal and trend decomposition using loess (STL) and an integrated learning strategy. First, the model adopts STL to decompose the original seepage pressure time series into seasonal, trend and remainder components, so as to avoid the deficiency of pattern confusion encountered in the previous predictions. Then, it identifies the variability characteristics of different components using an ensemble learning model that consists of a kernel extreme learning machine (KELM) optimized by the multi-strategy-improved sparrow search algorithm (MSISSA) and a convolutional neural network combined with a gated recurrent unit (CNN-GRU). In addition, the One-Factor-At-A-Time (OFAT) method is used to analyze the contributions of influencing factors to the different characteristic components of seepage pressure so as to change the weights of input factors and successfully increase model interpretability. Case study shows that while ensuring model interpretability, this new hybrid model improves prediction accuracy by an average of 48.44% compared to a single algorithm-based model and an average of 11.42% compared to other ensemble prediction models. This verifies the model and provides a new modelling approach for dam seepage safety monitoring.
		2024 Vol. 43 (9): 106-123 [Abstract] ( 21 ) PDF (8560 KB) ( 35 )

	124	Intelligent interpretation method for non-editable texts of hydraulic concrete materials
		LI Mingchao, LIU Leping, REN Qiubing, LI Wenwei, LYU Yuangeng, LI Xinyu
		DOI: 10.11660/slfdxb.20240911
		During the construction of a hydropower project, a large number of non-editable documents for hydraulic concrete materials are generated. Using manual interpretation methods to obtain texts is time-consuming, laborious and accuracy-uncontrollable, making it difficult to meet the demand for information management of material data. This paper develops an intelligent interpretation method for non-editable texts of hydraulic concrete materials. First, we construct a text detection model, HC-PSENet, based on pixel level segmentation, which integrates the backbone network of PP-HGNet to achieve accurate detection of text lines. Then, a professional corpus is created based on the domain knowledge to realize accurate character mapping. We construct a text recognition model HC-CRNN for hydraulic concrete materials, using detection text boxes and the professional corpus as its inputs, and adopt the backbone network of ResNet and the improved loss function C-CTC Loss to improve the accuracy of character classification. Finally, a transfer learning strategy is adopted to train the model with the self-designed dataset as an example; the effectiveness and superiority of our new method is verified through ablation and comparative experiments. The results show that it has a harmonic mean of 0.985 for detecting text regions and its accuracy of text recognition reaches 90.62%. It has an overall performance superior to classical methods and would provide new technical means for the automated reuse of non-editable text resources in concrete materials.
		2024 Vol. 43 (9): 124-136 [Abstract] ( 50 ) PDF (4074 KB) ( 90 )