Journal of Hydroelectric Engineering

水力发电学报

Office Online

Included Databases

The journal is included in the following databases:
(i)Scopus,
(ii)The Chinese Science Citation Database Source Journals,
(iii)The Chinese Science Journal Abstract Database,
(iv)The Chinese Science and Technology Papers Statistics and Analysis Database,
(v)China Newspaper Subscription Guide Information Database,
(vi)Chinese Academic Journals (CD).


2023 Vol. 42, No. 8 Published: 2023-08-25

	1	Evolution and historical comparison of hot droughts in Yangtze River basin in 2022 ^Hot!
		JIANG Yutong, HOU Aizhong, HAO Zengchao, ZHANG Xuan, FU Yongshuo, HAO Fanghua
		DOI: 10.11660/slfdxb.20230801
		Based on the fifth generation atmospheric reanalysis dataset ERA5 of the European Centre for Medium Range Weather Forecasts (ECMWF), we define two types of hot droughts or compound drought-hot events－simultaneous occurrences of meteorological drought/agricultural drought and high temperature. We examine the evolution of such an event occurred in the Yangtze River basin in the summer of 2022, and evaluate the variations in its several characteristics such as duration and spatial coverage. The results show that this hot drought began in June, became most severe in August, and weakened in September; its spatial scale varied significantly, starting from the middle and lower reaches, gradually expanding to the whole basin, and reducing to the middle and lower reaches by September. And compared with typical events in historical periods, its characteristic values were the largest. We find a significant increase in the characteristic values of the two types of compound drought-hot events in July and August from 1979 to 2022. The results deepen our understanding of the hot droughts and extreme events in a river basin and can be useful for coping with extremes under global warming.
		2023 Vol. 42 (8): 1-9 [Abstract] ( 360 ) PDF (5139 KB) ( 795 )

	10	Application of deep learning in prediction and early warning of ecological flows in rivers and lakes
		CHEN Hao, WANG Bei, HE Xijun, XU Yueping, GUO Yuxue, WANG Dong
		DOI: 10.11660/slfdxb.20230802
		This paper develops a new ecological flow forecasting method based on deep learning and a conceptual hydrological model with application to the Jiaojiang River basin in Zhejiang Province to improve the forecast accuracy of ecological flow early warning and the efficiency of ecological operation of water conservancy projects. This method calculates the ecological flow and warning threshold using the hydrological method, and screens model forecast factors through the principal component analysis. The results reveal the check values of most suitable ecological flows are 2.89 m3/s and 1.92 m3/s at the Baizhiao and Shaduan stations, respectively. We use precipitation and evaporation as input factors and the grid search method for optimal parameters searching, and have achieved a 100% qualified rate of the ecological flow warning level forecasts in all the years by using the eXtreme Gradient Boosting (XGBoost) algorithm. Our coupling prediction model based on XGBoost and the Xin’anjiang model can well complete the ecological flow early warning prediction and reservoir ecological flow regulation, laying a basis of decision-making for protection and supervision of water resources in rivers and lakes.
		2023 Vol. 42 (8): 10-20 [Abstract] ( 142 ) PDF (1628 KB) ( 544 )

	21	Effect of inflow uncertainty on water supply scheduling risk of inter-basin water transfer project
		HUA Xin, BAI Tao, LI Lei, ZHAO Yunjie, HUANG Qiang
		DOI: 10.11660/slfdxb.20230803
		To quantify water supply risk caused by runoff forecast uncertainty, this paper defines water supply risk based on the probability distribution of inflow uncertainty, and develops a water supply scheduling model for the Hanjiang-to-Weihe River Basin Water Diversion Project. Multi-scale water supply risk values with different forecasting errors are obtained. The critical forecasting error of risk escalation is clarified, and the influence of inflow uncertainty on the water supply risk of this cross-basin diversion project is revealed. The results demonstrate that for water supply risk, 15% is a threshold of the runoff forecast error; the relationship between forecast error and water supply risk follows a quadratic power function. The Sanhekou reservoir can activate its multi-year water regulation to mitigate water supply risk caused by forecast errors. The water supply risks are divided into three levels: light, medium and heavy, and the thresholds for risk level upgrading are determined to be 0.117 and 0.190, corresponding to forecasting errors of 24.0% and 32.7%, respectively. The results provide a decision-making basis for ensuring the water diversion safety of the project.
		2023 Vol. 42 (8): 21-31 [Abstract] ( 98 ) PDF (1057 KB) ( 434 )

	32	Impact of hydropower cascade development on river habitat connectivity and its path to optimization
		HE Xiaofeng, HUANG Xiang, CHEN Min, LI Jia, AN Ruidong
		DOI: 10.11660/slfdxb.20230804
		This study examines the impact of hydropower development on river habitat connectivity, and develops a connectivity optimization path coupling connectivity and benefits, through a case study of the Dadu River basin. We create a database for the 135 hydropower stations in the basin through data collection and remote sensing image identification, and quantify river habitat connectivity using the River Connectivity Index (RCI). The results show that 1) the RCI of this basin is 16.68 at present and will decrease to 4.2 when all the planned power stations are completed in the future, and that the spatial distribution of RCI shows a decreasing trend from upstream to downstream. 2) Hydropower stations located in the middle of the river network have a greater impact than those located in its headwater region or near its tributary. 3) The impact of different hydropower development plans on the connectivity varies significantly, and the connectivity can be improved effectively through reasonable planning while ensuring the development benefits. This study would help river habitat connectivity restoration and watershed strategic planning.
		2023 Vol. 42 (8): 32-41 [Abstract] ( 94 ) PDF (3827 KB) ( 239 )

	42	Simulations of water levels in East Dongting Lake and attribution analysis of its hydrological regime changes
		ZOU Jihu, HUANG Yuning, HUANG Feng, SHEN Xingzhi, QIAN Zhan, JIANG Heng, HAN Shuai
		DOI: 10.11660/slfdxb.20230805
		The hydrological regime in East Dongting Lake has changed greatly in recent years; it needs an evaluation on the contributions of different driving factors to the regime change. This study constructs a long short-term memory neural network model to simulate the lake’s water level variations, and uses the indicators of hydrological alteration (IHA) to evaluate the existing hydrological regime. Four scenarios are examined for the major contributing factors: changes in the flow in the Yangtze mainstream and the lake’s four tributaries, and changes in its topographic conditions. The results show that the Yangtze flow changes are the main factor driving the drop in flood season water levels in the lake and the shortened average duration of its low water level pulses. The tributary flow changes are the main factor driving the increase in the number of the lake’s water level reversals. The topographic changes have significantly lowered its water level, and this effect is significant in the dry season. The results help manage the lake’s water resources and evaluate hydrologic regime change factors for other river systems.
		2023 Vol. 42 (8): 42-50 [Abstract] ( 75 ) PDF (2320 KB) ( 306 )

	51	Long-term prevention and control method of tributary sand bars in sandy river reservoirs
		YANG Chen, LIU Fuping, LI Chaoqun, GENG Mingquan, LIU Ying, LIU Songlin
		DOI: 10.11660/slfdxb.20230806
		Sand bars often form at the mouth of the tributaries into a sandy river reservoir. They affect the normal functions of the reservoir, but no effective treatment method is available so far. This paper presents a long-term prevention and control method of these sand bars that is based on mobile diversion piles and verified by flume model experiments. The results show that in the case of no control measure, a sand bar forms in the tributary mouth, and develops at a speed proportional to the flow and sediment discharge in the mainstream. Its cross section shows a parallel uplift, its vertical profile takes an inverted V shape, and its highest elevation is formed in the highest turbidity zone of the intersection area. After the control piles are installed, the opening of a water barrier is closed during the high mainstream water level, so as to make most of the sediment settle down and deposit outside the barrier. In the low water level period, the opening is activated to make the water body already stored in the tributary flow through a narrow passage between two diverting walls, and to allow this flow to scour the sand bar so as to form a stable gully at its upper surface and supply as a connection of the main stream to the tributary. Our model experiments show this method can achieve the effect of long-term prevention and control of the sand bar. The method features a clear mechanism, low cost, flexible operation, and lasting effect, so its further improvement could lead to a new practical technology for long-term prevention and control of sand bars.
		2023 Vol. 42 (8): 51-60 [Abstract] ( 72 ) PDF (3161 KB) ( 195 )

	61	Numerical study on dynamic behaviors of cavitation bubbles in symmetrical position near right-angled concave walls
		ZHANG Yupeng, XU Qianqian, YU Zhiwei, CHEN Ting
		DOI: 10.11660/slfdxb.20230807
		Cavitation damage widely occurs in the flow passages of a hydraulic machine, and the right-angled wall is a common type of wall surfaces. However, understanding of dynamic behaviors of a cavitation bubble near a right-angled concave wall is very limited. This study is aimed to investigate the influence of a dimensionless distance parameter γ on the dynamic behaviors of a cavitation bubble in symmetrical position near a right-angled concave wall, focusing on the characteristics of the micro-jet and its influence on the wall. The results show two different types of micro-jets are generated during bubble collapsing, i.e., the main jet and the sideway jet. The main jet points to the intersection of the two perpendicular walls; the direction of the sideway jet varies with time, which may exert a force on the walls. Both jets impose an impact on wall pressure that is inversely related to the dimensionless distance parameter γ－a larger γ leads to a smaller impact on wall pressure. In the range of γ < 2.5, both jets produce considerable effect, but the main jet plays a dominant role in all the cases.
		2023 Vol. 42 (8): 61-68 [Abstract] ( 60 ) PDF (3022 KB) ( 335 )

	69	Extraction and recognition method of characteristic spectra for incipient cavitation of model turbines
		HAN Wenfu, NI Jinbing, GUI Zhonghua, MAN Zhe, DING Jinghuan, XIAO Wei, LI Dongkuo, WANG Gang
		DOI: 10.11660/slfdxb.20230808
		At present, incipient cavitation in a model turbine is identified as before using the manual method whose shortcomings are a long period of data acquisition, strong subjectivity, low accuracy, and low efficiency. To improve incipient cavitation identification, this paper develops an intelligent identification method of turbine cavitation－namely the intelligent recognition method of multimodal bubble sound PSVFR based on feature extraction of cannon sound spectra and special pulsation spectra. In this method, turbine cavitation noise data are processed using MTCSPC, a multistate algorithm independently-developed by the authors. By collecting the feature vectors of incipient cavitation tones, a matrix model is constructed; then calculation and judgment are made through feature comparison with the qualitative matrix in the sample database, so as to help the machine complete the learning and recognition of model turbine cavitation noise. Compared with previous technologies, this method improves the accuracy and efficiency of machine identification of turbine incipient cavitation, with a recognition efficiency reaching up to 80%.
		2023 Vol. 42 (8): 69-79 [Abstract] ( 83 ) PDF (5214 KB) ( 236 )

	80	Auto-coupling PID control method for hydraulic turbine regulation system
		HUANG Lirong, ZENG Zhezhao, ZENG Peng
		DOI: 10.11660/slfdxb.20230809
		To improve the hydraulic turbine regulation system with dead zones and mechanical delay, a control method based on the auto-coupling PID control theory is studied. First, we examine a delay turbine regulation system with dead-time links which delay, dead-time nonlinear factors, uncertainties and external disturbances are defined as the total disturbances; by introducing virtual controls, it is equally mapped to a double closed-loop system with an outer loop second-order linear disturbance system and an inner loop first-order linear disturbance system. Then, using the speed factor, we design an auto-coupling PD controller for the outer ring and an auto-coupling PI controller for the inner ring. Finally, the robust stability and anti-disturbance robustness of the closed-loop control system are analyzed in the complex frequency domain. The simulation results show that under different working conditions, the designed controllers gain better anti-disturbance robustness, and their dynamic quality and steady-state performance are improved significantly.
		2023 Vol. 42 (8): 80-88 [Abstract] ( 80 ) PDF (579 KB) ( 397 )

	89	Method for extracting frequency-domain modal parameters of pressure pulsations in hydraulic machines and its application
		ZHOU Jichen, NIU Xiangyu, LIN Guihai, LIU Xin
		DOI: 10.11660/slfdxb.20230810
		When operating at the off-design condition, the pressure pulsations within a hydraulic machine may contain multiple frequency components. In time domain analysis of the flow, the unsteady characteristics of the lower-amplitude subharmonic frequency components are often overshadowed by the time-domain evolution of the dominant frequency component. Based on the ideas of the modal parameter extraction methods in structural dynamics, this paper describes a new method for extracting frequency-domain modal information from the flow field, using the natural excitation technique. Modal parameters at different frequencies are obtained through complex response functions, and relevant codes are developed to apply this method to analysis of the unsteady flow fields in a mixed-flow water turbine. We examine the simulation results of the turbine operating at low flow rates, characterize the vibration modes of draft tube vortices, and reveal the relationship between the generation of higher-order frequency components in the draft tube and the rotational perturbation source in the bladeless section. Meanwhile, we give an analysis of the impeller excitation modes caused by rotor-stator interference and other factors. The modal results has been verified with theoretical predictions. Thus, our frequency-domain modal analysis method helps reveal information such as the sources and propagation of pressure pulsations at different frequencies.
		2023 Vol. 42 (8): 89-97 [Abstract] ( 67 ) PDF (1462 KB) ( 277 )

	98	Unsafe behavior recognition method of construction workers in water conservancy project
		ZHANG Sherong, LIANG Binjie, MA Zhonggang, DONG Fajun, WANG Chao, WANG Xiaohua
		DOI: 10.11660/slfdxb.20230811
		Unsafe behaviors of construction workers are the key factor leading to safety problems in the construction process of water conservancy project. Most construction sites adopt on-site safety inspection, wearable equipment, real-time monitoring, and other methods to identify unsafe behaviors, but such methods are time-consuming, laborious, expensive with low information level, and unfavorable to the timely discovery and early warning of dangerous behaviors. This paper presents a new method of unsafe behavior identification suitable for large scenes of water conservancy projects based on computer vision and deep learning. First, an improved method of YOLOv5 is developed to solve the problem of missing and wrong detection of small objects in construction workers and machinery in large scenes, and a multi-object object detection model of construction workers and machinery is constructed. Then, based on the target detection model, recognition methods are suggested for each of the routine unsafe behaviors, such as being close to the static danger area, dynamic construction machinery, and not wearing safety helmet, etc. Engineering application verifies that our identification method strengthens the means and intensity of construction site control and improves effectively the level of water conservancy engineering construction safety and intelligent control.
		2023 Vol. 42 (8): 98-109 [Abstract] ( 164 ) PDF (3705 KB) ( 485 )

	110	Method for lightweight crack segmentation based on convolutional neural network
		SHUI Yuhang, ZHANG Hua, CHEN Bo, XIONG Jinsong, FU Meiqi
		DOI: 10.11660/slfdxb.20230812
		When the general segmentation model is applied to the apparent cracks in the dam face concrete, the network suffers the problem of depth increasing that leads to excessive model parameters and certain loss of effective crack features. To reduce network memory occupation and feature loss, this paper develops a lightweight crack segmentation method based on a convolutional neural network. The network adopts an encoding-decoding structure, and uses a depth-separable convolution module and a lightweight feature extraction module to construct a cascade encoder; it is equipped with a decoder to fuse cross-scale information in the second stage of the encoder and to reconstruct the pixel-level geometric information lost in feature extraction to improve the accuracy of network segmentation. The experimental results show the model size of the network trained on the crack dataset of dam face concrete is 10.8 MB or a size reduction of 90.8% from U-Net, with its PA of 73.3% and IoU of 85.4%. The results verify the network is feasible in dam face crack segmentation and useful for improving the efficiency of dam face detection and maintenance.
		2023 Vol. 42 (8): 110-120 [Abstract] ( 689 ) PDF (2429 KB) ( 345 )