Journal of Hydroelectric Engineering

水力发电学报

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2016 Vol. 35, No. 1 Published: 2016-01-25

	1	Integrated management strategies for Dongting Lake ^Hot!
		NIU Xinqiang
		DOI: 10.11660/slfdxb.20160101
		Dongting Lake is the second largest freshwater lake in China, which plays an important role in guaranteeing water safety of the Yangtze River Economic Belt. Affected by poor connection development caused by river-lake relationship changes for decades, problems were brought about such as water resource shortage, deteriorated water ecological environment, navigation development atrophy, and also result in insufficient flood control and drainage capacity of Dongting Lake. The mechanism of river-lake relationship changes was studied, and the trends and its influence were analyzed since the use of the upper Yangtze River control projects. To implement the national development strategies for Yangtze River Economic Belt and Dongting Lake Ecological Economic Zone and following the philosophy of river-lake harmony and ecological civilization, innovative ideas of Dongting Lake Great Water Vein scheme is proposed in this paper against prominent problems during Dongting Lake harnessing, development and protection. Dongting Lake Great Water Vein project can unblock the river-lake connection, restore and adjust the river-lake relationship, improve the water carrying capacity and water ecological and environmental carrying capacity of Dongting Lake, promote the coordinated development of social economy and ecological environment protection with sustainable use of water resources.
		2016 Vol. 35 (1): 1-7 [Abstract] ( 308 ) PDF (801 KB) ( 648 )

	8	Derivation of staged operation rules for hydropower stations using inflow classification strategy
		LIANG Zhiming, WAN Biao, CHEN Senlin, AI Xueshan, MAO Zhonghua, XIAO Yao
		DOI: 10.11660/slfdxb.20160102
		In the optimal operation of hydropower stations, an optimal decision obtained by deterministic optimization for a certain period is influenced by the inflow in the adjacent periods. Due to the instability of inflow, the operation rules for some periods often become extremely complicated, resulting in a difficulty in rule derivation. To solve this problem, this paper presents a new idea of extracting staged operation rules using explicit mechanism and a practical method that divides the scheduling period into two parts, a stable period and a transition period, according to the rule patterns throughout the scheduling period, and then adopts different method of rule derivation for each period. For the transition period, we introduced a strategy of period-by-period inflow classification for an effective division of the upper and lower scheduling lines obtained by optimal decision, based on the inflow characteristics. To verify the robustness of this method, a case study was made for the Tianshengqiao-I hydropower station, and results show that the method is effective and advantageous in derivation of operation rules.
		2016 Vol. 35 (1): 8-18 [Abstract] ( 199 ) PDF (433 KB) ( 369 )

	19	Advances in derivation method for multi-reservoir joint operation policy
		GUO Xuning, QIN Tao, LEI Xiaohui, JIANG Yunzhong, WANG Hao
		DOI: 10.11660/slfdxb.20160103
		The effectiveness of multi-reservoir joint operation policy relies on two factors, the form and derivation method of operation rules. This paper summarizes the latest advances in multi-reservoir joint operation policy, along with its historical development and a review on the derivation methods for different rule forms. Future research directions for multi-reservoir operation are prospected. This overview comes to a conclusion that each of the methods has its own distinctive features and suitability, which corresponds to different periods of technical development in this field. Of all the methods overviewed, the simulation based optimization technique has been applied most widely in both theoretical and application studies, and it is particularly suitable for derivation of the joint operation policy for complex multi-reservoir systems.
		2016 Vol. 35 (1): 19-27 [Abstract] ( 337 ) PDF (397 KB) ( 756 )

	28	Recheck analysis of reservoir extreme flood control risk using inconsistent hydrological sequences
		HUANG Kai, FENG Ping
		DOI: 10.11660/slfdxb.20160104
		The consistency of hydrological sequences was lost due to climate change and human activities. To conduct a recheck analysis on extreme flood control risk using inconsistent hydrological sequences, we selected as the study area the watershed of the Xidayang reservoir that was subjected to significant changes in land surface conditions, and applied the hydrological variation diagnosis system to an annual maximum peak flow series of this reservoir to detect its change trend, change point, and type of change. Then, a frequency analysis method for inconsistent hydrological series was developed to calculate this peak flow series for the past and current land surface conditions, and hence the corresponding design peak flows of different frequencies was obtained. Finally, we took the check flood level of the reservoir as the control index on its extreme flood control risk and estimated this extreme risk using the frequency analysis method. The calculations reveal that for the past and current land surface conditions the extreme risks were 0.008% and 0.005%, respectively. It is obvious that these rechecked extreme risk values are lower than the check flood criterion, i.e. a 10000-year flood (0.01%). The results provide technical guidance for the Xidayang reservoir with respect to its dynamic flood level control, full utilization of flood resource in flood season, and improvement of comprehensive benefits.
		2016 Vol. 35 (1): 28-37 [Abstract] ( 244 ) PDF (595 KB) ( 419 )

	38	Area-mean rainfall updating by system response curve method and application to real-time flood forecasting of Fuchunjiang basin
		SI Wei, YU Honghui, BAO Weimin, QU Simin, ZHANG Qian
		DOI: 10.11660/slfdxb.20160105
		The accuracy of flood forecasts obtained from spatially lumped hydrological models is highly affected by the uncertainty in the estimates of area-mean rainfall that depend on the error type and magnitude of rain gauges and their density and pattern of space distribution. The effect of these errors is more prominent in a large basin with a small number of rainfall gauges. To improve the accuracy of real-time flood forecasting, we herein describe an updating method for area-mean rainfall estimation using rainfall system response curves. This new method takes a hydrological model as a response system between input and output, and updates the area-mean rainfall using the rainfall system response curves and least square method to minimize the error between the observed and simulated flow series. Then, the stream flow is recalculated using the updated area-mean rainfall series. Application of the method is demonstrated in combination with the Xinanjiang model tests, via a synthetic case and 14 historical flood events that occurred in the Fuchunjiang basin in Zhejiang during 2010–2014. The results show that the method can significantly improve the accuracy of real-time flood forecasts without increasing model structure complexity or the number of model parameters.
		2016 Vol. 35 (1): 38-45 [Abstract] ( 228 ) PDF (519 KB) ( 422 )

	46	Flow characteristics and minor losses in transition section from trapezoidal open channel to horseshoe-shaped tunnel
		WU Yongyan, LIU Zhaowei, CHEN Yongcan, YANG Yufeng
		DOI: 10.11660/slfdxb.20160106
		Flow characteristics and local losses in transition section from trapezoidal open channel to horseshoe-shaped tunnel has been studied and tested on a hydraulic scale model of the western main canal of water diversion project in Karamay. The model made of plexiglass, had a geometric scale of 1/25 in accord with Froude similitude. Longitudinal water surface profiles were measured in steady flow conditions of flow rate range of 3.88 to 17.05 L/s. At a flow rate greater than 13.37 L/s, water level was rising rapidly near the tunnel entrance and fluctuating in the tunnel. This should be a phenomenon caused by the flow turbulences generated by wall contraction. Minor loss coefficients of the transition section in a range of 0.19 to 1.24 were calculated using the measured water surface profiles and cross-sectional average velocities. As the contraction angle of the transition increases, the minor losses were decreasing first and then increasing. To solve the problems with the original design of the tunnel found in our experiment, the transition section was lengthened and the lengths of warped surface channel and rectangular channel were optimized. Measurements show smooth streamlines and a reduction in water surface fluctuations in the modified transition, along with a reduction in its minor loss to a range of 0.05 to 0.82. The results are helpful to the design of transition section from trapezoidal open channel to horseshoe-shaped tunnel in real water diversion projects.
		2016 Vol. 35 (1): 46-55 [Abstract] ( 353 ) PDF (992 KB) ( 579 )

	56	Study on microhabitat heterogeneity of spawning ground
		LI Tingyu, WANG Yurong, XU Shuang
		DOI: 10.11660/slfdxb.20160107
		Spawning ground, the reproduction place of fish, is an important and susceptive habitat. Weighted usable area has been widely used in evaluating the suitability of spawning ground. However, previous studies on the diversity of spawning ground were very rare. To describe the impact caused by the change in river discharge, a concept of microhabitat heterogeneity is presented in this paper based on the habitat heterogeneity in landscape ecology. Water depth and velocity patches were chosen as two major factors in evaluating the heterogeneous level of microhabitat and the Shannon diversity index was adopted as a mathematic principle. A case study of the Fuxing village downstream of the Jinchuan dam on the Dadu River was taken to identify the relationship of microhabitat heterogeneity versus river discharge. According to the results, the optimum flow depth-velocity heterogeneity occurs at the discharge of 156 m3/s.
		2016 Vol. 35 (1): 56-62 [Abstract] ( 196 ) PDF (890 KB) ( 437 )

	63	Study on flow uniformity at bend outlet of drop shaft structure
		GAO Xueping, LIU Jijun, ZHANG Han, TIAN Ye
		DOI: 10.11660/slfdxb.20160108
		Flow at the outlet of a drop shaft structure is difficult to achieve uniformity under the influence of its bend and straight sections. Meanwhile, reverse flow tends to occur near the diversion orifices. A RNG k-ε turbulence model was adopted in this study with experimental verification to make a three-dimensional numerical simulation on flow characteristics near the bend outlet of a drop shaft, and the effects of bend type and straight pipe length on the flow uniformity have been analyzed. The results show that if the length of straight pipe section is fixed at 2D (D is the diameter of straight pipe), a bend of gradual contraction can produce more uniform outflow than a regular bend of equal diameter (fixed and equal to the diameter of contraction outlet). If equal diameters are adopted, the outflow uniformity of two bends is comparable when the length of straight pipe adds 6D ~ 8D. The results are significant in guidance for design of the drop shaft inlet and outlet of pumped storage plants.
		2016 Vol. 35 (1): 63-69 [Abstract] ( 290 ) PDF (1176 KB) ( 474 )

	70	Experimental and numerical studies on hydraulic characteristics of sharp-crested side weirs in rectangular channels
		WANG Yingying, WANG Wen’e, HU Xiaotao, WANG Jiawei
		DOI: 10.11660/slfdxb.20160109
		Sharp-crested weir, often installed at the inlets of small open channels, is a simple, economic and practical device for high-accurate water measurement, but current understanding of its hydraulic characteristics is not deep enough. In this study, we have investigated the hydraulic characteristics of a sharp-crested side weir using the CFD code of FlOW-3D in combination with our experimental tests, and obtained hydraulic parameters for different weir heights and different flow conditions. Water surface profiles were simulated and compared with experimental measurement. A formula for discharge was derived from the test data. The results show that the relative error between the measured and simulated values was lower than 10%, indicating a good agreement between these two methods. The fitted formula has a satisfactory accuracy of relative error range of 1.07% ~ 5.9%. Thus, the numerical results would lay a theoretical basis for design of water-measurement devices.
		2016 Vol. 35 (1): 70-78 [Abstract] ( 197 ) PDF (917 KB) ( 547 )

	79	State trend prediction of hydropower generating units using time series combination model
		SUN Huifang, GUI Zhonghua, LI Linyang, ZHANG Yang
		DOI: 10.11660/slfdxb.20160110
		It is difficult to achieve trend forecasting by the traditional prediction theory, because the state parameters of hydropower generating units are nonlinear, non-stationary, and with a small sample size available. Therefore, a time series combination model has been developed in this study. Wavelet transform can focus into any details of the signal and decompose a state sequence into a non-linear trend part and stationary fluctuating parts. By applying such decomposition to the vibration state sequences of hydropower generating units, a Least Square Support Vector Machine (LSSVM) prediction model was used for the trend part, and an Auto Regressive (AR) model for the fluctuating parts. The forecasting outcomes of these models were integrated by the principle of superimposition to achieve a final prediction. A case study of vibration state sequences shows that the forecasted and measured values agree well. Thus, the combination model presented in this paper achieves a high accuracy and the results would be useful for motivating the status early-warning for hydropower generating units.
		2016 Vol. 35 (1): 79-86 [Abstract] ( 232 ) PDF (782 KB) ( 503 )

	87	Exploratory analysis on pressure fluctuation conversion in Francis turbine draft tubes
		XU Yongliang, QIN Daqing, ZHAO Yue, WANG Hongjie
		DOI: 10.11660/slfdxb.20160111
		This paper presents a prediction method of the fluctuation amplitude of pressure in Francis turbine draft tubes, using data conversion into two parameters: relative discharge to a zero-swirl unit discharge, and dimensionless pressure fluctuation amplitude relative to the velocity head at the runner blade outlet. We conducted a qualitative analysis on the velocity triangle at the runner outlet and compared this new method with the norm-recommended method in terms of pressure fluctuation in the draft tube cone of a Francis turbine. Then, the method was applied to the models of 12 power plants and their homologous prototypes, and comparison of the calculations gives a satisfactory similarity between the model and homologous prototype. Further, we compared the predictions with field test results and obtained a good agreement between them. Thus, our conversion method is effective and feasible for analysis of pressure fluctuations.
		2016 Vol. 35 (1): 87-94 [Abstract] ( 215 ) PDF (2584 KB) ( 420 )

	95	Stability study on gravel soil slope in Jin'anqiao Reservoir
		XU Wenchao, ZHANG Linhong, CHEN Jiahong, DAI Xueyu
		DOI: 10.11660/slfdxb.20160112
		The Jin'anqiao Reservoir located in the middle Jinsha River, has suffered different levels of landslide on the bank slopes since its impoundment in 2012, and variation in its seepage field is one of the main causes for such geo-hazards. In this study, we developed a two-dimensional saturated-unsaturated seepage model for gravel soil slopes in the impoundment region according to the engineering investigation, and simulated the evolution of seepage flow and the corresponding slope stability for the stages of initial filling, normal operation and drawdown, focusing the analysis on the influences of water level fluctuations and drawdown rate on saturation line and slope safety factor. Results show that at initial filling stage, the saturation line presents downward convex and the safety factor is increasing monotonically; in normal operation, the saturation line tends to vary gradually and the safety factor is decreasing monotonically and gradually; in drawdown period, the saturation line is upward convex and the safety factor is decreasing monotonically at a higher rate. The slope in the investigation area is an accumulation of ancient landslides, and hence it shows an unstable feature of slope safety coefficients less than 1.0 at all the three stages. This provides an evidence for high potential landslide in this region. The drawdown rate is inversely correlated with slope stability.
		2016 Vol. 35 (1): 95-103 [Abstract] ( 262 ) PDF (1511 KB) ( 436 )

	104	Application of granular friction rheology to simulation of rapid landslides with long travel distance
		FEI Jianbo, JIE Yuxin, ZHANG Bingyin, FU Xudong
		DOI: 10.11660/slfdxb.20160113
		When we use continuum theory to simulate large-scale rapid landside, the mechanism of the basal friction is still unclear. The Voellmy model is widely adopted in simulation at present, but it has some defects: 1) It can not well predict the flow process of the landslide tail. 2) It is verified that the model is not suitable to simulate small-scale landslides. 3) The model is empirical and lacks theoretical verification. 4) Some parameters in the model can only be obtained by back analysis. On the other hand, the frictional rheology of granular flow can well depict the mechanism of granular flow, and it has been verified by experimental results. In this paper, we introduced the granular frictional law into the simulation of rapid large-scale landsides, and then compared the granular frictional model with the Voellmy model. Computation results show that the frictional coefficient by Voellmy model is infinite with small flow depth, but that by granular friction model has the boundary. In the end, we computed a real landslide case by adopting the two basal friction models, and found that the computed results by the granular frictional model can depict the final deposition depth of the landside better than the Voellmy model.
		2016 Vol. 35 (1): 104-109 [Abstract] ( 268 ) PDF (1394 KB) ( 559 )

	110	Simulation of temperature field of Longkaikou RCC dam based on measured data
		XU Xiaorong, PAN Jianwen, WANG Jinting, YANG Jian, LU Ji
		DOI: 10.11660/slfdxb.20160114
		This paper presents a three-dimensional finite element model for simulation of the temperature field and its variation during the construction of Longkaikou RCC dam, with a full consideration of major factors: hydration heat of cement, cooling effect of water pipes, variable ambient temperature, and reservoir level. The simulation results demonstrate that the calculations of temperature are in good agreement with in-situ measurements. According to our prediction, a large zone of high temperature 28-30 ?C occurs in the dam layer between elevations EL1230-1260 m and it will gradually shrink after completion of dam construction through heat exchange with air and reservoir water; the mean temperature in the dam will be lowered asymptotically to a range of 20-22 ?C in ten years and remain there afterward. The temperature distribution patterns were found to depend much on the local dry-hot climate conditions in the valley and the effect of water cooling measures.
		2016 Vol. 35 (1): 110-117 [Abstract] ( 195 ) PDF (1904 KB) ( 439 )

	118	Multi-factor sensitivity analysis of underground powerhouse construction simulation using uniform design
		BI Lei, ZHONG Denghua, ZHAO Mengqi
		DOI: 10.11660/slfdxb.20160115
		Construction speed is a key issue to underground powerhouse construction management. In prediction of underground powerhouse construction speed using system simulation, there are many parameters whose small variation in value may lead to a great change in construction speed. Previous studies have been limited to sensitivity analysis only on a few main factors. An underground powerhouse construction simulation model, however, usually incorporates so many construction-disturbing factors that the traditional approach is unable to meet the requirements of multi-factor analysis. This article presents a multi-factor sensitivity analysis of underground powerhouse construction simulation using the uniform design method. We have analyzed the effects of various simulation parameters on construction speed and screened the susceptibility factors. This method was adopted in a simulation model of underground powerhouse construction speed for hydroelectric power stations, and the results show that the method is able to handle the multi-factor sensitivity analysis efficiently and accurately identify those susceptibility factors that have significant effect on construction. Thus, our method would lay a theoretical basis for evaluation and optimization of the simulation model parameters and construction speed of relevant practical projects.
		2016 Vol. 35 (1): 118-123 [Abstract] ( 150 ) PDF (707 KB) ( 418 )

	124	Extension and application of transverse cutting method for tensile strength measurement of concrete
		YUAN Qun, LI Liqing, LU Yao
		DOI: 10.11660/slfdxb.20160116
		The transverse cutting method for tensile strength measurement of concrete is further investigated based on the authors' previous study. A parametric numerical study was conducted and the results show that when the central angle of load blade increases in the range of 60° to 135°, the load distribution on the cylinder surface changes from approximately linear to parabolic, and the greater central angle, the more reasonable stress distribution on the splitting surface. The experimental study demonstrates that the test data become more stable and reliable when the ratio of cylinder specimen height to diameter is increased up to 0.7. The central angle has less influence on transversal splitting strength, while load blade width has relatively larger influence and the load device 5-90 is optimal. We have derived a formula for calculation of the splitting strength and applied this method to analysis of concrete material in practice, including carbonized concrete, partially carbonized concrete, and non-carbonized concrete, showing its unique advantage in testing of concrete tensile strength.
		2016 Vol. 35 (1): 124-135 [Abstract] ( 236 ) PDF (841 KB) ( 461 )

	136	Architecture design and application of cascade hydropower project management system based on digital river basin
		FAN Qixiang, JIN Heping, WENG Wenlin, ZHU Qiang, QIANG Maoshan
		DOI: 10.11660/slfdxb.20160117
		Aiming at the demand for digitalization by recent hydropower development in China, the application architecture of a cascade hydropower project digital river basin system has been designed and elaborated, and implementation principles of this complex system are formulated and discussed from four aspects: techniques, methods, ideas, and resources. Finally, we describe the practical implementation and achieved results of the digital project, digital migration, digital hub area, and digital reservoir system by China Three Gorges Corporation in engineering practice of hydropower development on the Yangtze River and the Jinsha River. Our results would be applicable to the design and construction of similar projects worldwide.
		2016 Vol. 35 (1): 136-146 [Abstract] ( 311 ) PDF (1992 KB) ( 633 )