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    15 March 2018, Issue 3
      
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  • China Rural Water and Hydropower. 2018, (3):  1-7. 
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    Abstract: The situation of water resources shortage in coastal cities is becoming more and more serious. According to the 1956 to 2013 in Qinzhou monthly rainfall, runoff and evaporation, temperature data, the DMC evaporation model and difference method is adopted for runoff reduction, calculation of surface water resources, predict its future trends; Based on the analysis of the base period, we further adopt the SCRCQ method to quantitatively analyze the contribution rate of typical watershed climate factors to the impact of runoff. Results show that: (1) Qinzhou surface water resources is 106.573 ~ 111.533 x 108 m3 relative error (4.4%), the reduction of water (natural - measured) trend rate of 0.406 x 108 m3, showed that give priority to with human activity to reduce the influence of other factors on runoff continues to increase, Compared with AR period, the decrease of runoff in Qinzhou typical river basin is mainly affected by climate change. Compared with AR, the contribution rate of other factors was significantly higher than that of rainfall, evaporation and air temperature factors, including 65.0 ~ 75.7% in the Qinjiang river basin. Qinzhou surface water resources under the general trend of decrease, to reduce the influence of other factors on runoff degree deepening, expanding, which will make Qinzhou face a more serious imbalance between supply and demand of water resources.
  • ZHANG Chun-hui , WEI Peng-kun , KANG Hui-ping, LI Wang-lin , GAO Shu
    China Rural Water and Hydropower. 2018, (3):  8-12. 
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    Located in the eastern part of Fujian Province,Pingtan is a comprehensive pilot zone for scientific development on economic zone for west bank of the Taiwan Straits. The development of Pingtan's social economy is restricted because of a serious water shortage. Thus, combining the hydro-geological conditions of Pingtan Luyangpu Area,the authors make a feasibility study of the construction of groundwater reservoir in northern Luyangpu,and identify the site of groundwater reservoir,and design the underground dam,recirculation and exploitation system,and carry out a numerical simulation by Visual MODFLOW. The conclusions are as follows: ① Groundwater reservoir can be built in the north of Luyangpu,and the total storage capacity is about 2 689×104 m3 ; ② In the case of no water transfer,the collection of Luyangpu surface runoff,as the artificial recharge water source of groundwater reservoir,the groundwater reservoir satisfying the annual maximum water consumption of life,ecology,agriculture and industry is 4 357×104 m3 next twenty years. However,it is necessary to further increase the intensity of groundwater recharge after the dry year. ③ Because of no cultivated occupied land,immigration relocation and less evaporation, groundwater reservoirs are an effective way of improving the utilization of rainwater resources in islands and also help to control the expansion of the landing funnel and prevent seawater intrusion due to the exploitation of groundwater. The results can be used as a reference for the development and comprehensive utilization of water in Pingtan and for the construction of groundwater reservoirs in coastal islands in China
  • China Rural Water and Hydropower. 2018, (3):  13-16. 
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    To strengthen the statistics of total water consumption is an important basic work of water resources management, which can provide the necessary foundation support for the daily work of water resources planning, management, conservation and protection. The statistics of water consumption in China mainly adopts the method of regional norm estimation, which is relatively rough and its accuracy needs to be improved. This paper discusses the theory and method of statistical error analysis of water, and quantitatively analyzes the error range of the statistical data of water consumption, in Heilongjiang Province as an example, this paper analyzes the water characteristics of industries such as agriculture, industry and live, through error analysis to select the appropriate sampling method, the error analysis of the agricultural water using ratio estimation of real irrigation area, industry water using industry-classified hierarchical estimation, living water using ratio estimation of resident population, the calculation results show that the error of total water consumption in the province is 2.63%, the calculation precision meets the statistical requirement. This study is of great significance to improve the sampling efficiency, precision and scientificity of water consumption statistics.
  • DUAN Zhi-peng, LI Ji-qing
    China Rural Water and Hydropower. 2018, (3):  17-21. 
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    With the global climate change intensified,Chinese regional water resources shortage is becoming increasingly serious. Adequate method used to study the varied pattern on precipitation is particularly important for water resources planning and management. Based on the time series of precipitation in Beijing from 1951 to 2015,the multi-scale characteristics of precipitation changes and the abrupt changes at different time scales are analyzed by using extreme -point symmetric mode decomposition ( ESMD) method,and the future trend of precipitation is judged. The results show that the precipitation sequence in Beijing is in the range of 2.6 years,4.3 years,14 years and 21.7 years,and the time of mutation in different time scales is also different. The variance contribution rates of each modal component prove that the inter-annual change has a strong influence on the overall precipitation change in Beijing. And forecast shows that the precipitation in Beijing will continue to decrease on a short-term basis
  • GUO Wei-dong, ZHOU Teng-yu , LI Jing-ku , YU Zhao-xia
    China Rural Water and Hydropower. 2018, (3):  22-28. 
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    Based on the Y-shaped junction water and sediment movement,the mathematical model of the two-dimensional water-sediment movement is used,and the river bed erosion and siltation is simulated. By comparing the simulated values of water level,velocity,flow field and river bed level with physical experiment values,the results show that the established two-dimensional water-sediment model can simulate the water-sediment movement of the Y -shaped junction well. It analyzes and obtains the scouring and silting characteristics of river bed varying with the confluence ratio,junction angle and river bed height difference. The results can be used to improve the interchange of river channel scouring and siltation theory,which can also be used to guide the river regulation,river network and river design and other fields of practical work.
  • WANG Zhong-min, LIU Jin-zhen, LIU Yang-yang, FAN Hao
    China Rural Water and Hydropower. 2018, (3):  29-32. 
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    There are more water transfer project in the Hanjiang River Basin, water transfer project changes thespatial and temporal distributionof water resources, solvethe water shortage crisis, but also bring some impact on the ecological environment of the downstream area. On the basis of early implementation of South-to-North Water Diversion Project the Hanjiang to Weihe River Project and the water resources allocation project in Northern Hubei province exacerbate the adverse effects on the ecological environment in middle and lower reaches of Hanjiang River. By setting differentwater diversionscenario, quantitative analysisofthe implementation ofa number of water diversion project on Hanjiang River downstream hydrology, water environment, aquatic and wetland ecological cumulative effect degree , and recommendations of Hanjiang River ecological environment protection is put forward .
  • China Rural Water and Hydropower. 2018, (3):  33-36. 
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    In this study, the characteristics of river system evolution are analyzed by calculating the river network density, water surface rate and tributary development coefficient in different periods of Haikou City. It is found that in the past 50 years, due to urbanization and other factors, there are different degrees of attenuation about water features, structural characteristics, and network complexity in Haikou City. The evolution of the river system in Haikou City will lead to the decrease of urban river network storage capacity, the poor ability of city to weaken the heat island, the deterioration of urban water environment, the rapid decline of residents' waterfront public open space and other environmental problems. This study is great significant to carry out the urban river system planning and flood control and drainage under the new situation.
  • CHEN Ping , FU Chang-feng, JI Xiao-guang , YU Jing-yao
    China Rural Water and Hydropower. 2018, (3):  37-39. 
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    As a kind of ecological treatment process for sewage purification,pre -reservoir technology can effectively restrict and reduce pollutants into reservoir. This paper uses the experience at home and abroad for reference,proposes a determination technique of the scale of pre-reservoir volume,and Yanghe Reservoir watershed as an example,the flood process line of the first flood for reservoir inflow in 2012 as a typical example,calculates the pre -reservoir volume of the four tributaries estuary. Results show that the pre -reservoir volume of Dongyanghe,Xiyanghe,Miwuhe and Mahe are 169×104 m3 ,144×104 m3 ,34×104 m3 and 29×104 m3 respectively. The results show that the actual head rain of once every three years for the principle to determine the scale of the pre-reservoir for each tributary of Yanghe Reservoir watershed
  • China Rural Water and Hydropower. 2018, (3):  44-49. 
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    A comparative analysis of dynamic changes of water pollution was conducted in Hun river and Liao river of Shenyang section using hydrology and water quality data during 2001-2015. And path analysis was used to model the relationship between the electrical conductivity and the other water quality indices. Result indicted that the water quality indices did not spatially differed at the different time scales (no-flood season, flood season, and annual) in Liao river in the last 15 years, while the temporal and spatial variability of Hun river is extensively low than Liao river. The water quality was consistently higher in Liao river than Hun river and both were higher in flood season than no-flood season. In the last 15 years, most water quality indices showed a significant increase in both river for no-flood season, while Liao river did not improve for most of indices in the flood season despite increases observed in Hun river. The most amount of variance contribution to electrical conductivity was explained by BOD (41.8%) in Hun river, and followed by chloride (29.6%), sulfate (19.8%), permanganate (-18.0%), ammonium nitrogen (11.3%), and fluoride (10.3%). For Liao river, chloride leaded the highest contribution (51.5%), and followed by ammonium nitrogen (36.3%), and COD (21.7%). It was concluded that this study provided preliminary referrals for the construction of water quality monitoring technology system in Shenyang, China.
  • China Rural Water and Hydropower. 2018, (3):  62-65. 
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    Irrigation uniformity is an important index in measuring the irrigation quality and hydraulic design of the drip irrigation system. In order to search the way to improve irrigation uniformity under low-pressure, pressure-compensated inner drip irrigation tape and pressure-compensated cylindrical drip irrigation tube were used in the experiment to measure different lateral inlet pressure, lateral length, emitter flow distribution in the space between irrigators and irrigation uniformity. The experiment result shows that irrigation uniformity would increase as lateral inlet pressure increased and lateral length decreased, and slowly decrease as the space between irrigators increased. Lateral length had the greatest impact on the uniformity of irrigation, with lateral type and the space between irrigators ranked second and third respectively. When the inlet pressure of two types of drip irrigation lateral was 2~5m, irrigation uniformity was higher than 85% and decreased slowly with the decrease of inlet pressure. While the inlet pressure was 0.5~2m, irrigation uniformity was significantly reduced, and the pressure-compensated inner drip irrigation tape was less than 80%, but the pressure-compensated cylindrical drip irrigation tube was still higher than 80%. When the lateral length of two types of drip irrigation lateral was 40~70m, irrigation uniformity was higher than 85% and decreased slowly with the increase of lateral length. While the lateral length was 70~90m, irrigation uniformity was significantly reduced, and the pressure-compensated inner drip irrigation tape and pressure-compensated cylindrical drip irrigation tube was more than 75m and 85m respectively, irrigation uniformity was less than 80%. Therefore, in order to meet the requirements of engineering design, which drip irrigation uniformity is not less than 80%, the pressure-compensated inner drip irrigation tape inlet pressure is higher than 2m, lateral length is limited to 75m; the pressure-compensated cylindrical drip irrigation tube inlet pressure is higher than 0.5m, lateral length is limited to 85m; it is practical to increase the space between irrigators to reduce engineering investment effectively.
  • JIANG Wei, CHEN Xiao-nan, HUANG Zhi-gang
    China Rural Water and Hydropower. 2018, (3):  66-71. 
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    Abstract: Based on the research data about the adoption situation of water saving irrigation technology in Yulin, the paper analyse the factors affecting farmers to adopt water saving irrigation technology by Binary Logistic Model and the effects of adopting water saving irrigation technology on farmers’ crop income. The results shows that the total planting area, the farmers’ understanding of water saving irrigation technology, the government’s subsidies for adopting water saving irrigation technology and the propaganda about water saving irrigation technology in the society have significant effects on whether to adopt water saving irrigation technology for farmers. Farmers’s adopting water saving irrigation technology has a significant effect on crop income.
  • LUO Tong-yuan, LUO Yu-feng, L Xin-wei, CUI Yuan-lai , YANG Shi-hong
    China Rural Water and Hydropower. 2018, (3):  77-80. 
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    In order to facilitate the application of daily reference evapotranspiration forecast data in real-time irrigation decision-making, we developed a Web-based daily reference evapotranspiration (ET0) forecast system of Jiangsu Province. The server side scripting language PHP (designed for the Web specifically) and the fast relational database management system MySQL were employed to simply and effectively acquire weather forecast data released by the National Meteorological Center, then weather forecast data were then imported to the database and 15 days ahead ET0 forecasts for 23 stations in Jiangsu were calculated through the calibrated Hargreaves-Samani (HS) model. Users can directly log on the website to inquery the future 15 days ET0 forecasts fore Jiangsu Province. B/S network structure and calibrated HS model were employed to ensure simple pages and high ET0 forecast accuracy. The ET0 forecasts can be used for crop water requirements, which provide scientific basis for irrigation decision-making.
  • LI Yang, ZHANG Yu, SUN Lan-qing, GUO Kai, TANG Yan, TIAN Yang, XU Ling, LU Ming-hao, YAN Wei
    China Rural Water and Hydropower. 2018, (3):  81-91. 
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    With the vibration problem of unit and pump house becoming more and more outstanding, the threat to pumping station could not be ignored. The vibration characteristics of vertical fully regulated axial flow pump in large pump station are studied in this paper, which can provide reference for the subsequent operation and management of similar projects. This paper takes Jiangdu four Pump Station No. 4 and No. 7 pump unit as an example to finish the spot test and data collected of multi state, multi measuring points and vibration parameters . It was concluded that the vibration of impeller casing of vertical axial flow pump is obvious under the condition of different blade running angle and different water level difference by drawing the amplitude statistics, the corresponding time-domain waveform and frequency spectrum and analyzing the variations of the main vibration amplitude, vibration frequency, angle with the water level. So the vibration value of water pump is mainly affected by hydraulic and mechanical factors.
  • WANG Zhi-yuan, WEN Hong-pu , QIAN Zhong-dong
    China Rural Water and Hydropower. 2018, (3):  92-95. 
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    Pressure pulsation in a double-suction centrifugal pump is one of the main factors affecting stable operation. The pressure pulsation signals in the test points and vibration signals on the bearing chock of the drive end were obtained and recorded under various operation conditions. The signals were analyzed by the fast Fourier Transform Method. The results show: the pressure fluctuations at blade passage frequency were affected by the flow rates. When the flow rates were at Q<0.28 Qn and Q>1.14 Qn,the pressure fluctuations at blade passage frequency were both greater. The pressure fluctuations at blade passage frequency propagated upstream and downstream,and the change trend of the pressure fluctuations at blade passage frequency at the top of the inlet pipe was similar to the one at the top of the volute basically,and the amplitudes were reduced uniformly. On the bearing chock of the test pump drive end,the pressure fluctuations at blade passage frequency could be represented in the vertical and horizontal vibration,and the horizontal vibration was affected more heavily by the pressure fluctuations at blade passage frequency than the vertical vibration. This research could expand the experimental technological approach,and provide reference for design and operating double-suction centrifugal pumps,which had theoretical significance and engineering value
  • China Rural Water and Hydropower. 2018, (3):  96-98. 
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    Single-stage and double-acting centrifugal pumps are widely used in small and middle sized irrigation pumping stations. It is difficult to assure data reliability and pump efficiency to select pump according to data sample from a specific pump manufacture chosen by the designer. A new method based on similarity theory was studied in order to deduce the rotating speed and diameter of prototype pump’s impeller according to certain relative parameters of the model pump. At the same time, a special software for single-stage double-acting centrifugal pump selection was developed with Fortran and C# programming language. By typing in head and flow of certain pumping station engineering, proper rotating speed and diameter of prototype can be worked out. The method turns out to be reliable according to the verification based on the data of the Second Rate Pumping Station of certain pumping station.
  • China Rural Water and Hydropower. 2018, (3):  99-104. 
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    Based on the numerical simulation of the initial scheme and the improvement scheme of TaiXing SiQiao combined sluice-pump station, this paper analyzes the pumping station intake sump flow patterns of the two schemes. The numerical simulation results show that: (1) The initial scheme flow of the pumping station intake sump appears side-direction, and the vortex and other bad flow patterns are generated in the intake sump, which affects the safe and stable operation of the pump. (2) The improvement scheme increased the transition section, which supplied the front inflow. And there were no vortex and other bad flow, so the pump can operate safe and stable.
  • CAI Xin , BIAN Sai-xian, CHEN Wei-dong , HUANG Hai-tian
    China Rural Water and Hydropower. 2018, (3):  105-109. 
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    To study the optimization of pump house structure,an optimization model is built by using the dimensions of the main part of the pump house as design variables,the construction cost of the pump house as objective function and the structural stability,the strength and the displacement of pump house as the main constraint conditions. The parameterization finite element model of the pump house is established. Then the optimal scheme of the pump house is obtained by using the optimization platform in ANSYS. Compared with the original design scheme,the optimal design scheme shows a decrease of 13. 2% in the cost of the pump house. All other results concerning displacement,stress and stability are all satisfactory,which indicates that the optimization effect is obvious and the economic benefits are remarkable
  • CHAI Li-ping , CAO Lin-song , LI Yue , YU Jia-feng , YAN Hao
    China Rural Water and Hydropower. 2018, (3):  110-115. 
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    Recirculation at the inlet of centrifugal pump impeller can reduce the efficiency of the pump and destroy the running stability of centrifugal pumps. In order to seek the influence of front vane impeller on vorticity,turbulent kinetic energy,recirculation at the impeller inlet and pressure fluctuation of centrifugal pumps,three impeller types are proposed in this paper: the basic impeller does not change ( scheme 1) ,straight blade is added at the front cover of the impeller ( scheme 2) ,cylindrical blade is added at the front cover of the impeller ( scheme 3) . On this basis,the centrifugal pumps of three impeller types are numerically simulated combined with the SST turbulence model. The result shows: compared with scheme 1,the head and efficiency of scheme 2 and scheme 3 are increased at all working conditions and the recirculation of wear-ring decreases. Vorticity region at impeller inlet and turbulent kinetic energy of scheme 2 are minimum,followed by scheme 3. It shows that the front vane impeller can reduce the hydraulic loss and improve the hydraulic efficiency of centrifugal pumps. Pressure fluctuation coefficient at the impeller inlet and within the volute of scheme 2 and scheme 3 is basically the same. They are all obviously less than scheme 3. It shows that the front vane impeller can improve the operation stability of centrifugal pumps.
  • China Rural Water and Hydropower. 2018, (3):  120-123. 
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    support vector machine (SVM) as the theoretical basis of improvement in the treatment of high dimension nonlinear problems, shows many unique advantages. Therefore, has the obvious superiority of the support vector machine model in the process of dam deformation prediction, and often using particle swarm optimization (PSO) algorithm for SVM model of the penalty parameter C and kernel function sigma optimization, but the standard PSO algorithm has premature convergence and easy to fall into the local minimum defects. Cauchy distribution function and density function is introduced, modified according to the nature of function change in the updating formula of particle position and velocity in the standard PSO algorithm, effectively improve the performance of optimization algorithm. The improved pso-svm model is used to predict the settlement and deformation of the Shuibuya concrete face rockfill dam, and compared with the prediction results of the svm model and the standard pso-svm model. The results show that the improved pso-svm model And the prediction accuracy is more excellent, which provides a good performance and high precision prediction model for dam deformation prediction.
  • SUN Chang-li, ZHANG Ting, DU Xiu-zhong, HUANG Jin-lin , DONG Ming
    China Rural Water and Hydropower. 2018, (3):  124-128. 
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    The traditional embankment material is a cohesive soil,and it is generally considered that the non-cohesive soil is not suitable for embankment. The small and medium-sized rivers in the mountain area with large particle size,wide distribution characteristics,the main component is mixed pebbles,sand and clay,compared with conventional soil,the composition is more complex. If the material as an embankment,need to solve the seepage,slope stability and erosion and other issues. In this paper,the physical and mechanical properties of the beach are studied by indoor and field tests,and the calculation is carried out. It can be used as one of the materials of embankment and can be successfully applied in the small and medium-sized river treatment projects in Shaoguan area of Guangdong Province,which can provide a reference for similar projects
  • China Rural Water and Hydropower. 2018, (3):  129-131. 
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    Horizontal gate is widely used in small and Medium ship lock, if the gate open too quickly, flow field in the chamber will change greatly, which leads to security threats on ship and interior wall wing of chamber; Slow opening of gate affects traffic lock efficiency. Based on the mathematical analysis of the shiplock model, besides the conventional PID control method, the PID control of the outer loop of the inner loop of the flow method and the non - linear control method based on the backstepping method are proposed to achieve the fast and stable control effect. The simulation results show that the double closed - loop control strategy can guarantee that the flow of the adjustment process does not exceed the limit, and the nonlinear control strategy has the advantage of fastness and stability.
  • LIU Yue-lou, HE Shi-hua, SHEN Chun-ying, WANG Pu
    China Rural Water and Hydropower. 2018, (3):  143-147. 
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    Plane gate has the advantages of the simple structure and reliable operation.However,the plane gate has a gate slot relative to the radial gate.When the plane gate in the opening and closing or normal working hours when the flow pulsating pressure will have a very adverse impact on the safe operation of the gate.And the gate slot undermines the continuity of the gate water flow channel,making the pulsating pressure under the gate more complicated.In this paper, the pulsating pressure of the under gate water is studied by using the pressure pulsation sensor.Respectively, in the gate slot and no slot under the conditions of the gate at the bottom of the measuring point and the gate side of the bottom of the test points for experimental analysis.The experimental data can be systematically analyzed to obtain the normal probability distribution of the pulsating pressure probability of the gate water flow,the pulsating pressure of the measuring point at the bottom of the gate under the condition of slot is better than that at the bottom of the gate under the condition of no slot.The experimental results provide a basis for studying the effect of the slot of the plane gate on pulsating pressure.
  • China Rural Water and Hydropower. 2018, (3):  155-160. 
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    Abstract: The hydraulic transients of pumped storage units during pump outage condition cause serious threat to the safe operation of pressure pipelines and power stations. Therefore, considering the increase of unit rotational speed and pressure of each node in the hydraulic unit as the two objectives, the optimal model of the guide vane closing law is established in this paper. The model is based on "single tube-double unit" type numerical calculation model for pumped storage units, and meet multiple constraint factors, such as the hydraulic unit adjustable safe computing threshold and speed governor oil. By comparing the results of numerical simulation and actual data unit project, the model can optimize the guide vane closing, guide vane closing time and the inflection point, the unit in the pump working power speed and the rate of increase of water hammer pressure on the appreciation of the smallest, and the number of speed fluctuation to meet the requirements of industry standards.
  • China Rural Water and Hydropower. 2018, (3):  161-165. 
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    According to the actual situation of the cushion spiral case of Baihetan hydropower station, the concrete structure, cushion laying scheme, structural deformation, concrete cracking and reinforcement of the spiral case are studied and calculated, and this gives engineering design a certain direction. The calculation and analysis show that the spiral case cushion is beneficial to reduce the cracking and damage of concrete, the concrete penetrating damage zone is not big, and the crack width meets the requirements of <Design specification for hydraulic concrete structures> (DL/T5057-2009). Considering the cracking of concrete, the uplift displacement and its distribution on the foundation of generator increases as compared with the linear elastic condition, but it will not cause the unit operation to be adversely affected.
  • YANG Meng-jiao, CHEN Duan, ZHANG Chang-bing, LI Jin-yao
    China Rural Water and Hydropower. 2018, (3):  166-170. 
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    Aiming at the hydraulic vibration of the multiple hydro -turbines in a hydropower plant,the N -S governing equations for incompressible flow with Realizable k-ε turbulence model were employed to simulate the three-dimensional transient flow through the whole flow passage for one penstock supplying water to the double Francis turbines. The pressure distribution,pressure pulsation at the typical monitoring points and vortex ropes in the draft tube variation were got,and the frequency spectrum and power spectrum density of the pressure pulsation were obtained by the fast Fourier transformation. The calculated results show that the amplitude of the pressure pulsation caused by the vortex in the draft tube is the largest,and its power spectral density values are also much larger than that of the other parts,which are the main hydraulic reasons to cause the vibration of the units. In addition,the vibration has certain differences between two hydro-turbines. The calculation results can provide a reference for the vibration resolution in the hydropower plants
  • ZOU Qiang, HU Xiang-yang, LI Wen-jun
    China Rural Water and Hydropower. 2018, (3):  171-175. 
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    In order to effectively solve the problem of weights calculation and uncertainties treatment in the decision-making process of urban flood control standard schemes, a new optimal selection method based on game theory and D-S evidence theory is proposed. Firstly, the game theory is introduced to gather various subjective and objective weights information, so as to obtain the comprehensive weights as scientific and reasonable as possible. And then D-S evidence theory is introduced to deal with the uncertainties of decision-making process, and grey relation analysis is employed to build the basic probability reliability function, and the D-S evidence theory is applied for information fusion; finally, the best scheme is put forward on the basis of the reliability function. Case study shows that the proposed method is simple, reasonable and effective, and can increase the utilization rate of weights information and describe the uncertainty of evaluation indexes as well as significantly reduce the uncertainty of decision-making, thus has important theoretical significance and good application value in practical engineering optimal selection.
  • ZHANG Tao , TAN Le-yan, LI Kai-feng , GUAN Qing-shuo
    China Rural Water and Hydropower. 2018, (3):  176-179. 
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    Two flood diversion dispatching models for the Xiaoqing River with floodway has been proposed. One model is mainstream active diversion controlled by its flood capability,floodway flood is corresponding. Another is floodway active diversion controlled by floodway flood capability first satisfied mainstream base flood flow,mainstream flood is corresponding. One -dimensional unsteady flow model is used to jointly calculate water line on 50 years standard design flood,the results show that differences in diversion process and volume are obvious between two models,although the second model increases floodway flood volume,it can decrease high level of parallel mainstream conducive to draining flood in affected branches,so it has greater diversion benefits. The research can provide a reference for similar river treatments and flood dispatchings.
  • DUAN Bin-bin, NIU Chun-xia , LIU Zhi-hui
    China Rural Water and Hydropower. 2018, (3):  180-185. 
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    In this paper, the characteristics of seasonal permafrost freezing and thawing and its effects on the melting of snow melt were studied by means of correlation analysis and regression analysis. The results show that: 1) the temperature has positive feedback effect on the permafrost in the lake basin. 2) when the permafrost melts, the rate of ablation is far greater than that of its freezing rate, while the melting time of low-altitude seasonal permafrost is shorter than that of high altitude; 3) as the snowmelt intensifies, the soil moisture of the soil surface and lower layer increases the trend, and as the permafrost melts, the soil infiltration intensity increases. 4) the thickness of the frozen soil is inversely related to the runoff of the basin, and the precipitation is directly proportional to the flood of the snow. This paper analyzes the effects of seasonal permafrost freezing and thawing and its effects on snowmelt flooding in order to provide reference for agricultural production and flood warning.
  • China Rural Water and Hydropower. 2018, (3):  186-189. 
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    The characteristics of suspended sediment vertical distribution have important significance on sediment diversion characteristics of canal nodes during the sediment-laden flow in channel system.To analyze the vertical distributions of suspended sediment concentration and particle size, the vertical critical value was obtained by the relationship of force balance during the suspended transport. On this basis, this paper analyzed the particularities of vertical distribution of coarse and fine particles, and formula of suspended sediment concentration and particle size distribution were further received for making some supplements to the previous vertical distribution formula. The results showed that the characteristics of sediment gradation in vertical distribution are mainly relevant to the particle size and flow turbulence intensity. Combined with the measured data when representative particle size was taken d15~d30 of sediment gradation in reference point, the model calculated results of sediment concentration and gradation distribution agreed with those observed very well.