An accurate and timely forecast of medium and long-term runoff forecast is of great significance to reservoir safety and water resources scheduling． In order to improve the prediction accuracy of long -term runoff in the Danjiangkou Ｒeservoir,from the physical perspectives of the long-term runoff,the data series from 1952 to 2008,the runoff is divided into three levels : wet,normal and dry,the correlation coefficient method and AIC criterion are used to sift out the highly correlated and independent factor sets,a long-term runoff forecasting model is constructed based on the principle of Mahalanobis distance discrimination analysis and compared with the prediction results of stepwise regression method． The results show that under the permutation error of 10%,the two models have achieved good prediction results． The research results serve as a reference for the operation of Danjiangkou Ｒeservoir．

In order to improve the accuracy of nonparametric statistics relying on large samples,avoid the linear hypothesis problem of hydrologic frequency analysis calculation in parametric statistics,this paper proposes a nonparametric regression transformation method of directly fitting empirical distribution function based on the nonparametric statistic theory and combined with transformation theory,which will be applied in hydrologic frequency analysis． Checked by Monte Carlo Statistical Test,this method,with good robustness,provides another effective way for hydrologic frequency analysis calculation

In view of the shortage of water resources and the low utilization of rainwater resources in the loess hilly gully regions,this study took the small watershed of the loess hilly gully region in Pengyang Countyas an example and used GF-2 ( 1 m) remote sensing image,soil type map and DEM ( 5 m × 5 m) as the basic data and comprehensive implementing 3S technology,soil conservation service ( SCS) hydrological model and Soil and water conservation ecological water consumption method． Study access to land use status,slope,surface runoff potential and other information．Based on the technical specifications of rainwater harvesting project and the characteristics of the study area,the paper determines the location and type of rainwater harvesting project and calculates the amount of rainwater resources and water and soil conservation ecological water consumption in the study area．The study results show that: the small watershed has 52 position suitable for cellar construction and 15 position for reservoir,and the appropriate area for constructing dam and courtyard rainfall collection layout is 8．29 and 22．27 hm2．The average annual ecological water consumption for soil and water conservation measures is about 2 047 600 m3 ,and the annual average amount of rainwater collected is 1 589 500 m3 ． The research methods and results can provide scientific guidance and theoretical support for the construction of rainwater harvesting projects and the rational development and utilization of rainwater resources

The source area of Nujiang Ｒiver is an important water conservation area and an ecological barrier construction area in Asia． It is of great significance to identify the mechanism of water circulation evolution and the composition of water source． Stable isotopes have proven utility since they reflect the integration of processes at smaller scales． Based on the data of water,precipitation and lake water isotopes during July and August,2017,the characteristics of precipitation and water isotopes in Naqu Ｒiver Basin are analyzed． During the Tibetan Plateau summer monsoon period,average δ18 O in precipitation and river water in July are more than those in August,which result from isotope fractionation due to the evaporation of raindrop and river water． The latitudinal and elevation effects of δ18 O in precipitation are not significant,and precipitation is the main factor for δ18 O． The δ18 O in the river water increases with latitude． The d-excess in river water decreases with increase in latitude in the north of Cuona Lake,but the opposite phenomenon appears in the south of Cuona Lake． It can be seen that lake water has an important regulating effect on the distribution of d-excess． The d-excess in river water is positively correlated with elevation． Because of many tributaries along the river,the isotopes in the river water decrease from upstream ( Cuona Lake) to downstream．

Hydrological time series forecasting is of great significance for hydrological and water conservancy decision-making． In view of the complexity of hydrological time series,the mixed kernel PSO-KELM models a prediction of hydrological time series: extreme learning machine ( ELM) method is used to study the prediction of hydrological time series,and in accordance with the idea of multiple kernel learning,the mixed kernel function is constructed by radial basis kernel function and polynomial kernel function weighted by a new mixed kernel function,the comprehensive advantages of ＲBF kernel function and polynomial kernel function,and the particle swarm algorithm( PSO) to optimize the parameters of the model,avoiding the tedious manual operation． The annual runoff of LanZhou Ｒailway Station and the measured data of annual runoff of Jingou Ｒiver Basin are used to verify the rationality of the new model． Two examples show that the newmodel can obtain better results than the BP model and the ＲBF model．

With the advancement of the national “the Belt and Road” strategy, Yunnan Province should give full play to the role of the southwest international water major channel. To promote the normal development of Lancang River shipping, it is of great practical significance to carry out research on its navigation support capabilities. Adequate runoff is an important condition for river navigation. Forecasting the driest runoff of the river provides an important reference for safeguarding navigation. In order to improve the prediction accuracy, the authors first proposed the use of SSA to reconstruct the influential factors, and then combined with PPA to form SSA-PPR model, and used model to predict and validate the most deadly runoff in the Lancang River, the results showed that the average relative error of SSA-PPR training period was 2.5%, the average relative error of test period was 6.2%, and the model accuracy for the first class, it is better than the PPA, and SSA-PPA can meet the need of dry season runoff prediction for Navigable.

Abstract:The paper is to study the influence of coal mining on the surface hydrological process of the Changhe Watershed in Shanxi Province,we constructed the rainfall interception model of natural vegetation and planting vegetation,soil infiltration model based on improved Green-Ampt model and runoff confluence model by using digital elevation model to established digital water system.The study utilized quantitative comparison and geostatistics method for analysis the influence of coal mining on vegetation coverage and soil saturated hydraulic conductivity,and seted up three different rainfall intensities for scenario simulation analysis. The results showed that the average vegetation coverage in the mining area increased from 0.382 to 0.460 from 2000 to 2015,and the average soil saturated hydraulic conductivity of the mining area was 34.375 cm/d,which was less than 44.426 cm/d of the non-mining area.When rainfall intensity was 2.5 mm/h, most of the rainfall was intercepted by the vegetation and less infiltrated into the soil;When the rainfall intensity was 8 mm/h,the vegetation canopy interception reached the maximum.After rainfall intercepted by vegetation and soil infiltration,The runoff is hard to form on the surface;When the rainfall intensity was 16 mm/h,rainfall accumulated and converged in a short time, and the confluence reached the maximum at the southwest exit of the watershed.

: In order to discuss the effect of rainfall on uncertainty of flood peak simulation in small-scale watershed in mountainous area and improve accuracy of prediction in there, the Xinanjiang model was chosen as the flood forecasting model in this paper to compare and analyze the runoff simulation under different inputs of rainfall deviation in small mountainous watersheds of Henan Province. It also discussed influence and rainfall input to flood peak simulation result under the condition of different preliminary soil dryness and wetness. The study result indicated: deviation of simulation value in small-scale watershed in mountainous area increases with increase of rainfall input deviation, the two presented positive correlation; with the preliminary changed of soil from dry to wet, the deviation of flood peak simulation was gradually getting smaller compared for the same rainfall input deviation, and the large degree of larger rainfall input is, the more obvious such smaller trend will be.

Pipeline irrigation is an important support in promoting the development of modern agriculture in Xiangyang city with its good topographic adaptability, timeliness as well as high efficiency in irrigation. Based on typical investigation of pipeline irrigation in Xiangyang city, analysis and conclusions were made about current experiences and existing problems, then countermeasures and suggestions were put forward for further development of pipeline irrigation.

The basic data and parameters of Haihe Ｒiver Basin water saving agriculture zoning system and the status quo level and the planning level years are set by using agricultural water-saving potential assessment formula of watershed dimensions,the agricultural watersaving potential values of such types as engineering,efficiency and composition type are evaluated,and then the rationality of these values are discussed,the key areas and water-saving measures are proposed in the future period,and in order to provide technical reference for relevant aspects to carry out assessment of agricultural water-saving potential and water-saving irrigation management．

The traditional acoustic water gauge chiefly used ultrasound to measure the level． Though the measuring precision of ultrasonic water gauge is higher,the range is small and the installation is troublesome,moreover,the measurement results are susceptible to environmental changes． Because of this,they are not good enough to meet usage requirements． In order to solve this problem,a kind of self-calibration acoustic wave gauge is designed by using the audible to measure the level in this paper．This water guage adopts sinc interpolation algorithm to deal with echo signal,so the measurement error of water guage is smaller,and it can be simply installed． In addition,the water guage is less affected by the environment． Finally,it can communicate with the telemetry station to report the water level in real-time by the ＲS485 bus or GPＲS． The experimental results show that the self -calibration acoustic water gauge can meet the demand of water level monitoring in small reservoirs．

contraposing the problem that existing definitions of drought and flood alternation are hard to describe the actual phenomenon, this paper gave a new definition considering three important features ,that is meteorological process, Soil dynamics process and crop water requirement process. Case study took Wudaogou area in Anhui Province as research, simulated soil moisture process and water logging process in rice irrigation,filtered out drought and flood alternating events in different rice growth period,and analyzed the particular process. The new definition results were more accurate and reasonable comparing with previous definitions, therefore the new definition can be used in areas where drought and flood alternation happened frequently.

With the diversification of water use in irrigation districts and the increasing water consumption of all water users, it is of great realistic significance to carry out the appropriate water allocation in irrigation districts. The water allocation model Considers the agricultural, industrial, domestic and ecological water use in the irrigation area, aiming at the minimum water deficit of all users. The weight method is used to solve this model and water resources allocation schemes have been worked out both on annual and monthly scale. The results show: The water shortage situation is greatly affected by rainfall. The water deficit is concentrated on agriculture in equal weight distribution programs. The water deficit is a problem of water resources and water supply project. The implementation of water-saving irrigation is an effective way to solve the intense competition in irrigation water.

Based on the pressure-state-response index system and the present status of water environment ecosystem in Henan,the ecological security assessment index systems of water environment in Henan are established． The indexes are analyzed by principle component analysis． The results show: The indexes are divided into three components,and the water environment ecological security in Henan are decided by the first component,such as population,total output value,the consumption of fertilizer,pesticide and film,COD and ammonia nitrogen discharge from industrial waste wate． Secondly,the water environment ecological security in Henan are controled by investment in treatment of 604 61169 627% 6 885%water pollution． From 2010 to 2016,the assessment value of comprehensive,pressure and response index kept rising on the whole．That dicated 6 047 8528 489%8water environmental quality in Henan improved gradually,but 60478528489% 8it increased lightly in recent two years． By increasing much focus and financial support on the water environment regulation,water quality and ability of coping the external pressure has been improved．

?The change of groundwater salinity affect the domestic water consumption and the growth of crops, especially in areas where groundwater is overexploited and agricultural water consumption is large.Taking Linzhang County as the research area, the paper collected the monitoring data of groundwater salinity of 3 monitoring wells from 2010 to 2015, and took monitoring well water level, pumping amount and regional rainfall as independent variables,taking salinity as dependent variable, then a GM(1,N) model based on the prediction of groundwater salinity is constructed, and the measured data of groundwater salinity are simulated and forecasted.The simulation results of the GM(1,N) model are compared with those of the GM(1, 1) model and the BP neural network model, respectively. The results show that the GM(1,N) model has the highest simulation accuracy.Therefore, the prediction results of GM(1,N) model are taken as the final prediction results of groundwater mineralization in Linxian County from 2016 to 2020.The results show that the salinity of groundwater in Linzhang County, from 2016 to 2020 shows a rising trend, and the results provide a reference for the management of regional groundwater and the regulation of water and salt.

Structures like flexible concrete mattress which influence the local substrata and the aquatic environment a lot are widely used in a type of common river regulation projects,the central bar protection． Based on the project of Daokouyao central bar protection,this study puts forward an ecological shoal consolidation method aiming at the channel central bar: through the introduction of out-soil and the tough pioneer vegetation including clover,reed as well as Bermuda grass． Before the vegetation breeds flourish enough,the straw -rope weavings are temporarily used as soil fixed meshes in case it is washed away． The results show that the engineering practice has a good ecological effect．The pioneer vegetation has thrived and other plant species have emerged a year after the implementation which both illustrate the method＇s suitability for generalization．

The process of urbanization will change the underlying surface of the city, affect the process of regional rainfall-runoff and increase the risk of the city facing flooding. In order to investigate the impact of land use change on design floods in the Shiyan River Basin in Shenzhen City, we interpreted the remote sensing image maps of Shiyan Basin in 1988,2002,2010 and 2016 and analyzed the changes of land use in the basin for 28 years. The SWAT model improved hourly steps was built for Shiyan River Basin to simulate the impact of land use scenarios on design flood in different periods of the basin. The results showed that the proportion of forestland and grassland decreased by 29%, the proportion of arable land decreased by 11% and that of urban land increased by 37% over the 28 years. With the reduction of cultivated land and the increase of urban area, the flood peak and flood volume of design floods with different frequencies have increased, and the peak time has also been advanced. The largest growth rate occured between 2002 and 2010, with an average increase of 205.6m3 / s in flood peak and 6342000 m3 in flood volume. In conclusion, the urbanization of the basin has had a great impact on the design floods of the basin, so the flood control abilities of the downstream area need to be checked in order to effectively deal with the flood process that may occur.

In order to learn the correction effect of different real-time correction technologies, this research took Jianxi river basin in Fujian province as an example. Three methods, the auto-regressive error correction method, Kalman filter and the Bayesian method, were adopted. As the results showed, all the three methods performed well compared with the forecast result before error correction. The Bayesian method correction results had less relative error(RE) while the Kalman filter method performed better on the peak discharge. As for the Nash Sutcliffe coefficient(NSE), the comparison results showed that the Bayesian method suit for short prediction period while the Kalman filter is better for the long prediction period which can keep high value.

Warning level is a characteristic water level proposed by hydraulic departments for dikes to prevent damage from floods． The warning level of rivers in some areas has been used for decades． The situation of river channel as well as flood conttol projects and the ability of protected objects to prevent damage from floods has changed a lot． The original warning level can not meet the demands of current flood control work． It is feasible and necessary to redesign the warning level in many areas． There is little research on the drafting warning level of rivers． In this paper,a method of calculating warning level of rivers is proposed． The method integrates the factor of hydraulic information,situation of flood control works and protected objects,then takes the main function of warning level as foundation,and points out the main influence factor on drafting warning level． A quantitative method is proposed,which has great reference value on drafting warning level forother rivers． And also,the method provides a new idea to the study of characteristic water stage for flood-control．

In order to investigate the reinforcement effect of geogrids in the enlarged embankment projects deeply, taking the typical embankment section of the ninth section of the Songhuajiang River mainstreamas an example, the finite element method is used to analyze the effects of different excavation and reinforced forms on the stability and settlement of the heightening and thickening embankments. The results show that the optimized slope section ratio is 1: 1.37, the safety factor is increased from 1.08 to 1.63 and the land use area is reduced by 36.9%, the required amount of earthwork is reduced by about 20m3; Both bench excavation and reinforcement can reduce the settlement, the effect of reinforcement is more obvious than the bench excavation, and the combined action is best; the closer the reinforcement locate to the bottom of the embankment, the lower is the differential settlement of the embankment, the more reinforcement layers are, the more obvious the effect is, but considering the economic benefits, not the more is better in the engineering. Economic and engineering benefits should be taken into consideration, and a rational choice of reinforcement treatment scheme should be chosen.

In order to explore the effect on eddy-eliminating method of guide cone in the closed sump,the simple factor analysis and CFDnumerical simulation are applied to calculate the flow field of closed sump and select ω-shaped back wall． ω-shaped back wall is consistent with the stream line in the suction sump． On this basis,CFD numerical simulation is conducted with the eddy-eliminating of the triangle guide cone and traditional guide cone． The results show that,for eddy-eliminating measures,with the height of triangular guide cone from 0 to 0．407 HZ /DL,the excessive triangle guide cone hinders water from entering the flared pipe． With the width of triangular guide cone from 0．5 to 1．0 BZ /DL,increasing width of triangular guide cone may increase the pumping hydraulic performance and pumping efficiency． However with the width of triangular guide cone from 0．5 to 1．0 BZ /DL,too broad traditional guide cone hinder water into the flared pipe． In the design discharge,whether triangle guide cone or traditional guide cone have a little effect on t

Three-dimensional ( 3D) morphology of rock fracture has a great influence on its hydraulic behavior． Experiments of water flow through rock joints are conducted to experimentally investigate the 3D roughness dependent non-linear flow characteristics in deformable rock fractures． The normal loads range from 1．0 MPa to 5．0 MPa． Granite samples with different grain thickness are selected． 3D morphology parameter is used to describe the joint surface． The non-linear flow characteristics are analyzed． Forchheimer＇s equation and the critical Ｒeynolds number are discussed． A new equation is proposed to describe the non-linear flow in rock fracture． In addition,the proposed formula is compared with existing models including Lomize ＇s equation,Forchheimer equation and Izbash ＇s law． The advantages and disadvantages of these models are analyzed in detail． The results show that the proposed equation considering 3D morphology is easier in the structure． It can be seen as an extension of the Izbash＇s law and has important engineering values．

Abstract: Baihetan hydropower station spillway tunnel has large structural size and high water flow velocity, inlet section of the lining concrete temperature control cracking is particularly important. The three-dimensional finite element method is used to simulate the construction process of the sidewall lining concrete in the inlet section of spillway tunnel in summer. At first, the adiabatic temperature rise of the concrete is inversely analyzed based on the monitoring results of the actual construction, and then the finite element simulation of a variety of temperature control schemes is carried out. Based on the comprehensive analysis of the temperature field, stress field and cracking safety factor, the program of temperature control is recommended and applied in the inlet section of the lining concrete. The result of on-site temperature control shows that the maximum temperature of concrete has been effectively controlled, temperature cracks have not appeared, and the target of temperature control and cracks prevention has been achieved.

This paper aims to propose a procedure for an interval estimate of serviceability limit state (SLS) probability of failure for single piles. The definition of curve-fitting parameters of normalized load-displacement hyperbolic curves for single piles is first presented. Then, the copula method is adopted to construct the bivariate distribution of the two curve-fitting parameters based on the test data for Augered Cast-in-Place (ACIP) piles. Moreover, the bootstrap method is used to characterize the statistical uncertainty in the bivariate distribution of the two curve-fitting parameters. Finally, both the point and interval estimates of SLS probability of failure for single piles are presented. The results indicate that sample mean, standard deviation, Kendall rank correlation coefficient and AIC scores derived from limited test data show a large variation. This variation further leads to statistical uncertainty in the bivariate distribution of the two curve-fitting parameters. By incorporating the statistical uncertainty in the bivariate distribution of the two curve-fitting parameters, the SLS probability of failure for single piles is presented as a confidence interval with a given level of confidence. In comparison with the point estimates, the interval estimates provide a more reasonable estimate of the SLS probability of failure for single piles.

In order to study the influence of pre-stress on the mode of axial flow pump impeller,FSI algorithm theory,Numerical method for adding ACT plug -ins are appilied to the WorkBench platform． The influence of pre -stress on the mode of axial flow pump impeller is calculated and analyzed．The results show that the application of pre-stress can really produce“stress stiffening”phenomenon． But the actual effect of this phenomenon is not obvious although it is under runaway extreme conditions． The natural frequency of the blade remains small． Under the rated speed the passing frequencies of the impeller and diffuser blade are 5Hz,8．33Hz,the natural frequencies of each order of the runner are much lower than that of the runner． Therefore,resonance will hardly occur in actual operation．

The tubular pump has the characteristics of high efficiency, compact structure, small size, good hydraulic performance and so on. In this study, the CFD numerical simulation method is used to design the tubular pump which is suitable for 7-10 m high lift, and the optimization of the impeller is focused. The characteristics and blade static pressure distribution of different schemes are analyzed and compared. Finally, the reliability of the numerical simulation optimization design of the high-lift tubular pump is verified by the model test results. The conclusion is that the design head of the tubular pump is 8.22 m, the efficiency of the device is 83.45%, the impeller efficiency is 91.46%, and the efficiency range is wider. The maximum efficiency point of model test is 83.22%, the design head efficiency is 81.98%, and the error range is small. The results show that the performance prediction accuracy of the tubular pump is high, and the validity of the optimization design is verified.

Saving energy and reducing consumption are conducive to the sustainable development of our economy． Therefore,it is very important to reduce the high power consumption of pump stations in water supply enterprises． Based on the hydraulic model of a water supply pipe network in a certain city in North China,the optimal scheduling of water supply pump station in Qingyuan Water Supply Plant is designed． Through genetic algorithm,the optimal scheduling scheme is calculated． After the optimal scheduling scheme is implemented,the pump station energy consumption decreases by 5．2%． The hydraulic model provides a highly efficient and energy-saving solution to pumping station optimization．

In order to study the effect of different angle setting diaphragms on the performance of centrifugal pump with centrifugal speed,a centrifugal pump with a specific rotational speed of 103 is used as the research object． Based on five kinds of full-flow numerical value simulation,centrifugal pump internal and external characteristics and pressure pulsationare obtained． The results show that the placement angle of the tongue has a significant influence on the external characteristics,the placement angle of the tongue is too large,the overall head and hydraulic efficiency decline．There is an optimum angle of placement of the tongue to make it increase hydraulic efficiency．At the same time,with the increase in the placement angle of the bulkhead,the pressure at the spiral tongue and the exit of the volute increases obviously,especially at 34°． The placement angle of the bulkhead greatly affects the streamline of the volute． The smaller the setting angle of the tongue,the smoother and smoother the streamline at the tongue and the outlet of the volute． When the setting angle of the tongue increasesby 34°,the obvious low-velocity zone appears at the lancing tongue． When the placement angle of the tongue is 22°,the amplitude ofpressure pulsations under each condition is obviously more than that of the other four forms,and the amplitude of pressure pulsations at theseptum increases firstly and then decreases and then increases． At 28°,the amplitude of pressure pulsation is the smallest,and the amplitude of pressure pulsation at outlet increases first and then decreases． Therefore,proper placement of the tongue increases the pressure pulsation at the tongue and the outlet of the volute casing of the centrifugal pump．

In order to investigate the hydraulic characteristic distortion of the pump set induced by coupling between the pump and the inlet and outlet conduit, taking a typical Shaft tubular pump set as a research object, using the Reynolds-averaged Navier-Stokes equations (RANS) and the standard turbulence model, the energy characteristics of the whole pump set are numerically simulated and compared with the model test. The calculation results reveal that the relative deviation of flux is less than 3.53% under the same net water head, which is valid in the range of 0 ~ 1.22m net water head. That verifies the rationality of 3D modeling, meshing and numerical simulation. On this basis, the hydraulic characteristics of the Shaft tubular pump set under different working conditions are studied. Research indicates: (1) There is a significant difference in the variation of hydraulic losses between the inlet and outlet conduit whether coupling or uncoupling; (2) In low flow condition, velocity circulation is much large in the pump suction inlet inducing water flow to rotate, and resulting in distortion of the water loss curve. The flow pattern are worsened and significantly correlated with pump instability zone. However, in high flow conditions the hydraulic characteristics is little difference between the coupled and uncoupled; (3) much more velocity circulation exists in the pump outlet, which leads to distortion of hydraulic loss curve of the outlet conduit. Spiral flow also exists in the outlet conduit, but its intension decreasing with flow rate increasing. Accordingly, the eddy angle on the outlet section increases.

Abstract :The free surface vortex of pump sump is an important factor affecting the operation stability of pumping station .In order to accurately judge whether the pumping station produces the suction vortex in the actual operation ,the paper studies the relationship between the submerged depth (H/D) and the number of submerged Froude number and the phenomenon of suction vortex, and the criterion of generating suction vortex is obtained. While the hydraulic model test of pumping station is used to verify the criterion.And the TJS Turbo Association standard(Japan) is applied to eliminate the scale effect of model in experiment. The results show that ,the inlet vortex experiment of pump station and the critical submergence depth and the number of submerged Froude numbers are basically consistent with the intake vortex in the pump station inlet .Therefore the critical submergence depth and the submerged Froude number can be used as the basis for the suction vortex in the inlet of the pump station .However, the pump inlet still has the type 3 or 4 vortex ,therefore prevention should be taken into consideration .As a result ,this study can provide reference for similar projects in the future.

In order to study the internal flow characteristics of a Francis turbine with long and short blades after the transformation of a hydropower station, the three-dimensional turbulence was calculated for the internal flow field of the full flow passage from the inlet of the turbine casing to the draft tube. The method was based on the N-S equation and the standard k-ε turbulence model under the condition of typical small flow, and the numerical simulation was carried out by using the simulation software CFX to obtain the flow of each flow component of the turbine. The calculation results show that the distribution of static pressure in the volute decreases uniformly along the centripetal direction, and the velocity vector increases uniformly. Vortex guide vane speed and pressure in the circumferential symmetry is good, and there are no significant vortex in the suction side and the outlet section. The length of the blade surface pressure distribution and the work surface no significant backflow and secondary flow. The flow lines in the draft tube are smooth and centrosymmetrically distributed, and the velocity decreases uniformly along the centripetal direction. Each streamline formed a more symmetrical vortex, and the center of the vortex without offset and no significant backflow tube. The research results have important guiding significance for the future operation and maintenance of the hydropower station turbine.

The commonly used water footprint calculation methods have ignored the evaporative water loss prior to the building dam,leading to an inaccurate assessment of water consumption of hydroelectric power plants． A new method is introduced in this study,in which gross water consumption( E) is replaced by net water consumption( ΔE) ． Therefore,the ratio between benefits of hydropower plant construction and cost of its energy and water consumption can be reflected more clearly． We compare the water footprint of 6 cascade hydropower stations in middle and lower reaches of the Lancang Ｒiver by applying the new method and traditional methods． The results show that the average water footprint is larger with the traditional method ( 2．38 m3 /GJ) than that with the new method ( 1．93 m3 /GJ) ． The traditional methods might overestimate the hydroelectric footprint of hydroelectric power． The degree of water surface area change is the key factor that affects the improved performance of water footprint calculation by applying the new method．

Rotor stator interaction (RSI) is a common phenomenon which happens in the fluid passing through rotating parts and stationary components. It becomes worsen on pump-turbine unit. For a specified pumped storage power station, prototype investigation was made on RSI induced powerhouse floor vibrations. For different working points, vibration magnitudes and propagation principles were obtained from the test. Vaneless zone pressures and power house vibrations were analyzed by the method of frequency analysis. The research indicates that different layers of power house have 100Hz as the main frequency, which is the RSI frequency. In each powerhouse floor, the RSI frequencies propagate with delays. For turbine mode, positive correlation of RSI frequency magnitude exists between vaneless zone pressure and powerhouse vibration, and with the load increasing the RSI frequency magnitude becomes larger. RSI magnitude of vaneless zone pressure in pump mode is weaker than in turbine mode.

With no adjustment on the start-up law of hydraulic turbine governor after transformation,an abnormal vibration occurred during the start-up process of the unit． For this reason,a simulation model of hydropower unit start-up process considering nonlinear factors is established．The influence of turbine runner characteristics,unit inertia time constants and initial water head on start-up process is analyzed． It is put forward that the adjustment of governor＇s start-up law should be emphasized in capacity expansion and transformation． In order to suppress the unit vibration,a comprehensive performance index is proposed to optimize the start-up law． The simulation results show that the optimized start-up process can reduce the water pressure fluctuation,and avoid a large vibration． Thus it can ensure safe and stable operation of hydropower units

To investigate the fluid properties change of the hump region of a prototype pump-turbine,3D steady numerical simulations are conducted for a given guide vane opening of 15 degrees by using the shear -stress transport ( SST) k －ω turbulence model． Based on the experiment data,the change law of the flow field in pump-turbines is analyzed with the decrease of flow in the different flow paths of the hump region． The results show that: the vortex is generated in the flow paths between the pressure surface of the guide blade and the suction surface of the stay blade when the unit is operated in the hump region．With the decrease of the flow,vortex motion regions spread to the whole tandem cascade．When emtering the low load zone,the vortex mainly focuses on the flow path between the outlet of the impeller and the inlet of the guide blade． Through the observation and analysis of swirling,it shows that strong swirling area mainly concentrates in the whole tandem cascade in the hump minimum and between the outlet of the impeller and the inlet of the guide blade when entering the low load zone．