Climate change has different degrees of impact on the spatial and temporal patterns of water resources and the water cycle. Taking the Upper Hanjiang river basin as an example, this paper analyzes the variation characteristics of hydrometeorological elements from 1961 to 2013 by linear regression method and Mann-Kendall nonparametric test. The Distributed Time Variant Gain Model (DTVGM) was constructed, and the applicability of this model in the basin was verified. According to the results of CMIP5 multi-mode set average, the change of precipitation, temperature and the runoff response process in 2011-2099 under RCP4.5 and RCP8.5 was analyzed. The results show that, from 1961 to 2013, the annual precipitation in the Upper Hanjiang River basin gradually decreased with time, the temperature increased significantly with time, and the annual average runoff decreased significantly with time. Under the two climatic scenarios, the precipitation in the Upper Hanjiang River basin will increase in the future compared with the baseline period, the temperature will increase significantly with time, and the runoff will decrease from the baseline period but will increase with time. The results indicate that in the future climate change, the hydrological cycle in the Upper Hanjiang River basin will be greatly affected, and there may be a certain degree of water shortage.

The water resource optimization allocation model is established with the minimum regional water shortage rate and the minimum pollutant emission as the objective function． Taking the valley in the lower reaches of the Fenhe Ｒiver as an example，this paper predicts the water supply and demand in 2025 on condition of 20%，50%，75% and 95% rainfall frequency． Aiming at the problem that the calculation of Moth－Flame Optimization algorithm takes a long time and is easy to fall into local optimum，the adaptive formula for the number of flames and the logarithmic spiral formula are improved． Through the simulation experiment of the test function commonly used in swarm intelligence algorithm，the optimization results of Moth－Flame Optimization algorithm before and after the improvement are compared and analyzed． The improved Moth－Flame Optimization algorithm is used to solve the model，and the results show that the water resource optimization allocation model is reasonable and effective，and the improved Moth－Flame Optimization algorithm has fast convergence rate and optimal performance， which can be used for an analysis of optimal allocation of water resources．

In recent years, extreme rainstorms in the Yangtze River Basin have become increasingly frequent. In this paper, by using the daily precipitation data at 670 rainfall stations in the Yangtze River Basin during 1960～2017, the spatial and temporal variation characteristics of rainstorm days and intensity in the Yangtze River Basin in recent 60 years were analyzed. The results showed that the rainstorm areas in the upper Yangtze River were located in the Jiamin River basin, and the rainstorm areas in the middle and lower Yangtze River were located in the Poyang Lake system. The rainstorm days in the upper Yangtze River were obviously smaller than those in the middle and lower reaches, but their intensity was close; The rainstorm areas in the Yangtze River basin moved northwest from April to September, and its location gradually moved from the two lakes to the Jiamin River Basin. The intensity of rainstorm increased first and then decreased from April to September. The strongest rainstorm in the middle and lower Yangtze River occurred in June, while that in the Jiamin River Basin occurred in July; The rainstorm days in the middle and lower Yangtze River increased significantly, while that in the Mintuo River Basin decreased significantly. The variation trend of rainstorm intensity in each water system of the Yangtze River Basin was not obvious, but it in Yuan River - Dongting Lake - the main stream of the lower Yangtze River had a significant increase trend, and it in the Minjiang River system had a significant weakening trend. The rainstorm intensities of 100-year, 50-year and 10-year recurrence intervals were 183, 160 and 112 mm/d in the upper Yangtze River, and 200, 174, 120mm/d in the middle and lower Yangtze River.

aiming at the urgent demand of medium and long term runoff forecast for water regulation in Shiyang River Basin, Based on the analysis of runoff characteristics of Shiyang River Basin, takes the Xiyanyang Reservoir as the research object and introduces 130 remote factors such as the atmospheric circulation index as the forecasting factors. Principal component analysis was used to optimize the factors, and the mid-long-term runoff forecast model based on physical cause analysis was combined with BP, Elman and PSO-SVR respectively to predict the annual runoff of Xiying Reservoir. The results show that the Elman and PSO-SVR medium and long-term runoff forecast models based on the principal component analysis meet the accuracy requirements of operation forecasting model in "hydrological information forecasting rules", Which can be used as a support model for mid-long term runoff forecasting in Shiyang River Basin, providing the basis for optimizing the allocation of water resources and water regulation in Shiyang River Basin.

As the drawback exists in data assimilation method for soil moisture simulation，the unscented weighted ensemble Kalman filter ( UWEnKF) based on unscented transformation and ensemble Kalman filter ( EnKF) is proposed，which improves the weight of the important ensemble member，and the ensemble members are symmetry about the mean values． The performance of UWEnKF is verified through the soil moisture assimilation experiment by assimilating the hourly in situ soil surface moisture observations into the one － dimensional ( 1 － D) Ｒichard equation at Meilin study area，eastern China． The results show that ① the one－dimensional Ｒichards equation can well simulate the soil moisture change，② data assimilation method can improve the soil moisture simulation accuracy，but the performance of assimilation method is related to simulation accuracy，③ UWEnKF can significantly improve soil moisture simulations and perform better than EnKF obviously in improving the accuracy of the model． Overall，UWEnKF is an efficient and practical data assimilation method，and is an important technique to improve the soil moisture simulation accuracy．

The first phase of the South-to-North Water Transfer Project has achieved a significant social, economic, ecological and other comprehensive benefits. In order to carry out the engineering management more scientifically and promote the benefits of the project, it is necessary to make a summary of the diverted water quantity during the initial stage of the project operation. In this paper, average water supply during the project planning stage and the amount of diverted water in the first phase of the east and middle route were introduced. Influencing factors of the utilization of the delivered water was analyzed, and corresponding suggestions for the construction and operation of the other projects were proposed.

It is essential to quantify the parameters＇ sensitivity to improve the crop water productivity． Summer maize is used as the research object so as to investigate the parameters＇ sensitivity in different soils，meteorology and tillage measures of summer maize water productivity． The extended Fourier amplitude test is used as the analysis method． Ｒesearch results show that the DNDC model can effectively simulate the soil moisture and crop growth process with 0～ 50 cm soil moisture，ETc，crop growth process and yield． Irrigation water volume， initial soil ammonium concentration，CO2 concentration，the second fertilization amount，rainfall and daily maximum temperature are factors which can limit summer maize water productivity in different hydrological years． When the hydrological age is changed from flood year to flat year and then to low flow year，the sensitivity of the irrigation water is higher than that of the fertilization amount． Therefore，the sensitivity of the limiting factor will be helpful to improve the regional agricultural water production efficiency and multi－elements，and thus enhancing the technical approach．

Dry drainage through intense evaporation from saline wasteland is an important way to control soil salinity in arid and semi－arid irrigation areas． In order to explore the effect of saline wasteland utilization on dry drainage，this paper selects three kinds of bare saline wasteland，covered with woody and herbaceous plants in the Hetao Irrigation District of Inner Mongolia respectively，and conducts a five－ month observation of soil water and salt dynamics in the irrigation season of 2018． A soil water balance is made to evaluate the evapotranspiration from the saline wastelands． The results show that halophytes can effectively reduce the evaporation from the soil surface， promote soil water consumption from deep layers through transpiration and disperse salt in soil profile． It is proved that halophytes planting in saline wastelands can increase the evaporation capacity and prolong the service life of dry drainage system． These findings serve as a theoretical basis for planning and designing dry drainage system in arid irrigation areas．

With the aim of reducing agricultural pollution caused by plastic films，the degradation properties of degradable films and their effects on growth and water use efficiency of maize are studied with results compared with the effects of plastic film in an open － field experiment in Hexi Irrigation area． The results show that: compared with the results of open－field experiment，the coverage of degradable membranes A，B，and C can significantly increase the number of root layers，root number and root dry weight in seedling and jointing stages． The plant height，leaf area and dry matter accumulation increased significantly during different growth stages． The number of grains per ear increases by 20．25% ～ 20． 79%，the 1000 －grain weight increases by 14． 44% ～ 21． 69%，and the yield increases by 37． 88% ～ 47． 01%． Degradable film does not show significant difference with plastic film． Compared with plastic film，the economic output and the water use efficiency of dry matter increases by 3．66% and 1．68% for test film A，while those of the test films B and C decreases by only 6．50% ～ 7．08% and 6．38% ～ 7．17%． However，from grain filling stage to maturity stage，the water consumption of test films B and C increases by 7．21% and 12．86%，while the water use efficiency of dry matter decreases by 15．31% and 12．61%，which indicates that the effect of degradable film on soil moisture conservation decreases sharply in the later stage of film mulching． The results show that it is feasible to use degradable plastic film instead of plastic film in agricultural production． It is suggested that the production enterprises should prolong the stable period of test films B and C to improve the effect of moisture conservation in the later stage of maize growth．

In order to explore the suitable lower limit of irrigation and rational irrigation times for the potato in the arid regions of Ningxia，the number of different field water holding capacity is used as the lower limit of soil moisture control to control the number of irrigation，and the different plant height，leaf area index and the different treatments are analyzed． Dry matter yield at the site，as well as WUE has impact on yield and water use efficiency． The results show that the minimum irrigation limit of 75% of the field water holding capacity of the average growth indicators are also large． For example，the lower limit of the tuber growth period is 70%． The average is 41．4 and 39．5 cm，and other treatment． There is a significant difference between the two groups ( P＜0．01) ，and there is also a certain role in delaying senescence at the late growth stage． The lower limit of irrigation is 70%． The maximum yield of Tianchi is 39 894．2 kg /hm2 ，but the water use efficiency WUE is 55% in the lower limit of irrigation，the average is 13．04 kg /m3 ，and the irrigation lower limit is 75%． The WUE is the smallest，averaging only 8．84 kg /m3 ． Fitting the relationship between the evapotranspiration and yield of potato． It was found that the index model had good results，and the coefficient of determination Ｒ2 reached 0．989 3． The analysis showed that when the potato ETa was greater than 440 mm，the potato yield drastically decreased，which was not conducive to water saving and the improvement of irrigation efficiency． Therefore，it is recommended that irrigation with a minimum irrigation limit of 70% of Tianchi be used as a reference for potato production in the region．

The situation of irrigation water use in farmland is complex and the statistical difficulty is great. In view of the problems existing in the commonly used statistical methods of irrigation water use in farmland at present, a statistical method of irrigation water use based on " Conversion of electricity to water" and reuse of irrigation return water is put forward, which is applied to the plain river network area. The calculation results are reasonable and can be used in the water resources bulletin and total water consumption statistics in the plain river network area. The report of irrigation water consumption provides technical support.

In view of the low level of irrigation management and informatization in China's irrigated areas, this study selects Jingtaichuan irrigated area as the research object to carry out the information system design and development of irrigation plan. The basic information of Jingtaichuan irrigated area irrigation planning information system design is combined with the current irrigation area by groups (villages), water distribution points, canal sections, water management units - such as grass-roots irrigation management organizations to check and report step by step. By using computer and Internet technology, the precision formulation system of irrigation plan was developed, realizing the accuracy, rapidity and efficiency of the annual irrigation plan formulation of irrigation management office, providing first-hand information for the unified formulation of irrigation plan and water dispatching scheme, and providing an efficient interactive platform for farmers' association, water users' association and irrigation area water management institution.

Membrane drip irrigation combined with concealed drainage technology is a composite water-saving irrigation and drainage technology that combines under-drip irrigation and concealed drainage technology. In order to explore the soil water, salt and organic matter migration rules of corn field crops under the technical conditions, the experimental sites were selected in the former Zhuerqin Village of Qianguo County, Jilin Province, through submerged drip irrigation combined with concealed drainage (T1) and sub-membrane drip irrigation Field trials were conducted in three different plots of (T2) and traditional planting (T3). The results showed that the change of the soil moisture content T1, T2, T3 in the same soil depth is 9.46%, 15.35%, and 23.49% in the corn growing season, respectively. Indicating that the membrane drip tube combined with the dark tube drainage can help to improve the soil water retention. The soils of T1 occurs different degrees of desalting, and the desalination rates of 20cm, 40cm and 60cm soil layers are 40.5%, 38.8% and 27.9%, respectively. In the late growth stage of T2 corn, salt accumulation in deep soil was observed, and the salt accumulation rate was 95.2%. The deep soil salt accumulation occurred under T3 rainfall conditions, and the surface soil returned to salt under drought conditions. At the late growth stage of maize of T1, the soil organic matter content increased significantly, T2 and T3 had the trend of declining. It’s indicates that under-drip irrigation combined with concealed drainage helps to increase soil organic matter content and facilitate crop growth .This study also uses Hydrus-1D to establish a water transport model with good simulation results and reliable models.

This paper presents a stochastic model for modeling daily suspended sediment concentrations ( SSCs) ，with the use of Copula function of accounting for temporal correlation． It first normalizes the daily SSCs observations by using the normalized quantile transform method to enhance the marginal distribution selection of SSCs． Next，the bivariate Archimedean copulas are used to construct the joint distributions of adjacent daily SSCs． Finally，the developed stochastic model is applied to generate long－term daily SSCs sequences of the Pingshan station on Jinsha Ｒiver． The widely used autoregressive ( AＲ) model results are also used as references，which shows that the proposed stochastic model can preserve the statistical characteristics of the historical daily SSCs with a high level of accuracy． The differences of statistical values between simulated and observed series are small． Above 98% of average relative errors of statistics are less than 10%，and the maximum is 4． 22%． In addition，the proposed model performed better than the AＲ model in preserving the skewness and lag － 1 correlation． This study suggests that the proposed Copula － based model is able to generate long － term daily SSCs data，which may have significant ramifications to water resources management

Ｒiver health assessment can judge and evaluate whether a river is in a healthy state，which not only helps river management department to determine management activities，but also provides a scientific basis for river protection and restoration． Based on the analysis of the connotation and index system of Liudong Ｒiver＇s health in Guizhou Province，this paper constructs a river health evaluation system consisting of 5 criteria layers and 15 index sets，including river physical characteristics，hydrological and water resources characteristics， water quality status，aquatic organisms，and social service functions． The health assessment score of Liudong Ｒiver was calculated by combining analytic hierarchy process and comprehensive assessment method． Our results show that the total health assessment score of Liudong Ｒiver is 82．32，and the river integrity scores of the eight divided sections are ranged from 82．91 to 89．34． The whole Liudong Ｒiver basin is generally in a healthy state，but some indexes of some river sections are still in an unhealthy state． Predictable measures should be taken to effectively control the occurrence or development of river ecosystem damage and significantly reduce the probability of ecosystem development towards an unrecoverable state and ecological restoration investment． 

This project takes eight rivers in Qinhuangdao as the main research object, and analyzes the annual average monitoring data of 20 cross-sections from 2010 to 2015. By establishing comprehensive water quality index based on the single-factor water quality index, we conduct pollution risk assessments on different river sections. Results show that the primary pollution factor of the river in Qinhuangdao is COD.Judging from the results of evaluation of spatio-temporal changes, the overall water quality of Qinhuangdao has gradually improved in recent years. Some cross sections have been significantly improved, and the concentration of major pollutants has dropped significantly. At the same time, there are rivers that exceed the standard, which mainly are the Yinma River and the Renzao river. The study will help control the total amount of pollutants entering the sea and governance coastal environment in the Qinhuangdao area, which may provide decision-making basis for the water resources management department.

The RCS was an innovation of the modern water environment management system, and one of the important ways to promote the national governance of water ecological in china. Combined literature analysis and GIS spatial visualization methods, the research on the spatial-temporal implementation pattern and policy impact of RCS show that: (1)The implement of RCS has undergone the individual initial stage（2007-2009）, the local diffusion early stage(2009-2014), the local diffusion late stage(2014-2016) and the overall promotion stage(2016-2017), which shows the trend of gradual rise in the early stage, rapid rise in the middle stage and steady implementation in the late stage.(2) The spatial extension processes is from east, northeast, southwest to northwest and Qinghai-Tibetan area, which has remarkable patterns of cross-regional effect, adjacent effect, axial effect and agglomerate effect. (3) The early implementation of the RCS was only individual behavior of some local governments. However, as relevant policies and regulations roll out at all levels and various departments, the temporal and spatial implementing processes of the RCS have been obviously affected by the policies and regulations of the central and local governments. In the coordination of the practice of the RCS, the launch of corresponding rules and laws and the comprehensive implementation of that system, various departments at all levels have worked together, and a central-local river system vertical management pattern has been developed, which gives sound policy support to China’s water environment governance and provides a practical lesson for the legalization of the national environmental governance system.

In this project, Yuliangjiang river section in Qingshuijiang river basin was investigated in karst mountains area. Based on the identification of relationship between groundwater discharge and river water environmental capacity （WEC）and its water quality, the water quality trend and pollution load was analyzed with Daniel trend analytical method and synchronized estimation model of water quantity and quality. And the WEC was calculated in multi-hydrological situation. The results show that the pollution load of ammonia nitrogen(NH3-N), total phosphorus(TP) and fluoride(F-) is 312.85t/a, 274.91 t/a and 311.82 t/a in the basin, respectively. These pollutants originate mainly from industrial and urban sewage and characterized by obvious spatial distribution. In control unit Ⅰ, the concentrations of fluoride had a significant decrease, the WEC of the main pollutants was not overloaded. In control unit Ⅱ and Ⅲ，the concentrations of TP , F- and NH3-N, had a considerable decrease, the former’s WEC of the main pollutants were overloaded, the latter’s WEC of TP was overloaded. In control unit Ⅳ, the concentrations of the main pollutants had not a unobivious increase or decrease, but the WEC of TP and F- were overloaded, and WEC overload of TP was exhausted. In control unit Ⅴ, the concentrations of TP and F- had a remarkable decrease，the WEC of the main pollutants were overloaded, these five control units need to be implemented for total pollutant control including NH3-N, TP as well as F-, and accurate reduction measures.

Due to the lack of attention to ecological flow, the development of Danjiang main stream hydropower has seriously affected the downstream river ecosystem. Therefore, it is urgent to propose standards and measures for the discharge of ecological flows. According to the measured runoff data of Jingziguan Hydrological Station, this paper mainly uses the hydrological method to calculate the river ecological flow. After analysis and comparison, the recommended values of the monthly ecological flow of the Danjiang main stream power station are proposed. The recommended ecological flow rate accounts for 12.3%~44.0% of the average annual flow, and the safeguard measures and suggestions for the discharge of ecological flow are proposed. This paper provides a reference for the water ecological protection of the Danjiang River, and has a certain significance for protecting the ecology of the Danjiang Wetland Nature Reserve.

To analyze the hydraulic characteristics of piston control valve in detail, steady-state conditions in different openings as well as transient conditions during opening and closing were investigated by numerical analysis. Curves of the flow coefficient, resistance coefficient and cavitation coefficient were obtained. Dynamic flow forces acted on the piston spool were compared while the valve opened and closed. And the flow field distribution was discussed as well. The flow characteristics of the valve is linear. The flow resistance is obviously only in small opening but it will decline rapidly with the increase of valve opening and the head loss will stay low thereafter. The minimum cavitation coefficient is 40.2 in this investigation, indicating that the allowable cavitation coefficient of piston control valve should be less than this value. As the fluid flow leads to opening tendency in this valve structure, both of the flow forces during valve opening and closing act in the open direction, and the former is less than the latter. In addition, flow field distributions of velocity, streamline, pressure and turbulent kinetic energy in different openings were studied to illustrate flow characteristics of the piston control valve.

Based on the model of water step-pumping system design of One pumping water engineering, it is analyzed that when the first pump station is already in operation, and the sets of pump units and the parameters are different in the following pumping stations, based on the first downstream pumping stations(pumping station Two),qualitative similarity analysis and calculation is done on pump performance curve, according to the water consumption of the first pumping station, various frequency pump performance curves are calculated based on the ratio formulas, various frequency and static frequency operating condition comparison analysis of is done on pumps in pump station Two, and pump real operating conditions and operating range are determined in various irrigation water flow. This research provides reference and guide for the determination of the rated operating conditions of the pump unit and the discharge matching in step pump stations project.

In order to solve the problem of water shortage in the arid zone of central Ningxia, the Guhai pumping station projects,"6+1" reconstruction project, was put forward by Ningxia Water Conservancy Department to increase the first stage pumping station by 3.8 m3/s. In order to solve the problem of increasing flow in the following pumping stations, this paper adopted alternate loading method for double-suction centrifugal pumps to improve the design of the impeller in the following pumping station. And four units in Changshantou and Daliumu pumping stations were put into trial operation and the impellers were revamped in Guhai pumping station projects. The results show that applying of alternate loading method for double-suction centrifugal pumps in Changshantou pumping station and Daliumu pumping station, the flow rate of the unit can meet the demand of increasing flow design of pump station. The pump efficiency increased by 13.6% and 5.4% respectively, and the efficiency of pumping station equipment increased by 9.2% and 2.4% respectively. The spot test pump and motor were running normally, and the vibration and noise were smaller than the pump unit without replacing the new impeller. The pumps run stably and the impeller inlet had no obvious cavitation. The research results provided a low cost solution for the improvement of increasing flow reconstruction of Guhai pumping station projects, and also provided a reference for the reconstruction of other pumping stations.

It can reduce the open frequency of reservoir in the water storage process that reasonably determining the timing of water storage during dynamic control of flood limited water level. In this paper, the concept of dynamic remaining water was proposed. An index system included the current flow, post-peak delay time, peak flow and peak-type index was constructed to characterize the raw of recession flow. And a multivariate linear regression model for predicting remaining water was established. With the dynamic remaining water, a method for determining the timing of water storage was put forward. Taking the Hekou village reservoir as an example, the results show that it can achieve the goal of dynamic control of flood limited water level by using the calculation results of multiple linear regression model.

In order to reduce the cascade reservoirs surplus water risk and increase utilization of hydropower resources, this paper proposes a method to control cascade reservoirs surplus water risk for frequently-occurred flood according to the principle of making full use of the storage capacity of reservoir which has better regulation performance and flood-water resources utilization. The method treats the range of beginning regulation water level, operation mode and so on as the control indexes of cascade reservoirs surplus water risk. Using typical flood process, this paper got the reasonable range of the control indexes of cascade reservoirs surplus water risk with iterative calculation. The method is used on cascade reservoirs located on the Wujiang River. In addition, it shows an advantageous result for formulating cascade reservoirs operation plan.

In order to solve frequent urban waterlogging problems in recent years, then taking Liede River basin in Guangzhou as an example, urban flood control and drainage model under the gate control is established based on SWMM model and GIS. In the design rainstorm of return period of 1,3,5 and 10 year, it is simulated the confluence process of drainage pipe network and river course of the river catchment and the effects of river drainage and drainage pipe under the control of gate. And the model is verified by four measured rainfall data. The results show that the model can reflect the actual drainage situation of the basin, and it has certain universality to drainage of small rivers in river network area. The optimal scheme of gate control in different sections of the river can realize the control of waterlogging water level in the river section. It provides reference for drainage and flood control planning, management and priority scheduling of urban river basin.

In order to avoid the damage caused by the water hammer, induced by pump-stop, to the long-distance water pipeline system. Hydraulic transition was necessary to analyzed to pump unit and pipeline system, so that reasonable safeguard measures was made. In this paper, method of characteristics is used to calculate the hydraulic transition process of water hammer caused by the accidental pump-stop in a water plant project. The unprotected measures, the protection measures for the valve two stage shutting off and the air valve, and one-way surge tank measures are respectively carried out for water hammer. The results show that under the unprotection measures, the accidental pump-stop will cause the liquid column separation and pump reverses. The reverse rotational speed exceeds the relevant standard. Under the unite protection measures of the slow-closing check valve and the air valve, the liquid column is mitigated, but cannot be avoided. The installation of the one-way surge tank effectively alleviates the liquid column separation phenomenon, and the water hammer pressure is within the pipeline design pressure range.

The agglomeration method is used to simulate the single particle crushing test and the material parameters affecting the particle breakage behavior were systematically analyzed. This work aims to provide reference for the selection of material parameters used in the discrete element modeling of particle crushing. The simulation results show that the effect of bond strength on single particle crushing is most prominent, and the particle crushing strength increases linearly with the bond strength.With the increase of friction coefficient between sub-particles, the bond becomes more and more difficult under shear stress, which cause the particle crushing strength increases accordingly.The local damping coefficient can inhibit the stress wave formed by bond broken, thus changing the spatial distribution of the agglomerate’s broken bonds. Therefore, it has a significant impact on the fragment size distribution of the agglomerate.

The typical profile of hardfill dam is the trapezoid with symmetrical upstream and downstream slopes. The dam has a large section with low stress level, economic and environmental protection, high safety and strong adaptability to the foundation. At present, there are many researches on the hardfill dam on soft rock foundation, but it is rare to study on it on overburden layer. The Huishui Barrage Engineering in Guizhou Province is a hardfill dam built on overburden layer. In order to analyze the feasibility of building hardfill dam on overburden layer, taking this engineering as an example, we established two 2D finite element models of anti-seepage curtain scheme and water cut-off wall scheme to calculate and analyze the seepage field, the stress and deformation characteristics of the dam foundation and the dam body and anti-sliding stability of sliding surface. The results demonstrate that they have good anti-seepage effect and meet the requirements of seepage stability, and that their settlement and stress of dam foundation are small and uniform, meeting the bearing capacity requirements of overburden layer. The stress level of both dams is low. And the sliding surfaces meet the requirement of anti-sliding stability. Therefore, it is feasible to construct a hardfill dam on overburden layer. And considering the safety and economic factors, the anti-seepage curtain scheme is more practical.

In order to study the hydraulic characteristics of the unilaterally divergent stilling basin, the RNG k-ε two-equation turbulence model was combined with the VOF method to calculate the water flow in the stilling basin. The calculated surface line, pressure and flow rate are compared to the model test results. The results of comparative analysis show that the numerical simulation is basically consistent with the results obtained by the model test. The in-depth analysis shows that the water flow produces a vertical axis vortex at the diverging side tail; the horizontal axis formed by the leaping roll moves upstream in the diverging side, and the water jumps to the tail. The shaft moves downstream on the diverging side; The turbulent energy may reflect the distribution of the pulsating pressure to a certain extent; the pulsating pressure on the front plate of the reverse arc segment and the stilling basin is large, and the design can strengthen the protection of these regions.

Tensile and tensile-shear failure of rock is a common failure in engineering. Based on Hoek-Brown criterion, this paper presents a finite element method to simulate the tensile and tensile-shear failure of rock. Firstly, according to the test data of rock, Hoek-Brown criterion can well describe the mechanical properties of rock under tension and tension-shear. At the same time, brittle failure is the main feature of rock under tension and tension-shear. So, brittle-plastic constitutive model is used to simulate the deformation and failure. Then, the solution method of stress drop is deduced, which is embedded in the finite element software ABAQUS. Then, the finite element simulation of the indoor test is carried out. The simulation curve fits well with the test data, the brittle-plastic constitutive model of Hoek-Brown can correctly reflect the failure characteristics of rock such as tension, tension-shear. Finally, the model is applied to a water conveyance tunnel project to analyze the feasibility of using segment lining on characteristic section, which provides guidance for the lining design of the project.

Flip buckets are commonly used energy dissipators in hydraulic engineering, different kinds of flip buckets play different guiding roles on flow water. Maerdang hydropower station faces difficult problems of flood discharge and energy dissipation for its high water head, huge flow velocity, centralized setting of the flood discharge structure, and it required high for scouring of the lower river bed, overall model test was made to solve the problems. In order to meet the design requirements that three holes nappe of spillway could cross-shore in the dead storage level and the downstream of river scouring should be shallower，contrast tests of oblique flip bucket, tongue-type flip bucket, straight wall slit-type flip bucket, and curved slit-type flip bucket, curved slit-type flip bucket properly were carried out, through the comparison, the curved slit-type flip bucket was satisfied the design requirements. The experimental study has some reference significance to similar projects.

Many small and medium-sized hydropower stations built in early years of China have encountered problems such as backward technology, aging equipment and declining efficiency. This not only fails to make full use of valuable hydropower resources, but also leave many security threats. The present study on key technologies for efficiency?improvements?and?capacity?additions?focuses on the optimization of the configuration of generator sets and hydropower resources. Research on achieving fuller utilization by means of optimizing the original hydraulic structure is rarely seen. Based on the efficiency?improvements?and?capacity?additions practice of Baiyutan Hydropower Station (Hengyang), this paper theoretically analyzes the characteristics of the water head loss of the inlet trash rack, and proposes a new method to maximize the station efficiency combining the optimization of the generator set and the inlet structure. This paper also introduces the construction scheme of the inlet structure optimization which hopefully will enrich the methods of efficiency?improvements?and?capacity?additions at?existing?small and medium-sized hydropower stations, and provided reliable experience for the subsequent cases.

The Partical two-phase flow model was used to calculate the three-phase turbulent flow of the full-flow channel in the small-flow working condition of long-segment mixed-flow turbine of the high-salt river high-head hydropower station. The calculation results show that the low pressure zone of the runner is mainly concentrated in the blade exit area. The lowest pressure occurs at the back of the long blade near the exit. The sediment volume fraction of the head and tail of the long and short blades is high. The sandstone volume fraction is the largest, which is consistent with the sediment wear in the front exit area of the actual power plant.