Taking Dawen River Basin in Shandong Province as an example, Mann-Kendall method was used to analyze the consistency of the 6 h, 12 h, 24 h and 3 d annual extreme rainfall data. The regional linear moment method was used to infer the design value of the site rainstorm, and the regional design value was compared with the single-station linear moment method. The spatial distribution map of the design value of the 50-year rainstorm in Dawen River Basin was drawn. The results show that the Dawen River Basin can be divided into 3 hydrometeorological homogeneous regions, and the optimal distribution frequency linetype is dominated by the generalized extreme-value distribution (GEV). The difference (mean absolute relative error) between the results of single-station L-moment frequency analysis method and regional L-moments frequency analysis method decreases with the increase of the length of the sample series, and the larger the return period is, the greater the gap is; The spatial distribution of the designed rainstorm values in Dawen River Basin is not uniform, but the distribution trend of each period is basically similar.

In order to evaluate the matching degree between water conservancy project for tobacco and tobacco drought in Guizhou Province, the daily rainfall data from 17 meteorological stations, tobacco production and water supply data of water conservancy project for tobacco during 2006-2017 was used to construct a matching degree evaluation model, and grade standard of matching degree was proposed. The results show that the water conservancy project for tobacco alleviated tobacco drought to a certain extent. However, the matching relationship between water conservancy project for tobacco and tobacco drought still needs to be improved. The matching degrees of Qianxinan, Qiannan, Anshun, Liupanshui, and Guiyang were 55.4%, 52.1%, 46.2%, 45.9%, 44.7%, and 34.4%, respectively, which were in the fourth grade with a poor matching degree. The matching degrees of Bijie, Qiandongnan, Tongren, and Zunyi were 31.7%, 28.6%, and 26.8%, respectively, which were in the fifth grade with a worse matching degree. In different growth stages, water shortage in root extension period mainly occurred in 90% and 95% effective rainfall frequency, and water shortage in prosperous and mature periods mainly occurred in each effective rainfall frequency. Additionally, the lowest matching degree occurred at the mature period. It is suggested that in the future, the layout of the water conservancy project for tobacco should focus on strengthening the construction in Zunyi, Tongren and Qiandongnan, and improve the rationality of the layout of water conservancy project for tobacco, as well as enhance the guarantee ability of drought resistance of tobacco.

In order to efficiently utilize water resources in the upper reaches of the Minjiang River Basin, based on hydro-meteorological data of the basin from 1960 to 2018, a variety of statistical theories were used to analyze the trend, cycle and abrupt point of runoff. The elastic coefficient method based on Budyko theory (Choudhury-Yang formula) and the comparative method of cumulated slope change rate (SCRCQ method) were used to analyze the attribution of runoff changes. The results show that the runoff decreases significantly at a rate of 12.5 mm/10a, and a sudden change occurred in 1993. There are 3 years, 8 years, 12 years and 18 years main cycles of runoff change, and the annual distribution is uneven, mainly concentrated in summer and autumn, accounting for 73.6%. Rainfall is the most sensitive to runoff, followed by underlying surface parameters, and potential evapotranspiration is the least sensitive. Choudhury-Yang formula and SCRCQ method calculated that the contribution rate of climate change to runoff reduction was 58.13% and 63.29%, respectively. Climate change was the main factor of runoff reduction in the study area, and the contribution rate of human activities to runoff reduction should not be underestimated, reaching 41.87% and 36.71%, respectively.

In order to investigate the non-stationary characteristics of runoff series in changing environments and to better predict the occurrence of flood events, taking Hutuo River in the Haihe River Basin as the research object, GAMLSS model was used to conduct a non-coherent frequency analysis of the runoff series during 1970 and 2012 by taking time, reservoir indicators and climate indicators as covariates. The results show that the runoff series of Hutuo River has obvious non-stationary characteristics with trend and abrupt changes. The GAMLSS model can better simulate the runoff series in changing environments and describe the flood regimes under the influence of climate change, thus outperforming the traditional model. Changes of the large-scale climate indicators NINO1+2 and NAO significantly affect the flood events in the Hutuo River, with increasing values of these two climate indicators indicating low flood risk and decreasing values indicating high flood risk.

In order to illustrate the influence mechanism of flow distribution on slope of urban asphalt road, two-dimensional shallow water equations were applied to simulate runoff characteristics on asphalt slope. Comprehensive sensitivity analysis was performed on multiple factors (cross slope, longitudinal slope, slope width, slope length, rainfall intensity and roughness coefficient) which caused different degrees of ponding on asphalt slope. The maximum flow depth was taken as the sensitivity analysis index. Both range and variance analysis were performed, through which the sensitivity ranking of the influencing factors were obtained and the significance level can be clarified as well. The results show that under overflow drainage condition, cross slope, pavement width and rainfall intensity have significant effects on flow depth; Slope length has no significant effect on flow depth. Flow depth is negatively correlated with cross slope, and positively correlated with rainfall intensity, pavement width and slope length, and negatively correlated first and then positively correlated with the roughness coefficient. The research results can provide reference for engineering practice.

Focusing on the influence of the project of water diversion from Yangtze River to Taihu Lake on the hydrodynamic characteristics of Gonghu Bay, the physical model of the wind-driven currents in Taihu Lake was used to analyze the influence on the hydrodynamic characteristics and the vertical flow velocity and planar circulation distribution in Gonghu Bay under the different wind speeds and different diversion flow of Wangyu River in the typical wind field in summer. The results indicate that the variation of Wangyu River diversion flow affects the hydrodynamic characteristics of Gonghu Bay mainly in the near and middle regions, but has little impact on Taihu Lake; The implementation of the water diversion project from Yangtze River to Taihu Lake significantly changes the vertical velocity distribution characteristics on the outlet axis of Wangyu River in the near and middle regions, but has no effect on the vertical velocity distribution characteristics at the junction section; The characteristics of the planar circulation in Gonghu Bay are affected by both wind speed and diversion flow, the changes of wind speed and diversion flow have a significant impact on the area, location and shape of the plane circulation. The research results can provide hydrodynamic theoretical support for evaluating the impact of the water diversion project from Yangtze River to Taihu Lake on the water environment of Gonghu Bay.

Analyzing the dynamic evolution and current situation of development and utilization of water resources is of great significance to the sustainable development and protection of water resources. The data of 1997-2020 water resources bulletins of 10 water resources zones, including Songhua River, Liao River, Hai River, Yellow River, Huai River, Yangtze River, Southeast China, Pearl River, Southwest China, and Northwest China, were selected to analyze the dynamic evolution of water resources and the current situation of development and utilization in these zones by using Kendall rank test. The results show that there are spatial differences in the dynamic evolution of water resources in China with the Yellow River region showing a highly significant increasing trend, the Songhua River basin showing a significant increasing trend, the Huai River basin showing a non-significant decreasing trend, and the rest of the basin showing a non-significant increasing trend. The Songhua River and Yangtze River basin show a weakly significant increasing trend, while the Liao River, Hai, Huai and Southeast rivers basin show a non-significant decreasing trend; The other water resources basin all show a non-significant increasing trend. The proportion of surface water is the largest, groundwater is the second largest and other water uses is the smallest. The water consumption of agriculture and industry in China's water use structure is on a highly significant downward trend after 2013, which corresponds to an increase in the efficiency of water use in agriculture and industry, a stable level of water use in domestic use and an increase in ecological water use year by year.

In order to explore the calculation method of water demand of water-reduced river landscape under hydropower development, combined with the data of hydrology and social economy in the region, this paper compared the changes of landscape characteristics after water reduction in similar projects. Taking the water reduction channel caused by Danba Hydropower Station as an example, the landscape evaluation factors were chosen comprehensively. Considering human visual effects, the landscape water demand evaluation system was established. A calculation method for the landscape water demand of the water-reduced reaches caused by the construction of hydropower stations was proposed. Based on the hydraulic model, the landscape indicators of each river section were calculated according to the determined index system, and the water volume required for the wide valley section, canyon section and county river section to meet the landscape requirements of water-reduced river channels is 70.4 m³/s, 64.8 m³/s, 50.7 m³/s. The 70.4 m³/s is taken as the landscape water demand of the whole reach of the reduced water.

The contradiction between the supply and demand of water resources becomes increasingly acute, so it is particularly important to optimize the allocation and efficiently utilize the limited water resources in the region. Water resources allocation in Hengshui city was taken as a case study. The demand of optimal allocation of Hengshui city water resources was considered comprehensively. The multi-objective optimal allocation of water resources model was established by taking the social benefit, economic benefit and ecological benefit as the objective function. The scheme of optimal allocation of water resources based on MOEA/D algorithm was given, and comparison experiments between the proposed scheme and the scheme based on NSGA-Ⅲ algorithm was done. The experimental results show that proposed scheme is superior to the scheme reported by literature, which can provide relevant support for the rational allocation of water resources in Hengshui city.

In order to explore the spatial and temporal distribution of water quality in the Yellow River basin and the causes of pollution, the monthly monitoring data of 7 basic water quality indicators at 8 provincial boundary stations of the Yellow River from 2015 to 2019 were systematically collected, and the spatial and temporal distribution characteristics and trend changes of water quality of the Yellow River were systematically analyzed by seasonal Kendall trend test method. Based on the surface water quality standard, the status of water quality was evaluated and the main pollution indicators were determined. The linear regression model was used to discuss the causes of pollution. The results show that the spatial distribution characteristics of most water quality indicators are middle reaches > lower reaches > upper reaches. The concentration values of water quality indicators at Tongguan station are significantly higher than those at other stations. TP concentration values at some stations in the middle and lower reaches of the river show a significant upward trend, especially at Gaocun and Lijin stations. From the perspective of spatial variability, the poor water quality of Tongguan station is related to the convergence of several seriously polluted tributaries in this section. From the perspective of seasonal variability, the seasonal distribution characteristics of TP concentration show that the non-flood season is less than the flood season. Under the effect of rainfall erosion in the flood season, agricultural phosphorus carried by tributaries flow into the river with the surface runoff formed by rainfall, resulting in the increase of TP concentration. The seasonal variation of NH3-N concentration in flood season is less than that in non-flood season, which is strongly correlated with air temperature. Higher flow rate and air temperature in flood season contribute to the dilution and degradation of NH3-N.

In order to comprehensively evaluate the water environment health status of Poyang Lake, a quantitative evaluation index system was established from three aspects of water quality, hydrology and aquatic organisms. The comprehensive weighting method combining analytic hierarchy process and coefficient of variation method was used to determine the comprehensive weights of indicators. The TOPSIS method was applied to construct the evaluation model, which determine the score of evaluation objects by combining the weights of indicators. The results show that there are seasonal changes in the water environment health status of Poyang Lake, and the two indicators of hydrology and aquatic organisms in summer are obviously better than other periods, so that water environment health grade is the highest and belongs to grade Ⅰ, with better coordination; The water environment health grade in autumn and winter is the worst and belongs to grade Ⅲ, among which hydrological condition is the main influencing indicator. This study can provide reference for water environment protection and construction of Poyang Lake.

In order to understand how the South-to-North Water Diversion Project has influenced the groundwater depth across the southern plains area of Beijing, this study collected the groundwater depth and water consumption measurements over the period of 2010-2020 in Daxing District. The geostatistical methods was carried out to analyze the spatial-temporal variability of the groundwater depth, and a principal component analysis (PCA) was used to evaluate the groundwater exploitation intensity over the period. The results show that the water diversion project has been putting the groundwater depth on a decline, reducing the average from 19.13 m over 2010-2014 to 17.67 m in 2015-2020, indicating a significantly constructive influence toward the groundwater depth recovery in the region. The nugget effect values of the groundwater depth, as calculated using the geostatistical semi-variogram model, dropped from 55.92% in 2010-2014 to 39.05% in 2015-2020. This decline indicates the weakening influence of human factors toward the groundwater depth. The PCA calculations show that the effect of regional water consumption on groundwater extraction intensity decreased from 2010 to 2020. Water consumption in industries, tertiary industries, and agriculture contributed to this tendency, while domestic water consumption stimulated groundwater extraction intensity. The findings turn out to be reliable theoretical and methodological references for groundwater resource management toward the regions along the water diversion routes.

With the development of the city, the contradiction between urban water supply and spring protection has become increasingly prominent, and the groundwater resources must be developed reasonably under the premise of ensuring that the spring water is not affected. Monthly rainfall and water level data of Botu Spring Group from 1990 to 2005 in Jinan area were selected to analyze the characteristics of rainfall recharge and the lagging response of water level in spring area to precipitation by statistical method. When the average of three-point movement of precipitation starts to correlate with water level in spring area, the average of ten-point movement of precipitation has the strongest correlation with water level in spring area. The current spring water level is closely related to the comprehensive rainfall in the first ten months. After ten-point moving average treatment of precipitation, through comparative analysis of groundwater exploitation data in urban area, east of Jinan and west of Jinan, it is proved that water level in spring area is closely related to groundwater hydrology unit in urban area and west of Jinan, and there is no hydraulic connection with groundwater hydrology unit in east of Jinan, so groundwater unit in east of Jinan can be reasonably exploited.

In order to study the applicability and error sources of reasoning formula method in design flood calculation in complex hilly areas, Morris screening method was used to analyze the sensitivity of reasoning formula method parameters. The applicability of reasoning formula method in different watershed areas was analyzed by comparing with hydrological comparison method and historical flood survey results. The results show that the area average rainfall is the main error source of the reasoning formula method, and the error tends to increase with the area of the basin. The reasoning formula method can still be applied to the basin with an area of 500-1 000 km² by reasonable selection of parameters. Taking Pujiang River Basin as an example, using the traditional area rainfall calculation method (without reduction), when the control section catchment area is about 100 km², 100-500 km² and more than 500 km², the error is 5.1%-5.3%, 11.2%-16.0% and 25.2%-25.5%, respectively. When the basin area is larger than 500 km², the calculated result is only about 0.2% smaller than the historical survey data after reasonable reduction of area rainfall.

In order to improve the accuracy of real-time flood forecasting in Jinhua River basin, the basin flood forecasting model coupled with Mike 11 Nam and Mike 11 HD and the real-time correction model based on Ensemble Kalman filter were established, and the real-time correction of flood forecasting in Jinhua River basin was realized. The simulation effect of the basin flood forecasting model on the main stations in the basin is good, and the simulation accuracy of flood discharge and flood level is high. When the real-time correction model is within 10h of the forecast period, the correction effect decreases with the increase of the forecast period, and the prediction error can be effectively reduced in the early stage of the forecast period. On the whole, the established basin flood forecasting model and the real-time correction model based on Ensemble Kalman filter can meet the application requirements of flood forecasting in Jinhua River basin.

In order to study the sponge urban transformation scheme of existing communities, taking an existing community in Hongshan District of Wuhan as an example, a SWMM rainfall-runoff model was established. Different LID combination schemes were determined according to the feasibility analysis of site conditions, space requirements and underlying surface characteristics. The runoff control and pollution load of each combination scheme under different recurrence periods in the study area were simulated. The simulation results of each combination scheme were analyzed from the ecological, social and economic aspects. The results show that the ecological and social benefits of biological retention facilities were high. The combination of LID facilities for laying infiltration trench, vegetative swale and biological detention facility has the best effect on runoff control, flood peak and pollutant reduction in the study area, and has good social and economic benefits, which is the best scheme.

To fully consider the temporal volatility and randomness of runoff and associated source & load in the optimal dispatch of hydropower and reduce spillage water, a probabilistic prediction method of annual scenarios for hydropower runoff and associated source & load was proposed to simulate the typical annual temporal scenarios of average daily runoff and associated source & load and their probability of occurrence. Several typical ten-day scenarios were generated by clustering with a self-organization mapping net (SOM). Then a ten-day scenario simulation model was built based on a Markov-chain probability matrix, a multi-scenario conditional probability matrix, and the similarity principle— "the closer historical year, the larger weight." It ensures that the simulated scenarios accurately fit the statistical characteristics of actual data (randomness, seasonality, and conditional correlation) for intra-year and reflect the trend evolution year-to-year. Combined with the fluctuation checks, annual temporal scenarios were simulated by the Monte Carlo method. Finally, the k-means scenario reduction was used to obtain typical annual temporal scenarios and their probability of occurrence. The results of an actual hydropower example show that the proposed method has the advantages of high accuracy, strong adaptability, and comprehensive prediction information.

For Guxian hydro-junction project, concrete volume is huge, and the construction period is tight, construction technology and parallel planning are key problems in the construction of high RCC gravity dam. Therefore, the simulation technology of discrete event system was introduced to establish the construction simulation model in line with the dam type characteristics of the dam to simulate and calculate the construction process of concrete partition, parallel and jump warehouse. After multi-scheme simulation, the flat inclined layer technology and the corresponding warehouse surface partition scheme were recommended, and the warehouse surface control criteria were put forward. It provides all-round data support for Guxian project, and its simulation model can be used as a reference for other similar projects.

In order to overcome the difficult problem of establishing multi-factor and non-linear complex relationship of reservoir sand discharge and achieve its accurate prediction, four machine learning algorithms including XGBoost, KNN, SVR and RF were used to predict and analyze the sand content of reservoir outflow based on the series data of Wanjiazhai reservoir from 2002 to 2020, respectively. The results show that the use of machine learning algorithms can effectively realize the reservoir discharge prediction considering different influencing factors. The applicability of different machine learning algorithms in reservoir discharge prediction varies. In comparison, the highest coefficient of determination R² of the reservoir discharge prediction model based on RF algorithm is 0.9349, and the corresponding average absolute error and root mean square error are the smallest, which are 2.974 and 4.886, respectively. The prediction effect of the RF algorithm is better than the other three algorithms. The proposed method can provide a theoretical basis for accurate prediction of reservoir sand discharge and optimization of scheduling scheme.

It is significant to achieve safe operation of the project and strengthen the construction of the whole life cycle safety supervision system of the dam to scientifically and rationally conduct a comprehensive evaluation of the earth and rock dam seepage control treatment scheme. From the four guideline layers of engineering risk removal effect, engineering management, engineering economy and engineering construction, this study constructed the evaluation index system of earth and rock dam seepage control treatment scheme. Aiming at the evaluation of the risk attitude of decision makers in the process of seepage control program selection, the risk attitude factor was introduced to assign interval evaluation to the indicators, and the subjective and objective weights were optimized based on game theory. And then the program was analyzed and evaluated using the improved TOPSIS model. The effectiveness of the preferred system was tested by taking a reservoir anti-seepage treatment alternative as an example. The results show that the method is feasible and effective for the selection of seepage control solutions.

Goss error detecting method of monitored dam deformation data is researched based on the fully convolutional neural networks (FCN). Firstly, the method of representation learning of artificially labeled data sets by FCN model was proposed to simulate engineers’ experience. Secondly, the FCN model for gross error detection was built and artificially labeled data sets were used for model training. Finally, the trained FCN model was used for gross error detecting of monitored deformation data of a gravity dam. The results show that the gross error in monitored dam deformation data can be accurately obtained by the proposed method, which can improve efficiency of dam safety management.

As an efficient, environmental and energy-saving transportation technology, the wheeled capsule transportation has promising application prospects. When the pipeline carriage was stationary in the pipe, it could be regarded as a crossing-cylinder structure. When water flowed around the structure, the vortices existed, which would cause energy loss. Therefore, the hydraulic characteristics at the downstream of the flow field around a pipeline car and the spatial vortices structure after the stabilized flow field were studied by numerical simulation, model test and theoretical analysis. The results show that the near-field areas of the downstream flow field of wheeled capsule with different diameters could be divided into the reflux zone and the jet zone. As the distance rose, the section-averaged velocity had a tendency of declining then rising in the near-field, and recovered the section-averaged velocity of pipe at the distance of the length of capsule. And in far-field, with the distance rose, the fluctuation of section-averaged velocity was gradually decreased, and the flow became stable. The eddy ring structures in the field were highly fractured, eddy structures were more on the side near the annular gap and less on the side near the pipe axis.

As a common safety problem in water diversion engineering, water hammer is often caused by abnormal operation of valves, So, it is necessary to conduct a comparative analysis of water hammer problems under different valve adjustment methods. The CFD technology and dynamic mesh technology were used to simulate different single and double valve adjustment modes, and analyze the fluctuation of water hammer pressure at different locations in the pipeline. The results show that when the single valve is adjusted, the first fast and then slow closing valve mode has an inhibitory effect on the water hammer within a certain range of fast shutdown; The fast closing amount is too large, which will play a worsening effect of water hammer; When the fast shutdown amount is 60%, the water hammer pressure can be effectively controlled, and the water hammer will deteriorate when the fast shutdown amount is 80%; When adjusting the double valve, considering the pressure before and between the two valves, it can be found that the “first 0.25 s off 60%, the last 0.25 s off 40%” method can avoid the occurrence of excessive pressure and negative pressure. The research result provides a design and operation scheme for the rapid shut-off process of the valve in practical engineering.

In order to reduce the negative pressure of the steps, reduce the influence of cavitation erosion and improve the effect of step dissipation, the trapezoidal energy dissipation pier was added into the convex angle of the traditional steps to form trapezoidal energy dissipation pier and step combined energy dissipator. The method of combining hydraulic model tests and numerical simulations was used to study the hydraulic characteristics of trapezoidal energy dissipation pier and step combined energy dissipator. The results show that there is negative pressure on the horizontal and vertical surfaces of the trapezoidal energy dissipation pier and step combined energy dissipator near the convex angle, and there is a possibility of cavitation failure; However, the aeration concentration of the negative pressure area in the horizontal level and the vertical surface of the step is basically greater than 5%, which can effectively reduce the harm of cavitation erosion; Within the study range, the trapezoidal energy dissipation pier and step combined energy dissipator energy consumption rate can reach more than 70%, and the energy dissipation rate decreases with the increase of the flow rate. This combined energy dissipator is conducive to reducing the cavitation hazard of step and improving the effect of step energy consumption, which can provide a certain reference basis for the design of step energy dissipator and existing step spillway reinforcement.

Vertical seam fishway has gradually attracted the attention of hydraulic engineering field because it can adapt to large amplitude water level, obvious energy dissipation effect and stable flow pattern. In this paper, the influence of the length width ratio of the pond on the hydraulic characteristics of the opposite side vertical slit fishway was studied by numerical simulation. The results show that the change of the length width ratio of the pond has little impact on the dissipation rate per unit volume; The attenuation along the main flow area first increases with the increase of the length width ratio of the pond, and then remains unchanged. The larger the length width ratio of the chamber is, the closer the maximum velocity in the chamber is to the vertical joint; The ratio of the main flow velocity to the maximum flow velocity (the maximum variation of the main flow velocity along the way) is within a certain range. The length width ratio of the pond is between 1.00-1.13, which can obtain better water flow pattern, larger reflux area and better water quality in the mainstream area of the fishway.

In order to solve the cavitation damage problem of the spillway with high head, three schemes were proposed. The aeration tank was added at pile number 0+130.73, 0+161.78 and 0+186.39, respectively, and the corresponding Fr was 6.65, 7.91 and 8.53. By means of RNG κ-ε turbulence model and physical model test, the aeration concentration and cavitation number indexes of the section prone to cavitation erosion were analyzed. The results show that the effect of adding aerator at pile 0+186.39 is better than the other two schemes, and the bottom aeration concentration is above 15% and the flow cavitation number is greater than 0.3 in the section prone to cavitation erosion, the cavitation failure problem in the drainage channel section can be effectively solved.

Based on the RNG Κ-ε double-equation turbulence model and the VOF two-phase flow model, the flow regime, flow velocity, pressure, energy dissipation, cavitation and sediment transport characteristics of the double volute chamber vortex shaft were studied using model test and numerical simulation. The results were in good agreement with the experimental values. The vortex chamber was more thoroughly dosed with gas through an aerator device, which reduced the possibility of cavitation erosion. The measured energy dissipation rate exceeded 75%, indicating a good energy dissipation effect. The sediment siltation existed at the bottom of the shaft for various particle sizes at various flow rates, reducing the depth of the stilling well. At low flow operation, the siltation might reached up to 72% of the stilling well’s depth. However, the sediment was cleared away after a big flood and the silt height was lowered to 1.6% of the well depth, enabling the cyclone shaft to have a sufficient water cushion for energy dissipation that would not interfere with its regular functioning. Control the size of the barrage in actual projects to prevent congestion caused by large particles of sediment entering the floodway. In actuality, the operating mode can be altered to control the stilling well’s silting height, ensuring that it has sufficient rich water cushion depth to match the cyclone shaft's design and regular operation requirements.

In order to reveal the influence of the gate opening on the hydraulic characteristics of hydraulic tunnels, a two-dimensional model of silt-releasing tunnel with different gate openings was established. The VOF method and standard κ-ε turbulence model were used for three-dimensional numerical simulation calculation of flow field in abrasive section of flood silt-releasing tunnel. The hydraulic characteristics such as flow state, velocity and pressure near the gate were obtained. The hydraulic characteristics under different gate opening degrees were analyzed to obtain the cavitation number from the gate to the threshold. The results show that when the gate operation opening is less than 1/2 maximum opening, the larger the gate opening is, the smoother the tunnel flow state is, the smoother the flow velocity near the bottom is, the lower the pressure difference between the upstream and downstream of the tunnel floor is. The smaller the gate opening is, the smaller the flow rate in the pressure cave is, and it is easy to cause sediment deposition; The greater the opening of the gate is, the more favorable the overall operation of the tunnel is. The research results have guiding significance for the optimization of the operating opening of the hydraulic tunnel gate and the anti-wear repair of the gate bottom sill.

In order to solve the problem of “seeing the sea in rainy season and having no water to use in drought” in cities in desert areas, taking Kuwait as an example, based on the concept of sponge city in conventional areas, combined with the actual climatic and geological conditions in desert area, the permeability coefficient of 5-50 m underground layer was calculated according to the experimental data obtained from the soil permeability test in N5-1 region. A number of seepage analysis schemes of rainwater storage tank were established, and different schemes were modeled and calculated. The results show that the combination of filling high permeability material around the rainwater storage tank and adding vertical recharge well at the bottom can solve the problem that rainwater cannot penetrate into the underground aquifer effectively.

Ground penetrating radar (GPR) has a broad application prospect in detecting the leakage area of water supply pipeline. In order to enhance the understanding of the response characteristics of GPR in the leakage area and improve the positioning accuracy of the leakage area, based on the finite difference time domain method, this paper simulated the response characteristics of ground penetrating radar for leakage at the bottom of metal pipes, and extracted the "three instantaneous" seismic attribution. The results show that the upper boundary signal of the leakage area is easy to be identified, and the internal signal has multiple reflections and oscillations. The reflection effect of the instantaneous amplitude attribution in the leakage area is similar to that of the original profile. The instantaneous phase attribution is obviously staggered, and the instantaneous frequency attribution is obviously attenuated. Instantaneous phase attribution and instantaneous frequency attribution can reflect the existence of leakage area and weak signal well, so the instantaneous phase attribution and instantaneous frequency attribution are preferred when analyzing the instantaneous attribution of leakage area. The research results can provide a reference for the interpretation of GPR pipeline leakage detection images and practical engineering applications.

In order to further analyze the permeability characteristics of cohesionless soil containing carbonate sand, South China Sea carbonate sand and fine grain quartz powder were used as test materials to prepare test soil samples. The GDS high-pressure triaxial apparatus test system and constant head permeameter were used to carry out research on the influence of carbonate sand content, initial void ratio and effective stress on the permeability characteristics of cohesionless soil. And then an empirical model of permeability coefficient considering effective stress was established. The test results show that when the content of carbonate sand is less than 40%, the grain structure is cohesionless soil matrix, and the pore structure is determined by fine grained soil; The structure of carbonate sand sample is the skeleton structure of sand particles, and the magnitude of permeability coefficient increases significantly; With the increase of effective stress, the permeability coefficient of the sample decreases significantly. An empirical model for the permeability coefficient of cohesionless soil with carbonate sand was established. The model parameters were closely related to the properties of the soil sample. The calculated values were in good agreement with the test values. The research results can provide reference for practical projects.

Aiming at the collapse and failure of high dangerous rock in Zhaojiaya, Xingshan County, numerical simulation methods were used to simulate the stability, evolution law and movement characteristics of the regional dangerous rock mass, so as to obtain the movement track, bounce height and impact energy of the collapsed rock. The results show that the Zhaojiaya dangerous rock has good stability under natural conditions. Under continuous rainfall or rainstorm, the fissure water gradually permeates, and there is the possibility of collapse and failure of the main control structural plane. After the collapse and destruction of the dangerous rock, most of the fallen rock will stay on the slope, and a few of the fallen rock will stop on the road at the foot of the slope after the collision and rebound. Combined with the actual situation of the site and RocFall simulation, the governance measures of "danger clearing + slope leveling + passive protection net" were proposed. The research results can provide reference for similar disaster control projects of high dangerous rock collapse.

The existence of fissures seriously affects the stability performance of rock structures, and how to reasonably describe the characteristic change law of nonlinear mechanics of rocks containing fissures has been an important research point in recent years. Based on this background, a smooth particle dynamics numerical simulation method (RSMPM) is proposed considering material point failure. The RSMPM was based on the basic calculation principle of the MPM algorithm, the Mohr-Coulomb damage criterion was adopted to traverse all material points in each calculation step, and the failure process was carried out for the material points that reach the damage condition. The dynamic fracture process of the rock was described by the failure process of the material points. The accuracy of the proposed numerical simulation method was verified by comparing the numerical simulation results (crack extension process, main stress cloud distribution) of single crack standard cube specimens and single crack Brazilian disc specimens with previous research results. The research results provide a certain reference for the application of smooth particle dynamics methods in rock mechanics engineering and the understanding of rock fracture mechanisms.

In the process of the rise and fall of the reservoir water level in the dry-hot valley reservoir area, the dry and hot conditions in dry and hot valley where the surface rock mass is located need to be considered, that is, the heat and wet cycle. Based on this, repeated shear tests of joint rock sample under heat and wet cycling were carried out. The results show that with the advance of the test period, the shear stress-shear displacement curve decreases as a whole, and the shear strength of the joint surface deteriorates obviously; The deterioration effect of shear strength under repeated shearing is particularly significant only in the initial state after the shear strength is modified; The deterioration effect of shear strength under heat and wet cycle is mainly concentrated in the first five cycles; After modification, the shear strength, cohesion and internal friction angle of the joint surface show a deterioration trend of “first fast and then slow” only under heat and wet cycle, which is consistent with the experimental results. The research results have guiding significance to the deterioration of rock mass and the stability analysis of bank slope in water-level-fluctuation zone of dry-hot valley.

In view of the problem that hydraulic concrete buildings in cold regions are vulnerable to early freezing injury during pouring construction and may affect the later healthy service, in order to study the strength damage law of early frozen concrete and optimize its ratio, Box-Behnken (RSM-BBD) response surface method was used to optimize the experimental design. The RSM response surface model was established by taking water binder ratio, fly ash content and air entraining agent content as variables. A GA-BPNN strength prediction model was constructed to predict the strength of early-frozen concrete accurately. Compared with the RSM model, the results show that the GA-BPNN has more accurate prediction performance and can optimize proportion design more efficiently. The goodness of fit R² and average relative error e_MRE by the GA-BPNN strength prediction model are 0.998 5 and 2.13%, respectively. The relative error between the predicted value of the optimal strength ratio and the experimental value is about 1%. The application of GA-BPNN strength prediction model can realize the efficient optimization of concrete freezing strength and its ratio.

In order to study the mechanical properties and damage mechanism of recycled brick concrete, the shape of recycled aggregate was regarded as a random concave convex polygon. Recycled brick concrete was regarded as seven-phase heterogeneous composite materials such as waste brick aggregate, waste concrete aggregate, new and old mortar, waste brick-new mortar, aggregate-old mortar, new and old mortar. Based on the ABAQUS development program of PYTHON, the numerical model of recycled concrete with different aggregate rate and different brick quantity was established. The meso-mechanical properties of recycled concrete containing brick with 45% coarse aggregate content were analyzed. The damage and failure patterns of recycled concrete containing bricks under load were studied. The results show that the algorithm is efficient in modeling, and can establish the mesoscopic model of recycled concrete containing bricks with different aggregate rates and different brick quantities, which can meet certain engineering requirements; The peak stress and elastic modulus of recycled brick concrete gradually decrease with the increase of brick quantity, while the peak strain increases with the increase of brick quantity; The damage and failure patterns of concrete with different brick quantities are basically the same.

The structure of large-scale shaft tubular pumping station is complex, the structure and size of each pouring block are different, and the temperature control index is also different. Especially in summer construction, it is very difficult to control temperature and prevent cracks. For different structural parts, refined peak clipping strength index should be adopted. In this paper, the equivalent cooling algorithm was used to simulate the peak-cutting intensity of cuboid pouring block under different water pipe layout, water temperature and water flow rate with different hydration heat inhibitor dosage and without hydration heat inhibitor. Then a series of quantitative formulas were put forward. According to the dosage of hydration heat inhibitor and peak-cutting intensity index, the layout density and water flow rate of cooling water pipes with corresponding water temperature can be calculated with these formulas. The results can provide quantitative reference for the establishment of temperature control measures for similar pumping stations constructed in high temperature season.

In order to study the temporal and spatial evolution characteristics of internal dynamic response and energy transfer of fresh concrete under the action of surface vibration load, a laboratory vibratory plate compaction test of fresh concrete was carried out. Real-time dynamic response characteristic parameters were obtained by acceleration sensors at different buried depths in the compaction process of vibrated concrete. The vibration signal was denoised by wavelet threshold denoising method. The temporal and spatial evolution law of internal motion energy of fresh concrete was analyzed by measuring point acceleration response. The results show that the aggregate particles near the surface vibration source mainly move vertically, and the surface of fresh concrete is obviously settled on the macro scale. With the increase of burial depth, the internal particles at the far end cannot get enough vibration energy, so it is difficult to overcome the extrusion force between particles and the friction resistance in the medium and maintain the initial equilibrium state, which is less affected by vibration. The vertical acceleration of internal particles is greater than the lateral acceleration during the vibration compaction of fresh concrete. With the increase of the compaction degree of fresh concrete, the vertical acceleration amplitude first decreases and then basically remains unchanged, while the lateral acceleration amplitude first decreases and then slightly increases. The vibration energy attenuation of concrete near the vibration source is the largest, but it is not significant with the increase of buried depth. The work in this paper can provide reference for the theoretical construction and in-depth study of vibration compaction of fresh concrete.

Dynamic strength is an important parameter for dam stability and safety analysis, which is of great significance to engineering design. Variable amplitude cyclic loading and unloading test was carried out to explore the effect of different confining pressure and cement content on the dynamic stress-strain relationship of cemented sand gravel (CSG) material by large dynamic triaxial instrument. Based on the Mohr Coulomb strength criterion, the evolution law of dynamic strength parameters of CSG materials during plastic deformation was studied by taking the dynamic strain as the plastic internal variable. The results show that the dynamic cohesion and dynamic internal friction angle increase with the increase of cement content. As the dynamic strain increases, the dynamic cohesion decreases rapidly, the dynamic internal friction angle increases, and the friction force generated by the shear slip between the aggregates dominates. When the peak dynamic stress is reached, the effective stress surface between aggregates decreases obviously, the dynamic cohesion decreases gently, the dynamic internal friction angle decreases with a certain hysteresis. The law of dynamic cohesion with dynamic strain conforms to the power function relationship. The law of dynamic internal friction angle and dynamic strain change conforms to the quadratic function relationship. The research results can provide a theoretical reference for the optimization of seismic design of CSG dam.

Taking a reconstruction canal section in Zuncun Irrigation District as the research object, this paper studied the sediment transport characteristics and scouring and silting change law of the canal. The causes of channel siltation were analyzed by sampling suspended matter, bed sand and measured velocity. The results show that the most serious siltation occurs at the head of the canal, and the siltation during the water shut-down period is an important factor causing the siltation of the canal. The flow rate of sediment carrying under each water conveyance condition is given, which provides the basis for the reduction of siltation and the efficient operation of the irrigation area in the future.

In order to solve the problem of benefit sharing amount, a quantitative model was established, and a case study was conducted on the application of the model and the corresponding benefit distribution ideas. The results indicate that the stakeholders of hydropower development projects mainly include the central government, local governments, hydropower enterprises and reservoir immigrants, and the net present value method can be used to construct the benefit sharing model, in which the stakeholders take the product of the sum of the present value of net cash flows of hydropower projects and their input shares as the sharing amount. The grey prediction method was used to solve the model. The case of Xiluodu Hydropower Station proves its rationality. It is suggested to establish a development fund for immigrants and safeguard the interests of other parties to open up a new situation of co-construction and win-win of hydropower development.

Taking the mixed-flow pump turbine as the research object, a fully elliptical volute was designed, which could meet the working conditions of the turbine and the pump. The ratio of the length and short half axis of the elliptical section of the volute was guaranteed to be fixed. The worm shell was designed by its outlet circumferential velocity and the circumferential velocity moment of each section, and the relationship between the size and flow rate of each section of the volute was given. Through CFD numerical simulation, the variation law of the circumferential velocity of the volute outlet and the circumferential velocity moment of each section was obtained. The distribution law of the velocity and pressure inside the volute was summarized, and the simulation results meet the design requirements, which has high practical application value.

The flow channel model and the shafting model of the turbine unit were established, and the fluid-solid coupling method was used to analyze the dynamic characteristics of the shafting system vibration of turbine unit induced by hydraulic factors under the steady-state conditions with different loads. The measured data were compared to verify the feasibility of the method. And then the correlation mechanism between the vibration characteristics and the internal flow characteristics under typical steady-state conditions was studied. The results show that the vibration characteristics of the guide bearing obtained by this method are basically consistent with the experimental values, and the trend of vibration changes with the change of load is consistent. Due to the positional relationship, the vibration characteristics of the water guide bearing and the upper guide bearing have a certain amplitude difference. The horizontal vibration amplitude of the unit is the largest due to the obvious vortex belt in the draft tube when running at 75% load condition. The research results can provide a scientific reference for the stable operation of hydropower turbine units under different loads.

A turbine runner of a certain power station often produces cracks due to excessive blade stress, which threat to the safe operation of the unit seriously. To solve the problem of the turbine runner blade stress, based on RNGk- ε turbulence model, the modeling and mesh of turbine components were carried out for a bulb tubular turbine. Through the runner blade thickening and angle optimization, CFD technology was used to optimize runner hydraulic performance and strength comparative analysis. The results show that the stress and deformation of the optimized runner blade are greatly improved, which meets the actual engineering needs and can effectively avoid the generation of runner cracks.

In view of the serious cavitation erosion and local cracks of water turbine runner after the capacity expansion and transformation of four runners in Shangyoujiang hydropower station in 1998, JF3057 turbine runner with excellent hydraulic performance was developed through numerical analysis and optimization design in 2017 for the innovation of unit ^#2 of the power station. The measured results of the prototype turbine after innovation show that the new runner has greater output and higher efficiency, and the vibration and the shaft runout are normal, but strong noise and metal roar within a certain load range exist in the turbine. In 2018, the strong noise and metal roar were basically eliminated after the blade outlet edge modification. After 5-year operation test and periodic inspections of the runner, the cavitation phenomenon of the new runner has been greatly improved, and the transformation of No. 2 turbine has been successful.

In order to solve the current situation that hydraulic turbine fault diagnosis relies excessively on expert experience and has low efficiency, the historical data of hydraulic turbine fault and relevant expert experience were used to establish the fault tree model for seeking the mapping between risk hidden danger and fault diagnosis. Through the conversion of fault tree model and Bayesian network model, the probability importance and sensitivity of root node were deeply studied by using the reverse diagnosis technology of Bayesian network. Hydraulic turbine components and fault causes were inferred to realize the fault diagnosis.

To meet the fault prediction needs of hydro-generator units in the context of big data, combining the characteristics of the attention mechanism with good feature extraction ability and the advantages of model robustness for multi-sensor information driving, this paper proposed a fault prediction system of hydro-generating units based on the attention mechanism and multi-sensor information driving. The system was applied to on-line monitoring of unit ^#8 in August for a hydropower station in Hunan Province. The actual operation results show that the system can effectively predict the vibration trend of the hydro-generator set and realize the intelligent prediction of the hydro-generator.

Phasor measurement unit (PMU) can measure phasors directly, which provides an important technology for dynamic safety monitoring. Aiming at PMU measurements experience errors, a dynamic state estimation method for generators based on cubature Kalman filter (CKF) was proposed. In this method, the fourth order dynamic equations of generators were taken as the system function. The fading factor was introduced into CKF to keep the residual sequence orthogonal at all times, which improves the adaptability of the estimation algorithm. The adaptability of the estimation algorithm was improved, and the defect that the estimation result deviates from the real value due to the uncertain parameters of the generator model was overcome. Simulation results verified the effectiveness of the algorithm.

In order to clarify the hydraulic performance of the submersible tubular pump device in Yangzhou Gate Pumping Station, the internal flow and hydraulic performance of the submersible tubular pump device were analyzed by numerical simulation combined with physical model test. The influence of the front and rear bulbs body on the energy performance of the pump device was compared and analyzed through the comprehensive characteristic index C.P.I, and the scheme of the submersible tubular pump device with the rear bulb body was optimized. The maximum efficiency of the submersible tubular pump device with the rear bulb body is 78.86 %, the flow rate is 314.86 L/s, the lift is 3.594 m, and the blade placement angle is +2°. When the blade angle is -4°, the runway speed of the prototype pump device is 295.19 r/min, which is 1.75 times the rated speed of the prototype pump device. The streamline of straight pipe inlet is smooth under each flow rate conditions, the local area of guide vane appears backflow and the spiral flow inside straight outlet conduit is obvious under small flow rate conditions. With the increase of flow rate, the proportion of hydraulic loss of bulb body and outlet conduit decreases firstly and then increases, and the proportion of hydraulic loss of bulb body and outlet conduit in the whole flow conduits of pump device is the largest. The research results can provide reference for pumping station engineering.

As a large steel structure in the open environment, the miter gate will form a non-uniform time-varying temperature field under the solar radiation, resulting in complex temperature effect on the structure. If not paid attention to the project, it may lead to safety problems such as weld cracking and structure instability. The temperature field of the structure was analyzed by changing the surface coating and using finite element software. The results show that under solar radiation, the gate panel and the top beam form a multi-temperature area array distribution of temperature field, and the beam system temperature distribution is relatively uniform. The surface coating has great influence on the temperature field of the gate. The coating with low radiation absorption rate can reduce the temperature rise of the gate components, and the maximum temperature can be reduced by about 25%. The distribution of temperature field is greatly improved, which can effectively prevent local stress concentration or excessive deformation in the stress field and deformation field of the gate.

In order to review the power generation capacity of the Three Gorges Reservoir under normal operation conditions, and explore the impact of different dispatch modes and upstream reservoir regulation, the preliminary design scheme, optimized operation scheme, and 2015/2019 edition scheme were taken as the calculation model. Considering the main control reservoirs in the upstream, the natural runoff series in Yichang station from 1946 to 1975 used in the preliminary design were selected to calculate the natural flow derivation for reflecting the inflow runoff characteristics of the Three Gorges Reservoir in the current stage. Using natural/return runoff as four dispatch models’ scenarios, the power generation capacity was analyzed. The results show that under current stage, the power generation capacity of the Three Gorges Reservoir is 100.8 billion kW·h, 14.3% higher than the design value; By optimizing the dispatch mode, the full storage rate in October can be improved. Compared with the design mode, the power generation capacity is increased by 5.5-9 billion kW·h; By the regulation of the upstream reservoir, the inflow runoff and the utilization rate of water resources is improved. The power generation capacity is increased by 0.8-2.8 billion kW·h.

Aiming at the problem of power system structure vulnerability, the advantage of multi-index evaluation can be combined with Pajek tool to identify the key nodes of power grid. First of all, based on the complex network theory, considering the power network topology characteristics, structural vulnerability evaluation index system of integrated power system was established. Secondly, in terms of evaluation methods, fuzzy comprehensive evaluation method and CRITIC method were used to calculate the subjective and objective weights of each evaluation index. Finally, combination weighting VIKOR was proposed to calculate the weight value of each node and obtain the ranking result of importance. Taking IEEE-118 system as an example and comparing with different evaluation methods, the results show that this method is feasible.