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.

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.

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.

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 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 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 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.

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.

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.

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.