Scientific assessment of the hydrological regime is an important part of the assessment of the health of the river ecological environment. The IHA indicators were used to quantitatively evaluate the change of hydrological indicators of Gaobazhou Station during the construction period and operation period of water conservancy projects in the Qingjiang River Basin. On the basis of analyzing the change law of five different IHA indicators, the overall hydrological situation change of Qingjiang River was analyzed by selecting three different RVA methods, which include the Nemero index method, the RVA method based on the European distance method and the RVA method considering the comprehensive weight. It shows that the results of the analysis of the hydrological situation in the Qingjiang River Basin by the three methods during the construction period and the comprehensive utilization period are moderate and highly changed, respectively, and the hydrological situation change in the Qingjiang River Basin has an increasing trend. The evaluation results of the RVA method considering comprehensive weights are similar to the previous two methods and are reasonable, which can better reflect the changes in the river hydrological situation after the construction of the water conservancy project in the Qingjiang River Basin.

To address the problem of excess pressure in the water supply network system, this paper proposed to add pressure reducing valves with certain opening in the system. With the objective of minimizing the square sum of the difference between the operating water pressure at each node and the minimum service head at the node, the pressure reduction valve optimized pressure leakage control model was constructed by combining the hydraulic balance constraint of the pipe network and the node pressure constraint. The model was solved by using genetic algorithm. Taking the main water supply network of southeast coastal towns as an example, the results show that the proposed model and method are effective and feasible, and it has better optimal effectiveness.

As an important factor in the ecological environment of lakes, aquatic plants play a key role in the restoration and management of lakes. The water blocking effect of aquatic plants has a significant impact on the flood storage and discharge process of lakes, so the impact of aquatic plants on the roughness has become an important part of the hydraulic research of ecological lakes. The height of aquatic plants is closely related to the roughness of lakes. The elastic modulus of aquatic plants is an important mechanical property parameter for calculating its deformation. The stem of aquatic plants is simplified as a cantilever beam with variable cross-section. Through the bending deformation test of eight aquatic plants, the tensile force, displacement and other parameters are measured, and the elastic modulus value is calculated. The basic range of the measured elastic modulus change of eight aquatic plants is obtained. The comparison shows that the elastic modulus of these aquatic plants increases with the growth age or total length.

In order to study the seepage characteristics evolution of rock mass in the water level-fluctuating zone under condition of water-rock interaction, the dolomite in the reservoir area of Wudongde Hydropower Station was selected as the research object in this paper. The variation law of fracture seepage characteristics was obtained through the single fracture seepage test. With the help of SEM and 3D surface contour scanning technology, the variation law of fracture surface microstructure and surface morphological characteristics was studied, and the influence mechanism of fracture seepage characteristics evolution law was discussed. The results show that in the process of water-rock interaction, when the seepage pressure is constant, the seepage decreases exponentially with the increase of confining pressure; When the confining pressure is constant, the seepage increases linearly with the increase of seepage pressure; With the increase of water-rock interaction period, the seepage of fractures decreases rapidly at first and then slowly, and then increases slowly and tends to be stable. The water-rock interaction softens and dissolves the minerals at a certain depth of the fracture surface, and changes the micropore structure and surface morphological characteristics. Under action of confining pressure, the fracture surface is more closed. The further reduction of effective crack width is the main reason for the decrease of fracture seepage.

In order to reveal the process and mechanism of outbreak of flash floods and causing disasters in ungauged areas, a numerical model of the transport of loose bodies under heavy rainfall floods was established in the Xiangxi River subbasin of Zhangshu City, Jiangxi Province. The process of heavy rainfall and the law of sediment transport were analyzed. The results show that for the river, the flow velocity is higher at the high terrain, slope drop change and the confluence area, and for the area with gentle slope and large catchment area, the increase of flow velocity at the confluence point is especially significant compared with other areas; The local water accumulation at the beginning of the basin, surface runoff occurs in a short period of time, and the gathered water scours out several gullies, and sediment is mostly deposited at the downstream outlet; The water depth and flow velocity of the basin are related to the rainfall. The greater the rainfall, the greater the water depth and flow velocity is, the more significant the scouring situation is. This study has positive significance for flash flood warning in the region.

Fissure distribution has a significant effect on mechanical properties and damage failure of layered rock mass with complex fissures. Based on the uniaxial compression test and DIC technique, the influence of fissure location and fissure angle on the mechanical properties and failure of the composite fissure rock sample composed of sandstone-like and martial-like rocks was analyzed. The results show that the mechanical properties of composite fissure rock samples increase with the change of fissure location from sandstone, interface and marble and the increase of fissure angle. Influence of fissure location on rock sample failure: When the fissure is in marble, the initial crack is easy to be the far-field crack in sandstone, and the surface spalling occurs in both sandstone and marble, but the failure is more obvious in sandstone, is prone to "H-shaped failure". When the fissure is at the interface and sandstone, it is easy to produce wing crack and anti-wing crack at the crack tip of sandstone. Exfoliation occurs only in sandstone, "1γ shape failure" and "y shape failure" are easy to occur, respectively. At the same time, the stress-strain levels σ and ε corresponding to the initial crack generation at the same fissure angle increase with the change of fissure position from sandstone, sandstone to marble and marble. Influence of fissure angle on rock sample failure: When α=90°, the tip is not easy to crack, and when α=45°, the tip is easy to crack. When the fissure location is the same, the σ and ε of α=90° are the largest, while the σ and ε of α=0° and α=45°are the smallest. "H-shaped failure" occurs when α=0° and "y-shaped failure" occurs when α=90°. The research results are instructive for practical engineering construction and design.

In order to explore the influence of water-binder ratio, fly ash, slag powder content and age on the compressive strength of full aeolian sand concrete, the compressive strength test of full aeolian sand concrete was carried out. The microscopic characterization of its physical composition was implemented in combination with XRD results. The compressive strength prediction model of full aeolian sand concrete was established by multiple linear regression. The results show that the compressive strength of full aeolian sand concrete increases first and then decreases with the increase of water-binder ratio. When the water-binder ratio is 0.4, the compressive strength is the largest. The growth effect of fly ash on compressive strength of aeolian sand concrete is not as significant as that of slag powder. The incorporation of fly ash and slag powder is easier to convert AFt into AFm. The established compressive strength prediction model has high accuracy and is suitable for sand concrete. The research results can provide theoretical basis and technical support for the engineering application of full aeolian sand concrete.

Drought index is crucial to the study of drought. With the influence of climate change and human activities, the frequency distribution of hydrological time series changes with time, so the nonstationary of drought index needs to be considered. The standardized precipitation index (S_SPI) considers that the precipitation obeys the Gamma distribution, the corresponding distribution function parameters are usually stationary and invariable. The actual distribution function parameters have a certain correlation with the time series. Therefore, based on the GAMLSS model, the nonstationary Gamma distribution model of precipitation series was constructed with time series as covariate. The nonstationary standardized precipitation index N_NSPI was calculated. Taking Yunnan Province as an example, the monthly N_NSPI and S_SPI during 1960 to 2019 were calculated respectively. Comparing the two indices, it is found that the overall trend of drought recognition results of the two indices is similar. However, in 1960~1985, the number and grade of droughts identified by N_NSPI were stronger than those identified by S_SPI, and the two were similar in 1986~2005. In 2006~2019, the number and grade of droughts identified by S_SPI gradually exceeded those identified by S_SPI. Further analysis shows that the N_NSPI with considering the time-varying distribution function parameters can more accurately reflect the actual drought situation.

In order to solve the sliding failure problem caused by the wet expansion and dry shrinkage of expansive soil in the North Xinjiang water supply project, lime, cement and sand and gravel were used as the main curing materials. Through unconfined compressive strength test, direct shear test, compression test and SEM test, the influence of test dosage on the mechanical properties of improved expansive soil and the formation mechanism of microstructure strength under different improvement methods were studied by combining macro and micro. The test results show that with the continuous increase of the amount of lime and sand gravel, the soil strength increases steadily, while the peak value of cement improved soil appears when the amount of lime and sand gravel is about 7%. For lime and sand gravel, when the amount of lime and sand gravel is about 6% and 30% respectively, the overall compressibility of the improved soil is low, the cohesion is large, and the shear and compressive strength is high, which can meet the requirements of engineering application. The SEM analysis of lime and cement stabilized soil with the best mix ratio shows that a large number of curly flake hydrated gel materials are generated, which significantly reduces the pores compared with the original expansive soil, and the aggregates are closely cemented. From the macro mechanical properties, the mechanical properties and stability of the solidified soil are greatly improved.

As the time goes by, the seal of the bearing oil tank cover of the hydropower station is gradually worn, the gap between dynamic and static increases, and the oil mist escapes seriously. In order to explore the influence of wear clearance and unit speed on oil mist leakage in oil tank seal, a geometric model of thrust bearing oil tank seal of generator was established. Using SST κ-ω turbulence model, steady state numerical simulation was carried out for oil mist leakage at different clearances (0.2 mm-2 mm) and rotating speeds (100 r/min-500 r/min). It is found that the influence of clearance value on oil mist leakage is much higher than that of rotational speed. With the increase of clearance, the throttling effect of sealing teeth is weakened, the sealing inlet pressure is reduced, and the oil mist leakage at the top of the tank cover is aggravated. The inlet and outlet velocity increases with the increase of wear clearance value. When the clearance value increases from 0.2 mm to 2 mm, the inlet velocity increases from 20 m/s to 113 m/s, the outlet speed increases from 76 m/s to 144 m/s, the leakage volume increases from 0.034 4 kg/s to 0.053 8 kg/s. The research can provide a theoretical basis for the optimization of sealing structure, the formulation of power station operation strategy, and the judgment of sealing performance.