Due to the existence of snow, melting snow and frozen soil, the hydrological cycle in cold regions has its particularity. In order to probe into the hydrological law of small watershed in cold region and simulate the process of runoff formation, the hydrological data of Yongcuihe River basin from 1994 to 2015 were selected as the research area. The SWAT model for runoff simulation in cold region was constructed, and the applicability of DEM with different resolution, as well as three kinds of meteorological data, CMADS data set and CFSR data set, in Yongcuihe River basin was analyzed. The results show that the SWAT model can simulate the runoff process of Yongcuihe River. DEM resolution has a great impact on the extraction of watershed features, but has no obvious effect on runoff simulation. The applicability of different meteorological data has significant difference, the simulation effect of measured meteorological data is the best, the simulation effect of CMADS data set is better, and the simulation effect of CFSR data set is worse, which provides a reference for further study of small watershed in cold region.

With the increase of the service life of the dam, inversion analysis of dam mechanical parameters based on the prototype monitoring data is necessary. At present, the dam inversion analysis model is still mainly based on the dam displacement monitoring data, which can only reflect the dam displacement law at the macroscopic level, while the change law of the strain field and stress field of the dam is ignored from the mesoscopic perspective. Therefore, a high arch dam mechanical parameter inversion model based on WOA-BPNN and MOEA/D was proposed, which consider both the dam displacement monitoring data and the dam strain monitoring data. The mechanical parameter inversion analysis of the arch dam was carried by the dam’s displacement data and strain data. The results show that the inversion parameter is more accurate and reasonable.

To study on water replenishment effect of ecological gate in the Tarim River Basin, the MODFLOW was used to establish the numerical simulation of the two-dimensional flow movement of the groundwater profile in the Wusiman section, and to analyze the evolution process of the groundwater flow field in 4 years. On this basis, the two schemes with or without ecological sluice were predicted and compared. The results show that in the fifth year under the two prediction schemes, compared with the single main river channel, the buried depth area less than 8 m in the study area increased by 6.62% by using the ecological sluice water conveyance scheme. The ecological gates restored the groundwater level far away from the ecological area of the main river channel, and the groundwater level on the north side of the section increased by 2-3 m on average. Compared with the single main channel water conveyance, the phreatic evaporation consumed by the increment of groundwater storage per cubic meter was reduced by 24.6%. The ecological sluice solves the problem that the groundwater level is difficult to recover in the ecological area far away from the main river channel under the traditional water conveyance mode, and creates conditions for the restoration of the river network ecosystem formed by multiple branches in the middle reaches and the safety belt of biodiversity along the main stream.

In order to understand the influence of thermodynamic coupling factors on the damage characteristics of hydraulic engineering concrete materials within 100 ℃, the temperature of concrete specimens is applied and stabilized by self-designed temperature control device, and non-destructive monitoring acoustic emission technology (AE) is used to monitor the uniaxial compression of concrete under different temperature environments. The AE ringing count and amplitude change during concrete failure at five different temperatures are explored, and the constitutive model of concrete damage under thermodynamic coupling is established according to the relationship between ringing count and stress. The results of the cumulative ringing count and amplitude show that the higher the temperature, the higher the number of damage events, the more severe the degree of damage, respectively, the cumulative ringing count increases by 5.25 times at 100 °C compared with 20 °C, and the amplitude can be increased by 20-40 dB in the late loading stage compared with the previous stage. The established damage constitutive model shows that the increase of temperature will increase the degree of damage of concrete, which provides a theoretical reference for understanding the influence of thermodynamic coupling on the damage of concrete materials.

At present, most variable-speed pumped-storage units use converters (AC excitation) to control power. There is a problem of reverse speed overshoot caused by rapid power changes, and the traditional governors are difficult to ensure good control effects, which affects the operating efficiency of variable-speed units. In order to study the control of the speed regulation system under the active power regulation of the variable speed unit, the speed regulation system of the variable speed pumped storage unit with adaptive backstepping sliding mode control (ABSMC) was proposed. Firstly, a mathematical model of the variable-speed pumped-storage unit speed control system including the optimal speed module was established. Secondly, taking the electromagnetic power as the system disturbance, an adaptive backstepping sliding mode controller for the variable-speed pumped-storage unit speed control system was designed and its stability was analyzed. Finally, a simulation test platform for the speed regulation system of the variable speed pumped storage unit was built, and the dynamic response simulation analysis of the speed of the variable speed pumped storage unit was carried out under the given power of the power generation condition. Compared with the sliding mode controller (SMC) and PID controller, the results show that the reverse overshoot of the controlled unit speed by the ABSMC is small, the adjustment time is short, and the effect of tracking the optimal speed is ideal. The effectiveness of the designed controller was verified.

Aiming at the Dakuaitian landslide in the Three Gorges reservoir area, which appeared cracks in July 2021 and intensified deformation in August, causing serious safety hazards to local villagers and infrastructure, 9-view Sentinel-1A uplift SAR image data from March 2021 to August 2021 were used as data sources to obtain the time-series deformation characteristics of the landslide in this time period by using SBAS-InSAR technology, and compared with the concurrent GNSS monitoring and geological exploration data. The results show that the deformation of the middle and rear part of the landslide is obvious and is in the state of creeping deformation; The signs of landslide deformation are in good agreement with the InSAR results, which verifies the effectiveness of SBAS-InSAR technology in landslide monitoring; The accumulated rainfall in the previous period and the short-time intense rainfall are the main factors that induce the current deformation of Dakuaitian landslide. This study shows that the SBAS-InSAR technology has a broader application prospect in the field of geological disaster monitoring and early warning in the Three Gorges reservoir area, and provides a reference for similar reservoir area landslide deformation monitoring and early warning.

The study of water-sediment processes and dam-land-erosion mechanisms under warping-dam-break conditions is of great significance for the construction and later management of warping dams in the Loess Plateau. Based on the literature research and field investigation, this paper identified the main causes of dam-land-erosion under warpingdam-break conditions, including the nature of the dam soil, the formation characteristics of the dam and the check dam break mode. It proposed that the process of dam erosions and gully erosions after warping dam failures was as follows: “warping dam failure → retrogressive erosion → scouring and undercutting → collapse of gully walls → mixed flow of water and sand”. Taking the ^#2 main dam in Macaoli of Lishi District in Lvliang City, Shanxi Province as an example, the numerical calculation results indicate that the water-sand process under the condition of warping dam failures was significantly changed by the siltation of the reservoir areas, and the dam lands have the role of shaving peaks and sinking sands.

When the magnetoelectric velocity sensor is used to test the vibration of the top cover, distortion is easy to occur due to the inherent characteristics of the sensor and the test conditions, and the data can not truly and effectively reflect the operation state of the water turbine top cover. The correlation among excitation force, vibration and strain was clarified through vibration theoretical analysis and stress calculation of top cover structure. Using finite element structural analysis to determine the weak position of the rigidity and strength of the top cover, the dynamic strain value based on this position was proposed as an indicator parameter for evaluating the operation status of the hydraulic turbine top cover. Based on the vibration value and dynamic strain value in the stable operation area, a mapping relationship between strain and vibration was established to solve the problem of inaccurate vibration measurement of the top cover. Taking a power plant unit as an example, the feasibility of the proposed method was verified.

Analyzing the spatial and temporal distribution characteristics of flash flood disasters is crucial for flood control and prevention. Taking Guangdong Province as an example, this study first compiled historical data on flash flood disasters in Guangdong Province from 2017 to 2021. Using methods such as standard deviation ellipse and kernel density, the spatial and temporal characteristics were analyzed, and the complex interaction relationships of triggering factors were explored. The results show that there were a total of 79 flash flood disasters, mainly concentrated in May and June, with uneven temporal distribution. The spatial distribution pattern of flash flood disasters exhibited a "dispersed east and west, concentrated north and south" pattern, with the northern cities of Heyuan, Shaoguan, and Meizhou being high-risk areas for flash flood disasters. Short-duration heavy rainfall was the main driving factor for flash flood disasters, with significant influences from topography, vegetation cover, and land use. The findings of this study can provide reference for flash flood disaster prevention and control in Guangdong Province.

For side channel spillways, although the adjustment section can be arranged on the downstream side to smooth the water flow, it is difficult to completely avoid the interference of the transverse axis spiral flow on the water flow pattern of the chute. Through numerical simulation, the impacts of the curved circulation in the turning section of the chute on the spiral flow on the lateral axis of the side trough were studied. The results show that when the direction of the circulation and the spiral flow are the same (the turning angle is 14.505°), the streamline in the bend rolls obliquely from the concave bank to the convex bank, the superposition of the flow velocity is obvious, and the circulation intensity intensifies. The lateral flow velocity of the outlet section of the curve reaches 3.29 m/s, and the height difference of the outlet water surface has reached 1.140 m (low left and high right); When the circulation flow of channel bend and spiral flow are in opposite directions (the turning angle is -5°); The water flow in the bend turns from both sides to the axis and then flows downstream, and the circulation phenomenon almost disappears; The lateral flow velocity at the outlet section of the bend decreases to -0.19 m/s, and the height difference of the outlet water surface decreases to -0.467 m (high left and low right). That is, the turbulence of the spiral flow in the upstream groove can be improved by providing a curved path in the chute.