The ultra-short-term reservoir water balance simulation of channel-type reservoirs is the key to the operation of the reservoir, but the results easily appear sawtooth oscillation. The calculation error is due to the fluctuation of the water level in front of the dam by extending the simulation time scale. Among the factors that cause the fluctuation of the water level in front of the dam, taking the load change as an example, the calculation error of water balance caused by the load change was corrected. An ultra-short-term water balance method for channel-type reservoirs was put forward based on one-dimensional hydrodynamics. The method established a one-dimensional hydrodynamic model of the river-reservoir area, and procured the accurate storage capacity by calculating the average water level instead of the water level in front of the dam, thereby eliminating the jagged error. The calculation results show that the simulation accuracy can be effectively improved after eliminating the influence of load changes. The ultra-short-term water balance method for channel-type reservoirs based on one-dimensional hydrodynamics can eliminate the sawtooth error and achieve high simulation accuracy.

In order to investigate the impact of typical ecological revetment fish-nest brick on the hydrodynamic characteristics of straight water conveyance channels, a 3-D numerical model (LES) incorporating fish-nest brick was developed using large-eddy simulation technology. Periodic boundaries were employed in the longitudinal direction to allow for the repeated development of water flow within the computational domain. The reliability of the numerical model was extensively validated through experimental data from flume tests. Subsequently, the LES model was used to simulate the hydrodynamic characteristics of channels containing fish-nest brick. The results indicate that the fish-nest brick divide the channel into a high-speed main flow region and a low-speed fish-nest cavity. The time-averaged flow velocity in the main flow region is approximately 1.8 times the cross-sectional average flow velocity (U₀), and a continuous distribution of vortices exists throughout the entire water depth range. Conversely, the time-averaged flow velocity and turbulence within the fish-nest cavity are at relatively low levels, making it suitable for fish habitat and the hatching of adhesive eggs. The mixing layer at the mouth of the fish-nest cavity exhibits relatively strong vortex structures, which significantly enhances turbulence intensity and services as the primary driving force for momentum exchange between the interior and exterior of the fish-nest cavity.

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 ZM Fishway is the rare vertical slot fishway with high altitude and the long length at the domestic and foreign. The effect of fishway is particularly vital for the gene exchange and population reproduction of the upstream and downstream fish. To investigate the effectiveness of the fishway, we monitored the species, quantity and environmental factors of fish by trap and video observation method from March to July in 2021. In total, 9 species of 143 680 fish belonging to 2 orders, 4 families and 7 genera were captured. The species and quantity of fish passing through were mainly Schizothorax oconnori, Schizothorax macropogon and Racoma waltoni, which were the main objects of fishway designed. The number and species of fish showed obvious seasonal and circadian rhythms. The number and species of fish in May and June were significantly higher than those in other months, and the number of fish during the day was significantly higher than that at night. The canonical correspondence analysis (CCA) results of fishway environmental factors show that the main environmental factors affecting the effect of fishway were the water stage and water temperature. The research results could provide reference data for the optimization and effective operation of the ZM fishway, and it was of great significance to the protection of fishery resources in the middle and lower reaches of the Brahmaputra River.

In order to maximize the comprehensive benefits of cascade reservoirs in the lower reaches of the Jinsha River, it is necessary to study the application mode of joint flood control scheduling. Adopting the flood process in different areas with the incoming water from the Jinsha River and the Minjiang River as the mainstay, the flood regulation calculation, flood control analysis, flood control storage capacity utilization, and cascade power generation benefit calculation of the cascade reservoirs in the downstream of the Jinsha River were studied by using relevant mathematical analysis methods. The flood control distribution method of the cascade reservoirs in the lower reaches of the Jinsha River to meet the goal of flood prevention in the Chuanjiang River was studied. The research results show that on the premise of meeting the flood control requirements of the downstream Chuanjiang River, from the perspective of making full use of flood resources and increasing the overall power generation benefits of cascade power stations, in the distribution and dispatching of flood control, it is recommended that the order of flood control storage capacity utilization of cascade reservoirs downstream of the Jinsha River is as follows: Wudongde Reservoir, Xiluodu Reservoir, Baihetan Reservoir. The research results can provide references for rational and scientific flood control operation of cascade reservoirs in the lower reaches of the Jinsha River and similar basins.

Reasonable data mining and accurate prediction and analysis of concrete dam deformation monitoring data are the key means to ensure the safe and long-term operation of the dam. Due to the impact of environmental variables such as temperature and water level, the dam deformation time series has periodic, nonlinear and other change characteristics. Existing intelligent algorithms can not capture the nonlinear relationship of sequences well, A concrete dam deformation prediction model based on EEMD-AEFA-LSTM model was proposed. Ensemble empirical mode decomposition was used to effectively decompose the deformation time series. The long short-term memory network model optimized by the artificial electric field algorithm was used to predict the decomposition components and reconstruct the prediction results. The deformation monitoring data of EX16 and EX24 measuring points of a concrete dam were selected for prediction research. The results show that the prediction accuracy of the EEMD-AEFA-LSTM model is significantly higher than that of the AEFA-LSTM model, PSO-LSTM model, and GA-LSTM model. The average absolute error, mean square error, and root mean square error of the prediction results are the minimum values, providing a new way for accurate prediction of concrete dam deformation.

To analyze the causes of turbine segmented shutdown device miloperation for a hydropower station in Central Asia, the structure of mechanical hydraulic control system of governor and its principle were described, and oil line of mechanical hydraulic control system was analyzed. It found that after the operation of the emergency pressure distribution valve, the pressure oil velocity in pipe was too fast, so the pressure of the control chamber of the segment closing device was reduced and the hydro-generator speed was too high because of the long closing time of the servomotor. The oil intake port of the control pressure oil of the stage closing device can be moved from the main pressure oil supply pipe of the emergency pressure distribution valve to the energy storage tank of the governor system. The feasibility of the scheme was verified by test.

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.

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.

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.