The geological conditions of Kala hydropower station are very complex and there are many re⁃ strictive factors in layout. In the feasibility study stage, tailrace surge chamber is set. In the optimal lay⁃ out of project, the water diversion and power generation system are moved outward as a whole, and the length of water transmission line is effectively shortened. According to the specification, the need of tail⁃ race surge chamber is in a critical state. Therefore, the transition process analysis and justification of cancelling the tailrace surge chamber in Kala hydropower station are carried out. The results show that the transition process of large fluctuation and small fluctuation can meet the requirements of specifica⁃ tion. It is proved that cancelling the tailrace surge chamber is feasible and has significant economic ben⁃ efits, which can provide reference for the design of similar projects.

The safety management for hydropower dam is a work that emphasizes both management and technology, and is an important part of implementing the main responsibility of power enterprises. This study provides an overview of the content and key points of safety management for hydropower dam, in⁃ cluding the implementation of laws and regulations, establishment and improvement of institutional mechanisms, talent cultivation and daily work, which can provide reference for the daily management of power enterprises.

This paper provides a systematic summary of the current status and development direction of the standards system, regulatory system, management mode and technology for dam safety of China′s hy⁃ dropower stations. Responsibility shared among power enterprises, government departments and Large Dam Safety Supervision Center is established as the dam safety management mode of China′s hydropow⁃ er stations. China has released 101 effective standards and formulated a system table for dam safety stan⁃ dards. China has established a regulatory system centered around Regulations on the Supervision and Management of Operation Safety of Hydropower Dams. In the future, China will revise regulations, im⁃ prove standards and develop technologies to enhance the emergency response capability, informatiza⁃ tion, intelligence and internationalization level of dam safety, and promote the stable and far- reaching development of dam safety management.

With the continuous development of basin-level clean energy bases, integrated regulation of hydro-wind-solar power has become an important direction for the development of existing hydropower stations, which presents challenges for the traditional regulation of cascade hydropower centralized con⁃ trol centers, and the introduction of systematic and integrated regulation theory and methods is required. In response to this, a multi-time scale sequential nested regulation architecture for integrated hydrowind-solar system is constructed based on the actual needs of the lower reach of Jinsha river basin. The core business model is analyzed, and an integrated regulation process is established to provide a system⁃ atic solution for promoting the new energy consumption and ensuring the safe and efficient operation of hydropower stations in the clean energy bases.

This study puts forward a vehicle for the inspection of penstocks in hydropower stations, which has been successfully applied to the safety inspection of the penstocks of Unit 4 in Manwan hydro⁃ power station, to ensure the safe operation of penstocks.

The uplift pressure and seepage volume are the most intuitive reflection of the foundation seepage behavior of concrete gravity dam. To get the general variation of the foundation uplift pressure and seepage volume of the gravity dam during operation period, the monitoring data of the main concrete gravity dams in domestic power industry are analyzed. The results show that it is a common phenomenon that the uplift pressure coefficient of partial foundation of the gravity dam exceeds the design value. However, due to the large safety margin in design, the anti-sliding stability of dam foundation could still meet the specification requirements in review and calculation. Under normal conditions, the foundation seepage volume of gravity dam is not greater than 5.0 L/s. The seepage flow of dam foundation of different projects is closely related to geological conditions, seepage control effect and earthquake, but has a weak correlation with dam height or dam crest length. The study results could provide some reference for monitoring data analysis and seepage safety evaluation of concrete gravity dams.

In order to enhance the real-time capability of flood risk analysis and adapt to the dynamic characteristics of flood evolution, a 3D real-time flood risk analysis system based on the B/S architec⁃ ture has been designed. This system employs a coupled approach of the breach flow calculation software BREACH and the 2D hydrodynamic numerical model for dam-break flood calculation and simulation. It integrates WebSocket technology for real-time data transmission and utilizes Cesium 3D visualization platform to display the flood evolution. The core functional modules of this system are scenario manage⁃ ment, real-time calculation and calculation result analysis of dam-break flood, which can support dy⁃ namic management, real-time calculation and result visualization of the dam-break process. The system was validated through the case study of a reservoir. The results showed that the system can effectively re⁃ flect the flood inundation process, obtain reasonable calculation results, and enhance the intuitiveness of flood risk analysis and the decision-support capability through visualization technology

The static leveling system for dam foundation of Daheiting reservoir has been in operation for nearly 20 years. During operation, abnormal values were detected at measuring points. Through the mon⁃ itoring system test, on- site and monitoring data inspection, and manual observation data comparison and analysis, comprehensive analysis and study of the abnormal conditions existing in operation are con⁃ ducted to find out the cause reasons, and it is determined that the vertical displacement of dam founda⁃ tion is normal and the dam body is operating stably, which can be used for reference to similar projects.

Taking factors affecting the accuracy of static leveling as the starting point, this paper analyz⁃ es the degree of influence of temperature difference and barometric difference in pipeline, pipe diame⁃ ter, etc, and proposes corresponding solutions. Also, this paper analyzes bubbles, liquid corrosion, dew condensation on float surface, contact friction, sensor measurement error and other factors, and proposes corresponding optimization methods. The error propagation rule of the static leveling system is explained and the pipeline test process is described, which can check whether the static leveling system works nor⁃ mally. Through comparison and analysis of artificial leveling observation data and automatic static level⁃ ing data of a typical project, it is concluded that after taking various methods, the measurement accuracy can meet the requirements of specifications.

To ensure the stability and reliability of gate opening and closing, a dual hydraulic cylinder configuration is typically used to drive the gate. Synchronizing the two cylinders becomes a critical fac⁃ tor when equipping the emergency actuator for the hoist. In this project, the method is applied that multi⁃ ple hydraulic hoists are able to share a single hydraulic emergency actuator for polling display of open⁃ ing during emergency operation. The emergency actuator is movable and once connected to the hydrau⁃ lic lines and cables, it can automatically identify the hoist number. The synchronized operation of two cylinders to open or close the gate is realized through relay interlocking protection, opening collection signal splitting and other mechanisms. The feasibility of using a single emergency actuator to alternately control three hoists is validated through on-site installation, testing and operation, which meets the ex⁃ pected performance and can offer reference for the emergency operation of similar hydraulic hoists in hy⁃ dropower stations.

Face-slab crack is considered as an influence factor of dam seepage to propose the seepage safety monitoring statistical model and RBFNN model. Combined with the specific project, the seepage monitoring statistical model and RBFNN model of a concrete face-slab rockfill dam are established, and the seepage flow is predicted. The prediction results are close to the actual monitoring values. At the same time, the weight of each influence factor of seepage flow calculated by RBFNN is not significantly different from the results calculated by traditional statistical methods, which shows that the model pro⁃ posed in this study is effective and applicable. The research results are of guiding significance for treat⁃ ment of the abnormal seepage flow mornitoring values of concrete face-slab rockfill dam with cracks.

Based on the digital twin platform, the intelligent engineering safety analysis and early warn⁃ ing system is studied and designed. The mechanism model of engineering safety monitoring is studied by using the data mining, intelligent analysis and diagnosis technology. To obtain early warning indexes for specific project, the evaluation system and criteria are developed, which has realized intelligent safety analysis and early warning. Moreover, it has been applied to a project and resulted in improvement of the accuracy and timeliness of early warning, enhancement of the level of intelligence, and decisionmaking support for the operation management department.

Acquiring dynamic material parameters of concrete dams is of great significance for verifying their seismic safety performance. At present, a common approach involves identifying the modal parameters of concrete dams from strong motion observation data and then constructing an objective function based on this information to optimize the material′s dynamic parameters. In this paper, modal parameters are identified based on strong motion observation data while simultaneously time-domain indicators from the seismic response sequence are extracted. A joint inversion of material dynamic parameters is conducted by constructing an objective function that combines both time-domain and frequency-domain information. Since the two objective functions differ in units and dimensions, a multi-objective optimization calculation is performed using the fast non-dominated sorting genetic algorithm with elitism strategies to obtain the Pareto optimal solution set for the dynamic material parameters of the concrete
dam. Inversion analysis of a specific engineering case demonstrates that the joint inversion method for concrete dam material dynamic parameters based on time-frequency domain information exhibits strong parameter identification performance and high stability, offering good application prospects in practical projects.

The purpose of online dam safety monitoring of hydropower stations is to dynamically evalu⁃ ate the dam safety status in real time, which can provide technical support for preventing dam break, overtopping and major structure damage. The online dam safety monitoring system should be practical, effective and useful. It is necessary to develop and approve a practical and effective monitoring plan be⁃ fore system development. Based on the statistics and analysis of the causes of dam failures in the dam en⁃ gineering history worldwide, this paper explains the risk identification and monitoring elements of dam operation safety, and proposes suggestions for the content, items and information organization of online monitoring, to provide reference in the development of online monitoring plan.

The deformable body of Guobu slope is on the right bank of Laxiwa hydropower station, 0.9~1.7 km upstream the dam. It is an ultra-large granitic rock slope with a volume of 102 million m 3 , affected by various deformation mechanism, mainly toppling deformation, and is classified as Class B Grade I. After the reservoir impoundment in March 2009, obvious deformation of Guobu slope is observed. Hence, scientific research, safety monitoring and risk control measures are carried out, including geological exploration, deformation monitoring, numerical calculations using various methods, and stability analysis. Due to the high deformation rate of Guobu slope in the early stage of reservoir impoundment, the deformable body of Guobu slope was assessed as a major hazard of Grade Ⅱ. In 2018, based on study results, Guobu slope was reclassified as a safety risk of Grade Ⅱ (acceptable risk of Grade Ⅱ). In October 2015, the reservoir water level reached the normal impoundment level of 2 452 m. Long-term monitoring data since then show that the deformation of Guobu slope has slowed down after the reservoir water level stabilized between 2 450 m and 2 452 m. The daily deformation rate by the monitoring point at the maximum deformation decreased to less than 2 mm/d. Currently, the deformable body of Guobu slope is generally stable, and the risk is controllable. This paper introduces the specific measures and achievements in the treatment of the deformable body of Guobu slope of Laxiwa hydropower station, for reference.

Concrete dams are affected by changes of water pressure and temperature, resulting in low ac⁃ curacy of combined prediction of deformation. To address this issue, a combined prediction model for concrete dam deformation based on drone oblique photography is constructed. This model calculates the horizontal distance based on the geometric principle of photography, corrects lens distortion and obtains the coordinates. Based on the SIFT feature domain, the local features of the image are extracted, a threedimensional model is constructed, the root mean square error of combined prediction is calculated, and the combined predictive values of variable weights are obtained. The prediction process is designed to realize real-time prediction. The practice results show that the horizontal displacement prediction is ac⁃ curate, and the vertical displacement prediction has the maximum error of 0.5 mm, which has a precise prediction result.

A high arch dam is located in an alpine valley with complex hydrogeological conditions. After impoundment, significant seepage has occurred in multiple drainage holes of the drainage tunnel of dam foundation on the left bank, which is a key concern of the project. To identify the cause of the seepage, based on the hydrogeological conditions during impoundment, seepage control and treatment measures, pseudo-random flow field method detection results, monitoring and inspection results, combined with nearly 10-year monitoring data under the 80 m cycle of reservoir water level fluctuation, a comprehensive analysis is conducted on the characteristics of seepage and seepage pressure in the drainage tunnel and behind the curtain, as well as the source of seepage. The results indicate that the curtain in dam foundation of the left bank is effective, the seepage and seepage pressure have decreased year by year and tend to stabilize, and the seepage volume is much smaller than the design pumping and drainage capacity of the dam foundation drainage well. The seepage mainly comes from mountain groundwater and downstream river water, and the seepage is safe and controllable.

Shape accel array is widely used as it′s automatic, precise and reusable. Combined with the application of shape accel array to the deep deformation monitoring of the slope of a hydropower station, this paper introduces the components and application of shape accel array. The practice shows that the monitoring data are reliable and the system is stable, worthy of promotion to similar projects.

Using finite element numerical model, combined with the geological conditions, material char⁃ acteristics and seepage field, a deep analysis of the seepage stability status of Luotian reservoir dam is conducted, and the safety performance of the dam is evaluated comprehensively. The results show that the seepage control of Luotian reservoir dam is good under various operation conditions, the saturation line rises as the reservoir water level rises, the seepage flow has little influence on reservoir water stor⁃ age, and the safety factor of anti-sliding stability can meet the requirements of regulations. The research results can provide theoretical support and technical assistance for the safe operation and management of Luotian reservoir dam, and can also provide useful references for the safety evaluation of seepage sta⁃ bility of similar projects.

To solve the problems that the transient deformation of dam structure is difficult to predict and the accuracy of deformation monitoring is not high, Beidou/global navigation satellite system technology is used to optimize the existing monitoring system, aiming to improve the monitoring accuracy as well as data transmission and processing speed of the system. The comparison results show that the optimized system is significantly better than the former in aspects such as degree of automation, deformation prediction accuracy, communication stability and monitoring accuracy, and the transmission and processing time of the optimized system is shortened by 11.7 s.