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.

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.

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.

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 safety technical standard system for hydropower dams serves as the safeguard mecha ⁃ nism for dam safety. In this regard, China has established specialized organizational bodies responsible for the planning, development and management of safety standards for hydropower dams. In nearly three decades of progress, standard development has been carried out in key areas such as safety monitoring, safety management and evaluation, safety risk assessment and emergency management, safety informati ⁃ zation and decommissioning management, gradually improving and refining the safety technical standard system for hydropower dams. This paper outlines the development history and achievements of hydro ⁃ power dam safety standards, elaborates future directions and tasks of standardization efforts, and intro ⁃ duces the latest released standards.

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.

The safety of hydropower dams is of significance for the lives and property of people, energy security, and the stability of economy and society. The dam safety monitoring system serves as the eyes and basis for supervising and evaluating dam safety, while routine monitoring and inspections of dam safety are a major task in the operation of hydropower stations. Timely detection of anomaly during dam operation requires not only a reliable dam safety monitoring system but also the practice of standardized and orderly monitoring and supervision. The former relies on technological advancement and progress while the latter depends on the continuous improvement of regulatory framework, technical standards, management concepts, as well as the competence and capabilities of personnel involved.

Work summary and practical considerations on online safety monitoring technology for hydropow ⁃ er station dams// by ZHANG Xiuli// Dam Safety Monitoring Center of National Energy Administration Abstract: The author summarizes the progress and achievements of the Dam Safety Monitoring Center of National Energy Administration in promoting online monitoring technology development for hydropow ⁃ er dam safety over the past two decades, highlighting that online dam safety management is an essential component of the dam safety lifecycle management system. It is crucial to promote and implement online dam safety management widely. The author emphasizes that the development of online dam safety moni ⁃ toring system should focus on practicality, and proposes four key recommendations of prioritizing practi ⁃ cality, emphasizing research on monitoring schemes and indicators, ensuring meticulous and accurate processing of routine dam safety monitoring data and inspection results, and paying close attention to the planning, design and oversight of online monitoring platform development.

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.

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.

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.

At present, the intelligent and smart safety management for hydropower dams in China is still at an early stage. Numerous institutions in the industry have carried out extensive explorations in intelli ⁃ gent operation and maintenance of hydropower dams, leading to the preliminary formation of an intelli ⁃ gent technical system for dam safety operation. This paper systematically analyzed the current status and practical demands of intelligent construction for hydropower dam operation safety. By examining the ap ⁃ plication of statistical models, neural networks, deep learning, knowledge graphs and AI large models, this study reviewed and discussed recent advances and future prospects in intelligence research of hy ⁃ dropower dams from the perspectives of intelligent information sensing, data-driven analysis, structural health diagnosis and intelligent decision support, aiming to provide some insights and reference ideas for smart dam development in future.

The Jiudianxia water conservancy project is located in the high altitude and cold area. Its dis⁃ charge tunnel on the left bank is easy to freeze due to the low temperature and the wind through tunnel. The durability of lining concrete in the tunnel is seriously damaged by the freeze-thaw cycle, which af⁃ fects the service life of the tunnel. This paper puts forward a design scheme of installing flat insulation gate at the opening of underground tunnel to solve the problems of seepage water freezing and cyclic freeze-thaw damage to the lining concrete.

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 design task of pumped storage project is heavy, the time is limited, and there are many disciplines involved. Therefore, traditional design methods are unable to satisfy the current situation and requirements. Using BIM technology, through meticulous application planning, the collaborative design is carried out, covering surveying, civil engineering, mechanical and electrical engineering, and other re - lated disciplines. It can significantly improve the rationality of design schemes, enhance the accuracy and quality of design results, increase the diversity of results, liberate the productivity of designers, and provide a solid foundation for the application of digital twin pumped storage power stations. This study briefly describes the way to choose a suitable 3D digital collaborative design solution for pumped storage power stations and carry out 3D digital design, as well as the value and advantages of 3D digital technol- ogy in the design stage of pumped storage power stations.

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.

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.

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.

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.

Based on summary of advantages and disadvantages of common safety inspection methods, technology and equipment of underwater safety inspection are studied and some solutions are proposed, such as miniaturized high-power ROV, multi-beam combined ROV and intelligent unmanned ships. These solutions have addressed challenges of underwater inspection in complex environment such as deep-buried large-diameter long diversion tunnel, high-head multi-bend penstock and high-flow open water area. Moreover, these technologies have been successfully applied to cascade hydropower stations in the Yalong river basin, which is worthy of reference for similar projects.