After the reinforcement of Longshan reservoir, there is a problem of settlement, which leads to cracks on the dam crest and has unknown impact on the dam operation safety. This study comprehensively uses pit exploration, drilling and geophysical exploration methods to evaluate the dam operation safety, analyze the current situation of dam filling, investigate and analyze the causes of cracks and settlement problems. Meanwhile, the impact of the infiltration line lowering caused by reinforcement is considered to conduct a preliminary evaluation of settlement. The results indicate that the settlement of Longshan reservoir is mainly due to the low filling quality in some areas of dam body and the infiltration line lowering, which leads to the consolidation settlement of filling material. Although the settlement situation still meets requirements, the risk of continued settlement cannot be ruled out. It is necessary to excavate the non- dense soil and rerun the thickening and reinforcement project. The relevant survey methods and analysis can provide reference for similar dam settlement problems.

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.

In recent years, a large number of pumped storage power stations have been built in China, and the reservoir engineering geological conditions determine the feasibility of the construction. Through on-site geological surveys and tests, the leakage and bank slope stability of the proposed upper reservoir are evaluated. Research has shown that the project is located in an area with prominent leakage problems. It is recommended to deal with the problems of dam foundation leakage and seepage around dam during the anti-seepage of upper reservoir basin. The engineering slope is generally stable. For the broken rock body affected by faults, as well as disadvantage blocks formed by the cutting and combination of faults, interlayer joints and dominant joints, the effective support measures should be taken in time according to the excavation exposing situation.

The major dam shell of Xiaolangdi water conservancy project is filled with rockfill materials containing siltstone, clay rock and other soft rocks. After years of operation, the soft rocks on dam surface have weathered into fragments, and part of soft rocks have been eroded into rockfill voids, which will have a certain impact on the physical and mechanical properties of rockfill materials in the dam shell, such as the permeability coefficient and shear strength, and may also affect the stability of upstream and downstream dam slopes. At the same time, Xiaolangdi dam has large dam height, complex and deep overburden, many kinds of dam materials and complex operating conditions, so it is necessary to study the properties of rockfill materials in dam shell. Through in-situ excavation and sampling, relevant tests of the grading, compactness and permeability of rockfill materials and original rock character and strength are carried out to conduct the experimental study on properties of rockfill materials in the major dam shell. The results show that the main character parameters of rockfill materials in the major dam shell slightly changed, and the weathering degree and compressive strength of rockfill materials have limited influence.

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.

Due to the relatively concentrated timing of water distribution periods, in order to meet the needs of water allocation within the year and improve the water supply guarantee rate, the Xinjiwa reservoir is constructed in Zouping city, as supporting works for the first phase of the East Route Project of South-to-North Water Diversion. This project can realize the water supply goal of South-to-North Water Diversion Project and provide support for the regional national economic development. Focusing on the construction of dams for the reservoir, the design schemes are compared and selected from two aspects: reservoir storage depth and dam foundation seepage interception scheme. The selected design scheme can meet the requirements of the reservoir, and can provide reference for reservoir construction in water supply areas along South-to-North Water Diversion Project.

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

Earthquakes, especially strong earthquakes, may easily cause dam accidents. The actual damage of the dam is determined by the earthquake intensity, which is related to the earthquake magnitude, hypocenter depth, geological structure and the distance between the dam and the hypocenter. To realize the graded warning for dams under the condition of earthquake, it is necessary to use the statistical model to quickly calculate the earthquake magnitude at the dam site and compare it with the design standard. By computer programming, the above-mentioned functions can be realized, which can quickly locate the dam that may be damaged by the earthquake and realize rapid early warning for the dam.

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.

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.

Combined with the operation management of reservoir dams, this paper first analyses the main contents of current research on engineering ethics in the field of hydraulic engineering. And then, based on social and natural dimensions, from the aspects of reservoir resettlement, reservoir degradation and decommision, public education, reservoir big data, reservoir management scope, reservoir aquaculture, biodiversity of reservoir area, etc., this paper discusses how engineers should correctly handle the interpersonal relationship as well as the relationship between mankind and nature in accordance with the code of engineering ethics.

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.

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.

Regulations for operational safety management of hydropower dams are the basis for practice. This paper systematically sorts through the existing regulations for operational safety management of hydropower dams,as well as clarifies the functions of the regulations and the division of responsibilities in dam operation and safety management.Then it is pointed out that tight supervision is formed in China, namely the power enterprises take the main responsibility,the National Energy Administration and its agencies perform supervision duties and Large Dam Safety Supervision Center supplies technical super- vision services for dam operational safety.

The underground powerhouse of pumped storage power station is deeply buried, and is affected by many factors such as drainage gallery, water filling of tunnel, complex geological conditions and natural groundwater, so the complex seepage field is often formed. Based on the FEFLOW software, a three-dimensional steady state model of seepage including water transmission tunnel, underground powerhouse, drainage gallery, surrounding rock and fault is established. According to the simulation results, the initial seepage control and drainage scheme is optimized, eliminating unnecessary drainage galleries in the middle horizontal section and lifting drainage galleries in the lower horizontal section to discharge seepage water in the form of natural flow. The total seepage flow of drainage galleries and cavern group in the powerhouse area is 8 048.16 m ³ /d, which provides a greater flexibility for the selection of drainage pumps for underground powerhouse.

Sensors are needed on site to monitor the safety of water conservancy and hydropower projects.As well,cables are laid to monitoring stations to collect data.Specific installation structures are re- quired for monitoring sensors inside the building,and the centralized cables may exert certain impact on the project.This paper introduces the methods for cable connection,laying and protection,explores the layout and management of piezometer tubes for foundation of concrete dams,studies the installation structure of monitoring sensors for shield tunnels,proposes optimization measures,and proposes the use of horizontal and vertical waterproof cables for key parts of pumped storage power stations with ultra- high water pressure which can substantially reduce the potential risks caused by safety monitoring devices to hydraulic structures.The relevant experience has been successfully verified in practice and can be used as a reference for similar projects.