Along with the development in construction of high dams and large reservoirs, large scale and light weight hydraulic steel gates with increasingly larger sizes, higher working heads and greater discharging capacity have been adopted in water conservancy and hydropower engineering. The safety and flexible operation of hydraulic steel gates become crucial to the security of the dams and the downstream people's life and property. This paper summarizes and discusses the developing trends and the main problems to be studied through a comprehensive analysis on the advances and achievements in the research of large hydraulic steel gates. We found out that the research focuses on the following key problems: reasonable layout of the space frame structures of large radial gates under comprehensive conditions; optimization design methods based on the reliability of space structure systems; calculation theories and methods of deep beams, thick plates and other rigid frame structures; dynamic stability and vibration control of radial gate space frames under flow induced vibrations; failure mechanism of low temperature and low cycle fatigue under cold environment; innovation in light stable bionic tree structures of hydraulic steel gates; optimization of the structures and hydraulic characteristics of super-sized steel gates for ecological landscape; life cycle safety intelligent monitoring and diagnosis of hydraulic steel gates; development and application of super steel material, glue-welding and other new technologies.

It is extremely difficult to carry out fine management and control of the full life cycle of water conservancy objects due to their large quantites, a wide range of types, a wide spatial distribution, complex operation environments, and many interrelated factors. To solve this problem, a fundamental approach is to combine a certain water conservancy big data technology characterized by association analysis with a professional mechanism model characterized by causality, integration and fusion, and efficient process; to analyze the massive and multi-source data intelligently; and to proactivily present useful highly-visualized results to management decision-makers. This paper provides a review on the concept of water conservancy big data and its technology system, along with an overview on the research status quo of natural law analysis, situation research and judgment, trend prediction, and decision optimization for water conservancy. We find that the future trend in big data technology development is toward scenario-based demands, management integration, analysis intelligence, service platforms, and guarantee systems. In water conservancy big data application, data are fundamental, analysis is the core, and the ultimate goal is to improve the efficiency of water treatment by using big data technology. Thus, we should deeply tap the real demands of water conservancy business management; integrate the panoramic data in the fields of water disasters, water resources, water environment, water ecology, and water engineering; comprehensively lay out the research on basic theories and core technologies, so as to accelerate the deep integration of big data technology with water conservancy and support the complete transformation and upgrade of water governance in China.

The performance of hydraulic turbines, as the core mechanical equipment for developing hydropower, determines the development and utilization rate of hydropower. Driven by the progress of modern science and technology, hydraulic turbine technology has made a great progress in China, it has experienced the developing stages of introduction, absorption, digestion and recreation, and now has reached an internationally advanced level after a rapid development over recent two decades. This paper focuses on the key research advances made in the field of turbine technology in the past two decades, based on a comprehensive synthesis of research achievements in this field in China and abroad. The progress is summarized in three parts: hydrodynamic foundation of hydraulic turbines, optimal design theory of hydraulic turbine flow components, and development of new hydraulic turbines. This paper also discuss the problems in some of the research fields and present a prospect for the development trends in hydraulic turbine technology.

Stepping into the new century, China has a number of major water conservancy projects built or under construction. Most of them feature with public welfare or quasi-operation, and adopt the PPP financing pattern and a governance framework of "government leading + market mechanism". This paper chooses three representative major water conservancy projects using the PPP pattern already built or under construction, and examines their top-level governance structure. We find that the pattern can be aimed at a single construction of the project, not necessarily at the whole project. And the responsibility for project implementation can be taken by the project entity established by the government, not necessarily by the financing enterprises. Case analysis indicates that various ways can be found to apply the PPP model or establish the project entity, but both applications are not independent from each other. Hence, it is necessary to combine both and then select a satisfactory project top-level governance structure. In this work, a method for designing feasible schemes is developed and optimal schemes determined using an entropy weight-VIKOR method, on the basis of analysis of the top-level structure as demonstrated above.

This paper presents a novel method for urban flooding risk assessment, incorporating social information that was not yet or less considered in previous studies. We have obtained flooding data from an urban storm water model and collected social information from webpages using the web crawler technology. Then, using these two types of information, we build an assessment index system of urban flooding and an exponential model, so as to achieve a comprehensive evaluation of urban flooding risk for the study area. Application to a study site, the Qingnishier region in Dalian, shows that for the 50- and 100-year return periods, the calculated areas of high-risk zones are 0.53 km2 and 1.24 km2, respectively, if only the flooding information is taken into account, while they become 1.12 km2 and 1.50 km2, respectively, if the social information is also included, revealing considerable increases in the latter case. Incorporating social information in the model will significantly raise the flooding risk level in strategic locations such as densely populated urban areas, traffic arteries, but it will lower the risk level in those unimportant areas, which indicates an improvement of the modeling.

With popularization and application of the project general contracting model in the water conservancy and hydropower industry, the integrated design and construction model led by design has become an effective means of reducing costs and increasing efficiency, unified management, and scientific decision-making. This paper reviews the recent advances in the research of general contracting models, design models, construction models, and design and construction collaboration models for the water conservancy and hydropower industry in China and overseas; and clarifies the current pain points of this industry and its major bottlenecks in developing and implementing such integrated models. We investigate the key roles and concept of applying the informatization technology forefront, deepening technological innovation and practice, and adopting the top-down design and lean construction models in solving the existing problems of low design optimization efficiency in design and construction integration, cumbersome mutual feedback of design and construction information, and low level of intelligent construction. To further develop this concept, taking the digital twin technology as a basic application framework for the future, we expound key research directions for further research, and suggest how to promote the integrated design and construction in hydropower development and overcome the shortcomings in water conservancy informatization.

The total number, maximum height and engineering scale of concrete dams in China rank the first in the world, and their long-term safety is a focus of public attention. Deformation is a comprehensive performance of concrete dam structures, especially the long-term deformation, a key index for evaluation of the structure behaviors, health status, and their evolution of a dam in long-term service. This paper summarizes the state of arts in creep calculation models for dam concrete and foundation rock and in the methods and models for safety monitoring and early warning of high concrete dam long-term deformation, based on analysis of the latest construction of concrete dams in China and concrete dam failures caused by long-term dam deformation. To ensure the safety of concrete dams in long-term service, future studies should focus on three issues: evolution of structure performances under the coupling effect of multi-factors, long-term structure deformation behaviors under the coupling effect of multi-fields, and evaluation of performance improvement under reinforcement measures.

This paper first reviews the advancements in dam construction and development in hydraulic engineering, and summarizes the conceptualization of digital dam and its related research achievements. Then, we present an interpretation of the difference between the two concepts of digital dam and smart dam, based on a brief discussion on several disadvantages of digital dam, including insufficient depth in intelligent analysis of massive data and relatively low fusing level of site monitoring, simulation analysis and intelligent control. Smart dam is a new concept that is based on the digital dam conceptualization but emphasizes a specific form of dam development, i.e. adoption of new-generation information technologies as a basic means, such as Internet of things, intellectual technology, cloud computing, and big data. This concept also means a specific intelligent system of dam management and operation that is dynamic, refined, and perceivable in analysis and control. Besides, a smart dam often has distinctive features such as integrity, interoperability, fusion-expansibility, autonomy, and robustness. Third, we describe a basic framework of smart dams in detail, including a real-time information perception module, an interconnected real-time transmission module, an intelligent real-time analysis module, and an intelligent real-time management decision system, focusing on analysis of the progress and superiority of smart dams over digital dams in independent information collection, smart reconstruction analysis, intelligent decision, and integrated visualization. Finally, we explore key directions of smart dam research in fundamental theory, key technology, and management and operation system.

The fusion of mechanism and data is crucial to accurate and efficient assessment of the dam life cycle state and reservoir regulation. This paper discusses the major problems in dam construction and the development of fusion models, and suggests three types of structure for a mechanism-data-driven model－series, parallel and hybrid－along with a brief description of its basic characteristics and applicability. Then, the application and applicability are demonstrated in detail through an example of temperature field analysis for a concrete arch dam. Results show that this fusion model is more accurate and stronger in analysis, prediction and generalization of dam construction and operation, and it is applicable to complicated dynamical-evolving data. Compared with the traditional model, all the three model structures are advantageous. The mechanism-data-driven model provides a new perspective and paradigm for solving the problems of parameter inversion, monitoring and analysis, and strategy optimization in the stages of dam construction, operation and maintenance.

The Wudongde and Baihetan hydropower stations on the Jinsha River are the largest hydropower projects under construction with application of the most challenging technologies under complicated environmental conditions. Construction of the 300-meter super high concrete arch dams is faced with multiple key technological obstacles and management challenges in safety and high quality. Based on the principle of intelligent closed-loop control of comprehensive perception, real analysis and real-time control, this paper deeply integrates the modern information technologies with hydropower engineering construction and formulates an intelligent dam construction technology route focusing on the core construction processes and main business processes. To meet the demands of building these two dams in safety and high quality, key technologies ? such as whole-process real-time monitoring of concrete construction, real-time control of concrete temperature, whole life cycle safety and work performance evaluation, performance review of low-heat cement concrete dam, and in-depth research of an intelligent construction platform iDam ? have been explored and applied, and related intelligent control equipment and management systems have been developed. Engineering practice shows that the key technologies and management platforms achieved in the intelligent construction have greatly improved the technology performance and management efficiency of project construction, enhanced the core competitiveness of Chinese hydropower industry, and provided better technical support for the development of hydropower project and infrastructure construction along the Belt and Road.

To implement the dual-carbon strategy, energy is the main battlefield and electricity the main force; developing a new power system with new energy resources as the main body is the only feasible path to achieving carbon neutrality. This paper examines the emission reduction targets, electricity composition, and structure of the power industry under the dual-carbon strategy, and demonstrates that accelerating the construction of conventional hydropower stations and pumped storage power stations is an important basis for solving problems and challenges such as the reliability and long-term regulation capabilities of the new system. Based on the hydropower resources endowment and the development status, we present a strategic idea of strengthening the coordinated development of hydroelectric power and new energy, and redefine the development path of building clean energy bases and energy storage plants and accelerating the construction of pumped-storage power stations and cascaded conventional hydropower reservoirs. This new positioning of hydroelectric power in the new system not only provides basic electricity but plays its capacity function. Thus, we suggest certain policy should be formulated to speed up the construction of clean energy bases and energy storage plants. Our findings could help the revision and compilation of the planning schemes and regulations.

With increasingly frequent and severe urban flooding disasters, construction of sponge cities that is based on the low impact development (LID) technology, is becoming a new principle for urban storm water management in China. In this study, a storm water management model (SWMM) was developed to simulate the flooding in the Qinghe catchment in Beijing, and urban rainfall-runoff processes in the conditions of different scales of LID measures and different return periods of design storms were simulated and analyzed. The results showed that for shorter return-period storms, reduction in peak flow and runoff volume achieved by combining these measures was up to 66.2% and 49.4%, respectively, while for extreme floods, the reduction in runoff volume was only 11.5% and no considerable reduction in peak flow was achieved. This indicates that the adopted LID facilities are effective in changing the rainfall-runoff processes of shorter return-period storms but ineffective in reducing floods of longer return periods. This conclusion is helpful for flood control, drainage management, and construction of a sponge city in Beijing.

Tidal current energy is a type of renewable and sustainable marine energy. Despite the complexity in exploitation, considerable improvement has been achieved since the beginning of the current century. This paper discusses the hydrodynamics progress through the perspective of equipment design and industrial application of tidal current energy technology, including tidal resources estimation, kinetic energy conversion, converters, and tidal farm array arrangement and design, then summarizes representative hydrodynamics problems, their theoretical models and numerical methods. Technical characteristics of converters and supporting structures are also analyzed to highlight new problems and developing trends in the present stage, offering references for optimal design of tidal energy converters and power station projects.

Based on the fifth generation atmospheric reanalysis dataset ERA5 of the European Centre for Medium Range Weather Forecasts (ECMWF), we define two types of hot droughts or compound drought-hot events－simultaneous occurrences of meteorological drought/agricultural drought and high temperature. We examine the evolution of such an event occurred in the Yangtze River basin in the summer of 2022, and evaluate the variations in its several characteristics such as duration and spatial coverage. The results show that this hot drought began in June, became most severe in August, and weakened in September; its spatial scale varied significantly, starting from the middle and lower reaches, gradually expanding to the whole basin, and reducing to the middle and lower reaches by September. And compared with typical events in historical periods, its characteristic values were the largest. We find a significant increase in the characteristic values of the two types of compound drought-hot events in July and August from 1979 to 2022. The results deepen our understanding of the hot droughts and extreme events in a river basin and can be useful for coping with extremes under global warming.

Current hydropower development in the lower Jinsha River encounters great technical and management challenges, including complicated and harsh natural conditions, rapid changes in social environments, diversified interests, and trans-regional multi sub-projects. This requires further improvement on the existing capability of large-scale project construction for forecast, analysis and control of the projects to minimize their uncertainties brought about by human factors, changing environments and construction conditions, so that the target of six managements of construction projects can be better achieved. To this end, a concept of intelligent dam was formulated and introduced into the construction management of Xiluodu ultra-high arch dam, and intelligent construction technologies were developed and applied to typical dam construction procedures. Based on these applications, this paper describes a theory of intelligent management of large-scale construction projects that was formulated by combining current project management trends with extensive applications of information technology. We also present a technical framework of this new type of management that applies a closed-loop intelligent control principle developed in this study and featured with comprehensive sense, accurate analysis, and real-time control. This framework have five key components: starting from a 3D GIS/DIM structure and multi-source data, targeting at the capability of creating life-long asset value, dynamic simulation and real-time control of actual working states as its core technology, a TGPMS/iDam system as a platform for comprehensive task integration, and N-dimensional enhanced collaborative management as its guideline. The new management framework and theory presented in this paper would be helpful in shaping and upgrading traditional construction project management to a new level characterized by informatization, digitalization, and intellectualization to achieve better project construction in quality, safety and efficiency.

This article reviews the historical development of dam construction, summarizes the developing trend and key technologies of intelligent construction of dams, sorts out the relationship between the key issues in intelligent construction and intelligent control, and presents a basic control theory for intelligent construction of dams. The concept and definition of intelligent control and its characteristics, theoretical structure and elements are elaborated in detail, and "intelligent decision-making plus automatic control" is clearly defined as its two core elements. On this basis, an intelligent control system for dam construction－featured with the functions of autonomous perception and cognitive information, intelligent organization planning and decision-making tasks, and automatic control of executive agencies to accomplish goals－is constructed; its design concept, component elements, module characteristics, and application levels are explained. This intelligent control theory lays a theoretical basis for solving a variety of dam construction problems: structural service state control, full life cycle safety performance evaluation, construction risk prediction, early warning during dam construction, and cost control. It is also essential to realize the intelligent construction goal of high quality, high efficiency, safety, economy and greenness.

The Xiluodu hydropower station is the world’s top three to date, with its overall scale and technical difficulty ranking high globally among the large hydropower projects. In its construction, a great many technical problems have been solved and a wealth of management innovation accomplished. Using the case study method, this paper describes systematically a batch of innovation achievements in the dam construction, such as intelligent construction technology of 300m-class super-high arch dams, temperature control and crack prevention technology for mass concrete and lining concrete, and construction technology of high-velocity-flow spillway tunnels with large flood discharge and giant underground powerhouses. We also examine the fruits achieved via the concept of green hydropower construction, implementation of environmental planning and design, and innovation in construction technologies. We suggest and discuss a number of new concepts and methods–a concept of standardized, orderly, coordinated and healthy construction management for large hydropower projects; a project management system comprising six goals and nine supporting factors; an innovative management mode of industry-university-research-application collaboration; a method to optimize engineering planning, design and construction; a one-step finishing method based on dynamic analysis of complex rock mass engineering. These achievements ensure safe, high quality and efficient on-schedule construction of this hydropower station and its stable operation, generating tremendous social and economic benefits and

When the Mann-Kendall (MK) method is used to detect the trend in serially correlated hydrological series, it is often difficult to obtain an accurate result, due to the influences by significant higher-order autocorrelation components or the trend damage in removing the lag-1 autocorrelation in the series. Aiming at this difficulty, this paper presents a hybrid MK test model combining a modified over-whitening (MOW) process and assembling the change point tests in regression and variance and the detrended methods to segment the original series and provide a set of suitable sub-series to over-whitening. In this model, the over-whitening is calculated in sections to remove the high-order autocorrelation while destroying the original trend component as little as possible. The test results of the runoff series at Linjiacun, Shenmu, Zhaoshiyao and Hengshan hydrologic stations indicate that the segmental over-whitening process can retain the trend change in the original series when eliminating its significant lag-high autocorrelation and ensure more accurate results in the MK trend test on over-whitened series.

Climate change is closely related to energy-power supply and demand. In the summer of 2022, the upper reaches of the Yangtze River experienced three worst cases: the highest temperature, longest continuous hot days, and lowest rainfall in the same period in history. This resulted in a daily power shortage of 17 million kW and 370 million kW?h in Sichuan, a major hydropower province, and imposed a significant impact on its social and economic development and people’s livelihood. To guarantee energy and power safety, it is of great significance to establish power planning mechanism and some countermeasures for power supply guarantee in extreme weather. This paper presents an analysis on the impacts of extreme weather in the 2022 summer on the power supply guarantee in Sichuan, and examines the shortcomings of previous electric power development. We suggest certain countermeasures for the period of power transformation－such as water-wind-solar-thermal energy complementarity, and a coordinated development of power supply and power grid.