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.

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.

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.

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.

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.

Construction of large-scale hydropower projects is faced with the complexity of production factor flow, the accuracy and effectiveness of physical measurement, and the problems in forward-looking and real-time management caused by the differences in management systems, business processes and technological processes of all parties involved. This paper reports a series of in-depth studies on how to integrate engineering construction and information technology for hydropower development in the lower reaches of Jinsha River, such as positioning technology and other new-generation information technologies. These studies focus on conducting integrated research and development of a hybrid superposition positioning technology with different accuracies in positioning and different speeds of response in complex environment; formulating a standardized process flow with a uniform management form and coding system for each specialty of electrical construction; developing mobile online application systems; conducting research and development of key process intelligence technologies and equipment systems; and building an information system through the whole process of project pricing. Achievements in these studies ensure the acquisition of comprehensive, true, accurate and real-time data through project construction management, and realize digital dynamic control over the whole process of engineering construction ? flow factors of personnel and equipment, core business processes such as quality and safety; key technological processes such as concrete pouring temperature control and cement grouting; and real physical costs such as unit engineering measurement. The management technologies presented in this paper would promote the optimization of whole management chains such as business chain and process chain, and lay a basis for intelligent construction, and it should be a core part of intelligent technology in engineering construction.

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.

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 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.

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.

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.

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.

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.

In recent years, informatization has improved gradually in hydraulic engineering management, but it is still impossible to achieve paperless file management in a short time. Extra efforts has to be spent on the informatization system in construction sites, which somehow limits the progress and development of information technology. In addition, information in the centralized database is also easy to be tampered, limiting its use in engineering management. Block chain, featured with distributed storage and chain data structure, has shown a great potential in data tamper-proof and traceability. Based on block chain, this paper develops an improvement on the construction management system in hydraulic engineering, which involves specifying a node composition in the system, defining the categories of transactions for construction projects, presenting the data structures of transaction and block, and designing the architecture of the block chain and the system. Application scenarios for typical engineering projects are provided, demonstrating an innovation of block chain application in hydraulic engineering.

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.

The achievement of carbon peaking and carbon neutrality goals mainly relies on innovation in clean energy projects such as hydropower, wind power, photovoltaic and pumped storage projects. Most of the previous studies focus on general scientific and technological management issues such as innovation strategies, management systems, and resource allocation, but lack a holistic understanding of the innovative characteristics of clean energy projects and an analysis of the existing empirical research on different kinds of clean energy project innovation. This paper presents a new system of innovation indexes for these clean energy projects, and reveals the status of innovation in their development through an industry survey. We also identify the main problems in the innovation and their causes, and suggest its future direction and scope. The results have both theoretical and practical implications for clean energy project innovation.

In recent years, water level in Poyang Lake has changed significantly, threatening the ecological security of wetlands. First, this paper uses the Mann-Kendall method to analyze water level changes in this lake in the period of 1990 to 2016.Then, we construct a BP neural network model for simulation of the lake water level, and quantify through scenario analysis the temporal and spatial characteristics of the contribution made to the lake level change by the flow changes in the Yangtze mainstream, lake inflows from the Poyang’s sub-basins, and the topographic change. In time evolution, flow variations in the Yangtze mainstream is the main driving factor of the decreases in the average monthly water level at all the hydrological stations from July through September, and topography is the main driving factor of the decreases in the Poyang’s water level in dry season. Spatially, in the period of July to November, the pull down effects of the Yangtze mainstream flow on the monthly average water levels at different stations rank in a decreasing order as Xingzi station, Duchang station, Tangyin station, and Kangshan station; the pull down effects of topography rank as Duchang station, Xingzi station, Tangyin station, and Kangshan station. Changes in topography are the major cause of the maximum water level variations that occur at the Duchang station.

Based on the cusp-catastrophe model of nonlinear theory, this paper examines the influence of water flow conditions and the relative position of sediment particles on riverbed on the nonlinear dynamic characteristics of sediment transport, formulates the state variables and control variables of this model, and constructs a new cusp-catastrophe model for qualitative description of bedload transport. Through coordinate transformation and topological transformation, a nonlinear bedload transport rate formula is derived. This formula is verified against previous measurements and compared with other formulas of the same theory and the classical formulas. We explain the difference in calculations of low-intensity sediment transport using different formulas, and present an analysis on the cause of sudden changes in the calculation accuracy of high-intensity sediment transport. And the influence of incipient shear stress of bedload motions on the formula of sediment transport rate is discussed. It is verified that our nonlinear formula is reasonable with good applicability.

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.

This paper discusses the difference between waterproofing of building structures and seepage control of hydraulic structures based on the development and application history of geomembrane materials. Through referencing, analysis, exploration and innovation, we describe a new type of dams, namely geomembrane face rockfill dams that use geomembrane as the main material for seepage control. Several projects are analyzed to demonstrate the trend in dam seepage control development. It is thought that geomembrane will become one of the best choices for seepage control in concrete face rockfill dam (CFRD), even can be an inevitable alternative for face rockfill dams and roller compacted concrete dams.