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.

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.

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.

As a typical multiphase heterogeneous material, concrete has been widely used in high-rise buildings, bridges, dams, nuclear power stations as well as other industrial and civil structures. The whole process of concrete production, transportation, construction, curing and hardening, and its nonlinear mechanical and deformation response subjected to complex loading environments are generally dominated by the physico-mechanical properties of meso-scale ingredients and fabrics, including aggregates, mortar and their interfaces. This paper presents a literature review on the state-of-the-art concrete meso-scale mechanics, emphasizing the development progress on experimental investigation on meso-scale ingredients, pre-processing modeling approaches, and numerical modeling methods for concrete. An in-depth review is also presented on selected aspects on the forefront of the meso-scale concrete mechanics, including the fracture failure mechanism, size effect, multi-scale coupling and rate effect. Finally, some recommendations for future studies are provided.

Studies on the attribution of runoff variation under climate change and human activities are valuable to understanding runoff change. This paper analyzes the quantitative contribution of climate change and human activities to runoff variation, using the Budyko assumption and TOPMODEL with application to a case study of the Beiluo River basin of the Wei River. We have examined 25 scenarios of temperature and precipitation changes in the possible range of climate changes, and analyzed the influence of all these scenarios on the runoff. Simulation results show that historic precipitation and runoff took a decreasing tendency while temperature had a rising trend and both temperature rising and precipitation decreasing made contribution to runoff change. But human activities were the major cause for runoff decreasing over the last 50 years and this had a contribution rate up to 58.9% and 65.2% by the two methods respectively. Under different scenarios, the variation in monthly runoff shows a wide range and the influence of precipitation change is stronger than that of temperature change, indicating precipitation change as a major factor of the future variation in water resources.

In this paper, the recent developments in seismic safety evaluation and aseismic measures for high rockfill dams were reviewed, including advanced constitutive models, dam-foundation-water dynamic interaction, high-performance non-linear dynamic FEM software, numerical simulation of failure process, and aseismic measures of concrete slab, and etc. After that, some future research trends on earthquake-resistance analysis of high rockfill dams were discussed, such as the seismic response analysis, mechanical properties and constitutive relations of rockfill, computing technology, and seismic safety evaluation method.

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.

Climate change and rapid urbanization have modified the process of urban eco-hydrologic cycle, aggravating urban problems such as water shortage, water environment pollution, water ecology destruction, and rainstorm flood disaster. This paper presents a systematic summary of the core indexes and control points of sponge city construction in new and rebuilt urban areas with different planning objectives, to obtain the spatial optimal allocation scheme and multi-objective cost-benefit optimal curve of a system coupling low impact development (LID) facilities or green infrastructure (GI) with urban gray infrastructures. Aimed at the existing issues in research, a regional optimal allocation pattern of rainwater infrastructure is constructed, comprising three major parts–performance index database of rainwater infrastructure, cost-benefit quantification, and computer aided decision-making. The key parameters and performance indexes of typical LID facilities in numerical calculation and model simulation are discussed. Then, the method of quantifying sponge city construction with cost and benefit indexes is analyzed by applying the theory of environmental economics. Finally, multi-objective intelligent optimization schemes are explored for improving urban water environment, water ecology, water resources, and water security with limited cost input. Meanwhile, model simulations are combined to realize the virtuous cycle and sustainable development of urban ecology and hydrology.

This study investigates cracking resistance behaviors of ultra-high volume fly ash conventional dam concrete (UHVFACDC) at early age using a temperature-stress testing machine (TSTM), with a comprehensive consideration of temperature history, constraint, deformation and stress of concrete from the prospective of wholism to overcome the deficiency in the traditional methods of thermal cracking property evaluation of concrete at early age. The experimental results show that in comparison with the reference concrete, this fly ash concrete has lower hydration temperature rise, and cracking temperature and its cracking temperature drop is larger. And during hardening, it manifests a smaller coefficient of thermal expansion and a higher degree of tensile creep. All this indicates that UHVFACDC of great early-age cracking resistance is a promising type of green high-performance dam concrete.

Despite the many challenges facing African economic development, the growth trend continues. With the increasing power demands in various countries, the construction of power infrastructure in Africa is full of opportunities. Africa is rich in hydropower resources with huge development potential, and 80% of the potential are concentrated in the Zambezi, Congo, Nile and Niger River basins. Under the One Belt and One Road initiative, a large number of Chinese enterprises have gone global to invest in hydropower projects in Africa and promote China-Africa cooperation in power sector. This paper summarizes the hydropower resources and development levels of the four major river basins through a large amount of data and information, and discusses the key completed and planned hydropower projects in these basins with details. Finally, we examine in depth the major problems and challenges facing Chinese enterprises in the development of hydropower projects in Africa, and offer corresponding suggestions from four aspects: strategic planning, cooperation model, risk prevention, and personnel training.

Rapid urbanization has an adverse impact on urban rainfall-runoff processes and may increase the flood risk of urban regions. This study considered intensive human activities, such as increases in impervious area, changes in river network morphology, drainage system laying, and water transfer. We have developed two storm water management models (SWMM) based on remote sensing image and field survey, considering different urbanized scenarios and human disturbances and using measured streamflow data for model calibration and validation. Precipitation with different return periods was taken as model input to analyze the changes in flood characteristics caused by urbanization. The results indicate that these two models can produce good estimation of storms under the scenarios examined. The surface runoff after urbanization was 3.5 times larger than that before urbanization; the coefficient of runoff jumped from 0.12 to 0.41 and the amount of infiltration decreased from 88% to 59%. After urbanization, the time for overland flow concentration was shortened while the time for river concentration became longer; the flood peak time did not indicate much difference in this study. The peak flow of 20-year return period after urbanization is larger than that of 100-year return-period before urbanization. The results in this study would provide technical support to planning and management of urban storm water and evaluation on the low impact development technology.

Pumped-storage power plants (PSPs) aim to solve the conflict between power supply and demand at the peak and trough of power consuming, ensuring grid safety, economic growth, and stable production. Invasion and biofouling of golden mussel (Limnoperna fortunei) in PSPs, however, is attracting wide public attention because in recent years the biofouling has caused severe problems in the operation of PSPs. The specific operation mode of PSPs is commonly taken as the major cause for such biofouling in water intakes and tunnels. A PSP releases water stored in its upper reservoir to the lower one when it generates power during peak power-consuming hours, and pumps water back to its upper reservoir during low demand hours. During water releasing and pumping, golden mussel veligers are stirred up from the reservoir bed and transported into the intakes, tunnels, and the other structures reachable by the flow; then they are settled down on the walls of all the structures they have touched, causing biofouling, structure corrosion, and even pipe clog. Particularly, the small tubes of the PSP cooling water system are under a high risk of being clogged, often causing a shutdown accident. This study presents an overview on the latest advances in preventive measures against golden mussel biofouling in PSPs based on previous studies, overseas experiences, and our own experiences. For large-scale water-intake pipes of PSPs, the risk of clogging is low and therefore the basic strategy should focus on pipe wall resistance to the corrosion. Certain environment-friendly, economically-desirable coating materials, e.g. SK-Polyurea and SK-Epoxy YEC, which have been shown very effective in terms of biofouling resistance and pipe-wall durability, are recommended according to our experimental study. For small-scale PSP cooling water systems, we propose a control device of the veliger density in water flow that integrates the measures of attachment-attracting, settling, and veliger killing and thus effectively reduces biofouling risk.

This paper presents a new intermittent wave energy generator (WEG) with a hydraulic energy storage accumulator that converts unstable wave energy into stable output power in electrical power generation, and describes its components and working principle along with a real-time control method for stabilizing the output power based on experimental test database. Theoretical models were constructed for the relationship of load versus working pressure and the relationship of hydraulic motor pressure drop versus opening ratio of the proportional flow valve. The latter relationship was verified by experimental data collected using LabVIEW, and a control curve of the opening ratio was used to stabilize the flow rate of hydraulic motor. Experimental results show that the output power of generators can be maintained stable within a certain range and the new WEG, when combined with hydraulic energy storage accumulator and real-time control based on experimental test database, is an effective device for generation of stable and smooth output power.

Dynamic Soil-Structure Interaction (DSSI) problem is one of the most important issues in the dynamic analysis of structures. Numerical simulations are widely applied to the study of DSSI effects owing to the rapid progress in computational power and numerical schemes. In a numerical method, DSSI system is portioned into a finite domain surrounding the structures (near field) and an infinite region (far field) by either direct method or substructure method. The modeling of the near field may consider nonlinear behaviors, while the modelling of the far field must satisfy the radiation condition at infinity and allows the input from an external source in some occasions. In this paper, various numerical methods that are, in the authors’ opinion, commonly used in the DSSI analysis are reviewed.

In view of the severe situation of urban flooding in China and the development of previous flood simulation models, this paper points out that refining urban flood simulations is a focus in the future studies. Data acquisition methods based on the low-altitude UAV-based photogrammetry can provide high-resolution ground information such as flooded areas in a city, helping build complete databases. By summarizing typical technical indicators and application of this new technology, we demonstrate that it has the advantage of low cost in acquisition of easily updated large-scale data and hence is widely applied in numerous fields. And it also makes it easier to develop or refine flood simulation models through collecting data of landuse, topography, and flooded area, among others. In addition, technologies like three-dimensional modeling and monomer modeling can serve the purpose of better digitalization and refinement of flooding process simulations and result display. Although problems still remain in the application of photogrammetry technology to flooding simulation, it should have a good application prospect as it is improved and further developed in future.

Studies of rill flow hydraulic characteristics are essential to understand the mechanism of rill erosion and develop soil erosion prediction models. This paper presents an analysis on hydraulic characteristics of the rill flows on slope land based on a series of runoff scouring laboratory experiments for the conditions of different soil bulk densities (1.2, 1.35 and 1.5 g/cm3), flow discharges (2, 4, 8 and 16 L /min), and land slopes (5°, 10°, 15°, 20° and 25°). The results show that both flow discharge and land slope are important factors influencing flow velocity. And flow velocity can be expressed in a power function of land slope and flow discharge with the former as the major factor; soil bulk density has a certain influence on flow velocity and its effect varies with land slope. The Reynolds number, varying in the range of 248 to 1932, is independent from soil bulk density or land slope, and has a linear relationship with flow discharge. All the rill flows tested are supercritical of Froude number greater than one. The influence of soil bulk density on the Froude number also varies with land slope, similar to that of flow velocity. The resistance coefficient in the range of 0.04-0.955 increases first and then decreases with the increasing slope or flow discharge, and its dependency on soil bulk density is significant, manifesting a decreasing trend in the case of mild or steep land slope.