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Human-induced breaches in the dikes of the major river systems were a common phenomenon in late imperial China. The article examines cases mainly related to the Yellow River and how these cases were dealt with on the basis of the legal code. While the extensive coverage of such cases in legal documents is an important reminder of the high degree of attention that the state paid to hydraulic installations, the phenomenon also needs to be understood as an manifestation of societal conflicts resulting from the pressures of the demographic and environmental developments of China in the late imperial period. [ABSTRACT FROM AUTHOR]

The development of coalbed methane (CBM) in China is susceptible to the influence of microstructure. Therefore, it is crucial to understand the extension laws of hydraulic fractures and engineering responses in coal reservoirs affected by microstructure development. Utilizing the Dahebian block in western Guizhou as the study area, this investigation examines the coal reservoir characteristics, fracturing, and drainage engineering analysis of the well DC1 group in the region. The aim is to discuss the spatial distribution characteristics of hydraulic fractures, geological controlling factors influenced by microstructure, and their corresponding engineering responses. The results indicate that, for coal reservoirs unaffected by microstructure, the extension laws of the fracture network in both longitudinal and planar directions are influenced by burial depth and the regional stress field. In the microstructural belt, tectonic stress dominates, causing changes in the ground stress field. Consequently, the hydraulic fracture network deviates from the direction of the maximum principal stress during the extension process. When a secondary fracture is nearby, the hydraulic fracture network extends towards the shortest path radial secondary fracture direction, leading to a rapid increase in fracture width per unit length until it intersects with the secondary fracture. Additionally, the presence of secondary joints near the microfault structure decreases fracturing pressure and results in a dense distribution of the fracture network. This promotes the formation of a complex fracture network, favorable for fracturing. The extension of the fracture network in complex structural development areas is influenced by the microfault structure between wells, which is reflected in the fracturing construction pressure and fluid output. This accounts for the significant variations in the early drainage performance of CBM wells. [ABSTRACT FROM AUTHOR]

Taenioides sp. is a small temperate fish originally known to inhabit muddy bottoms of brackish waters in coastal areas of China. However, it began to invade multiple inland freshwaters and caused severe damage to Chinese aquatic ecosystems in recent years. To investigate the sources and invasive history of this species, we examined the population structure of 141 individuals collected from seven locations based on partial mitochondrial D-loop regions. The results revealed that the genetic diversity gradually decreased from south to north, with the Yangtze River Estuary and Taihu Lake populations possessing the highest haplotype diversity (Hd), average number of differences (k), and nucleotide diversity (π) values, suggesting that they may be the sources of Taenioides sp. invasions. Isolation-by-distance analysis revealed a non-significant correlation (p = 0.166) between genetic and geographic distances among seven populations, indicating that dispersal mediated through the regional hydraulic projects may have played an essential role in Taenioides sp. invasions. The population genetic structure analysis revealed two diverged clades among seven populations, with clade 2 only detected in source populations, suggesting a possible difference in the invasion ability of the two clades. Our results provide insights into how native estuary fish become invasive through hydraulic projects and may provide critical information for the future control of this invasive species. [ABSTRACT FROM AUTHOR]

The Dujiangyan Irrigation Project, a globally well‐known hydraulic engineering project, is significant for the Chengdu Plain. In recent years, due to water supply scarcity in the Chengdu Plain and increasing flood disasters in the Min River, the Moertan Reservoir was constructed to alleviate these pressures. The construction resulted in a mid‐reach embankment along the Min River that forced channel narrowing and triggered changes in channel morphology, flow and bedload transport. This study utilised field measurements coupled with physical and numerical models to simulate the resulting characteristics of flow, bedload transport and topographic change for different flood frequencies in the Dujiangyan reach following emplacement of the Moertan Reservoir. The results indicated that following extensive hydraulic regulation, the flow‐bedload transport characteristics and morphodynamics exhibited similar behaviours across different flood frequencies. The presence of a mid‐channel gravel‐cobble shoal (GCS) divided the flow into multiple branches, with the right branch systematically dominating flow and bedload transport across all flood frequencies. Further downstream, the Fish Mouth Levee effectively diverted nearly equal amounts of flow through the Inner and Outer rivers. In contrast, approximately 20% and 80% of the bedload was transported through the Inner and Outer rivers, respectively. The findings were beneficial in providing a reference for the flood season management of the Dujiangyan Irrigation Project and the maintenance of associated hydraulic engineering projects. [ABSTRACT FROM AUTHOR]

The coastal lowlands in East China are very sensitive to climate change and marine disasters, and much large-scale hydraulic engineering was recorded in the historical documents of the Late Holocene. In this study, AMS 14C and OSL were used to date three sedimentary profiles from the north and south coasts of inner Hangzhou Bay, and grain size and geochemical analyses including organic carbon, macro-elements, and alkaline earth metals were performed, while hydraulic engineering records in historical documents were compiled, in an attempt to reveal the sedimentary records of extreme climatic and hydrological events over the past 3000 years and to probe into the correlation between them and hydraulic engineering. The results show that the intensified chemical weathering during ca. 200 BCE to 900 CE in East China corresponded to the warm and humid climate during the Qin-Han and Sui-Tang dynasties. Salinity intrusion with rising local water levels occurred in the lowland plains along the south coast of Hangzhou Bay from 120 to 895 CE. Low-salinity water intrusion from 32 to 488 CE was also recorded in the stratigraphy of lowland plains along the north coast of Hangzhou Bay. The sedimentary records of the East Tiaoxi River basin show river floods about 2000 years ago. The above sedimentary records indicate that the relative sea level rose in the Hangzhou Bay area during the Qin-Han and Sui-Tang Warm Periods, resulting in frequent salinity intrusion and river floods, which coincided with the historical records of hydraulic engineering such as the construction of seawalls, river levees, and the enclosure of lakes for restoration of river floods during the Han and Tang dynasties. Such coincidence reflects that climate change profoundly affected the hydrological environment of the coastal areas in East China as well as the response of the human societies. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Management / Gongcheng Guanli Xuebao is the property of Journal of Engineering Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Xiaolangdi Dam is a key project for the control and development of the Yellow River. It bears the functions of flood control, controlling water and sediment in the lower reaches, ice prevention, industrial and agricultural water supply, power generation, and so on. Its safety is related to people's life and property safety and local economic and social development. It is of great significance to carry out comprehensive and regular deformation monitoring for dams since the deformation is an important evaluation index for dam safety. Interferometric Synthetic Aperture Radar (InSAR) technology has been a rapidly evolving technology in the field of space geodesy in recent years. It offers advantages such as high monitoring precision, extensive coverage, and high monitoring point density, making it a powerful tool for monitoring deformations in hydraulic engineering projects. Based on Sentinel-1 data covering the Xiaolangdi Dam from September 2020 to November 2022, the PS-InSAR technique was used to obtain the surface deformation of the Xiaolangdi Dam, and reservoir water level data on image acquisition dates were obtained for joint analysis. The results show that there is a large deformation in the center of the dam crest of the Xiaolangdi Dam, while both sides of the slope and downstream dam foot are relatively stable. The time series deformation of the dam body is closely related to the reservoir water level change. When the water level increases, the dam body tends to deform downstream; when the water level decreases, the dam body tends to deform upstream. The deformation and water level of the Xiaolangdi Dam exhibit a clear negative correlation. There is no significant cumulative deformation on the dam slopes or at the base of the dam. However, cumulative deformation occurs over time in the central area of the dam's crest. The deformation process at the central area of the dam's crest follows a continuous and non-disruptive pattern, which is consistent with the typical deformation behavior of the Xiaolangdi earth–rock dam structure. Therefore, it is judged that the current deformation of the Xiaolangdi Dam does not impact the safe operation of the dam. InSAR technology enables the rapid acquisition of high-precision, high-density deformation information on the surfaces of reservoir dams. With an increasing number of radar satellites in various frequency bands, such as Sentinel-1 and TerraSAR-X, there is now an ample supply of available data sources for InSAR applications. Consequently, InSAR technology can be extended to routine monitoring applications for reservoir dam deformations, especially for small and medium-sized reservoirs that may not be equipped with ground measurement tools like GNSS. This holds significant importance and potential for enhancing the safety monitoring of such reservoirs. [ABSTRACT FROM AUTHOR]

Seepage is the primary cause of dam failures. Conducting regular seepage analysis for dams can effectively prevent accidents from occurring. Accurate and rapid determination of seepage parameters is a prerequisite for seepage calculation in hydraulic engineering. The Whale Optimization Algorithm (WOA) was combined with Support Vector Regression (SVR) to invert the hydraulic conductivity. The good point set initialization method, a cosine-based nonlinear convergence factor, the Levy flight strategy, and the Quasi-oppositional learning strategy were employed to improve WOA. The effectiveness and practicality of Improved Whale Optimization Algorithm (IWOA) were evaluated via numerical experiments. As a case study, the seepage parameters of the Dono Dam located on the Baishui River in China were inversed, adopting the proposed inversion model. The calculated seepage field was reasonable, and the relative error between the simulated head and the measured value at each monitoring point was within 2%. This new inversion method is more feasible and accurate than the existing hydraulic conductivity estimation methods. [ABSTRACT FROM AUTHOR]

In July 2021, Typhoon In-Fa (TIF) triggered a significant indirect heavy precipitation event (HPE) in central China and a direct HPE in eastern China. Both these events led to severe disasters. However, the synoptic-scale conditions and the impacts of these HPEs on future estimations of return periods remain poorly understood. Here, we find that the remote HPE that occurred ∼2200 km ahead of TIF over central China was a predecessor rain event (PRE). The PRE unfolded under the equatorward entrance of the upper-level westerly jet. This event, which encouraged divergent and adiabatic outflow in the upper level, subsequently intensified the strength of the upper-level westerly jet. In contrast, the direct HPE in eastern China was due primarily to the long duration and slow movement of TIF. The direct HPE occurred in areas situated less than 200 km from TIF's center and to the left of TIF's propagation trajectory. Anomaly analyses reveal favorable thermodynamic and dynamic conditions and abundant atmospheric moisture that sustained TIF's intensity. A saddle-shaped pressure field in the north of eastern China and peripheral weak steering flow impeded TIF's movement northward. Hydrologically, the inclusion of these two HPEs in the historical record leads to a decrease in the estimated return periods of similar HPEs. Our findings highlight the potential difficulties that HPEs could introduce for the design of hydraulic engineering infrastructure as well as for the disaster mitigation measures required to alleviate future risk, particularly in central China. [ABSTRACT FROM AUTHOR]

Water system plays a key role in the coupled human‐nature system, and ancient people's experiences to build a water‐adaptative way of life still shed light on human's pursuit for climate resilience today with their innate traditional ecological wisdom. In this paper, taking the Huai'an‐Yangzhou Section of China's Grand Canal, and particularly its hydraulic engineering system as an example, we show the system's success in addressing the multi‐dimensional challenges in a historical geographical context, as well as its landscape‐shaping power across the entire lower Yellow‐Huai River Basin up until today. Therefore, we argue that the system is not merely a hydraulic engineering project, but a cross‐scale adaptive strategy that has deeply impacted generations of people's way of livelihood with its intrinsic resilient nature. We attribute the success to the advantages brought about by the "distributive hydraulic engineering" approach, which is reflected in the ancient Grand Canal‐management, over the "master‐structure dependent" approach which appears to be the common practice in modern hydraulic engineering. For testing the hypothesis, we build complex system models representing the two approaches with the Qingkou Hydraulic Nexus as an example, and by running long‐term simulation, we evaluate the performance of the two approaches with respect to long‐term resilience. We show from a complex network perspective that the former has significant flexibility advantages, and outperforms the former in multi‐goal fulfillment capacities and long‐term resilience especially under a low‐tech, tight resource constraints condition. We conclude the paper with discussions on the implications of the findings, and argue that though with limitations, the traditional ecological wisdom as reflected in the Grand Canal case, with its holistic approach and flexibility design, still sheds lights on today's large‐scale hydraulic engineering projects that pursue a resilient solution for long‐term adaptive survival for the mankind. [ABSTRACT FROM AUTHOR]

Most dams in China have been operating for a long time and are products of the economic and technical limitations at the time of construction. Due to decades of aging engineering and ancillary problems, these reservoirs pose great threats to the safety of local people and the development of the surrounding economy. In this study, the surface deformation information for the Banqiao Reservoir is monitored with the small baseline subset–synthetic aperture radar interferometry (SBAS-InSAR) method using 80 Sentinel-1A images acquired from 3 January 2020 to 20 August 2022. Additionally, ground measurements from the BeiDou ground-based deformation monitoring stations were collected to validate the InSAR results. Based on the InSAR results, the spatiotemporal deformation features of the dam were analyzed in detail. The results show that the deformation in most areas, including the dam in the study area, is relatively stable, and the regional deformation velocity of the Banqiao Reservoir dam and other hydraulic engineering facilities varies between −1 mm/y and −4 mm/y. The Ru River area has a relatively obvious subsidence trend, and the maximum subsidence velocity reaches 30 mm/y. The InSAR monitoring results are consistent with the change trend in the BeiDou ground-based deformation measurement results. The monitoring results for the reservoir dam area provide a reference for local sustainable development and geological disaster prevention. [ABSTRACT FROM AUTHOR]

The SiXianJiao (SXJ) is the first-order exchange node of the West River and the North River and redistributes water (mass) to the downstream river network in the Pearl River Delta (PRD), South China. The lateral SXJ waterway plays a critical role in flow (mass) diversion between the West River and the North River, forming a unique H-shaped compound river node. Previous studies mainly focused on Y-shaped bifurcation and confluence nodes, and there is a lack of research on deltaic H-shaped river nodes. This study established the Delft3D model to investigate the driving forces and influences of flood diversion at the SXJ node. The results showed that the H-shaped SXJ river node was usually in hydraulic equilibrium but was often disturbed by large water level differences between the two rivers, due to unbalanced and asynchronous upstream flood waves. The large water level differences drove mutual flood diversion through the lateral SXJ waterway, which synchronized the downstream discharge and reduced the peak water levels (flood hazards), resulting in similar water levels or hydraulic equilibrium in the two rivers. There exists a critical flow fraction—about 75.9% (West River)—at which the incoming flow from both rivers presents similar water levels at the SXJ node, resulting in little flood diversion. Above the threshold, the flood water will divert from the West River to the North River with a maximum rate of −11,900 m3/s, accounting for 20% of the West River, reducing the peak water level up to 1.48 m at Makou. Below the threshold, the flood water will divert from the North River to the West River with a maximum rate of 11,990 m3/s, accounting for 55% of the North River, reducing the peak water level up to 6.63 m at Sanshui. Meanwhile, the discharge fraction at downstream Makou (Sanshui) maintained a near-constant value during individual floods and fluctuated around 76.6% (23.4%). This critical discharge fraction and the analytical approach are of significance in flood-risk management and hydraulic engineering design in the PRD. The concept model of the H-shaped compound river node clearly elucidates the flood diversion mechanism via the lateral SXJ waterway and may work for other similar river nodes as well. [ABSTRACT FROM AUTHOR]

Copyright of Pearl River is the property of Pearl River Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the development o£ China's economy, the implementation scale and scope o£ hydraulic engineering projects are increasing, and the application of anti-seepage technology has an important influence on the construction quality of hydraulic engineering. In this paper, the significance and problems of the application of anti-seepage technology in the construction of hydraulic engineering projects were mainly analyzed, and specific application strategies were proposed. [ABSTRACT FROM AUTHOR]

Seepage is a main cause of dam failure, and its stability analysis is the focus of a dam's design, construction, and management. Because a geological survey can only determine the range of a dam foundation's hydraulic conductivity, hydraulic conductivity inversion is crucial in engineering. However, current inversion methods of dam hydraulic conductivity are either not accurate enough or too complex to be directly used in engineering. Therefore, this paper proposes a new method for the inversion of hydraulic conductivity with high application value in hydraulic engineering using an improved genetic algorithm coupled with an unsaturated equivalent continuum model (IGA–UECM). This method is implemented by a new code that fully considers engineering applicability. In addition to overcoming the premature convergence shortcomings of traditional genetic algorithms, it converges faster than Bayesian optimization and tree-structured Parzen estimator inversion algorithms. This method is verified by comparing the water head from drilling exploration and inversion. The results of the inversion are used to study the influence of a cement grouting curtain layout scheme on the seepage field of the Hami concrete-face rockfill dam in China, which is used as an engineering application case of the IGA–UECM. The law of the seepage field is reasonable, which verifies the validity of the IGA–UECM. The new inversion method of hydraulic conductivity and the proposed cement grouting curtain layout in this study offer possible strategies for the design, construction, and management of concrete-face rockfill dams. [ABSTRACT FROM AUTHOR]

The flow facility of aerofoil has presented the excellent hydraulic conditions and high flow measurement accuracy. However, the complex curve of aerofoil can restrict to promote the water measuring facility. This study is based on the portable imitating aerofoil measuring flume with simple structure to explore its applicability in the final trapezoidal channel. Among them, the 1/4 elliptic curve coupled with arc curve was used to approximate the complex aerofoil curve. The hydraulic trials were carried out in the Laboratory of Hydraulic Engineering and Hydraulics of Northwest A&F University in Shaanxi Province, China in 2022. A concrete trapezoidal channel was prepared (the flat slope, bottom width = 30 cm, channel depth = 30 cm, top width=90 cm, and side slope coefficient m = 1). The portable water measuring flumes of imitating aerofoil were all made of hollow wooden materials. A total of 35 trial schemes were designed, including one set of aerofoil chord length, five sets of contraction ratios, and seven sets of flow discharges. The lab experiment was used to only measure some specific hydraulic parameters, whereas, the computational fluid dynamics (CFD) platform was utilized to simulate the internal flow fields. Furthermore, the hydraulic performance was compared between the aerofoil flume and the imitating via the FLOW-3D software after the hydraulic trials. A systematic analysis was made to clarify the effects of contraction ratio and flow rate on the hydraulic performance of imitating aerofoil flume. The results showed that the numerical simulation was better agreed with the experimental, with the error of less than 4.91%, indicating the accurate and reliable modelling. More importantly, the aerofoil measuring flume remained the smooth flow and the small depth of backwater after simplification. The flow pattern was also obtained after numerical simulation. The water flow was stable at the upstream of the flume, whereas, the water level dropped faster at the downstream of the throat, where the water surface strongly fluctuated with the high flow velocity. Part of the water flow was generated some vortices near the side wall under the action of the transverse velocity. The upstream Froude numbers were less than 0.5 under all working conditions, and the backwater depth was less than 7.6 cm, fully meeting the requirements of flow measurement and channel safety. The best hydraulic performance was achieved in the contraction ratio ranging from 0.60 to 0.64. The high accuracy of flow formula was also observed using energy equation and critical flow principle, indicating the average flow measurement error of 2.75%. As such, the imitating aerofoil maintained the excellent hydraulic performance of the original aerofoil. Consequently, the high accuracy of flow measurement and the more simplified curve can be expected to easily promote the portable water measuring flume in the last small cross-section trapezoidal channel for the irrigation districts. [ABSTRACT FROM AUTHOR]

As an important function of hydraulic engineering, power generation has made a great contribution to the growth of national economies worldwide. Therefore, it is of practical engineering significance to analyze and predict hydropower generation and its economic benefits. In order to predict the amount of hydropower generation in China and calculate the corresponding economic benefits with high precision, Ensemble Empirical Mode Decomposition (EEMD), Adaptive Moment Estimation (ADAM) and Gated Recent Unit (GRU) neural networks are integrated. Firstly, the monitoring data of hydropower generation is decomposed into several signals of different scales by the EEMD method to eliminate the non-stationary components of the data. Then, the ADAM optimization algorithm is used to optimize the parameters of the GRU neural network. The relatively stable component signals obtained from the decomposition are sent to the optimized GRU model for training and predicting. Finally, the hydropower generation prediction results are obtained by accumulating the prediction results of all components. This paper selects the time series of China's monthly power generation as the analysis object and forecasts the economic benefits by constructing the fusion prediction model. The RMSE EEMD-ADAM-GRU model is reduced by 16.16%, 20.55%, 12.10%, 17.97% and 7.95%, respectively, of compared with the NARNET, EEMD-LSTM, AR, ARIMA and VAR models. The results show that the proposed model is more effective for forecasting the time series of hydropower generation and that it can estimate the economic benefits quantitatively. [ABSTRACT FROM AUTHOR]

Flash flooding is a type of global devastating hydrometeorological disaster that seriously threatens people's property and physical safety, as well as the normal operation of water conservancy facilities, such as reservoirs, so an accurate assessment of reservoir risk for certain areas is necessary. Therefore, the purpose of this study was to propose a novel methodological approach for reservoir risk modelling based on the feature selection method (FSM) and tree-based ensemble methods (Bagging and Random Forest [RF]). The results showed that: (1) the J48-GA based ensemble models achieved higher learning and predictive capabilities compared to conventional ensemble models without the FSM. (2) For the classification accuracy, the J48-GA-RF (96.4%) outperformed RF (96.0%), J48-GA-Bagging (93.9%) and Bagging (93.5%). And the J48-GA-RF achieved the highest prediction AUC value (0.995), an almost perfect Kappa indexes value (0.926) and the best practicality value (30.88%). (3) In particular, the results indicated that all of the models showed high performance, both in training and in the validation of a dataset. Additionally, this study could provide a reference for disaster managers, hydraulic engineers and policy makers to implement location-specific flash flood risk reduction strategies. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A rotation irrigation is normally implemented in water-shortage regions, such as Xinjiang area of western China with widespread drip irrigation. Nevertheless, the conventional rotation irrigation group is generally divided into the fixed districts in the manual calculation. A better solution is thus highly demanding in this inefficient calculation. The rotation irrigation group is also representing the prominent regional and hydraulic characteristics in recent years. Therefore, it is necessary to clarify how to divide the rotation irrigation group in practice. Furthermore, the operation of the irrigation system needs to gradually complete the whole plot irrigation under the turn-on and turn-off valve sequence of several branch pipes in a rotation irrigation group. Correspondingly, there is a relatively high labor intensity in the operational mode, but with low investment cost, simple maintenance, and wide popularization, compared with the automatic operation of drip irrigation. In this study, a hybrid mathematical model was proposed to explore a better solution using the flow balance and structural constraints in the technical standards and division principles. Neighborhood characteristics were determined from the spatial distribution of branch pipes in the rotation irrigation group. The neighborhood search strategy and the repair of infeasible solution were given in the radius threshold range, further to find the critical path of the maximum extent. Four algorithms were selected to solve the model separately, including the genetic algorithm (GA), Greedy-GA, Tyson polygon-GA (Voronoi-GA), and Grid GA. The GA adopted the branch pipe model of actual number coding. The chromosome coding indicated that the branch pipe was opened in that group. The initial population was constructed using the Random, Greedy, Voronoi polygon, and Grid. The spatial distribution of branch pipe was applied in the neighborhood search strategy, further to serve as the structural feature in the rotation irrigation group. A uniform crossover strategy was adopted for the crossover and mutation of the offspring population. A competitive and elite retention strategy was adopted for the selection mechanism. Furthermore, the neighborhood structure represented the use of characteristic information. In the case of the rotation irrigation group, the spatial distribution of branch pipes presented critical structural characteristics. The specific search procedure was: first to establish the adjacency matrix of branch pipe, then to generate the reachable matrix using the Warshall, finally to calculate the critical path set for each valve, thereby converting the code. In a matrix form, the fundamental and non-key matrix was generated using a reachable matrix. Then the temporary path set was calculated and sorted to compare the valves in the non-critical matrix row for the standard deviation index. Feasible solutions were selected to update the matrix using four indicators from standard deviation, path length, connectivity, and running time. Furthermore, an optimal combination was achieved, where the mean flow rate in the rotation irrigation group was 260.06 m³/h, the standard deviation was 10.9 m³/h, the path length was 7 342.6 m, the mean path length was 8 105.2m, the mean path length within the group was 386.4 m, and the mean connectivity was 22. The neighborhood search strategy of the critical path was adopted to balance the distribution of branch pipes under the condition of objective function, suitable for daily management and maintenance. The Grid-GA and repair presented an excellent performance on the rotation operating group in a grip irrigation, particularly without the dimensional disaster in the multi-dimensional combination. Consequently, the hybrid optimal model and algorithm here can meet the hydraulic calculation and engineering requirements in modern agriculture. [ABSTRACT FROM AUTHOR]

The Yellow River floodplain represents a fertile landmass that contributes significantly to human welfare and thus has been colloquially known as the birthplace of Chinese civilization. The sediment-laden nature of the Yellow River gave rise to a super-elevated channel belt, which is prone to failure particularly in the summer months when excessive precipitation occurs, resulting in cataclysmic floods traditionally regarded as "China's Sorrow." Therefore, a deeper understanding of levee breach frequency in this area is especially important for the assessment of socio-economic risk of levee breaches associated with future climate changes. To better understand the nature, evolution, and driving mechanisms of levee breaches on the lower Yellow River, it is necessary to place the instrumental data within a longer time framework. Here, we retrieve past information about levee breaches on the lower Yellow River since AD 11 from various documentary sources such as official histories of China. We evaluated each line of descriptions and narratives about the location, timing, and nature of each event in these documents, ending up with a detailed timeline of levee breaches on the lower Yellow River during the last 2000 years on an annual time scale. Our results reveal remarkable variations in the frequency of levee breaches superimposed on a long-term increasing trend. In addition to climate changes, the iterative embankment-siltation-breaching process caused a feedback: more breaches result in much more channel siltation, which in turn leads to even more breaches. The enhanced farming in the Loess Plateau played a pivotal role in the formation and operation of this positive feedback. Our findings may not only help improve the assessment of socio-economic risk of levee breaches associated with future climate changes, but also provide consulting information for hydraulic engineering and infrastructural designs in the lower Yellow river area. [ABSTRACT FROM AUTHOR]

People often need precipitation data when building hydraulic engineering, especially the maximum daily precipitation data, so it is very important to study the maximum daily precipitation for hydraulic engineering. The spatiotemporal distribution characteristics of annual and seasonal maximum daily precipitation in the Hengduan Mountains were analyzed based on the maximum daily precipitation data collected at 30 meteorological stations between 1971 and 2013. The following results were obtained. The annual and seasonal maximum daily precipitation gradually increase from north to south; in comparison, the temporal variations in the annual and seasonal maximum daily precipitation are not significant. Except for winter, the standard deviations and coefficient of variation values of maximum daily precipitation in the other time scales are negatively correlated with both elevation and latitude, and most of those correlations are significant. Shape parameters of maximum daily precipitation have no significant correlation with either elevation or latitude, whereas the scale and location parameters have significant correlation with both elevation and latitude at different confidence levels. In addition, except for summer and autumn, there are significant negative correlations between maximum daily precipitation and elevation and latitude at different confidence levels during different return periods in the other time scales. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Accurate assessment of stage–discharge relationships in open channel flows is important to the design and management of hydraulic structures and engineering. Flow junctions commonly occur at the confluence of natural rivers or streams. The effect of flow junctions on the stage–discharge relationship at mountain river confluences was found by measuring velocity fields and water levels in experimental models. The results show that the backwater and accumulation–separation at flow junctions affect the flow structures and patterns in the channel; also, flow confluences may induce complex flow characteristics of backwater and flow separation at river junctions, indicating potential submerged flooding disasters within the confluence zone. The impacts of flow junctions on the stage–discharge relationship are investigated for two physical confluence models built from river confluence prototype systems in southwest China. The results show that the presence of tributary river inflows tends to increase the water level of the main river. This is important for flood control, flood-risk evaluation and engineering (e.g. hydropower station construction) in mountain rivers. Finally, a comparative quantitative analysis based on flow motion equations is conducted to evaluate the stage–discharge relationship in both uniform and regular confluence systems. The results indicate that more accurate prediction can be made when taking into account the flow non-uniformity induced by flow separation, backwater and distorted bed in the junction region. [ABSTRACT FROM AUTHOR]

Several studies have shown that lake littoral zones often support high methane (CH4) emissions. In this study, we measured CH4 emissions from two vegetation meadows in the littoral zone of Poyang Lake, China, from October 2014 to May 2015. CH4 emissions in the meadow dominated by Carex cinerascens were 11.27 ± 11.29 mg CH4 m−2 h−1, which were significantly higher than emissions in the meadow dominated by Artemisia selengensis (2.99 ± 1.67 mg CH4 m−2 h−1). Between-species differences in CH4 emission were caused by differences in belowground biomass. The results also showed distinct seasonal variation in CH4 emissions in this area; fluxes reached a maximum at the peak of the growing season and reached a minimum after the summer flood, when plants began to germinate. There were two peak values in the Carex meadow, and belowground biomass controlled the seasonality of CH4 emissions. Our results suggest that plant biomass may be a key factor controlling CH4 emissions in the littoral zone of Poyang Lake, highlighting that CH4 fluxes vary with vegetation type in littoral wetlands and demonstrating that spatial variation in CH4 emissions must be considered when estimating regional CH4 emissions in Poyang Lake. Considering climate change and the operations of a proposed hydraulic engineering project, changes to the hydrologic regime in this region may significantly affect CH4 emissions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new method to describe hydrological connectivity in plain river networks. • Graph theory and comprehensive connectivity indices were integrated in this framework. • The hydrological connectivity decreased by 50% over the past century due to hydraulic facilities. • The area of lake wetlands decreased sharply but the importance of the same lake patches increased. • Determine the optimal hydrological connectivity is a challenge. The proliferation of hydraulic facilities worldwide has greatly hindered the lake wetlands ecosystem services through impacting hydrological connectivity. However, developing a general method to evaluate hydrological connectivity in the plain river-lake wetlands networks heavily influenced by hydraulic facilities remains challenging. In this study, we present a novel framework for the hydrological connectivity evaluation of lake wetlands whilst considering different types of hydraulic facilities. By generalising lake wetlands into patches and rivers into edges, a river topological network connecting lake wetlands was constructed based on graph theory, and connectivity indices were calculated through three dimensions: individual patches - inter-patches - and study area, respectively. Using detailed historical topographic maps and high-resolution satellite data, this new framework, combining graph theory and connectivity indices, is applied to a river-lake wetlands district with dense sluices/pumping stations in eastern China. Results show that (1) Although the number of lake wetlands remained relatively stable over the past century, the average area decreased by 18.44%, and the density of hydraulic engineering boomed to 2.2/km2. (2) The increases in hydraulic facilities and the decrease in lake wetlands areas significantly reduced the degree of hydrological connectivity, resulting in the overall connectivity value decreasing from 0.97 in the 1910s to 0.45 in 2019. (3) The importance of the same lake wetlands patch has progressively heightened in the last hundred years. This study provides an effective method for quantifying hydrological connectivity in plain river-lake wetlands with dense hydraulic facilities and could shed light on lake wetlands protection and restoration. [ABSTRACT FROM AUTHOR]

Highlights • Target fish were identified after investigation and sample ecological analysis. • Different indicators of the fishway are assigned to determine the optimal fishway. • Simulate the flow velocity of the river and ensure that is suitable for target fish. • Simulate fishway with different partition spacings and determine the suitable one. Abstract In order to mitigate the threat that hydraulic engineering will have on the fish's living environment, fish migration can be accomplished by building fishway. This paper takes the Diversion Dahaerteng River to Danghe Reservoir project in Gansu, China as an example. Through field investigation and data analysis, it was found that the main fish in the study area was Triplophysa. Through the comparison of the advantages and disadvantages of the fishways, it is determined that the fishway and the nature-like fishway are suitable. By constructing the evaluation method, the 19 indicators of the fishway were scored from the aspects of ability to lure fish, ability to pass fish, fish adaptability, engineering quantity, operation and maintenance, and the nature-like fishway was determined to be the best choice. The surface runoff from March to August is calculated by the P-III curve to simulate the flow field of the Dahaerteng River under the conditions of maximum, minimum and average runoff. The flow velocity of the simulation results is suitable for the Triplophysa migration, and the right bank is suitable for building nature-like fishway. The fishway section is rectangular, with a slope of 1%, a width of 2 m, and a total length of 520 m. It is arranged with a staggered baffle, and the revetment is rough masonry stones. The inside of the fishway is inlaid with pebbles so that the roughness of the fishway is more than 0.03. Then, numerical simulation calculations were carried out for the fishways composed of the partitions of 10 m and 5 m apart. The comparison shows that the fishway with the partition gap 5 m is closer to the right bank of the river, which is suitable for Triplophysa migration and survival. For later evaluation and adjustment, an observation room and a fish collection pool are provided near the entrance of the fishway, and an observation room is provided near the exit. This paper can provide reference for the planning, construction and post evaluation of fishways. [ABSTRACT FROM AUTHOR]

• Pan coefficients (K p) of China D20 pans ranged from 0.29 to 0.91 across China. • The seasonal relationship of K p was Summer > Annual > Autumn ∼ Spring ∼ Winter. • K p of the China D20 pan was most sensitive to relative humidity. Data of open water evaporation (E ow), such as evaporation of lake and reservoir, have been widely used in hydraulic and hydrological engineering projects, and water resources planning and management in agriculture, forestry and ecology. Because of the low-cost and maneuverability, measuring the evaporation of a pan has been widely regarded as a reliable approach to estimate E ow through multiplying an appropriate pan coefficient (K p). K p is affected by geometry and materials of a pan, and complex surrounding environment variables. However, the relationship between K p and different environment variables is unknown. Thus, this study chose China D20 pan as an example, used meteorological observations from 767 stations and introduced the latest PenPan model to analyze the sensitivity of K p to different environment variables. The results show that, the distribution of annual K p had a strong spatial gradient. For all the stations, annual K p ranged from 0.31 to 0.89, and decreased gradually from southeast to northwest. The sensitivity analysis shows that for China as a whole, K p was most sensitive to relative humidity, followed by air temperature, wind speed and sunshine duration. For 767 stations in China, K p was most sensitive to relative humidity for almost all the stations. For stations north of Yellow River, wind speed and sunshine duration were the next sensitive variables; while for stations south of Yellow River, air temperature was the next sensitive variable. The method introduced in this study could benefit estimating and predicting K p under future changing environment. [ABSTRACT FROM AUTHOR]

• A detailed model is formulated to optimize the reservoir operation. • The trade-offs among social, economic and ecological benefits are presented. • Operational strategies are compared for achieving the comprehensive benefits. Balancing the multiple purposes of reservoir operation, including the social, economic, and ecological aspects, has become one of the most complicated problems facing the managers and operators worldwide. This paper formulates a detailed mathematical model to optimize the reservoir operation during the flood season, considering the three major operational purposes, i.e. flood control (social purpose), energy production (economic purpose), and management of sediment transport (ecological purpose). The entire formulations conform to a nonlinear programming (NLP) model, which can be solved effectively and efficiently by the Multi-Start Solver from the LINGO software through equivalent transformation. This model is applied to the Three Gorges Project (TGP) in China, which is the world's largest and most complex hydraulic engineering in operation. Three typical flood hydrographs (i.e. dry, normal, and wet scenarios) are selected as model inputs under the three strategies (i.e. design operating rules, increasing the flood control water level (FCWL), and impounding in advance). The trade-offs among these three major operational purposes are quantitatively analyzed. Moreover, phosphorus (P), one of the sediment-associated environmental factors, is introduced for exploring its responses to various scenarios and strategies. Results indicate that a higher fore-bay water level leads to a greater energy production, a smaller flood peak but less sediment and P transports to the downstream. Under the design operating rules, the maximum energy production of the TGP can reach 560, 620, and 699 × 108 KWh, respectively, in dry, normal, and wet scenarios, corresponding to a flood peak of 25000–27500 m3/s, a sediment load of 1517–1999 × 104 t, and a P load of 3152–3740 × 104 kg to the downstream. Whereas, the maximum sediment loads are 2796, 4640, and 5377 × 104 t, and the maximum P loads are 4021, 5345, and 5784 × 104 kg, respectively, in dry, normal, and wet scenarios, corresponding to an energy production of 500–588 × 108 KWh, and a flood peak of 38600–52500 m3/s to the downstream. In terms of achieving the comprehensive benefits of the TGP, impounding in advance is a better choice than both the design operating rules and increasing the FCWL, for it can increase the energy production and the probability of full refill with almost no increase in flood risk to both the dam and the middle and lower reaches of the Yangtze River as well as smaller reduction in the sediment and P transports. The formulated detailed mathematical model is a general one that is applicable to a variety of reservoirs owning multiple operational purposes. Moreover, the achievements gained from this paper will provide important references for the managers and operators. [ABSTRACT FROM AUTHOR]

Abstract Massive bed degradation (20 m in 7 years) has been observed in the Shi‑ting River, Sichuan Province, China, since the 2008 Wenchuan Ms. 8.0 earthquake. The reason for the massive bed degradation has not been well understood. A hypothesis has been proposed that relates bed degradation to the augmentation of sand supply after the earthquake. The effect of sand on gravel mobility (magic sand effect) has long been observed in laboratory experiments. In this paper, we study whether the augmentation of sand supply and its magic sand effect can lead to the observed massive degradation at decadal scales. A one-dimensional river morphodynamic model is implemented to study the problem in general at field scale and in context of the gravel-bed Shi‑ting River. Sediment transport is calculated with the Wilcock and Crowe (2003) relation, in which the magic sand effect is explicitly embedded in terms of a function relating reference Shields number to the surface sand fraction. We find that the augmentation of gravel supply leads to bed aggradation, whereas the augmentation of sand supply can indeed lead to bed degradation and surface fining. The magnitude and timescale of bed degradation are not sensitive to the sand supply rate but are sensitive to the flood intermittency factor , i.e., the fraction of time the river is in flood. However, an unrealistic flood intermittency factor (≥0.3) would be required in order to match the observed timescale of bed degradation, thus indicating that the magic sand effect might not be the governing reason for massive bed degradation in the Shi‑ting River, and by implication in gravel-bed rivers in general. Our simulation results also indicate that despite the fact that magic sand effects are not explicitly included in most sediment transport relations, they are at least partly built in via the hiding function that is contained in most sediment transport relations for gravel-sand mixtures. While here we use the Shi‑ting River as an example, our results have applicability to gravel-bed rivers subjected to augmentation in sand supply in general. Highlights • Augmentation of gravel supply leads to bed aggradation • Augmentation of sand supply leads to enhanced gravel transport and bed degradation • Magic sand effects alone cannot induce the observed river incision at decadal scale • Magic sand effects can be partly incorporated with a dimensionless hiding function [ABSTRACT FROM AUTHOR]

Abstract Neck cutoff is an essential process that significantly changes the morphodynamic characteristics of a meandering bend. In reality, however, observing natural processes of a neck cutoff is very difficult. In this study, we artificially triggered neck cutoffs by excavating a 0.4 m (width) × 0.5 m (depth) ditch to connect the beginning and ending of two highly convoluted bends along a meandering tributary of the upper Black River, a major tributary of the Upper Yellow River situated in the northeastern side of the Qinghai-Tibet Plateau in China. Our morphologic and hydraulic measurements in summers of 2013, 2014, 2016, and 2017, the subsequent hydraulic-geometry analysis, and three-dimensional simulation showed that both artificial ditches expanded fast to the size comparable to the former channel in a three-year period and the oxbow channel was disconnected from the former channel quickly, though sediment supply may be limited in this area. The morphological adjustment was featured by (1) distinct temporal trends of the development of the width/depth ratio between the two cutoff channels, (2) different diversion factors of the total discharge to the cutoff channel, and (3) diverse interaction patterns between cutoff and former channels. These discrepancies were supported by simulated different three-dimensional velocity distributions in the two cutoff channels, suggesting the importance of the clustered local velocities. Comparing these results with those reported in earlier studies showed that besides channel slope, unit stream power, and bank strength, the diversion angle between the cutoff and former channel played an important role in controlling channel adjustment. The discrepancy of the adjustment processes between the cutoff channel in this study and those in two previous ones revealed that channel adjustment after neck cutoff behaved differently under different physical settings and require more field-based studies. Highlights • This was the first study on meander rivers in the Qinghai-Tibet Plateau of China. • We measured three-year morphological adjustments of two meander bends after artificial neck cutoffs. • Rates of channel adjustments were mainly controlled by the diversion angle at the entrance of the cutoff channel. • Cutoff channels in this area may adjust their morphology quickly to the pre-cutoff conditions within three years. [ABSTRACT FROM AUTHOR]

Shale gas is likely to play a major role in China's transition away from coal. In addition to technological and infrastructural constraints, the main challenges to China's sustainable shale gas development are sufficient shale gas production, water availability, and adequate wastewater management. Here we present, for the first time, actual data of shale gas production and its water footprint from the Weiyuan gas field, one of the major gas fields in Sichuan Basin. We show that shale gas production rates during the first 12 months (24 million m 3 per well) are similar to gas production rates in U.S. shale basins. The amount of water used for hydraulic fracturing (34,000 m 3 per well) and the volume of flowback and produced (FP) water in the first 12 months (19,800 m 3 per well) in Sichuan Basin are also similar to the current water footprints of hydraulic fracturing in U.S. basins. We present salinity data of the FP water (5000 to 40,000 mgCl/L) in Sichuan Basin and the treatment operations, which include sedimentation, dilution with fresh water, and recycling of the FP water for hydraulic fracturing. We utilize the water use data, empirical decline rates of shale gas and FP water productions in Sichuan Basin to generate two prediction models for water use for hydraulic fracturing and FP water production upon achieving China's goals to generate 100 billion m 3 of shale gas by 2030. The first model utilizes the current water use and FP production data, and the second assumes a yearly 5% intensification of the hydraulic fracturing process. The predicted water use for hydraulic fracturing in 2030 (50–65 million m 3 per year), FP water production (50–55 million m 3 per year), and fresh water dilution of FP water (25 million m 3 per year) constitute a water footprint that is much smaller than current water consumption and wastewater generation for coal mining, but higher than those of conventional gas production in China. Given estimates for water availability in Sichuan Basin, our predictions suggest that water might not be a limiting factor for future large-scale shale gas development in Sichuan Basin. [ABSTRACT FROM AUTHOR]

In order to setup a space coordinate system, the central line between the two levees of the Lower Yellow River was extracted as the horizontal axis by ArcGIS based on the investigation and interpretation of remote sensing images in the research area. We used the line perpendicular to the center line as the longitudinal axis and the outlet gate of Xiaolangdi Reservoir as the coordinate origin. We had made statistical analysis about the status quo and the spatial distribution of typical water conservancy projects in the lower Yellow River based on the space coordinate system. The results show that the variation of the distance between the two levees in the lower Yellow River is piecewise. One is from Xiaolangdi Reservoir to Aishan and another one is from Aishan to the estuary of the Yellow River. The average distance between levees is 7. 46 km in the former section and there also exists inner cladding line in this section. The average distance between levees of the latter is 2. 70 km, and exists extremely narrow levee distance (0. 55 km and 0. 67 km). The changes in the number of vulnerable spots show the characteristics of bimodal distribution and the control works is the single peak distribution. The average number of the engineering is 0. 27 per kilometer along the Yellow River downstream and the form of the engineering can be divided into four types such as single curved, double curved, multiple curved and straight. The bending degree of the engineering is distributed between 0. 3-1. 0 The average contact ratio of control works is 67% and the average contact ratio of vulnerable spots is 56% in the Lower Yellow River. [ABSTRACT FROM AUTHOR]

China is rich in offshore wind energy resources and the development of its offshore wind power is considered a practical solution to today's energy requirements. In the field of offshore wind power and, in contrast to more developed countries, China still has a problem with both a weak technical support system and underdeveloped technologies. To shed some light on present day technological advancements in this area, this paper uses the Beijing IncoShare Patent Database as well as patent maps to conduct statistical analyses on the evolution, regional distribution, variation in type and International Patent Classification of patent applications for offshore wind power in China. The research indicates that policies aimed at bolstering technologies were the cause of the observed rapid growth in offshore wind power patents from 2006 to 2013. Regional distribution of these patents is concentrated in Eastern China, with little activity in either Central or Western China. At present, a significant percentage of patents on Chinese offshore wind power have expired, so it is recommended that China both increase its capacity for technical industrialization and reinforce its protection of intellectual property rights. Furthermore, insufficient research on motors, hydraulic engineering and ship propulsion plants is a constraint to technological progress and future policy which aims at improving China's prospects for offshore wind power should focus on these areas. [ABSTRACT FROM AUTHOR]

We build copula function-based joint distribution models for the annual maximum flood peaks of the Yangtze River and Poyang Lake, to analyze the coincidence probabilities, using scenarios that combine with the impoundment of three Gorges, define influencing indexes and relative contribution rates on flood coincidence at varying frequencies. The study shows the probabilities for coincidence of floods with 1000, 100, and 10-year return periods in both Yangtze main stem and Poyang Lake are respectively 0.02, 0.19 and 2.87%, with higher coincidence probabilities for shorter return periods; when 1000-year flood occurs in the Yangtze, the probabilities for Poyang Lake to encounter flood of the 1000, 100, or 10-year magnitude are higher than 16.08, 42.48 or 74.77% respectively; Poyang-Yangtze flood coincidence is affected by operation of the hydraulic engineering. The lowering of flood peaks caused by the Three Gorges impoundment and regulation of the lake have respectively reduced the probabilities of Poyang-Yangtze flood coincidence by about 7.0 and 1.97%, with average relative contribution rates − 33.82 and − 17.1%; influenced by hydrological projects in Poyang basin, variations in Poyang’s inflow flood have displayed an average contribution rate of 20.4% for the negative effect on extreme (P < 5% or P > 90%) flood coincidence, while having a positive contribution rate of 38.2% on floods of other return periods. The results can help increase our understanding of flood coincidence, and support flood control efforts in Poyang Lake; its analytical approach may also be useful to other applications of copula functions. [ABSTRACT FROM AUTHOR]

As the interface between the fluvial upland system and the open coast, global estuaries are facing serious challenges owing to various anthropogenic activities, especially to the Changjiang Estuary. Since the establishment of the Three Gorges Dam (TGD), currently the world's largest hydraulic structure, and certain other local hydraulic engineering structures, the Changjiang Estuary has experienced severe bathymetric variations. It is urgent to analyze the estuarine morphological response to the basin-wide disturbance to enable a better management of estuarine environments. North Channel (NC), the largest anabranched estuary in the Changjiang Estuary, is the focus of this study. Based on the analysis of bathymetric data between 1880 and 2013 and related hydrological data, we developed the first study on the centennial bathymetric variations of the NC. It is found that the bathymetric changes of NC include two main modes, with the first mode representing 64% of the NC variability, which indicates observable deposition in the mouth bar and its outer side area (lower reach); the second mode representing 11% of the NC variability, which further demonstrates channel deepening along the inner side of the mouth bar (upper reach) during 1970–2013. Further, recent erosion observed along the inner side of the mouth bar is caused by riverine sediment decrease, especially in relation to TGD induced sediment trapping since 2003, while the deposition along the lower reach since 2003 can be explained by the landward sediment transport because of flood-tide force strengthen under the joint action of TGD induced seasonal flood discharge decrease and land reclamation induced lower reach narrowing. Generally, the upper and lower NC reach are respectively dominated by fluvial and tidal discharge, however, episodic extreme floods can completely alter the channel morphology by smoothing the entire channel. The results presented herein for the NC enrich our understanding of bathymetric variations of the Changjiang Estuary in response to human activities, which can be well applied to other estuaries subject to similar interferences. [ABSTRACT FROM AUTHOR]

In this paper, premature failure of the O-ring gaskets for the electric hydraulic system in a nuclear power plant in China was investigated. A series of macroscopic and microscopic analysis methods were conducted to identify the root causes of this unexpected failure, and the results showed that mismatch of the sizes between the O-ring gaskets and the groove of metal union was the primary reason, which gave rise to the permanent distortion and surface damage of the O-ring gaskets, and consequently leading to fracture under service conditions. Countermeasures were then proposed to prevent the recurrence of similar incidents, and were proved effective on site. [ABSTRACT FROM AUTHOR]

The Interconnected River System Network Project (IRSNP) is a significant water supply engineering project, which is capable of effectively utilizing flood resources to generate ecological value, by connecting 198 lakes and ponds in western Jilin, northeast China. In this article, an optimization research approach has been proposed to maximize the incremental value of IRSNP ecosystem services. A double-sided chance-constrained integer linear program (DCCILP) method has been proposed to support the optimization, which can deal with uncertainties presented as integers or random parameters that appear on both sides of the decision variable at the same time. The optimal scheme indicates that after rational optimization, the total incremental value of ecosystem services from the interconnected river system network project increased 22.25%, providing an increase in benefits of 3.26 × 109 ¥ compared to the original scheme. Most of the functional area is swamp wetland, which provides the greatest ecological benefits. Adjustment services increased obviously, implying that the optimization scheme prioritizes ecological benefits rather than supply and production services. [ABSTRACT FROM AUTHOR]

Several small reservoirs and a large number of check dams had been constructed in the Wangkuai reservoir watershed after 1970s, and flood time series lacked stationarity, which affected the original design flood hydrographs for the Wangkuai reservoir. Since the location, storage capacity and drainage area of the large number of check dams were unknown, we present a method to estimate their total storage capacities (TSC) and total drainage areas (TDA) by using the recorded rainstorm and flood data. On the basis of TSC and TDA, the flood events which occurred in an undisturbed period were reconstructed under current conditions to obtain a stationary flood series. A frequency analysis was subsequently performed to assess the design flood peak and volume for both small and medium design floods with a 10-200 year return period. For large and catastrophic floods, it was assumed that the upstream check dams and small reservoirs would be destroyed, and water stored in these hydraulic structures were re-routed to the Wangkuai reservoir by unit hydrograph. The modified flood peak and volume decreased for floods with a 10-200 year return period when compared to the current design flood. But for large design floods with a return period exceeding 500 years, peak discharge increased. This study provides a new method for design flood calculation or modification of the original design flood in watersheds with a large number of check dams. [ABSTRACT FROM AUTHOR]

Statistical modeling of hydrological extremes is significant to the construction of hydraulic engineering. This paper, taking the Yingluoxia watershed as the study area, compares the annual maximum (AM) series and the peaks over a threshold (POT) series in order to study the hydrological extremes, examines the stationarity and independence assumptions for the two series, and discusses the estimations and uncertainties of return levels from the two series using the Generalized Extreme Value (GEV) and Generalized Pareto distribution (GPD) models. For comparison, the return levels from all threshold excesses with considering the extremal index are also estimated. For the POT series, the threshold is selected by examining the mean excess plot and the stability of the parameter estimates and by using common-sense. The serial correlation is reduced by filtering out a set of dependent threshold excesses. Results show that both series are approximately stationary and independent. The GEV model fits the AM series well and the GPD model fits the POT series well. The estimated return levels are fairly comparable for the AM series, the POT series, and all threshold excesses with considering the extremal index, with the difference being less than 10% for return periods longer than 10 years. The uncertainties of the estimated return levels are the highest for the AM series, and next for the POT series and then for all threshold excesses series in turn [ABSTRACT FROM AUTHOR]

Acoustic velocity is an important parameter to evaluate the mechanical properties of fractured rock masses. Based on the in situ acoustic velocity measurement data of ~20 hydropower stations in China, we assessed the acoustic velocity increase of rock masses as a result of consolidation grouting in different geological conditions, such as fault sites, weathered areas and excavation-induced damage zones. We established an empirical relationship between the acoustic velocity of rock masses before and after consolidation grouting, and examined the correlation between acoustic velocity and deformation modulus. A case study is presented about a foundation consolidation grouting project for an intake tower of Pubugou Hydropower Station. The results show that different types of rock masses possess distinct ranges for resultant acoustic velocity increase by consolidation grouting. Under a confidence interval of 95 %, the ranges of the increasing rate of acoustic velocity in a faulted zone, weathered zone, and excavation-induced damage zone are observed to be 12.7-43.1, 12.3-31.2, and 6.9-14.5 %, respectively. The acoustic velocity before grouting and its increasing rate can be used to predict the effectiveness of consolidation grouting. [ABSTRACT FROM AUTHOR]

While it is generally believed that the agricultural colonization of the middle Yangzi wetlands began in Tang-Song times, newly discovered texts show that the early Han state administered river dikes in the region. The texts, which were written between 192 and 121 bce, calculate dike sizes in order to estimate corvée requirements for dike maintenance and discuss the area of new farmland to be created. Our picture of the early history of the Yangzi region has been distorted by the northern focus of early texts, but archaeological discoveries are correcting this bias and suggest that the conversion of the Central Yangzi lowlands to farmland began many centuries earlier than previously believed. [ABSTRACT FROM AUTHOR]

Rock-filled concrete (RFC) was developed in China in 2003 as an application of self-compacting concrete (SCC) that can then be used as “normal” concrete for massive concrete constructions. RFC is produced by filling the voids of rock blocks with SCC, which has good fluidity and segregation resistance. To guarantee the required workability of SCC, a mix design method for SCC based on its paste rheological characteristics was developed. The proposed method yielded practical benefits by saving on the amount of laboratory work, testing time, and raw materials. The integrated performance of RFC was studied by conducting tests on its compaction, compression strength, tensile strength, and permeability. Results indicated that RFC meets the requirements of hydraulic concrete. With two types of construction technology in practical application, RFC exhibits remarkable advantages, such as high construction efficiency, low cost, low heat of hydration, and low environmental load. These advantages contribute to a simpler construction management and an easier quality control, signifying that RFC is a promising technology in hydraulic engineering. [ABSTRACT FROM AUTHOR]

Highlights: [•] A systematicapproach for Overall Process Safety Management in tunnel construction. [•] Safety system design, analysis, control and effect assessment are covered. [•] Experience to deal with challenging technical issues in complex environments. [ABSTRACT FROM AUTHOR]

Aims. We attempted to establish some guidelines for the selection of transmural stents during endoscopic drainage of PFCs by retrospective review of the clinical data obtained from three tertiary hospitals. Patients and Methods. Clinical data of 93 patients with attempted endoscopic drainage of symptomatic PFCs were obtained through chart review and prospective follow-up. Results. Treatment success for acute pseudocyst (n = 67), chronic pseudocyst (n = 9), and WOPN (n = 17) was 95.3%, 100%, and 88.2%, respectively (P = 0.309). Clinical success for single-stent drainage was 93.9% (46/49) versus 97.4% (37/38) for multiple-stent drainage (P = 0.799). Secondary infection for single-stent drainage was 18.4% (9/49) versus 5.3% (2/38) for multiple-stent drainage (P = 0.134). Secondary infection for stent diameter less than or equal to 8.5 F was 3.4% (1/29) versus 17.2% (10/58) for stent diameter larger than or equal to 10 F (P = 0.138). Conclusion. EUS-guided transmural drainage is an effective therapy for PFCs. Single-stent transmural drainage of PFCs is enough and does not seem to influence clinical success. The number or diameter of stents does not seem to be associated with secondary infection. [ABSTRACT FROM AUTHOR]

The metagenomic approach was applied to characterize variations of microbial structure and functions in raw (RW) and treated water (TW) in a drinking water treatment plant (DWTP) at Pearl River Delta, China. Microbial structure was significantly influenced by the treatment processes, shifting from Gammaproteobacteria and Betaproteobacteria in RW to Alphaproteobacteria in TW. Further functional analysis indicated the basic metabolic functions of microorganisms in TW did not vary considerably. However, protective functions, i.e. glutathione synthesis genes in 'oxidative stress' and 'detoxification' subsystems, significantly increased, revealing the surviving bacteria may have higher chlorine resistance. Similar results were also found in glutathione metabolism pathway, which identified the major reaction for glutathione synthesis and supported more genes for glutathione metabolism existed in TW. This metagenomic study largely enhanced our knowledge about the influences of treatment processes, especially chlorination, on bacterial community structure and protective functions (e.g. glutathione metabolism) in ecosystems of DWTPs. [ABSTRACT FROM AUTHOR]

The cofferdam built at the inlet of the diversion tunnel may be left due to incomplete blasting demolition, which affects the river closure. Several indexes have been used to evaluate the difficulty of river closure, but all indexes suffer from their limitations in use. Thus, it is more useful to combination multiple indexes to analyze the impact of residual cofferdam. Taking the river closure project of a Hydropower Station in southwest China as an example, the influence of the residual cofferdam heights on the river closure was studied by experiments. The discharge of river closure is 590 m3/s and 758 m3/s. In this paper, the results of studies on a 1:50 scale hydraulic model based on the Froude similitude relationships are presented. The test results show that the discharge capacity of the diversion tunnel is reduced by 27.2% at most when this height is more than 2 m. The residual height mainly affects the maximum of stream energy with unit width, which increase by more than 50% at most compare to Non-existent residual cofferdam. However, the final drop, max-velocity along the gap axis, the local scour of riverbed and the flow pattern of the gap are basically not affected. In addition, with the height increase, the bank collapse is intensified, and the amount of dumped material with medium size increases, especially when it reaches 4 m, the large or Extra-large size stones begin to be dumped. Based on the comprehensive evaluation of multiple indexes and the type of dumped material, it is shown that the residual cofferdam height more than a certain value, the value is 2 m for the case study, will significantly increase the river closure difficult. [ABSTRACT FROM AUTHOR]