This paper studies the application of partial L-moments to frequency analysis for estimation of design flood with large return period to reduce the disturbances of small floods in the flood series. Monte-Carlo experiment was conducted to examine the statistical properties of partial L-moments. This paper analyzes the imitative effect and evaluates the errors in estimation of design flood by using the annual maximum flow series at five hydrological stations in Shaanxi province. The results show that the partial L-moments method has good statistical properties. In comparison with traditional L-moments, this method can better describe the data samples in flood analysis and improve the estimation accuracy of design flood. Thus, it is a reasonable and effective method for flood frequency analysis.

Runoff and sediment conditions of the Jinghe River were categorized into rich, normal and poor states, by using a P-III-type distribution and the data series at Zhangjiashan hydrological station from 1932 to 2008, and the evolution trend of runoff-sediment combination (RSC) was examined by the theory of Markov processes. An analysis of transient probability shows that the combinations tend to be rich-rich or poor-poor. In synchronous self-transient probability, rich-rich combination is the most probable with a value of 0.72, while in asynchronous self-transient probability, normal-poor is the most probable with a value of 0.50, and the synchronous-asynchronous transient probability of poor-normal combination is greater. An analysis of RSC encounter risks with the Copula method reveals that rich-rich encounter risk is the highest value of 27.9% in synchronous frequency, but differences exist in asynchronous ones. In general, the synchronous encounter frequencies are higher than the asynchronous ones. Finally, an analysis on the recurrence period of RSC is presented.

This article points out problems in the unreasonable methods recommended in Specifications on water conservancy computation of hydroelectric projects DL/T-5105-1999 for the calculations of runoff regulation and water power of hydropower stations, and suggests ideas for improvement on these methods. It is demonstrated that the improved method can avoid or correct the unreasonableness in method classification, low accuracy in calculation, and indeterminacy in conditions simplifications, etc. The improved method has been verified via application to a number of projects and its calculations are reasonable and more accurate. It could give more firm power output in comparison with the conventional method.

This study demonstrates the dual characteristics in the elements of operating rule for multi-reservoir water supply, i.e. water-supply policy and water-allocation policy, and analyzes the roles and significance of these two policies. We focus on a summary and review on the advances in the research and use of operating charts, operating functions, and other specific forms of the operating rule for multi-reservoir water-supply operation. We also suggest some directions of further study to improve multi-reservoir water-supply operation.

Traditional optimization methods, when used to solve the mathematically complex and high-dimensional problem in optimal operation of a cascade hydropower station system, often encounter dimension disaster and trapping into a local optimum. This paper presents an immune-shuffled frog-leaping algorithm (ISFLA) that adopts a clone-selecting algorithm in population space in the SFLA framework. ISFLA constructs subgroup shuffling and executes operations of cloning and selecting, meanwhile it adopts an advanced step-updating policy to improve local search ability. It has been applied to optimized operation of cascade hydropower stations for short-term power generation. Results show that ISFLA has better efficiency and superiority to standard SFLA, particle swam optimization, or progressive optimization algorithm.

Urban modification of rainfall over Beijing metropolitan region has been extensively examined. A review on previous studies is presented focusing on the main approaches and conclusions and the exsiting key issuess. The approaches fall into two categories, i.e., observation-based approach and model-based approach. Their ultimate objective is to separate the signatures of urban impact on rainfall from that induced by large-scale climatic variability and ambient local environment. In the recent studies remain four key issues that should be properly addressed in future, i.e., coupling effects of urban and topograhic characteristics, spatio-temporal tendency of urban impact, uncertainty in aerosol effects, and complexity of simulation in urban canopy. Future studies should further enhance observational network and improve the atmospheric models in description of cloud microphysics and representation of urban land surfaces.

This article adopts the maximum carrying population to develop a model of water resources carrying capacity in the Guangxi Beibu Gulf economic zone, considering its water resources available, existing development and utilization of water resources, and water demand per capita. We also present an evolution analysis of this capacity over the period of 2005-2030 using an indicator of water resources overload degree. The results show that on the premise of rational use, the water resources carrying capacity in this zone is good overall, but that in Beihai city and Nanning city is already in overload. On the premise of maximum utilization, the capacity is overall in much surplus, but it will be overloaded in Nanning after 2020.

The agricultural water resources carrying capacity in the Beilin district of Suihua have been studied based on its water resources data from 1996 to 2012 with a method of fuzzy comprehensive evaluation. Results show that this capacity falls between levels II and III, suggesting that the existing exploitation of this district's agricultural water resources is in gradual transition toward the maximum development. The evaluation score for the period of 1996-2004 was dropping from 0.39 to 0.36, but the bearing capacity from 2004 to 2012 had a trend of slight rising, which indicates an effect of the relevant measures taken by the local government to ameliorate the bearing capacity after realizing the restriction of agricultural water scarcity on local economic development.

Acceptable risk criteria is one of importance research in engineering risk analysis and risk control method, which is aimed at the basis of life economic, social and environmental aspects of the risk assessment values and as a judgment of whether risk undertaker accept the risk. The paper describes the basic principles and methods of determining acceptable risk criteria, combines with the actual situation of our country and bases on the dam break data and proposes that acceptable risk can be 10^-5 by the annual probability of failure. Social tolerable risk can be 10^-4 and the number of affected people of 1000 is intolerable up limit. It is based on the ALARP principle and proposed the F-N curve of dam acceptable risk criteria. There is certain guiding significance for making acceptable risk criteria for dam engineering management.

 According to both the model tests and numerical simulations with realizable k-ε turbulence model and VOF model, analysis and calculations of the spiral flow in a compound internal energy dissipation spillway tunnel are presented, focusing on velocity distribution, rotational flow angle, turbulence kinetic energy, turbulence dissipation rate, and energy dissipation rate. The results show that radial flow velocity occurs in the vortex generator as a result of unfavorable tangential flow at the generator inlet. Over radial direction, the axial velocity is distributed symmetric with its peak close to the tunnel wall, while the tangential component is anti-symmetric with its peak close to the core water-air interface suggesting a combined eddy. Rotational flow angle in the vortex generator and blocking-expansion device changes more rapidly along the tunnel than that in the spiral-flow tunnel at middle section. Turbulence kinetic energy and turbulence dissipation rate are greater in the vortex generator and blocking-expansion device. The calculated total energy dissipation rate of about 83% is split into 5% in shaft section, 28% in swirl-flow section, and 50% in blocking-expansion device. The blocking device can not merely reduce cavitation potential, but increase energy dissipation rate.

This paper derives formulas for calculation of the relative contraction of water depth and the relative hydraulic jump depths in the most unfavorable condition, based on the energy dissipation formulas given in the sluice design specification. Because the most unfavorable state of energy dissipation for sluice generally occurs not at the maximum flow, engineers often blind spreadsheet deriving for stilling basin depth design. We apply the extreme value theory and dimension theory to analyze the most unfavorable stilling basin depths, and suggest concise formulas for three stilling basins of coastal tidal drainage gate, sluice on a plain river, and sluice with a great water drop on a mountain river. Example calculations show that these formulas are accurate, reliable, and convenient.

This paper presents an experimental study and numerical simulations of the flow in an energy dissipator of Y-shape flaring gate pier, stepped spillway, and stilling basin. The flaring gate pier, if with an unreasonable lateral contraction in flood releasing conditions, often produces water splashes that jump over the sidewalls. Three different shapes of sidewall flaring pier were experimentally tested and compared for their overall flow pattern, water wings behind pier, overflow surface pressure, pressure on stilling, and velocity distribution. Results reveal that the flow patterns and energy dissipation in the stilling basin are good when the flaring piers take contraction angles of 19.03° and 17.07°, 19.98° and 13.80°, or 19.98° and 7.0°. And water splashing over the sidewalls can be avoided with the angles of 19.98° and 7.0°.

Surge tank is a structure crucial to the stability of governing system and regulation quality. Thomas critical stable section area is a significant design criteria, but it neglects the effect of water interia in surge tank. This inertia could affect stable section area and governing quality if a surge tank has a long lateral pipe connecting to the intake tunnel, such as in a pumped storage station or high water head hydropower station. By theoretical analysis, numerical computation and engineering example in this paper, it is proved that the water inertia in a surge tank with a long lateral pipe helps to decrease the stable section area and improve regulation quality in small fluctuations and that neglect of water inertia in design is safer.

Jinping II power station is located on the lower Yalong River mainstream with an installed capacity of 4800 MW, and its first unit was put into power generation in December 2012. It has four water diversion tunnels of average length 16.67km, a water diversion and power generation system that is featured with super-long tunnels and huge tunnel cross sections. At the stage of feasibility study on this system, a lot of computation and analysis have been done; at the bidding and construction drawing stages, major adjustments are made on the tunnel structures for a variety of reasons, resulting in a hydraulic transient process extremely complicated to compute. To ensure the safety and reliability of the tunnel system under hydraulic transients, a large amount of computation, analysis and model test has been conducted in previous studies. This paper summarizes the main characteristics of the system and its modification during construction, compares the calculations by different research institutions, and estimates the extreme values of system parameters for the power plant in large fluctuation conditions, the system operation stability in small fluctuation conditions, and the amplitude of generation output in hydraulic disturbance conditions by comprehensive analysis. These results are very useful for safe and stable operation of the project.

This paper describes a simplex-differential evolution hybrid algorithm to analyze experimental water quality data of river stream, and estimates water quality parameters for a 1-D river under longitudinal dispersion and a 2-D river under transverse diffusion. This algorithm combines the features of simplex method and differential evolution method: the former has a strong local search ability and fast convergence but higher dependence on the selection of initial parameters; the latter has an strong global search ability and fewer controlled parameters but weak local search ability. The combined algorithm has advantages in both random searching and deterministic calculation, and well balances the local against global search ability. Numerical experiments show that this new algorithm is of fast convergence and cost saving in analysis of experiment data of water quality and estimation of water quality parameters of river stream, and thus it has a good application potential.

Discharge through a rotary flow spillway tunnel with blockage and its influencing factors were studied with model test and theoretical analysis. This discharge is closely related to the flow pattern in the tunnel: it is a weir flow when the tunnel inlet and shaft are not submerged, while an orifice flow when submerged. In the condition of submerged tunnel inlet, the discharge is influenced by both the vortex generator inlet and blockage orifice, and the flows at these two locations follow the law of pressurized orifice flow. At the generator inlet, the discharge coefficient depends on the energy loss upstream and the local pressure, and the latter is the main factor. At the blockage orifice, it depends not just on the energy loss upstream, but on the variations of flow swirling behaviors caused by the blocking device, such as relative cavity radius, rotary angle, and relative wall pressure. At the generator inlet, this coefficient is 0.4 at contraction ratio m=0.56 and in the range of 0.55~0.65 at m£0.18, while at blocking orifice, it is close to 0.5 at m=0.56 and in the range of 0.25~0.32 at m£0.18. An expression for calculation of the cross-sectional area of generator inlet has been derived.

According to the problem of insufficient performance for water pollution migration simulation, On the basis of water pollution event data and spatial data integration, the main watercourse was decomposed to multi-scale triangle face for forming water quality infinitesimal. The halftone patterns and mesh view model was set up. A Digital Earth visualization service framework was constructed with 3S data, tiles-pyramid, OGC standard, high-performance computing，interoperability environment etc as principal part. And a system was realized for application test. The experiment results show that: this method can effectively express the status of pollutants evolution, and describe the migration process of water pollution more intuitively with topography data collected and provided by Digital Earth.

 By theoretical analysis, numerical calculation and engineering example, it is proved that stage-discharge relation of downriver decrease surge-chamber ground swell, and makes little difference to other guaranteed regulations because of buffer action of surge-chamber. Boundary condition of constant water level is safe because stage-discharge relation reduces stable sectional area of tailrace surge tank, and improves governing quality. But which is unsafe in power station without tail surge tank because fluctuation of tail water directly influence pressure in the draft tube and make it worse.

linearized space state model is established in consideration of open channel water level fluctuations, which is transformed to transfer function to describe small fluctuation in hydropower station. Effect of water level fluctuations in tail water open channel on regulating system stability region was analyzed based on Hurwitz stability criterion. The results show that open channel has slight influence on stability range in hydropower station without tailrace surge chamber; length and depth of open channel has an evident influence on stability region in in hydropower station with tailrace surge chamber, and water level fluctuation in open tailrace tunnel make for the stability of small fluctuation transient process.

Seismic response analysis of high CFRD under different inputted earthquake waves is studied using a 3-D authentic nonlinear dynamic analysis method. Performances of a dam under site evaluated wave, specification wave, and measured wave, are evaluated and compared, including acceleration and shear stress response, permanent deformation, slope dynamic stability and anti-seismic safety. Among these three types of waves, site evaluated wave produces the strongest response. It is essential to meet the safety requirement in the case of specification wave, while it is often hard to select proper measured wave. This work would be useful for seismic design of high rock-fill dam.

Dynamic response characteristics of the structures constructed on a deep overburden layer are affected obviously by the seismic motion characteristics of soil layer, because the characteristics of seismic motion transmitted from the bedrock under this deep layer are varied greatly by the deep overburden layer. This paper develops the analysis models of ground seismic response considering the horizontal and vertical structural characteristics of the deep overburden layer, and studies the influences of these structural characteristics on the seismic motion of soil layer using a finite element method based on effective stress analysis. The results show that the seismic motion characteristics of deep overburden layer are affected greatly by topographic condition of bedrock, thickness of soil layer, variations of structural characteristics in horizontal direction, existence of soft layer, and new structures constructed on ground. The structural characteristics of soil layer has a relatively complicated influence on the seismic motions of soil layer, it not just significantly affect the amplitude of seismic motion input from bedrock, but also apparently vary the frequency spectrum characteristics of the seismic motion.

Selection of proper seismic input is important for seismic response analysis of hydraulic structures. Analytical formulae are derived herein for calculation of equivalent loadings for 2-D plane P waves and plane waves via viscous-spring boundary on the basis of previous studies and the theories of wave motion. They can be applied to an artificial boundary and model the effects of obliquely incident seismic waves. The results of numerical examples show that this method has a high accuracy for P waves or waves and can be useful for computation of structure-foundation interaction under obliquely incidences of waves.

 Earthquake occurs more frequently in recent years. With a large number of water conveying engineering under construction, aseismic performance of long-distance exposed steel penstock becomes significant. The fact that travelling wave effect has an influence on seismic response of spatial structures with a large plane scale, has been known and accepted widely. The effect of travelling wave on an exposed long steel penstock for inverted siphon is computed by a nonlinear time history method in this study. The results show that travelling wave effect can enlarge seismic deformation and stress responses in the main components of penstock, such as bellow expansion joints, supports, and steel pipe. Its extent much depends on wave speed: the smaller the wave speed, the more significant such an effect. When wave speed exceeds 1000 m/s, the seismic responses are approaching to the ones without this effect. The responses also depend on the structural characteristics of penstock. Thus, in checking aseismic safety of an exposed steel penstock, an accurate model must be adopted and travelling wave effect should be considered for the pipe of low celerity (i.e. below 1000m/s). These results can be useful to aseismic design and analysis of similar structures.

A hydraulic model of pump-turbine unit which has “S” characteristic curves, was developed to study the effect of MGV on the “S” characteristics and determine the openings of pre-opened guide vanes in the “S” operation region. The external characteristics and internal flow were simulated by using a three-dimensional incompressible flow model, with a model for turbulence calculation and the SIMPLEC algorithm coupled with a second-order upwind scheme for discretization and solution of flow field. The simulations were verified with experimental data. Analysis on the calculated internal flow and external characteristics reveals that the MGV method can effectively prevent the unit from entering turbine braking mode. As the pre-opening increases, the flow non-uniformity becomes more significant and the water ring between runner and guide vanes tends to disappears gradually. The vortex rope in draft tube can be weakened by increasing the pre-openings. These results would provide a basis for stability of pump-turbine at start-up stage.

In one side-intake pumping station, unfavorable flow patterns in its forebay and sump existed, harming the operation of its pump units. CFD simulations by a commercial code revealed large-scale recirculations in sumps No.1~No.10 and water whirls along the semicircular back wall. To control these unfavorable flows, three sets of flow-control devices were installed in the sump. By CFD analysis and comparison of these control schemes, an effective scheme is to install diversion piers, a straight baffle plate, and two upright columns in the sump. As a result of this scheme, the large-scale recirculations disappear, the cross-sectional distribution of axial velocity in the sump is uniform with an increase of 3%~11% in flow uniformity, and the flow whirls around the back wall are also suppressed. The flows into all the suction pipes are distributed uniformly and symmetrically. This work would be applicable to intake sumps of similar pumping stations.

 Installed capacity is an important indicator of a hydropower station, its scale directly related to the energy efficiency, efficiency of water resources use, and rational utilization of equipments and investment etc. The factors of installed capacity are not the same for hydropower stations of different regulation performances. This paper divides hydropower stations into two types, good regulation performance and limited regulation performance. A general procedure and the existing issues in the practical work of making choices for the stations of different performances are discussed, proceeding from the factors influencing the choices of installed capacity. Through the analysis of examples, confirmed the correctness of the factors in this paper, which provided a reference for the choices of installed capacity. Last, this paper suggests that it is necessary to expand the installed capacity of the existing hydropower stations timely but this should depend on the timing.

Hydraulic engineering is the earliest field in China to implement project management theory, and project managers' central role is one of its main features. Excellent project managers have an ability to guarantee a smooth achievement of project objectives. How to select outstanding project managers and what ability and quality project managers must have, attract the concerns of domestic and foreign researchers. The authors have conducted filed interviews and questionnaire surveys on the projects managed by the hydraulic project construction and management center of one city in China, with the survey scope covering the managers, organizers and employees of the center, its supervising sectors, and the contractor. Analysis of the present survey data and previous studies show that the quality required of hydraulic project managers can be evaluated in three aspects, i.e. management skill as the most importance, personal quality, and background knowledge as the least importance.