Abstract:The characteristics and advantages of the big data method are discussed in this paper. In the method, mathematical formulas are replaced by intensive data in order to precisely describe the temporal and spatial variation of hydrological phenomena or the solution of a differential equation. The reasons why hydrology needs big data and technical support for obtaining hydrological big data are also discussed. The big data method may inspire the innovation of scientific thinking and become a way of solving complex problems in hydrology.

Abstract:According to the actual conditions along the Jialu River, we selected the Zhongmou and Fugou Hydrological Stations as the control sections, and calculated the ecological instream flow requirements of the Jialu River in different frequency years using three kinds of improved wetted perimeter methods, including the slope method, the curvature method, and the multi-objective evaluation method. The results show that the calculated ecological flow requirement is greatest when using the multi-objective evaluation method(r=2), and least when using the curvature method. It is more reasonable to use the multi-objective evaluation method(r=2)to calculate the ecological flow requirement of the Zhongmou section, and to use the slope method to calculate the ecological water requirement of the Fugou section.

Abstract:A one-dimensional experiment of adsorption of biogas slurry by unsaturated homogeneous soil at constant room temperature was conducted in order to investigate the adsorption characteristics of total nitrogen from biogas slurry. The conductivity and total nitrogen content of percolates were measured with different concentrations of biogas slurry, soil densities, and infiltration heads of biogas slurry. The average pore-water velocities and hydrodynamic dispersion coefficients under different experimental conditions were obtained through fitting of the experimental data using the convection-dispersion model of solute transport and CXTFIT2. 0 software. The experimental results showed that the peak values of the conductivity of percolates in experimental schemes with higher soil density was less than those in schemes with lower soil density; the differences between the peak conductivity of the percolates and the conductivity after the peak point increased with the concentration of the biogas slurry; with the increase of the biogas slurry concentration, the adsorption curves gradually moved towards the right, and the time corresponding to the turning point of adsorption curve and the total nitrogen content in soil increased, but the relative concentration of the percolate at the turning point, the average prove-water velocity, and the hydrodynamic dispersion coefficient decreased under the same soil density and head conditions; with the increase of the infiltration head, the time that the soil needed to reach saturation of the adsorbed total nitrogen decreased, and the average pore-water velocity and hydrodynamic dispersion coefficient increased under the same biogas slurry concentration and soil density conditions; and, with the increase of soil density, the time corresponding to the turning point of adsorption curves and the hydrodynamic dispersion coefficient increased, but the average pore-water velocity decreased under the same biogas slurry concentration and head conditions.

Abstract:According to the actual situation in which the cross-sectional topographic data are discontinuous for hydrodynamic and aquatic environmental simulations, topographic interpolations for strongly curved reaches, river confluence, and braided rivers were conducted with the triangular mesh method, inverse distance weighting method, and Kriging method using the Huangpu River as an example. The reliability of these three interpolation methods was analyzed and compared. The results show that, for strongly curved reaches, river confluence, and braided rivers where topography varies significantly, the interpolation results of the triangular mesh method are unstable, with high errors and significant fluctuations, indicating that this method failed to reflect the actual topographic situation. The “buphthalmos” phenomenon may appear when the inverse distance weighting method is used. Compared with other methods, the Kriging method shows higher reliability. When fewer cross-sectional data are used, the results of the Kriging method show lower error and higher robustness than the other two methods. Based on the interpolation results of the topography of the Huangpu River with the above-mentioned three interpolation methods, a mathematical model was used to compare the tidal level processes, and the results show that the computational precision of the Kriging method is the highest.

Abstract:In order to study the effects of the spacing of nozzles on the dilution efficiency of a multi-hole diffuser, the realizable k-ε model of the Computational Fluid Dynamics(CFD)software Fluent was used to simulate the effective cross-flow velocity, the jet concentration trajectory, the velocity field, and the concentration field of two tandem jets in cross-flow with different spacing. The results show that, as the spacing of nozzles increases, the sheltering effect of the first jet weakens, the effective cross-flow velocity increases, and the degree of curvature of the jet concentration trajectory increases. Near the jet, there is an exponential relationship between the concentration trajectory and the distance downstream of the nozzle with an exponent of 1/2, and an exponential relationship between the concentration trajectory and the spacing of nozzles with an exponent of -0. 27. At more distance from the jet, there is an exponential relationship between the concentration trajectory and the distance downstream of the nozzle with an exponent of 1/3, and an exponential relationship between the concentration trajectory and the spacing of nozzles with an exponent of -0. 18. The spacing of jets has little influence on the concentration of the first jet. However, the concentration of the second jet decays faster in the direction of flow when the spacing of nozzles decreases, and the concentration grows more stable when the distance from the nozzle is greater than eight times the nozzle diameter.

Abstract:In the calculation of one-dimensional soft clay ground consolidation in deep soil, initial stress and additional effective stress distributions in soil greatly influence the degree of consolidation of ground. With regard to this problem, one-dimensional nonlinear consolidation governing equations of soft ground under uniform loads are derived and solved with the finite difference method, based on the assumptions that the initial stress in soil varies with the ground depth, and the additional effective stress caused by external loads changes with both ground depth and consolidation time, as well as the hyperbolic model of the soil stress-strain relationship. Formulas for the degree of consolidation and settlement of ground are presented. A case study shows that the degree of consolidation of ground calculated with the finite difference method agrees with the traditional analytical solution, and the computational efficiency of the finite difference method can be effectively improved when the segmental calculation method is used throughout the consolidation process. The results of another example show that the settlement of ground calculated with the finite difference method agrees with the in-situ data. The suggested method can greatly simplify the consolidation calculation and is of high applicative value in engineering.

Abstract:With a focus on the problems of cavitation damage and the decrease of the energy dissipation rate caused by increasing flow depth and decreasing aeration for traditional stepped spillways under a large discharge rate, a hydraulic jump-aeration stepped spillway was developed, producing aerated flow on the stepped spillways by means of hydraulic jump aeration. Through a physical model test, the air-entrainment characteristics of the hydraulic jump aeration basin were studied, including the effects of the approach flow condition, the length and end sill height of the aeration basin, and hydraulic jump flow regime on air entrainment characteristics. The results demonstrate that the submerged jump shows a better air entrainment effect for the bottom and walls within the aeration basin and the region behind the end sill, and the hydraulic and geometric parameters affect the hydraulic jump flow regime and then affect the air concentration. It is crucial to present a suitable flow regime for air entrainment into the flow on the stepped spillway using the hydraulic jump aeration basin.

Abstract:In order to study the permeability of highly permeable embankment foundations with suspended cut-off walls, a series of seepage-stress coupling experiments with cut-off walls of three different heights in different axial stress states were carried out. Results show that seepage failure is more likely to occur at the bottom of cut-off walls because of high seepage velocity there, the average seepage gradient of the embankment foundation decreases with the increase of the height of cut-off walls, and the seepage gradient at the bottom of cut-off walls is always maximum along the seepage contour line. Stress states have large effects on the seepage gradient of sand gravel foundations with suspended cut-off walls. There is a parabolic relationship between critical seepage gradient of piping and axial pressure. The seepage gradient causing seepage failure at the bottom of cut-off walls increases linearly with the increase in axial pressure. Based on these results, a linear empirical formula for the seepage gradient causing seepage failure at the bottom of cut-off walls, denoted by the axial pressure, is established.

Abstract:Based on the gravity similarity criterion, a hydraulic model was built so as to study the variation characteristics of the dynamic hoisting force and static holding force of the gate and the hydrodynamic characteristics of its bottom frontier during the operation process of the pressured plane gate located in the middle of a long water delivery tunnel for a water distribution network. The results show that the hoisting force changes greatly within the range of the small opening degree and the maximum hoisting force occurs near the relative opening degree of 0. 05. The holding force and hoisting force show a similar change with the gate opening. Compared with the non-perforated girder, the maximum opening and closing forces for the bottom girder with an opening rate of 27% decrease by 5. 7% and 7. 8%, respectively, showing a small reduction. The vibration of the gate with a designed type of bottom frontier is stable for the project and resonance of the gate and water flow is nearly impossible, guaranteeing the stability of the gate operation.

Abstract:To overcome the disadvantages of conventional dam deformation monitoring methods, which are high labor intensity, long cycle, and acquiring of only pointwise information, a recently developed technology, called ground-based synthetic aperture radar interferometry(GBInSAR), was applied to dam deformation monitoring. Based on an analysis of the GBInSAR system and imaging characteristics, a numerical model for atmospheric phase correction using a stable reference point was established and applied to monitor the deformation of the Geheyan Dam. The results show that at a location of 1 300 m downstream of the dam, atmospheric disturbance caused an error of up to 85 mm. Atmospheric disturbance interfering with the sight of radars was the main factor decreasing the accuracy of dam deformation monitoring with GBInSAR technology. After elimination of the influence of atmospheric disturbance, the results of dam deformation monitoring with GBInSAR technology agreed with plummet observations. The results also show that the deformation of the water release gate at the surface outlet was significantly greater than the dam body deformation, and it increased with the rise of the water level.

Abstract:Due to the limitations of techniques, conditions, and methods for river ice field observation, it is difficult to obtain large-scale and long-sequence data regarding river ice processes. Remote sensing technology can be used to effectively collect and deal with vast amounts of complex temporal and spatial-scale information. In this study, a Landsat8 remote sensing image was used as the data source, and the optimal band combination was obtained through comparison of single-band information and joint analysis of the correlation coefficient, information entropy, and the optimal index. The maximum likelihood method of supervised classification was used to interpret and analyze the remote sensing image data from the Sanhuhekou River bend of the Inner Mongolia reach of the Yellow River over various periods in the winter of 2013 to 2014. Through analysis of the interpretation results, the growth and melting processes and characteristics of river ice over different periods in the study of the river bend were determined. The results of this study show that TM743 is the optimal band combination for interpretation of the remote sensing data, and the interpretation image can reflect the growth, melting, and transport processes of river ice at a large scale in the winter. In combination with meteorological and hydrological data, the interpretation image can explain typical river ice phenomena, providing technical support for analysis of river ice theory and mechanism studies.

Abstract:In order to determine the defensive capability of the downtown section of flood wall in Shanghai along the Huangpu River, using monitoring data of flood wall elevation from 2012 and design parameters of the flood wall along the Huangpu River, the Monte Carlo method was applied to calculate the overtopping probability of the flood wall with different tide levels under the current conditions and future conditions of sea level rise, propose evaluation criteria for overtopping risk analysis of the flood wall, and quantify the corresponding overtopping risk. The results show that the current defensive capability of the flood wall is clearly insufficient and Huangpu River flood prevention is inadequate considering the rising water level of the Huangpu River in recent years and the continuing sea level rise that will occur in the future. The high-risk area of overtopping is concentrated upstream of the downtown section of the flood wall. The overtopping risk of the flood wall is related not only to the lack of elevation but also to different designed tide levels adopted in different sections.

Abstract:In order to optimize the layout and number of holes and geometric parameters such as the section shape, area, and outlet pipe diameter of the oil bath in hydrodynamic design of a runner-pump for the thrust bearing of hydroelectric units, a method for performance prediction and optimization design suitable for the flow passages of the runner-pump is presented in this paper. Through combination of different geometric parameters, the influence of the size and shape of the main flow passage components on hydrodynamic performance of the runner-pump was analyzed using the performance prediction method based on multi-condition numerical simulations. In this way, a hydrodynamic optimization design method for the runner-pump based on cooperation throughout the circulation system, which can improve the performance and reliability of the hydrodynamic system for self-circulating system design, is proposed. The results show that, compared with the original runner-pump, the average head is increased by 4m, the average efficiency is increased by 5. 5%, and the H-Q curve can guarantee better stability of the system under varying condition operation for the optimized runner-pump under the same test conditions.

Abstract:The flow patterns of a stilling basin with free discharge at the end sill of the basin downstream of a sluice are complex. Thus, the hydraulic characteristics and layout of the basin are significant to the engineering design and operation. Based on a hydraulic model test, the relationship between the stilling basin length and the end sill height was analyzed, and the layout method of the stilling basin is put forward: First, according to the Froude number in the inlet section of the stilling basin, the height of the end sill is preliminarily selected on the basis of the selected bottom elevation of the horizontal segment. Second, through adjustment of the end sill height and calculation of the water depth at the top of the end sill, the ratio of the sum of the two variables mentioned above to the water depth after the hydraulic jump is controlled within a range of 1. 15 to 1. 2, and then the ratio of the length of the horizontal segment of the stilling basin to the length of hydraulic jump can be reduced to within the range of 0. 8 to 0. 85. This method can reasonably determine the hydraulic and shape parameters of the stilling basin with free discharge at the end sill.

Abstract:The sluice gates of the Baishiyao Hydro-Junction in the Beijiang River were selected to study the influence of the sluice gate opening mode on flow features and navigation flow conditions in the entrance area of an approaching channel downstream of the hydro-junction. Three-dimensional(3D)numerical simulation was conducted on the influence of different sluice gate opening modes on the navigation flow conditions in the entrance area of the downstream approaching channel. The results show that the influence of sluice gate opening modes on the navigation conditions is small when the flow is low, and the influence of sluice gate opening modes on the navigation conditions is large when the flow is high. For the sluice gates of the Baishiyao Hydro-Junction, a single opening of the left sluice gate or intensive opening of the left sluice gate with opening at intervals of the right sluice gate will prevent the navigation flow conditions of the right side of the first-line ship lock from meeting the requirements in the entrance area of the downstream approaching channel. To ensure the safety of navigation, it is suggested that the right sluice gate of the Baishiyao Hydro-Junction be opened or else all the sluice gates be opened during flood drainage.

Abstract:The finite element method was used to simulate the temperature and stress fields of the ninth discharge section of the Longkaikou Roller-Compacted Concrete(RCC)gravity dam throughout the process of the construction and operation periods. The gravity load, hydrostatic pressure, temperature load, change of Young’s modulus with age, and creep effect of concrete were considered in the calculation of the stress field. The results show that high tensile stresses of 3 to 4 MPa occur near the discharge orifice in the construction period, but decreas to 2 MPa in the operation period. High tensile stress also occurs in the upper portion of the dam due to the high pouring temperature in summer and a large temperature drop after construction, but the stress state will be improved after 10 years of operation. The compression stress of the dam is less than 2 MPa, except for higher compression stress at the dam heel due to stress concentration. The stress states near the discharge orifice and in the dam body indicate that the dam is basically safe.

Abstract:Bragg resonance phenomena, occurring as waves propagating from the sea to shallow water under particular topographic conditions, were studied to provide a scientific basis for the design of estuarine and coastal protection engineering and the forecast of morphodynamic evolution. The definition and characteristics of wave Bragg resonance as well as the significance of research are introduced, and the pros and cons of four approaches for study of the phenomena are reviewed, including field observation, theoretical analysis, numerical simulation, and experimental investigation. Major achievements regarding the types of wave Bragg resonance, the formulas of the low-order resonance reflection coefficient, and high-order resonance numerical simulation are summarized. Three important topics for further intensive study are proposed, including the negative drift of dominant frequency, the characteristics of the irregular wave Bragg resonance, and the generation mechanism of Bragg resonance under wave-current interactions.

Abstract:The formation and development of high-resolution sequence stratigraphy and its application in the comparison of Quaternary and fluvial facies strata are reviewed. Potential future applications of high-resolution sequence stratigraphy in division and comparison of the Quaternary aquifer are analyzed. Using the high-resolution sequence stratigraphy theory, the relationship between the base level cycle, accommodation, and stratum response can be analyzed, the isochronal stratigraphic framework of fluvial facies can be established, and the distribution characteristics of different microfacies and spatio-temporal distribution of a fluvial sand body can be found, which is conducive to the reasonable division and comparison of the loose Quaternary aquifer(group)of fluvial facies in plain regions. In the application, quantitative study should be strengthened. On the basis of defining the time range, all levels of base level cycles can be identified and divided on specification. Special attention should be paid to distinguishing the auto-cycle and allo-cycle of the fluvial facies stratum based on the sedimentary dynamics analysis of geological process-response.