For the pump-stopping water hammer prevention of the floating pumping station water-conveying system, in addition to ensuring the safety of the pump unit and the pipeline, the impact of the water hammer pressure on the movable rocker pipe and the floating boat should be considered to ensure the stability of the floating boat. The numerical simulation of the pump-stopping transient of a floating pumping station water-conveying system under large range variable water source level was conducted. The results show that the lowest inlet water level is the most unfavorable condition for water hammer prevention. Under the condition that the pump outlet valve refuses to close, if the unit’s reverse speed exceeds the standard and the maximum reverse flow is reached within 3 s after the pump-stopping. The axial-flow check valve is recommended for the pump outlet valve considering the valve driving capacity requirements, the unit reverse speed and water hammer pressure. In the water hammer protection scheme of "pump outlet axial-flow check valve + air chamber on shore + intermediate check valve + hammer-prevention air valve", the axial-flow check valve ensures that the pump unit does not reverse, the air chamber and air valve reduce the maximum water hammer pressure and improve the negative pressure condition in the pipeline, and the intermediate check valve reduces the pressure oscillation amplitude and oscillation time in the pump outlet and rocker pipe. Therefore, the water hammer prevention problem in the floating pumping station water-conveying system is effectively solved.

For underflow energy dissipation, the arrangement of the grille shortens the length of the stilling pool and makes it easier to adapt to changes in terrain conditions. The two-phase flow of water and gas in the round-bore Γ-shaped grille type stilling pool was numerically simulated by the aeration model in FLOW-3D. The results show that the concentration of longitudinal bottoming gas decreased (31.3% →8.0%) along the way, and decreased significantly at the grid position, the minimum number of holes in front of the grid (^#6 section) was 5.6, the number of holes near the grid was about 9.0, and the number of holes behind the grid was much greater than 9.0. The bubble size near the bottom of the grid front axis increases along the course (0.9 mm→8.1 mm), and the bubble size of the near bottom plate after the grid decreases along the way (1.6 mm decreases to close to 0 mm). It can be considered that the bubbles with smaller diameters in large flow velocity areas play a major role in aeration corrosion reduction, which has obvious protective effect on the solid boundary of concrete, and the structure of the stilling pool including the grid is not easy to occur cavitation erosion damage.

The distribution of measured operating data of hydraulic turbines is non-structural and uneven density. The moving least squares method was used to fit the measured operating parameters to obtain the spatial characteristic surface of the water turbine, which can reflect the local characteristics of data surface and avoid the distortion caused by the differences of data distribution density. The Riyadh criteria was used to perform preliminary data filtering. The support radius was adaptively determined by local fitting across different ranges of discrete sample points. The robust moving least square surface reconstruction model was established combined with the Mahalanobis distance denoising method. Compared with the least squares method, the example calculation results show that the moving least squares method fits the operating characteristics of hydraulic turbines with higher accuracy and supplements the local data effectively. The result can reflect the operating characteristics of hydraulic turbines authenticity, which provides a reference for correcting the operating characteristic curve given by the turbine manufacturer.

In view of the issue of the traditional questionnaire survey method with high human and time costs, a set of resettlement survey system based on B/S framework and cloud platform was designed on the basis of the analysis of the business needs of the survey of post resettlement support monitoring and evaluation of large and medium-sized reservoirs in Ningxia. The system implements the import, update, deletion of historical data, as well as the addition, modification, query, statistical analysis, and other functions of sample information through two subsystems: the household survey of mobile terminal and the data management of PC terminal, and was applied to survey work examples. Compared with the traditional survey method used before, the application results indicate that it has increased the average number of daily survey samples by about 1.5 times, saved 78% of the labor and time costs required for the collation and filing of survey data, and greatly reduced the repeated printing and output of paper survey forms, and to effectively avoided the less of paper data.

To ensure the structural safety of the double row steel sheet pile cofferdam and control its water use area, the single-factor sensitivity analysis method was carried out to study the impact of various items on the deformation of cofferdam, and the PLAXIS software was used to implement the 2D and 3D finite element calculation. The results show that the elevation and tension of tie rod, and the specification of steel sheet pile have little impact on the deformation of cofferdam in soil; Compared with the width of the cofferdam itself, the deformation of cofferdam is more affected by the width of inner foot, so the width of the inner foot should be increased as much as possible; The depth of the outer sheet pile has no obvious impact on the deformation of the cofferdam, so that it can be reduced appropriately, and the depth of the inner sheet pile can be increased; The effect of the transverse structure on controlling the deformation of the cofferdam is not obvious, and other measures can be taken to strengthen the connection between the inner and outer sheet pile. The research ideas and calculation results can provide reference for structural design optimization of steel cofferdam in similar projects.

Maintaining ecological flow in a river is an important initiative to coordinate water resources development and utilization with river ecological protection. Most of the existing ecological flow calculation methods are limited by insufficient ecological data, difficult ecological modeling. In this paper, a Bayesian hierarchical model based on phytoplankton biomass was established to investigate the hydrological-ecological response relationship. The relationship between phytoplankton biomass and flow and water temperature in pre-flood, flood and post-flood periods was analyzed by taking the Shaying River as a case study. The results show that the Bayesian hierarchical model can identify the complex hydrological-ecological response relationship, and the advantage of hierarchical analysis improves the availability of short series data; The probability of biomass-flow covariate parameter β greater than 0 in pre-flood is 0.683, and the probability of less than 0 in flood is 0.577, and the guarantee of flow in the river channel in pre-flood and the control of discharge in flood have positive effects on phytoplankton biomass; Under the ecological flow conditions that meet the design requirements, the predicted maximum and minimum biomass improvements occur in river section 7 (+32.05% before flood, + 871.80% during flood, and +81.79% after flood) and river section 3 (+3.91% before flood, +1.16% during flood, and +2.89% after flood), respectively.

The change of hydrological situation and the operation scheduling of the downstream of the hub make the water level at the inlet and outlet of the fish channel change at all time, and the fish channel is running improperly. The insufficient inlet water depth will cause water drop and hinder the backtracking of fish. The integrated model was used to analyze the hydraulic characteristics under different water level combinations at the inlet and outlet of the fishing channel. The results show that the hydrodynamic changes of the fish tunnel tank chamber are mainly concentrated in the pool chamber near the inlet, and the greater the influence is closer to the downstream. When the inlet water level decreases, the water drops at the inlet and it is difficult for fish to trace; When the inlet water level rises, the inlet velocity slows down rapidly. In view of the design inlet flow velocity is 0.60 m/s-1.00 m/s, the maximum drop between the outlet of the fish channel and the inlet water depth is recommended to be controlled at 1.00 m. At the same time, appropriate water replenishment measures should be taken according to the water depth of the inlet to form effective lure flow rate at the inlet, and there is a good linear relationship between the supplementary water flow and the inlet water depth.

To analyze the impact of the construction of the Hengsha Dongtan (Phase 6-8) project on the Yangtze River Estuary, a two-dimensional tidal flow model was established using Delft3D, and tidal level and velocity calibration verification was conducted using existing hydrological data from 2008 and 2016. Based on the hydrological conditions in normal and flood years, the hydrological conditions, such as tidal volume, tidal level, and flow field in the main tributaries of the Yangtze River Estuary before and after the implementation of the Hengsha Dongtan Phase 6-8 Project were simulated. The results show that under two flow conditions, the construction of the Hengsha Dongtan Phase 6-8 project has a relatively small impact on the rising and falling tide flows of the main tributaries of the Yangtze River Estuary. The variation of high and low tide levels in the Yangtze River Estuary does not exceed 0.01 m, and the variation of high and low tide levels in the water area where the project is located does not exceed 0.02 m; The project has no significant adverse impact on the large-scale flow field structure of the Yangtze River Estuary. The rising tide velocity of the Beigang Waterway and Beigang Beisha Jiahong has decreased, with a maximum decrease of 0.03 m/s in Beigang Waterway and 0.02 m/s in Beigang Beisha Jiahong. The rising tide velocity of the Hengsha Channel and the North Channel of the Yangtze River Estuary has remained basically unchanged. Under the current riverbed terrain and engineering boundary conditions (all of the Hengsha East Beach project has been completed), there is a northwest southeast channel on the northeast side of the beach surface. The northern edge of the eighth phase project and the northern edge of the downstream sand body have a high ebb tide velocity, with a maximum velocity of 1.5 m/s or above, which is not conducive to the stability of the Hengsha East Beach regulation project.

Aiming at the shortcomings of hydropower unit vibration signal denoising using ensemble empirical mode decomposition (EEMD), a denoising algorithm based on an improved fruit fly optimization algorithm (RFOA) for optimizing the EEMD noise IMF component threshold was proposed. Firstly, the noise signal was decomposed using the EEMD algorithm to obtain the IMF components, and then the correlation coefficient method was used to determine the noise signal and the effective signal. Then, the RFOA was used to determine the noise signal IMF component threshold. Finally, the sample entropy of the obtained IMF components was used as a feature vector input of the GRNN algorithm for vibration mode recognition. Compared with the wavelet threshold method and the EEMD-GA method, the results show that the proposed algorithm has the highest signal-to-noise ratio and the best denoising effect.

In order to explore the impact of river level and total rainfall duration on the drainage performance of rainwater pipe network, an integrated SWMM generalized model of pipe network and river in a certain industrial park was constructed. Based on the rainfall events with a return period of 5 years and the total rainfall duration of 2 h and 24 h, the drainage conditions of rainwater pipe network and river in industrial parks with different initial river levels were simulated and analyzed. The results show that when the initial river level is low and the outlet is free outflow, river level has little impact on the drainage performance of the rainwater pipe network. When the outlet is submerged, with the increase of the initial river level, the proportion of overloaded pipelines and overflow nodes in the drainage system increases, the overload time and overflow time are prolonged, the peak flow of outlets and pipeline nodes decreases, and the peak flow of node which is closer to outlet decreases more sharply. Based on the same rainfall return period and the initial river level, compared with the short duration rainfall, the proportion of overloaded pipelines and overflow nodes in the long-duration rainfall is larger, the overload time and overflow time are longer, and the peak flow of outlets and pipeline nodes decreases greatly. When designing the storm water drainage system with river-pipe network, it is advisable to check the drainage performance of storm water drainage system for 24 h rainfall and different river levels.