This paper analyzes the development course of irrigation in China and the key points of construction in different period, and summarizes the main achievements. This paper has sorted out the major national strategies and new requirements for irrigation since 2017, and pointed out three unbalanced and inadequate problems in the development of irrigation. According to the future requirements, this paper puts forward five countermeasures, e.g. to realize the transformation, to determine the scale and layout of irrigation with rigid constraint of water use, to promote the modernization of irrigation, to strengthen scientific and technological innovation and demonstration, and to develop irrigation with both hands.

Existing open ditch drainage systems in the rice-wheat rotation area of southern China affect the efficiency of agricultural machinery and restrict quick development of agricultural modernization. Construction of subsurface drainage systems can improve land utilization and agricultural production efficiency. In this paper, the layout of the subsurface drainage systems for rice-wheat rotation croplands in the ZhaoGuan Irrigation Area of Jiangdu District, Yangzhou City, Jiangsu Province is analyzed by using the farmland drainage model-DRAINMOD. The simulation results show that during the crop harvest, the number of machine working days is affected by the buried depth and spacing of subsurface drain pipes. As the drain depth decreases and the spacing increases, the number of working days gradually decreases. With the same rainfall frequency and groundwater depth, the machine working days in rice harvest season are more susceptible to rainfall than that in wheat harvest seasons. In the rice harvest period, based on the requirements of large machine operation requirement, when the drain depth is 80~100 cm, the maximum drain spacing that meets the 90% and 95% probability is respectively 26.0~32.0 and 14.0~21.0 m. Based on the requirements of small machine operation, when the drain depth is at 80~100 cm, the maximum drain spacing satisfying the 90% and 95% probability is 26.5~33.5,18.0~23.0 m, respectively. Findings from this research may provide a technical reference subsurface drainage system design of to meet trafficability requirement of machine harvest in similar rice-wheat rotation areas.

In this paper, the characteristics of large water-bearing water in the Yellow River water diversion area are not applicable to the traditional water-saving irrigation method, and the filtration study of the Yellow River sandy water in Tanglai Canal is carried out. Through the test comparison method, the water filtration test is carried out by using four treatment schemes: seepage well S, buried horizontal filter L, buried vertical filter V, buried vertical + horizontal filter R. The test results show that: ①The needle-punched nonwoven fabric has a good sand-blocking effect, and the higher the non-woven fabric specification, the more obvious the sand-blocking effect. ②The flow rate of filtered water per unit time and unit length from high to low is: S>R>L>V, respectively 0.137 6, 0.031 1, 0.022 7, 0.015 6 m³/(h·m), which shows that the seepage well (S) is the optimal solution. ③When the R, V, and L groups are tested for 50 h and the S group is for 70 h, the sediment concentration in the filtered water is less than 0.4 kg/m³, and the maximum sediment particle size is 0.112 mm. Only 0.077% of the larger than 0.1 mm, the water quality can meet the drip irrigation requirements. ④After the farmland water filtration test, the research idea of non-full flow filtration of sandy water in the Yellow River Irrigation District is feasible and has certain scientific guiding significance.

The variation of evapotranspiration and its influencing factors in Xilin River Basin are revealed, which can provide scientific basis for drought and flood monitoring and water resources management in Xilin River Basin. Based on MOD16A2 remote sensing products and the verification of measured data, the change rule and influencing factors of ET in Xilin River Basin from 2000 to 2017 are studied by using trend analysis and correlation analysis, and the change characteristics of ET under different land use types are analyzed. The results show that the annual ET value has a high spatial differentiation, showing a low trend in the northwest and a high trend in the southeast; the annual average ET of different land use types is forest land > cultivated land > unused land > grassland > construction land. The correlation between ET and precipitation and NDVI is the greatest, with an average correlation coefficient of 0.65 and 0.72, respectively. In addition, topographic factors have a great influence on ET change, ET change increases with elevation, which accords with the characteristics of exponential curve change. ET increases first and then decreases with the increase in slope, which accords with the characteristics of quadratic curve change; while the ET of middle slope is obviously higher than that of other slopes, and the ET value of flat slope is the smallest.

In order to reduce soil salinization in Hetao Irrigation District, make full use of light and heat resources, and improve the utilization rate of idle farmland, the experiment of spring wheat-broccoli multiple cropping under different irrigation amounts is carried out, and the effects on yield, water use efficiency and nitrogen fertilizer partial productivity are studied. An analysis is made to find the optimal amount of irrigation in the spring wheat-broccoli multiple cropping mode. The results show that the different irrigation amount (2 175, 2 700, 3 225 m3/hm2) and the different irrigation amounts of broccoli (2 325, 2 730, 3 000 m3/hm2) can increase the corresponding yield and water use efficiency. Among them, when the irrigation amount of spring wheat is 2 700 m³/hm², the yield, water use efficiency and nitrogen fertilizer partial productivity increases by 28.72%, 38.40% and 94.81%, respectively, and the overall increase effect is better. When the irrigation amount of broccoli is 2 730 m³/hm², the yield, water use efficiency and nitrogen fertilizer partial productivity increases by 32.83%, 42.56% and 77.82%, respectively, and the increase effect is better. Through comprehensive consideration of the yield, water use efficiency and nitrogen fertilizer partial productivity increase in the two crops, it is suggested that the optimal irrigation amount of spring wheat-broccoli multiple cropping mode should be 2 700~2 730 m³/hm².

In order to improve the prediction accuracy of the Reference Crop Evapotranspiration (ET0) in the greenhouse environment, Fireworks Algorithm (FWA) is proposed to optimize the crop reference evapotranspiration model established by Extreme Learning Machine (ELM), which effectively solves the data fluctuation problem caused by the random input weight matrix and the bias matrix of the Extreme Learning Machine in the process of data prediction, improves the prediction accuracy of Extreme Learning Machine. By taking the greenhouse environment data as the input of the model, the FWAELM model is established with reference evapotranspiration ET0 as the output, and the results are compared with the ELM model prediction results. The outcome shows that the root mean square error, mean absolute error and model deterministic coefficients of the FWAELM model are: 0.115 6, 0.143 6, 0.943 8, better than ELM's 0.403 5, 0.346 7 and 0.819 0, FWAELM model has higher prediction accuracy. In addition, the prediction accuracy of the model under the absence of meteorological parameters is studied. The results show that the prediction accuracy of the model is still high when the parameters are three or more, which is suitable for the prediction research on greenhouse ET0.

A precise and non-destructive monitoring model of chlorophyll content in winter wheat is established to provide scientific basis for the fertilization regulation and yield evaluation of winter wheat. Based on the measured spectral reflectance and SPAD value of winter wheat canopy, the correlation between the spectral reflectance and SPAD value of winter wheat canopy after transformation is analyzed. Based on this, a monitoring model of SPAD value of winter wheat canopy during the whole growth period under different spectral transformation forms is constructed. The results show that the sensitive bands in the form of spectral transformation are selected according to the principle of the highest correlation between reflectance after spectral transformation and SPAD value of monitoring canopy. Among them, jointing-heading stage is a first-order differential (503 nm), heading-filling stage is a first-order differential (543 nm), and filling-maturing stage is a first-order differential (726 nm). The whole growth period is divided by R930 (724 nm). Considering the characteristics of each growth period,a suitable regression model combination under different spectral transformation forms is constructed, i.e. model combination 1. Considering the simplicity and practicability of the model, a one-dimensional quadratic regression model of single spectral transformation value, i.e. model 2, is constructed. The determinant coefficients R2 of model 1 in each growth period and the whole growth period are 0.836, 0.855, 0.917 and 0.890, respectively. Compared with model 2 of the same period, the determinant coefficients R2 increases by 24.4%, 6.1%, 57.8% and 37.8% respectively, which indicates that the monitoring effect of suitable model combination under different spectral transformation forms in different growth stages is better than that of single spectral transformation value quadratic regression model.

By constructing the evaluation index system of water resources carrying status in Nanjing, this paper uses fuzzy comprehensive evaluation method, combined with AHP method to evaluate the water resources carrying status of each district in Nanjing in 2015, 2020 and 2030, and based on this, the obstacle factors affecting water resources carrying status in Nanjing are identified and analyzed by using the improved obstacle factors diagnosis method. The results show that from 2015 to 2030, water resources carrying status in all districts of Nanjing is medium or poor, and the overall situation is first improved and then deteriorated. The obstacles mainly include the water quality compliance rate of water function area, the amount of sewage discharged per 10 000 yuan of GDP, the water resource per unit area and the population density. Through comprehensive evaluation and obstacle factor analysis, this paper provides a scientific basis for water resources planning and management in Nanjing, and has important practical significance.

Groundwater is very important to the socio-economic development and sustainability of ecology and environment. Its increasing contamination is one of the biggest issues in China. The Groundwater Pollution Prevention Implementation Plan issued in April 2019 has proposed detailed objectives and detailed procedures for groundwater pollution prevention in China, which emphasizes the importance of the awareness of groundwater contamination and assessment of groundwater vulnerability. In this paper, groundwater vulnerability of Shaanxi Province is assessed by using the modified DRASTIC model. Seven hydro-geological parameters: D-depth to water table, R - net recharge, A-aquifer media, S-soil media, T-topography, L-land use and C-hydraulic conductivity are calculated in ArcGIS, and each DRASTIC parameter is also assigned a rating, ranging depending upon the specific value and characteristics of the parameter and its significance, finally the groundwater vulnerability result is acquired. This study proves that GIS-based DRASTIC model is an effective tool for the groundwater vulnerability assessment which can also be modified very easily considering the data availability of the study area. The results indicate that the area ratios of very low, low, moderate, high and very high zones are 22.6%, 18.9%, 33.8%, 17.6%, 7.1% respectively. The groundwater vulnerability of southern Shaanxi Province is higher than that of the north.

In order to understand the interaction between surface water and the groundwater in Qingshuihe Basin in Chongli Area, the environmental isotopic D, 18O and 222Rn in surface water and groundwater are analyzed, the study results show that: the calculation results based on the D and 18O, the surface water in middle stream of Donggou River have been recharged by groundwater and river water upstream, the percentage of groundwater recharge is 56 %; the calculation results based on the 222Rn, the average seepage rate of surface water is 27.8 m3/(d·m) in the upstream section, and the average recharge rate of groundwater is 17.6 m3/(d·m). It is concluded that, the groundwater and surface water interaction is the main characteristics and processes of water cycle in Qingshuihe Basin, and groundwater recharge is the main sources of surface water in draught seasons.

Reservoir operation objectives such as flood control, power generation, water supply and shipping all have influence on each other. Meanwhile, relative importance of operation objectives and influence factors are not clear. Therefore, it is difficult to evaluate the multi-objective risk of reservoir operation accurately. Combined with risk assessment index, multi-objective risk analysis model for reservoir operation based on catastrophe evaluation method is established in this paper. According to the different main functions of reservoirs, two multi-objective risk assessment methods, which take the lowest comprehensive risk as the dispatching objective and flood control risk as strict constraints, are defined respectively. The application to the risk assessment of Danjiangkou Reservoir operation shows that the evaluation result is in good agreement with the existing optimal operation schemes, and verifies rationality of the proposed methods，which preferably offer a new approach and idea to risk management of reservoir operation.

Due to the shortage of current methods in groundwater level prediction, the rule of maximum similarity is proposed to describe the relevance between samples on the basis of theory of similarity forecast. Maximum connection degree is used to measure the similarities among historical samples of groundwater level quantitatively with time series consistency analysis. Steps of modeling and solving a five-element connection degree model for groundwater level prediction is applied in monthly and inter-annual depth forecast at 18# observation well in Zhongmu County. The results indicate that goodness of fit and trend between predictive value and measured value is optimal. Besides, the model is proved to be high prediction accuracy and better generalization with posterior-variance-test.

The Huaihe River Basin is located in East China with a large population and is also an important grain producer. As the basin is in the plains and the rivers with slow flow, short-term torrential rains may cause the flooding of rivers. Taking a storm runoff process on July 20-22, 2003 as an example, the precipitation distribution process of 25 stations in the basin is used to analyze the precipitation distribution process and the NCEP/NCAR reanalysis data is used to comprehensively analyze the weather system that formes the storm. The study indicates that the rainstorm is mainly concentrated on the upper reaches of the basin and developed from the west to the east. In the weather system that caused the rainstorm, the subtropical high is southerly than the previous period. Under the northeastern region, the subtropical high can't block northward, forming an east-west shear line over the Huaihe River Basin. The water vapor from the South China Sea gathers at this shear line, and strong convergence occurs at the lower level while divergence at the upper level. This is an important cause of the heavy rain.

This paper briefly describes the calculation methods of eco-water demands in river abroad, and thinks that hydrological method is the most suitable for the research of eco-water demands in China at present. The eco-water demands is complementary to the ecosystem of river basin, which should conform to the seasonal characteristics of hydrology and meteorology and adapt to the seasonal requirements of hydrology. The goal of eco-water demands is related to the development and utilization of water resources in the river basin and people's understanding and demand for ecology. Basically unchanged the annual duration guarantee rate, revised the monthly eco-water demands of the flow-duration guarantee rate method, which is in line with the characteristics of the river basin and is coordinated with common methods and evaluation standards.

In order to study the hydro-chemical characteristics and causes of drinking water source of concentrated deep groundwater in Fuyang City，fourteen deep groundwater samples are collected and tested. Mathematical statistics and Piper three-line graph are used to analyze the composition and types of hydrochemistry. Gibbs graph and correlation analysis are used to discuss the origin of hydrochemistry. The results show that: Na+ is the main cation in drinking water of concentrated deep groundwater in Fuyang City and the main anion is HCO-3. Hydro-chemical types are generally HCO-3-Na+. Gibbs diagram and correlation analysis results show that, deep groundwater in Fuyang City is affected by both rock weathering and evaporation, evaporation is the main factor. In addition, changes in the external environment also have impact on the chemical composition of ionic water.

In order to improve the treatment effect by applying constructed wetland on high-salt organic waste water; sandstone, activated carbon, zeolite and sawdust are used as wetland fillers for planting wetland filling and solving plant problems. Spider orchid, reed, vetiver, and strange willow are planted 14 species of wetland plants such as Reed, Scallion, Windmill, Avicennia, Kandelia, Iris, Lamu, Papyrus, Lythroxy, and Sea Sang are planted. Tailwater of hazardous waste is investigated during the operation of vertical flow in the constructed wetland. The removal efficiency of the pollutants, and analysis of the filler configuration and plant species are carried out. The results show that the vertical flow constructed wetland has certain removal effects on organic matter, nitrogen and phosphorus in high-salt wastewater, reed and vetiver show the best growth among all the plants,the capacity of CODCr removal by constructed wetland can be sorted in: activated carbon > zeolite > sandstone > sawdust; the order of NH3-N removal is: zeolite > activated carbon > sandstone > sawdust; TP removal capacity is sorted in: zeolite > sandstone > activated carbon > saw sawdust. The vertical flow constructed wetland fillers from the top to the bottom are a gravel layer of 0.4 m, a special filler layer of 0.4 m, a sandstone layer of 0.4 m, and a gravel layer of 0.3 m. The special fillers are activated carbon and zeolite. In order to enhance the removal of CODCr and NH3-N by special fillers, 0.3 m of them can be laid in the original position, thus the plant roots are wrapped. In addition, 0.1 m special fillers can be laid in the upper drainage pipe trench. In order to increase the removal effect of TP by constructed wetlands, 0.1 m limestone can be mixed and laid in the gravel layer. The system has better effect on removal of pollutants in the tail water of hazardous waste treatment stations, which improves waste water quality to the surface water Ⅳ water discharge standard, providing theoretical basis and technical reference for the construction of artificial wetlands in hazardous waste treatment stations.

The long-term management of rural river has always been a short board. In addition to the government-led routine and typical methods, attracting social forces to participate in rural river management and protection is an increasingly important way, which is an important embodiment of the strategy of “strengthen with both hands” water control strategy in the new era. This paper explores the participation of social forces in rural river management and protection mode, and achieves long-term management objectives by using win-win mechanism named “Protecting rivers with rivers”. And taking Lishui City in Zhejiang Province as a case to carry on the empirical analysis of this model. Provide theoretical guidance and practical reference for social forces to participate in the rural river, implementing the long-term management mechanism of “protecting rivers with rivers”.

Lake restoration from pushing over farming and planting dikes has proved to be an effective method for improving water environment in lakes. The hydrodynamic characteristics of lakes after restoring have a great impact on lakes' ecological environment. In this paper, hydrodynamic model for plain river networks is used to simulate the velocity and water depth of Wugong Lake after retreating to the lake. The influence of water exchange period and river entering lake on the flow of lake water body is also analyzed. The results show that the flow of the lake is smooth, and it is not to produce deposition in catchment. The lake formed by retreating has a positive impact on the improvement of the ecological environment.

The aeration characteristics of stepped spillway dam face are the fetter of combined energy dissipators development, and the aerator and transition steps have a positive effect on the aeration characteristics of stepped surface. This paper adopts the method of hydraulic model, twelve groups of experiments are carried out in combination with the Ahai hydropower station. The aerator of height 11.67 mm and 16.67 mm and Angle 8 ° and 10 ° and four groups transition steps, the impact on the aeration characteristics of stepped surface. The results show that the aerator angle of 10 ° and height of 16.67 mm better than seven other group of aerator. Therefore, with the aerator of angle and height increase properly, the position of the lower edge of the flow in contact with the step surface moves backward, the aerator of nappe length and area and concentration accompanies growth. On the basis of the shape of the aerator, the transition step is set as a large 25 mm 33.33 mm (width height) steps. The aeration characteristics of the step surface are better than those of the other three types of transition steps. Therefore, the moderate increase in the shape of the transition steps is more conducive to the aeration of the transition steps. Through an analysis of the results of 12 groups of experiments, the aerator angle of 10 °and the aerator height of 16.67 mm and transition steps are set to 25 mm×33.33 mm (width x height) of the steps, the stepped spillway dam face of aeration characteristics will be relatively optimal for 12 schemes.

With the development of science and technology, the technical and process defects of traditional two-dimensional design in water resources and hydropower projects are increasingly exposed, and the emergence of BIM makes it possible for the three-dimensional collaborative design among different specialties in engineering projects. This paper discusses the advantages of three-dimensional collaborative design based on BIM, the selection of collaborative platform, the technical standards of BIM, collaborative design mode and verification process. Taking Autodesk three-dimensional design platform as an example, the application points of three-dimensional collaborative design for major specialties of water resources and hydropower engineering are summarized. The implementation mode in this paper can provide reference for the popularization of three-dimensional collaborative design in water resources and hydropower industry.

The sea-dike is an important infrastructure to protect coastal areas from tides and waves, with composite sections being the most common section type. Based on the RANS equation and VOF method for viscous incompressible fluid, two-dimensional and three-dimensional numerical wave flumes are established by using boundary wave-making technology and porous media combined with radiation boundary wave-absorbing technology. The wave quality of regular and irregular waves is analyzed. The regular wave overtopping on a typical two-section sea-dike is simulated and validated. For the typical three-section sea-dike with steep downhill, gentle uphill and platform in the middle, the numerical simulation of irregular wave overtopping is carried out. The interaction between waves and sea-dikes is studied by means of flow field analysis. The simulation results agree well with the physical model results, indicating that the established model is highly accurate and practicable, and can be further applied to engineering practice.

According to the actual engineering characteristics and requirements of the fish, a three-dimensional turbulent numerical model of the natural-like fishway combined with slot and orifice is proposed, and the results are verified by the model test. The influence of the orifice, the bottom width and the side slope on the hydraulic characteristics of the pools is analyzed from three aspects: the flow pattern, the attenuation of velocity along main stream and the turbulent kinetic energy. The results show that the natural-like fishway has the clear mainstream, good flow pattern, little turbulent kinetic energy and obvious three-dimensional flow structure, and the maximum flow velocity of the bottom orifice and the vertical slot is about 1.0 m/s, can meet the four famous domestic fishes' swimming capabilities. The orifice increase the swimming path for fishes living in middle and bottom water layers and make the flow pattern more abundant, can improve the efficiency of fish passing.And the change of the bottom width and side slope has little effect on the hydraulic characteristics of the pools, in practical applications, it can be adjusted to the topographic and geological conditions.

With the continuous construction and commissioning of high-core rockfill dams under complex geological conditions in China, the response characteristics of dam deformation to boundary factors such as dam height and overburden have become hot issues of engineering concern. To this end, based on the characteristics of the dam type of high core rockfill dams, the mechanical parameters of the dam body and the foundation material, and the overburden conditions, 20 kinds of calculation numerical simulation schemes are proposed according to different dam heights and overburden thicknesses. The relationship between the deformation characteristics and the value of the dam body of the high core rockfill dam and the boundary conditions under complex foundation is explored. The results show that the dam height and the overburden are positively correlated with the dam deformation, and the impact on the dam settlement is greater than the horizontal direction, but the response relationship will vary with the variety of the ratio between dam height and overburden. When the overburden exceeds a certain thickness, the effect of the increment is obviously attenuated under a certain dam height. When the dam height is increased to a certain value under a deep overburden thickness, the incremental effect will also decrease.

Vertical anti-seepage system is one of the most important parts of landfills. Its function is to effectively reduce the penetration rate of pollutants into surrounding soil and groundwater. Due to unreasonable design of landfill cut-off wall in some areas, its anti-seepage effect cannot meet expectations or the cut-off wall will be damaged under the action of landfill leachate. At present, there are few studies on the permeability of the landfill cut off wall. In order to provide theoretical support for the safety and rationality of the vertical anti-seepage system of landfills, finite element software is used to simulate the vertical anti-seepage system of a landfill in Jiangsu Province. The movement of landfill leachate under different conditions is simulated by establishing different working conditions, and the anti-seepage effect and safety of cut-off wall are researched. The simulation results show that it takes at least 15.86 years for leachate to penetrate the wall, which meets the design requirements. The maximum gradient under different working conditions is 5.16, which accords with national standards, indicating that the wall is safe and reasonable, and filtration erosion will not happen.

By taking the riverbed dam section of intercepting sand dam of a pumped storage power station as an example, the linear elastic model and the nonlinear model are used to study the influence of foundation fault on the ultimate seismic capacity of the dam. Based on the instantaneous instability of the dam under the earthquake effect, the damage of the dam-foundation system, the evolution process of the seepage field and the anti-sliding safety coefficient time-history curve are calculated. The maximum seismic effect that the dam can withstand is 2.18 times design earthquake in the linear model and 2.67 times design earthquake in the nonlinear model. The results show that the fault at the bottom of the gravity dam foundation has a great influence on the stress state at the top and bottom of the corridor. Considering the nonlinearity of the foundation fault material, the main cause of the sliding failure of the dam is the curtain damage and the large area damage of the fault. The nonlinearity of the fault material and the influence of the damage on the seepage field can better simulate the ultimate seismic capacity of the dam under complex foundation conditions.

After many years of operation, the safety evaluation of aqueduct was needed to determine the operation behavior of aqueduct so as to provide scientific basis for further reinforcement or reconstruction. Due to the long construction period of the aqueduct, the lack of original design data caused great difficulties in the structural safety evaluation of the aqueduct. Taking a hyperbolic arch aqueduct as an example, on the basis of on-site safety inspection, the aqueduct was reproduced by three-dimensional laser scanning technology, and the three-dimensional point cloud model of the aqueduct was established. After date processing, the solid model was formed and the three-dimensional numerical calculation was carried out. Combined with the calculation results of arch ring stability, the mechanical properties of the tank body and supporting structure were analyzed, and the safety evaluation of the aqueduct structure as a whole was achieved.

The rivers in the mixed areas of hills and plains have complex conditions of production and flow, and it is difficult to effectively simulate the flooding of rivers by using a single method. Taking a hill and plain compound channel in the small watershed in the north as an example, based on the HEC-RAS model, in the absence of hydrological data, the river channel has been flooded for 10 years. The results show that the HEC-RAS model uses the calculation method of hilly and plains area division compared with the non-division, the former is more in line with actual situations. At the same time, this method can be applied to the river channel line estimation with complex flow regime, which can be used as a reference for improving the precision of flood control planning and flood control prediction.

By analyzing the basic elements of flood prevention and rescue, based on information flow and material flow, this paper puts forward the trinity flood prevention and rescue system composed of three parts, which are composed of rescue teams, warehouses and social rescue force. By analyzing the relationship between people, money and things, based on the measurement model of the quantity of flood prevention and rescue materials, this paper puts forward the idea of demonstration and method of the scale of the rescue system, and provides a demonstration for the flood prevention and rescue departments at all levels to establish the trinity flood prevention and rescue system. In order to adapt to the reform of the management body of the national tube suit, this study explores the social rescue mode beneficially.

In the current study, several indicators are selected from the aspects of the disaster risk, environment and bearing body, and the chain structure is introduced to establish a comprehensive assessment model on urban flood and waterlogging risk, according to the evaluation theory of natural risks. Comprehensive flood risk of Shenzhen under different grades of extreme precipitation are evaluated by combining GIS spatial analysis based on meteorological, topographic and geo-morphological, urban drainage networks and socio-economic data. The results show that: ① The northeast and southern parts of Longgang District, the Central Pingshan New Area, the North of Baoan District, and the Qianhouhai of Nanshan District are the high value areas of the comprehensive risk of flood and waterlogging in Shenzhen. With the increase in extreme rainfall grades, the high risk area has gradually expanded to most parts of the central and western regions, Longgang District and most areas of Pingshan New District, the middle part of Yantian District and the middle part of Dapeng New Area. ② The low value area of flood comprehensive risk is mainly located in the south and north of Dapeng New Area. ③ The results of flood comprehensive risk assessment in Shenzhen City corresponds to the spatial distributions of flood risk indexes, which confirmes the validity and rationality of the comprehensive risk assessment of urban flood and waterlogging based on chain structure.

China has a large number of irrigation and drainage pump stations. In recent years, the development of large and medium-sized pumping stations has become the main part of China's irrigation and drainage networks. However, with the continuous improvement of the power of the pump in the large-scale pumping station under construction, the problem of excessive energy consumption and operational stability has become increasingly prominent. Single-stage double-suction centrifugal pump is a common pump type in irrigation and drainage pumping station. In this paper, a single-stage double-suction centrifugal pump is analyzed, which is used in the renovation project of Baifudu Pumping Station of Guhai Yangshui Project in Ningxia. Results show that the most obvious advantage of the double-suction centrifugal pump designed by blade loading distributions and V-shaped staggering technology compared to the traditional type is it has a wider high efficiency zone and lower pressure pulsation. The result also enriches the design and modification method of single-machine double-suction centrifugal pump, which has certain reference significance for the future pump station reconstruction double-suction centrifugal pump.

The flow of pump station has been measured accurately for a long time and it has an important practical significance for promoting the economic operation of the pump station unit and guiding the pump station to operate efficiently, safely and reliably. In order to solve the effect of sound attenuation and sound absorption of ultrasonic flowmeter on flow measurement accuracy after long-term operation of pumping station, and technical problem of accurately obtaining pump station flow in real time, technology scheme of measuring the flow of pump station combined with differential pressure method and ultrasonic flowmeter is proposed, and the mathematical relationship between flow rate and differential pressure is derived. An accurate flow measurement of differential pressure is realized at Denglou Pump Station and the continuous stability of the flow rate of the pump station is improved. At the same time, it solves the calibration problem of increasing flow error of ultrasonic flowmeter after running for a long time, and summarizes and analyzes the method of on-site flow measurement at the pumping station, and provide a reference for similar pumping stations in measuring the flow.

In order to analyze the influence of the bridge pier position on the hydraulic performance of the side-intake pumping station, numerical simulations are carried out at different distances of 55, 90, 130 and 160 m from the front wing wall of the trash rack bridge, and the number and design parameters of the bridge are determined by referring to the design of the trash rack bridge in the East Route of South to North Water Diversion Project. The conclusions are as follows: with the bridge moving towards the bend, the distance from the wing wall of the forebay becomes farther and farther, and the influence of the trash rack bridge on the intake condition of the pumping station becomes weaker and weaker. When the distance between the bridge and the wing wall reaches 160 m, the average hydraulic loss of the suction box has been reduced to 0.171 m. At this time, the average hydraulic loss of the passage is almost the same as that without the bridge, indicating that the influence of the increase in the bridge on the intake condition of the pumping station has basically disappeared. This study can provide some reference for the layout of Liulaojian Pumping Station and the relevant trash rack bridge.

In order to explore the variation of the gas flow rate in the gas-liquid two-phase flow to the internal flow field of the high-speed centrifugal pump, the gas-liquid two-phase numerical simulation analysis of the high-speed centrifugal pumps based on the ANSYS CFX Euler non-uniform flow model are carried out to study the high-speed centrifugal pumps. The results show that the efficiency and head characteristics are linear with the gas content. The higher the gas content, the lower the efficiency and the lift, the more serious the effect on the performance of the high-speed centrifugal pump. The gas volume distribution gradually changes from the suction surface of the blade to the trailing edge of the blade. At the point of migration, a large amount of accumulation occurs at the impeller exit, and phase separation occurs nearly 10% of the gas content. Under the condition of gas content, the time domain of the tongue and impeller outlet monitoring point fluctuates greatly at t=0.02 s. The main change amplitudes of each gas content rate occur at the leaf frequency and its octave. When the gas content is higher than 5%, the pressure pulsation amplitude of the tongue and the outlet is greatly affected, that is, the gas content is 5%. The critical point affects the speed of the high-speed centrifugal pump pressure fluctuation amplitude. High-speed centrifugal pumps have a lower gas content range than conventional high-speed centrifugal pumps.

The sediment wear of hydraulic turbines running in muddy rivers is very serious, especially the high head Francis turbine. The internal flow characteristics of Francis turbine with long blade and long head on a muddy river are numerically predicted. The results show that, under small flow and design conditions, the flow field and pressure distribution of turbine are stable, the area with the highest sediment concentration is located at the head of the blade and near the lower ring at the outlet, the region with the highest sediment velocity is located on the back of the long blade, the sediment velocity on the surface of the runner blade under design conditions is obviously higher than that under small flow conditions. According to the sediment concentration distribution and flow characteristics on the blade surface of the runner, the abrasion of turbine runner blades can be further predicted, which serves as a reference for the study of sediment wear of hydraulic turbine in multi-sediment river power stations.

Reservoir resettlement project is an important part of the whole water conservancy project. The smooth implementation of resettlement will directly affect the implementation of other projects in dam areas and reservoir areas. In this paper, an example of an immigration project in China is used to establish GM (1, 1) model with grey system theory. The deviation forecast and analysis of the six migration population data in the three years of the project are made, and the rationalization suggestions are put forward. The purpose is to make the resettlement department timely and quantitatively understand the deviation of resettlement progress, and provide an effective basis for the progress control of the whole project so as to promote the resettlement work as planned. The analysis results show that the model is highly accurate in predicting the deviation of resettlement progress of reservoir resettlement and can be used for medium and long-term predictions. At present, the relocation and resettlement work of the project is lagging behind the planned completion time, and effective measures should be taken to speed up the progress of the project.

For the load rejection transient process of pumped storage power station, the three-dimensional internal flow field and characteristics of the main inlet valve under the conditions of guide vane operation rejection and guide vane - main inlet valve linkage operation are studied in this paper. Firstly, a three-dimensional simulation model for the main inlet valve is established, and the boundary conditions for the flow field simulation are determined. Then, by using the Realizable k-ε turbulence model, the three-dimensional transient flow processes inside the main inlet valve under two closing modes are simulated. Finally, the three-dimensional simulation results are compared with the one-dimensional simulation results and the evolution processes of the internal flow field under the two closing modes are analyzed. The results show that the CFD simulation results of three-dimensional transient flow in the main inlet valve under load rejection are highly precise. The internal flow field in the main inlet valve is complex during the dynamic water closing process. The eddy changes the internal flow direction and then causes the pressure loss. Great pressure variation in valve chamber is a hidden danger for the safe operation of units. The maximum pressure in the valve chamber appears at the pivot under two closing modes, which is relatively small under the linkage operation mode.