In order to accurately obtain the spatial distribution characteristics of soil total salt at the regional scale and its interannual dynamics. In this paper, the Jingtaichuan electric power irrigation area in Gansu Province is taken as the research area. Based on soil total salt data measured at 16 monitoring sites in 2015, the spatial interpolation module in ArcGIS software is used to interpolate the soil total salt data in the region by using the inverse distance weight method, the spline function method, the trend surface method and the ordinary kriging method. The analysis shows that the inverse distance weighting method has the highest precision and is consistent with the actual monitoring results, which can accurately reflect the temporal and spatial variation and distribution characteristics of soil total salt content. The spatial interpolation results of the soil total salt observation data in the study area in 1994, 2001, 2008 and 2015 using the inverse distance weighting method showed that the maximum soil salt content in the study area increased year by year, from 2.2648% in 1994 to 3.2294% in 2015. The minimum total salt content of the soil decreased in addition to the individual years, and the overall increase also showed an increasing trend. The average salt content continued to increase in 2015, reaching 1.228%, an increase of 0.1167% over 1994; The soil salt distribution in the study area is low in the southwest and high in the northeast. And the total salt content of the soil in the southwest region showed a decreasing trend while the northeast region showed an increasing trend. The results can provide reference for water salt regulation and salinization control of soil salinization in the study area.

Irrigation directly affects the greenhouse gas emission process of farmland as an important measure to regulate soil moisture status. Drip irrigation has also attracted wide attention for its impact on greenhouse gas emissions as a new type of water-saving irrigation technology. The effects of drip irrigation on soil N2O emission in farmland are reviewed. Drip irrigation changes the soil microflora and the gas transmission rate by regulating soil moisture and soil temperature and then affects the production and emission rate of N₂O in the soil. Drip irrigation does not destroy the soil structure, water, fertilizer, gas, heat, stable internal conditions, suitable for crop growth, promote the mineralization of soil organic nitrogen. However, there are still some shortcomings in the spatial heterogeneity of greenhouse gas emissions under drip irrigation conditions and the simultaneous quantitative research on various greenhouse gases(For example, research is done on the difference between N₂O emission fluxes in soil dry and wet areas under drip irrigation conditions and the contemporaneous effects of different types of greenhouse gases). In the future, it is necessary to strengthen the monitoring of the simultaneous discharge of various greenhouse gases under drip irrigation and N2O emissions from different soil regions, and to increase the research on the mechanism of soil microbial production of N2O gas in the drip irrigation mode from the molecular level, in order to build an environment-friendly agricultural model.

The surface roughness of sand particles in micro-irrigation directly affects the waterhead loss of sand filter layer and the ability of holding impurity particles in raw water, and thus affects the filtering effect of the filter layer. In order to quantitatively analyze the surface roughness of sand particles, three kinds of quartz sand filter layer with the diameter range 1.0~1.18,1.18~1.4 and 1.4~1.7 mm respectively are studied as research objects. Fifteen quartz sand samples are selected as samples for each filter layer. The surface roughness of sand particles is characterized by root mean square height of surface morphology, skewness of surface height distribution and kurtosis of surface height distribution. The roughness parameters are measured by three-dimensional surface topography instrument. And the roughness parametersare analyzed by statistical analysis method. The results show that the fluctuation ranges of surface wave crest and trough of the three kinds of sand particles accounts for 15.6%,,14.6% and 13.1% of the equivalent particle size of the particles respectively，and indicate that the surface roughness of sand particles is relatively large. And the kurtosis of the surface height distribution of quartz sand particles is relatively large also, which indicatethat the surface topography of sand particles is relatively concentrated. At the same time, the skewness of the height distribution on the surface of quartz sand particles is negative, which indicates that the proportion of sags on the surface of quartz sand particles is larger. In order to make quartz filter materials more suitable for micro-irrigation system, larger grains of quartz filter materials should be selected, and the process of sand filter materials should be improved, so that the roughness of sand filter materials can be increased appropriately.

Considering the problem that soil salinization has seriously affected soil environment and crop yield in Yinbei Irrigation Area of Ningxia Province, through the contrast test method of solar subsurface pipe drainage area and non-subsurface pipe drainage area, the influence of long-term continuous drainage of solar subsurface pipe on soil environment and oil sunflower yield in 2017 and 2018 is emphatically studied. The results show that the average groundwater depth in two years has increased by 4.5% and 6.4%, the average salinity of groundwater has decreased by 7.9% and 9.0%, and the average desalination rate of soil is 4.7% and 8.2%, respectively. At the same time, the yield and water production efficiency of oil sunflower has been improved. The yield of oil sunflower has been improved by 13.8% and 21.6% respectively in two years. The irrigation water production efficiency was increased by 13.3% and 21.8% respectively. The crop water production efficiency has been increased by 16.4% and 22.9% respectively. Based on the comprehensive test results and economic costs, irrigation water is used twice during the growth period, once before sowing and once in winter, and drainage water is continuously discharged during the growth period from May to September. This system is suitable for the irrigation and drainage of oil sunflower under the condition of local solar subsurface pipe drainage in huinong.

The residual plastic film will directly change the wetting process and affect the moisture in the soil distribution and effectiveness. By applying the quaternary quadratic orthogonal rotation combination test, significant regression equations between the soil wetting front running time and the initial soil moisture content, the soil dry density, the residual film content, the buried depth of residual film are respectively obtained and the interactive response analyses are conducted by the regression analysis and significance test. The results show that the initial moisture content, soil dry density and residual film content are the main factors affecting the wetting front migration time. And influence size orders of the three factors are follows: the initial moisture content >the soil dry density >the residual film content. The soil wetting front migration time increases gradually with the increase in the soil dry density and the residual film content. The wetting front migration time presents the linear decrease tendency with the increase in the initial moisture content. The interaction analysis shows that when the residual film content is greater than 150 kg/hm², the wetting front migration time remain stable throughout with the increase in the soil dry density. When the soil dry density is greater than 1.41 g/cm³, the wetting front migration time decreases with the increase in the residual film content. It can be seen that the residual film not only has a blocking effect on the wetting front, but also has a flow effect.

In precision agricultural soil measurement, there will be patches which are quite different from the nearby soil, because of the spatial and temporal variability of soil. This paper integrates the location information of PATCH in the field and transforms it into a variant of TSP problem. In this paper, an improved ant colony algorithm is used to solve TSP problem, and the reliability of the algorithm is verified by MATLAB. The improved ant colony algorithm is also used to solve TSP problem, and the reliability of the algorithm is verified by MATLAB. The optimal path is obtained to save the fuel and running time of the machine.

Taking the minimum annual cost of pipeline system as the objective function, the pump lift H and continuous pipe diameter D as design variables, a definitive design optimization model of pressurized irrigation pipe network for pumping stations is established and solved by Excel planning and solving method. The example shows that, compared with the traditional economic flow rate method, Excel planning and solving method is a practical and highly-valuable solution when the pipe network layout is known. It can not only save a lot of engineering investments but also increase designer's design level and efficiency.

The monitoring results of ecological dispatching during the operation period of the Three Gorges Project for many years show that the implementation of ecological dispatching to promote spawning of the four giant carps has achieved remarkable results. In order to ensure the operability and sustainability of the ecological dispatching scheme, the hydrological and hydraulic conditions require the operation of the reservoir itself and the breeding of the four giant carps should be considered comprehensively in the formulation of the scheme. By quantifying the operation constraints of the Three Gorges-Gezhouba cascade reservoir, this paper constructs a model to evaluate the feasibility of ecological dispatching at different times. The results show that ecological dispatching is suitable when the water temperature fits in the first and middle of May. It will increase the risk of discarding water of Gezhouba Dam and affect the decline of reservoir from the second ten days of May to the first ten days of June. The ecological dispatching can be carried out in combination with flood control dispatching from the second ten days of June to the first ten days of July. The research results serve as a reference for the compilation and start-up of the ecological dispatching plan of the Three Gorges Reservoir in the real-time dispatching process.

In order to protect the ecological environment of the Youjiang River Basin, coordinate the economic interests of the Yujiang River and the Pearl River, and better stimulate the ecological environment protection behavior in the upper reaches of the region, through analyzing the current status of water ecology in the Youjiang River Basin, existing problems, existing ecological compensation policy environment and Its position and role in the Yujiang River Basin and the Pearl River Basin, by using the externality theory, this paper analyzes and proposes the water ecological compensation model of the Youjiang River Basin. Through the benchmarking related ecological protection planning and regionalization results, based on the actual Baise city, the content of water ecological compensation in the Youjiang River Basin, the compensation subject and object, compensation standards and compensation methods are proposed, and the water ecological compensation mechanism framework of the Youjiang River Basin is initially constructed. Finally, a targeted compensation policy proposal is proposed to provide reference for the implementation of ecological compensation.

Considering the problem of urban river water retention and water environment deterioration brought by urbanization in Taihu Basin in recent years, the main district of Xicheng area in Taihu Basin is selected as a typical area, and a one-dimensional unsteady hydrodynamic water quality coupling model is constructed to explore the effect of water transfer on the flow fluidity and water environment. A variety of schemes have been worked out for the cooperation of various hydro-junctions and sluice stations, so as to explore the influence of water transfer on the river network in Taihu Basin, and to quantitatively evaluate the improvement of different levels of water transfer schemes on water fluidity and water environment in the study area. The results show that the well-configured water transfer scheme can effectively improve the water environment of the main district of Xicheng area. After a certain amount of water is exceeded, the improvement effect of river water quality is very small with the increase in flow.

The Eco-system of the paddy field has a very significant meaning for the constitution of the whole agricultural Eco-system. The Eco-system of the paddy field can provide growth condition for different kinds of living things, at the same time, it provides important products and services for the survival and development of human beings. In this paper, our research is based on the rice field of Hunan Province. And the method of forestation cost, industrial oxygen production process, and equivalent factor method, as well as other different methods are adopted in this paper to calculate the eight functions of the paddy field Eco-system. The result shows that, in 2016, the service value of paddy field Eco-system in Hunan Province is 24 700 Yuan/hm², among which the the positive service of the paddy field's eco-system is 43 600 yuan/hm², and its negative ecological value is 18 300 yuan/hm². The positive ecological value is almost twice as much as the negative value. Therefore, evaluating the ecological value of the paddy field's eco-system has a very significant meaning for the whole agricultural eco-system and the research of regional environment.

China is exploring the application of PPP mode in the field of rural pollution, but faces many challenges, so it is of practical significance to accurately identify and analyze the risk factors of rural sewage treatment PPP projects. From the perspective of whole lifecycle, 21 risk factors are identified through literature review and Delphi method. Then these risk factors were divided into six levels through applying the interpretative structural model and the MICMAC method to reveals the internal relationship between risk factors, and puts forward policy suggestions. The analysis suggests that the contracting and operation stage are the key stages, the bidding risk is the most fundamental risk factor. This study can provide the reference for the future research on risk sharing and control, as well as the basis for investment decisions and risk management of government departments.

Based on the observed runoff and sediment transport series of Nanning, Guigang, Dahuangjiangkou, Wuzhou and Gaoyao hydrologic stationsin the past 60 years, the temporal and spatial variations of runoff and sediment discharge in Xijiang Golden Waterway are analyzed from three aspects: the variation along the course, the inter-annual variation and the annual variation. The results show that the runoff and sediment of Xijiang Golden Waterway mainly come from the main stream of Xijiang River, and the annual runoff and sediment discharge of each hydrologic station increase with the increase in mileage basically. The annual runoff and sediment discharge shows a decreasing trend as a whole, and the downward trend of Xunjiang and Xijiang reach is greater than Yujiang reach, and the annual runoff of each hydrologic station shows a “dry-rich-dry-rich-dry” change during the years. The annual sediment transport in Dahuangjiangkou, Wuzhou and Gaoyao hydrologic station shows a “low-high-low-high-low” change during the years; the annual distribution of runoff and sediment transport in Xijiang Golden Waterway is very uneven, and the construction of large-scale reservoirs reduces the uneven distribution of runoff and sediment in the year, which makes the runoff and sediment proportion decrease in the flood season.

In order to study the characteristics of water pollution in Niyang River Basin, based on the monitoring data of water during the flood season and dry season in 2018, principal component and correlation analysis are used to comprehensively evaluate the pollution characteristics of water indexes in Niyang River Basin. The results show that organic pollutants are major contaminants, and the river is polluted by nutrient pollutants.The pollution status of the Niyang River is more serious in dry seasons than in flood seasons. The variation in the principal components and the cross-section comprehensive rankings between the dry and flood seasons also indicate that rainfall might affect the water quality of the river.The spatial distribution of water index concentration is closely related to the distribution of agricultural non-point source pollution sources in the basin. The overall spatial and temporal distribution of water quality in Niyang River shows that the downstream water quality is the best, the middle reaches are seriously polluted, and the upstream water quality is better than that in the middle reaches and worse than the downstream.

Argumentation of sewage outlets setting is of great significance for water pollution prevention and ecological environment protection of the Yangtze River. The analysis of the discharged pollutants influence on water quality is an important task of sewage outlet setting argumentation. Baesd on MIKE-21 hydrodynamic model, a two-dimensional hydrodynamic model of river section is established to simulate the migration and distribution of major pollutants as COD,BOD₅,NH3-N,etc. The results show that MIKE-21 model has high simulation accuracy and reasonable simulated results for pollutant diffusion process in the reach of the Yangtze River. It basically reflects the influence of sewage discharge on water quality, and can be used as the evaluation basis for the argumentation of sewage outlet setting.

In order to realize the rational development and utilization of water resources of Hara Lake in Qinghai Province, based on field investigation and laboratory test results, the hydrological characteristics and water environment problems of the Hara Lake Basin and its surrounding areas are studied. The research results show that the development of rivers and lakes in the Hara Lake basin is complex.It has not only a large water resources reserve but also complex hydraulic connections. At the same time, the mineralization degree of local surface water is relatively high and the water quality is relatively poor, but it can still meet the basic needs of life and production. There are four types of groundwater chemical types, and the water quality is excellent. The water quality of a small amount of groundwater is very poor. In addition, the primary water environmental geological problems in the area mainly include soil salinization, soil desertification, lake degradation and glacier degradation, while the secondary water environmental geological problems are mainly caused by human engineering activities, and the problems of soil desertification, lake degradation and glacier degradation are relatively serious, to which enough attention need to be paid. Through this study, the hydrological status of Hara Lake is grasped, which serve as a basis for the later development of water resources.

In order to study the impact of the Longyangxia Reservoir on the variation of downstream runoff and sediment load conditions, the annual runoff and annual sediment load at the Guide Hydrological Station downstream of the reservoir are taken as the research data, and the complementary ensemble empirical mode decomposition method is used to analyze the runoff and sediment load at multi-time scales before and after the reservoir construction. Based on the multi-time scale entropy and Nash-Sutcliffe efficiency co-efficient the complex fluctuation characteristics of the runoff and sediment load decomposition sequences are analyzed before and after the reservoir construction and the contribution of each component to the original sequence. The results show that the reservoir operation has a significant impact on the variation of runoff and sediment load downstream of the reservoir, and the impact on sediment load is greater than that of runoff, and the correlation between runoff and sediment load changes at different time scales. The reservoir operation will aggravate the complexity of the runoff and sediment load system. However, with the increase in the multi-time scale fluctuation period, the complexity of runoff and sediment load decomposition sequence decreases and the predictability increases. The information content of runoff and sediment load is concentrated on the medium and high frequency components, and the periodic variation of runoff and sediment load fluctuations before and after the reservoir construction are considered comprehensively. It is recommended that the monitoring and research periods of runoff and sediment load in the upper reaches of the Yellow River should be 4~7 years and 3~4 years respectively.

By using the data of MOD10A2 snow cover from 2007 to 2017, combined with digital elevation model and meteorological data, the influence of topographic and meteorological factors on snow cover in the mountainous area of Hotan River Basin in Xinjiang is analyzed. The results show that the spatial and temporal variation of snow cove is affected by elevation. 3500 meters below the basin, the annual snow cover fraction gradually shifts from “U” to “V” type. In the middle and high areas with an altitude of 3500~5500m, the variation of snow during the inner-annual shows the secondary process of “ablation, increase, ablation, increase”.The difference of snow cover from different slope band is obvious, and the average of 12.4°~19.5° The snow cover rate is 68.68%, the snow cover rate in the 0°~5.3° zone is only 28.01%, and the snow cover in the different slope zone is the east slope zone. The average snow coverage rate in the last eleven years is 60%. Snow cover coverage is similar to slope, aspect and elevation. Due to changes in meteorological conditions during the year, the maximum snow coverage during the year often occurs in February and March, with a maximum of 76.9%. Snow cover in the Hotan River Basin is closely related to temperature changes.

Water resources monitoring and management is one of the important tasks related to the sustainable development of the national economy. The accuracy, real-time and stability of water monitoring is the key to fully implement the most stringent water resources management. Faced with a wide range of water monitoring stations, China still adopts the traditional mode of manual operation and maintenance monitoring and management. There are problems such as extensive management methods, low operation and maintenance efficiency, and high operation and maintenance costs. In order to solve the above problems, this paper proposes an active operation and maintenance management mode based on automatic fault diagnosis, which mainly includes four modules: fault information collection, fault diagnosis, fault assessment and fault handling, realizing real-time monitoring and operation of faults in water resources monitoring system. An efficient management model for dimensional science scheduling. The technical achievements have been applied to the water resource monitoring system of Anhui Province, which provides technical support for the stable improvement of water resources monitoring capacity in Anhui Province.

In order to understand the multi-year precipitation characteristics of Jinjiang River Basin in Jiangxi Province，based on the daily precipitation data of 9 rainfall stations in the basin from 1957 to 2013，this paper uses linear trends，5-year moving average，Mann-Kendall trend test， Pettitt catastrophe test，cumulative departure and Morlet wavelet analysis to analyze the precipitation series of different regions in Jinjiang River Basin. The results show that: ① The average annual precipitation over the river basin is 1 617.5 mm，and the spatial distribution shows the characteristics of decreasing from upstream to downstream. The upward trend of precipitation is mainly affected by the middle and downstream areas with the trend of 9.59 mm/(10 a). The 1990s are the years with more precipitation in the Jinjiang River Basin，and the annual precipitation shows a trend of “less-more-less” in the statistical years. ② The spatial distribution of seasonal precipitation is the same as that of annual precipitation. The precipitation in each region is mainly concentrated on spring，followed by summer and winter，and the least in autumn. The precipitation in summer，autumn and winter shows an upward trend，while the precipitation in spring shows a downward trend. The trends of precipitation in the upper reaches of the river basin in spring and in the middle reaches of the river basin in spring and summer are significant. The monthly precipitation is mainly concentrated on April to June，accounting for 45.72% of the annual precipitation. The precipitation in June is the largest，while the proportion of precipitation from September to December is relatively small. The percentage of precipitation in each month of each region is not significantly different from that in the river basin. ③Through Pettitt test，it can be found that the sudden changes of spring，summer and autumn in each region are more consistent， which are spring (1984)， summer (1991) and autumn (1980). The sudden changes of summer in the middle reaches of the river basin are also significant at 0.1 level，and the sudden changes of annual precipitation and winter precipitation are more scattered in different regions. According to the analysis of cumulative departure, the same sudden change point of annual precipitation in each region is 1991，and the winter precipitation is 1986. ④ The main cycle of annual precipitation in different areas of the Jinjiang River Basin is relatively obvious，all of which are 31 years. The sub-cycle is around 13 years，but it is not obvious.

As a major component of the water crisis, water shortage and water environmental pollution are widespread in the process of social and economic development in Jilin Province. In this regard, from the five subsystems of population, economy, ecology, water resources and water environment, the system dynamic model of water resources carrying capacity system in Jilin Province was established, and the status continuation type, water saving type, environmental protection type and comprehensive coordination type were adopted. The results show that the status continuation type is the worst in both water quantity and water quality, which is the worst solution; water-saving water quantity type and environmental protection type have made achievements in alleviating water supply and demand pressure and improving water environment quality, respectively. The comprehensive coordination type is excellent in both the water quantity and the water quality, and is the optimal solution. In 2025, the water resources carrying capacity of the four types is ranked as comprehensive coordination type > environmental protection type > water saving type > status continuation type.

Paper is based on the runoff data of the Qianjiang hydrological station of the Red River in the Xijiang River Basin, Da Huangjiang Estuary Hydrological Station of Xun River, Wuzhou Hydrological Station and the Gaoyao Hydrological Station of the Xijiang River from 1957 to 2016. The Mann-Kendall test, 5-year moving average, cumulative anomaly curve methods,T test and sequential clustering method are used to analyze the variation of annual runoff in the Xijiang River Basin. The results show that the inter-annual deviation coefficient of the four-station runoff is relatively small. The characteristics of abundance and dryness have certain synchronization, and the flood station and flooding are prone to occur in Qianjiang Station. According to the trend test analysis, the trend of the four stations is the same, and the change of Qianjiang Station is significant. The Qianjiang Hydrological Station occurred abruptly in 2002, and the other three hydrological stations did not show significant mutation points. The results can provide a scientific basis for water resources utilization in the Xijiang River Basin.

The joint dispatching of muti-reservoir has many kinds and complicated relationships, which is the difficulty and focus of reservoir dispatching research. A small amount of water shortage generally does not cause significant losses, but exceeding the user's demand elasticity range will cause major economic losses. This paper comprehensively considers the water use units in the study area, such as living, irrigation, industry, agriculture, etc., and establishes a mathematical model of joint operating of multi-reservoirs for conventional water-unconventional water and local water-external water transfer coupling. The model is solved by simulating the human-machine adaptive iterative algorithm, and the non-local water sources such as Yuecheng Reservoir and Dongwushi Reservoir and the non-local water sources such as the diversion river water from the South-to-North Water Diversion Project and the Yellow River water from the Dongfeng Canal are taken as examples. The rationality analysis of joint operating muti-reservoirs is carried out at 25%, 50% and 75% of the annual years. The rationality analysis has finally reduced the system losses of Yuecheng Reservoir and Dongwushi Reservoir and maximized the water supply satisfaction rate.

By applying the two-dimensional shallow water equation to the main stream of Haihe River in the urban section of Tianjin, the flood in two different scenarios under the different return periods is simulated and calculated. The results show that the two-dimensional shallow water equation can simulate the flood evolution of the river, and the flood pressure affected by the flood can be effectively alleviated when the drainage pumping station is added downstream. However, a single engineering measure can no longer guarantee the flood safety of urban river channels, more diversified measures are needed.

Normal transformation and linear hypothesis are commonly used in flood probability forecasting methods, which may lead to the loss of information and affect its applicability to flood process. In this paper, the Copula function is combined with the model condition processor (MCP). Without the normal-linear condition constraint, the flow distribution function with the forecast value as the condition is directly deduced to construct the Copula-MCP flood probability prediction model. Taking wangjiaba section of huaihe river as an example, this paper adopts the Copula-MCP model to realize the flood probability forecast based on the deterministic forecast results of the Antecedent Precipitation Index Model (API).The results of the study on 25 floods from 1990 to 2010 show that the Copula-MCP model is superior to that of the probability prediction results of the MCP model, and the expected value prediction of the Copula-MCP model is also superior to that of the API model results.

An effective way to mitigate flood risk lies in implementing a real-time forecast and warning system based on a rainfall-runoff model. This paper uses GIS technology, combined with DEM, soil and land-use data to extract watershed information, and constructs HEC-HMS rainfall-runoff model for mountain flood forecasting in Qingxi River Basin. According to the formation process of rainfall runoff, the SCS-CN curve, SCS unit hydrograph, exponential recession and the Muskingum method are used to calculate the runoff volume, direct runoff, base flow and flow routing respectively. It has selected six flood events for model calibration and four flood events for model verification. The results show that the average the Nash efficiency coefficients of the flood in the verification period is 0.792, the average correlation coefficient is 0.84, and the flood peak appearance time difference is within 3 hours and meets the forecast requirements, which indicates that the model is suitable for hydrological simulation of the Qingxi River Basin. It can provide reference for mountain flood forecasting in the middle and small river basins of Sichuan Province.

The triaxial compression constitutive relation of plastic concrete with clay and bentonite age (540 d) is studied. The stress-strain curves of plastic concrete under different confining pressures are fitted according to the fixed lateral pressure triaxial test. The results show that under medium and high lateral confining pressures（σ₁=0.4 MPa，σ₂=0.6 MPa）,（σ₁=0.4 MPa，σ₂=0.8 MPa）lateral confining pressure stress-strain curves are basically the same. Medium and high pressure stress-strain curve segment rising slope and the peak pressure are larger than in（σ₁=0.2 MPa，σ₂=0.4 MPa）the low pressure side stress - strain curve rising slope and the peak pressure. In addition, the calculation formula of peak secant modulus and the constitutive model of triaxial compression under the condition of plastic concrete lateral pressure are proposed, which provides numerical simulation analysis for plastic concrete under triaxial compression conditions. On this basis, the engineering application of plastic concrete is further promoted.

Cement mortar is used as rock-like material and hydraulic fracturing tests of fractured rock mass under different injection flow rate and uniaxial compressive stresses are carried out by using water-solid-thermal coupling test system, electro-hydraulic servo universal test machine, dynamic data acquisition and analysis system and self-designed high-pressure water sealing device. The results show that under the action of no axial tension and compression, the larger the injection flow rate is, the shorter the time of splitting failure is, and the easier the splitting failure occurs, and the ratio of hydraulic splitting initiation pressure to splitting pressure P_ini/P_Ic is linear with the injection flow rate. Under the condition of constant injection flow rate, the axial compressive stress along the vertical fracture direction restrains the hydraulic splitting of the specimen, and the parallel splitting failure occurs. When the axial compressive stress along the crack direction is small (0.1~0.3 MPa), it restrains the hydraulic splitting of mortar samples, and when the fracture direction is large (0.4~0.5 MPa), it promotes the hydraulic splitting of mortar samples.

PCCP pipeline is buried in the ground under the influence of external environmental factors, prestressed steel wire may be damaged or corroded, when the corrosion reaches a certain degree, there is the possibility of steel wire fracture, when the number of broken wire reaches a certain degree, there is the risk of pipe explosion. As an effective way to find out the hidden danger of project safety, broken wire monitoring can grasp the project operation status in time and obtain the relevant information of project safety. At present, the domestic for broken wires monitoring analysis mostly limited to theoretical and experimental stage, through a combination of ultra-large diameter PCCP domestic engineering concrete operation, broken wires of different pipe joint monitoring data, to explore the influence factors of pipeline caused by broken wires, maintenance and safety of the pipeline conveyance to provide theoretical and technical reference.

There are many small reservoirs in our country. It is difficult and risky to carry out safety supervision due to the limitation of funds, personnel and technology. On the basis of sorting out and analyzing the characteristics and key points of safety supervision of small reservoirs, the classification supervision model of “single reservoir-region/basin reservoir group-trusteeship of scientific research institutes” for safety of small reservoirs is discussed and put forward. Combining the needs of different levels of users and using the advantages of modern information technology such as cloud computing, Internet of Things and big data, the cloud platform framework for classification supervision of small reservoir safety is designed. The cloud platform for dam safety monitoring and supervision of small reservoirs in Chengdu is constructed by relying on the trusteeship of scientific research institutes. It is well applied and helpful to improve the safety supervision capability of small reservoirs.

In order to study the contact loss of the laterite core wall and the filter, ST30-3 permeameter is used to carry out the contact loss tests of laterite with different dry densities and sand filter at three seepage directions. The occurrence and development process of contact loss are investigated. The change in seepage velocity and permeability coefficient with hydraulic gradient and the influence of seepage direction and dry density of laterite on contact loss are discussed. The results show that the development process of contact loss can be divided into stable stage, transitional stage, secondary filter formation stage and failure stage. With the increase in hydraulic gradient, the permeability coefficient firstly remains constant or slightly increases, and increases obviously after the initial gradient is reached. It tends to be stable in secondary filter formation stage, and suddenly increases at failure gradient. The increase in dry density of laterite and the decrease in the intersection angle between the seepage direction and the contact interface both help to improve the resistance to contact loss.

For the GNSS single system dam safety monitoring is vulnerable to the uneven distribution of satellites, resulting in insufficient effective solution period and the inability to accurately obtain stable coordinate sequences that meet the dam's mm-level monitoring requirements. Taking the measured data of the dam of LANGYA Mountain Pumped Storage Power Station as the research object, the feasibility of continuous quasi-static mode based on GPS/BDS combined positioning in safety monitoring of dams is studied. The advantages of GPS/BDS combined positioning compared with single GNSS system in dam safety monitoring are analyzed from the aspects of visible satellite number and PDOP value. Performing Kalman filtering and averaging on the single-day safety monitoring coordinate data of the dam, and performing sliding test on the self-designed movable pedestal frame, the results show that the GPS/BDS combined positioning can obtain stable dam monitoring data in real time through the initial measurement in a continuous quasi-static mode, and has a monitoring sensitivity better than 1 mm. It is a great significance for analyzing the long-term trend changes of the external structure of the dam.

River bank collapse is a major problem faced by China's embankment safety, especially before and after flood seasons; river bank collapse induces a large number of landslides into the river channel, destroying the embankment, silting up the river channel, affecting shipping. In view of the bank slope instability under the water flow, this paper comprehensively considers the influence of slope surface water level, groundwater infiltration, water rush, pore water pressure, hydrostatic pressure and so on. On the basis of basic hypothesis, the stability calculation model of wedge-shaped bank slope under the synergistic effect of multiple factors is constructed, and the use of poles is used. The limit equilibrium method is used to derive the calculation formula of the stability safety factor of the bank slope under different working conditions, and then the influence of each factor on the stability safety factor of the shore slope is analyzed based on bank collapse of Furong dike, Yangzi river, Pengze County. The results show that it has a great influence on the stability of bank slope for the rise-fall and the difference between surface water level and groundwater level, and the scouring depth also directly affects the stability of bank slope.

Contact scouring is a dynamic condition that causes osmotic deformation and crack channel expansion in a weak interlayer. In order to study the contact scouring mechanism of seepage in weak interlayer, a coupling model of fracture flow and seepage of muddy soil is established. The Navier-Stokes equation is used to describe the fracture flow, and the Brinkman-extended Darcy equation describes the seepage of the muddy soil around the fracture channel. According to the corresponding boundary conditions, the flow velocity distribution of the crack flow and the surrounding muddy soil seepage are obtained. Based on the failure mode of soil particle sliding start, the critical hydraulic gradient calculation method for contact scouring of weak interlayer is proposed by combining the flow velocity characteristics of water flow in the fracture with the force characteristics of soil particles. The analysis of the example shows that the calculated results are basically consistent with the experimental results and have engineering guiding significance.

Both steady and unsteady numerical simulations of the volute centrifugal pump, with n_s=157 of one impeller, are calculated to study the applicability. In the steady simulations, the effects of different phase angles are analyzed, simultaneously different time steps are studied in the unsteady calculations. The steady calculation is only applicable for the external performance simulation at the design condition, with the head and efficiency calculation errors of 4.9% and 2.9% respectively. The calculations of the different phase angles are just effective for the external performance simulation near the design condition, of which the head and efficiency calculation errors are almost 7.1% and 3.2% respectively. And in the unsteady calculation, 4° is selected as the time step and 20° is the saved time interval. The predicted head curve is better than the steady one, and the calculation error of the head and efficiency at the design condition is about 1.1% and 1.8%. However, the head calculation errors of the small flow condition and the large flow condition are about 10%. The main conclusions are as follows: in the hydraulic design processes, if only the external performance of the high-efficiency point is concerned, the steady calculation can be chosen. When the head curve is completely concerned, the unsteady calculation should be used.

Considering the problem of energy-saving and consumption reduction in pumping stations, an optimal dispatching model in stations is established, and the particle swarm optimization algorithm is improved by using chaos theory, and the optimization of dispatching schemes in stations is studied. The results show that the hybrid particle swarm optimization algorithm has fast convergence speed and high accuracy, and is more suitable for optimal dispatching of pumping stations. When three-period optimization analysis is used, the optimal scheme consumes 233 400 degrees of power and saves 346 000 degrees of power, and achieves better optimal dispatching results.

Based on the continuity equation of incompressible fluid and the Reynolds time-averaged N-S equation, the CFD technique is used to numerically simulate the straight tube outlet conduit in horizontal pumping station. By changing the outlet conduit profile, the internal flow characteristics and hydraulic loss of the water channel are analyzed. Studies show that when the cross-sectional shape of the outlet conduit is designed to be rounded and deformed, the plane direction and the elevation direction gradually enlarged, the flow pattern in the flow conduit is the best. The flow conduit section is designed to be flat in the plane direction and then flattened, and in the form of uniform expansion in the direction of the facade, the flow state is better.When the section is designed to be first diffused and flat in the direction of the faade and the plane, the flow pattern of the outlet conduit is the worst.

The operation optimization of single-stage pumping station is realized by the reasonable selection of the combination of pumping station units under different working conditions. By analyzing the relationship between the flow rate, head, speed and efficiency of the pumping device, the working condition of the pump device is determined, and the daily operation optimization scheduling model of the single-stage pumping station based on the dynamic programming method is constructed, with the goal of minimizing the total daily operating cost. Thereby the optimal daily scheduling scheme for the single-stage pumping station is determined. Jiuwei Port Pumping Station of Nantong Yanhuan Ding is selected as the research object. Based on the existing operating data of the pumping station, based on the comprehensive consideration of the daily electricity price, head and flow changes of the pumping station, the optimal operation model of the pumping station is adopted and divided into two layers, the first layer is the daily economic operation optimization model of the pumping station, and the minimum operating cost of the pumping station is determined. The second layer is the pumping station operating efficiency optimization model to determine the optimal pumping station efficiency in different periods. The operation model is solved by the interval discrete dynamic programming method. The results show that when the total water delivery volume is constant, the time-sharing electricity price is the main factor affecting the daily running cost of the pumping station and the flow distribution in each period. Taking the typical working conditions of the Jiu-wei-gang pumping station as an example, the optimized pumping station operation scheme is better. The operating cost per unit of the previous day is reduced by 18%. This model has some guiding significance for realizing the daily economic optimization operation of single-stage pumping stations.