Within the hierarchical decision structure of reservoir pre-impoundment operations， the parameter equifinality of hydropower generation leads to non-uniqueness of optimal solutions， i.e.， the “ill-posedness” of solving reservoir operation optimization problems. Under such circumstances， the realization of operation benefits is affected by whether the reservoir operator selects the refill plan in favor of flood safety， implying that not only competitive relationship but also cooperative potential exists between flood control and water conservation. In light of this， a cooperation incentive （CI） model based on the lower-level satisfaction is developed to provide a mechanism to promote the water conservation department’s cooperation with the flood control department and enhance the reservoir operation benefit. Based on the framework of ill-posed bilevel programming， regarding the actual decision characteristics， the model described the nonlinear correlation between the cooperation willingness and the expected benefit of the water conservation department given certain flood control rule， so that the probability of selecting the refill plan in favor of flood safety can be derived. The CI model is solved by using multi-swarm evolutionary particle swarm optimization algorithms. Quantitative indicators are proposed to evaluate the Pareto efficiency loss and overall goal achievement of the reservoir operation optimization under cooperation. In the Three Gorges Reservoir pre-impoundment case study， the results are compared with those of the optimistic， pessimistic， and partial cooperation models. Results show that the CI mechanism motivates the benefit concession of the flood control department to increase hydropower generation and encourage the water conservation department’s choice in favor of flood safety. Further， the efficiency loss in operation decisions due to competitive gaming process can be more prominently reduced. Findings also indicate that nonlinear satisfaction-expected benefit relationship can better describe the practical decision making in reservoir operation.

With the gradual decrease in freshwater resources， the gradual increase in energy demand and the continuous change of food supply structure， coupled with the characteristics of both interdependence and competition among the three， the interaction of water-energy-food becomes more complex. In order to ensure water security， energy security and food security and achieve synergistic and optimal management of the three， the efficient use of resources and sustainable development， Ningdong Base， a drought-sensitive area combining resource-based water shortage and seasonal water shortage， is taken as an example. This paper proposes a simulation model of water-energy-food system in Ningdong Base based on the Multi-Agent model， which constructs a simulation framework of water-energy-food in Ningdong Base by considering the water-energy-food system in Ningdong Base as a cooperative and symbiotic network system constituted by a number of relatively independent and autonomous Agents. The attributes of each Agent are defined， the interaction rules between Agents and between Agents and environmental elements were designed， and the water-energy-food simulation model of Ningdong Base is developed based on the MESA library， a multi-agent modeling tool in Python language， to simulate the system evolution process of Ningdong Energy and Chemical Base. The results show that with the growth of population， the water allocation， energy consumption and food consumption in the living department show a rising trend. The water allocation in the food department shows a changing trend corresponding to the change of crop yield. The water allocation in the energy department of the Ningdong Base shows a rising trend， and the annual growth of the water allocation in the prediction year is about 0.08 billion m³. With the yearly growth of the area covered by ecological greening， the water allocation in the ecological department also shows an increasing trend year by year. The annual energy that can be delivered out of the base has a measured annual growth rate of about 19.85% and a predicted annual growth rate of about 3.53%， and is expected to increase to 4.96×10⁷ tons of standard coal by 2025.

To address the insufficient consideration on water level safety requirements at flood control stations in conventional reservoir flood control operation， this study proposes an optimal flood control operation method for reservoir group coupled with water level calculation at basin flood control stations. First， the station water level characteristics are analyzed through the multi-site water level and flow relationship to identify the key factors affecting the water level. The input features for water level calculation are screened according to the correlation between the influencing factors and the water level. The multi-layer feed-forward back propagation neural network （BP neural network） is introduced to fit the complex non-linear relationship between the input features and the observed water level， to realize the accurate calculation of water level at the station. Then， the safety margin index is proposed to quantify the station water level safety. With the objective of maximizing the overall safety margin of the downstream flood control stations， the optimal flood control operation model for cascade reservoirs， coupled with BP neural network， is constructed. Finally， a hybrid optimization algorithm （DPSA-POA-PSO） is developed to solve the model by combining the advantages of the Dynamic Programming Successive Approximation （DPSA）， Progressive Optimization Algorithm （POA） and Particle Swarm Optimization （PSO）. The results show that the water level calculation accuracy of the BP neural network is significantly improved by considering the station water level characteristics， and the flood level fitting deviation for typical floods is limited within 0.05m. Compared with the DPSA and PSO algorithms， the downstream overall safety margin from the hybrid optimization algorithm is improved by 0.88% and 2.58% in the joint operation of three cascade reservoirs， and is improved by 0.85% and 1.87% in the joint operation of five cascade reservoirs. Meanwhile， the derived operation schemes satisfies all the guaranteed water level requirements， which provides reliable support for improving the basin flood control safety.

Floods are one of the major natural hazards threatening human life and property safety. The study of the impacts of catchment attributes on the occurrence of different flood types helps to grasp the physical mechanism of flood occurrence and provides an important theoretical basis for scientific and effective flood prevention. Most scholars mainly use physical model simulation and statistical methods to study the impacts of catchment attributes on flood occurrence. The statistical method proposed by Stein et al.（2021） has the advantages of requiring less precision in data， simplicity in operation， and the ability to analyze separately for cold， dry and wet regions. The method of Stein et al.（2021） has not been applied in China， so it is necessary to use this method to analyze the impacts of catchment attributes on different flood types in cold， dry and wet regions of China. In this paper， flood classification decision trees are used to classify floods in 201 watersheds in China， and the impacts of catchment characteristics on different flood types in cold， dry and wet regions are analyzed by the empirical cumulative probability comparison method. The main conclusions of this study are as follows： ROS and ER floods occur more frequently in cold regions， in which ROS floods are significantly weakened by basin area and mean elevation. ER floods are mainly exacerbated by snowfall and rainfall， and weakened by soil moisture content. LR floods， which occur most frequently in dry regions， are mainly exacerbated by rainfall and snowfall. For SM and LR floods， which occur more frequently in the wet regions， SM floods are mainly exacerbated by rainfall and clay content and weakened by sand content and average slope， while LR floods are mainly exacerbated by rainfall and clay content and weakened by slope and sand content. Based on the findings of this study， water management authorities can rationally plan engineering and non-engineering measures to intervene in the dominant watershed characteristics where flooding occurs， and target against different types of flooding in the watershed.

In order to study the law of flood migration， assess flood damage degree and grasp the response mechanism of major disaster factors to flood disaster elasticity， help provide an ecological approach to urban rainstorm and flood disaster management and improve urban disaster prevention and mitigation capacity， this paper takes the urban area of Jinan City as the research area， divides 28 catchment areas， combines the flood CADDIES model based on cellular automata theory， simulates the flood situation of different scenarios in the urban area of Jinan City by using actual storm rain patterns and design rain patterns， constructs the flood recovery capability evaluation model based on watershed scale changes， and constructs a double-iteration model with the help of data processing tools. And the paper designs four different flood scenarios under different conditions to evaluate and study the elastic results of flood disasters in the urban area of Jinan City under different scenarios. The results show that the C1~C4 catchment areas are located in mountainous areas and other areas with higher terrain have higher resilience indices for flood disasters in various scenarios. The elasticity index of each catchment decreases with the increase in the return period. The elasticity index of most catchments decreases with the increase in the rainfall duration. The greater the catchment depth threshold， the greater the flood elasticity index. The following conclusions are drawn： Through the combination of actual rain pattern and design rain pattern， the flood inundation migration process at different times in Jinan City is simulated and verified by CADDIES model， which shows the law of the phenomenon of “flooding in the south and flooding in the north”. The recurrence period， rainfall duration and water depth threshold are the important factors affecting the flood disaster resilience of the catchment area. The catchment area with higher elevation in the southern mountainous areas has obvious regional advantages in terms of flood disaster elasticity. The closer the catchment area is to the urban area， the smaller the area of land use types such as grasslands and forests that are conducive to rainwater absorption and infiltration， while the weaker the resilience of flood disasters.

In order to investigate the characteristics， spatial and temporal distribution patterns and evolution patterns of agricultural water stress in China， this paper constructs the agricultural water stress index model to measure the agricultural water stress across the country， and analyzes the spatial and temporal distribution patterns with the help of visualization tools， and analyzes the spatial differences， dynamic evolution and spatial correlation patterns by using the Dagum Gini coefficient decomposition， Kernel density estimation and Moran index model. The results show that： ①the national agricultural water stress index decreased from 2.13 to 1.59 from 2005 to 2021， and the regional stress index ranked from high to low as east > west > central > northeast； ②the stress index of nine regions， including Beijing， Tianjin， Hebei， Shanxi， Henan， Shandong， Jiangsu， Xinjiang and Ningxia， is greater than 1 during the period under examination， and the agricultural water stress index is roughly the spatial distribution pattern of decreases “from north to south” and “from northeast to southwest”； ③Dagum decomposition results show that the overall Gini coefficient of China's agricultural water stress level only decreases slightly， and the contribution of hypervariable density is the main source of the total difference； ④The Kernel density estimates show a dynamic evolution pattern of “decreasing crest， moving to the left， shortening the right tail， and increasing the width”； ⑤The spatial Moran index has been significantly positive since 2014， and is mainly distributed in the first， second， and third quadrants. The study concludes that although China’s agricultural water stress index is declining， it is still high overall； the unsustainable agricultural water resources are mainly concentrated in North China， Bohai Sea Economic Zone and Northwest China， and the inter-regional （intra-regional） stress index shows obvious unbalanced evolution characteristics； the spatial clustering characteristics of agricultural water stress mainly show high clustering （16.67% of areas）， low clustering （50% of areas） and low spatial clustering （50% of areas）. The spatial agglomeration of agricultural water resources pressure mainly shows three patterns of high agglomeration （16.67% area）， low agglomeration （50% area） and low agglomeration （30% area）.

The synergy of water resources allocation pattern and land space pattern is the important foundation to ensure the economic and social development. In order to evaluate water resources spatial balance scientifically and reasonably， this paper calculates the four dimensions comprehensive indicators of water conservation， rigid water demand， water resources development and utilization through the methods of entropy， water load index， Equilibrium based on theory of system of spatial balance of water resources. Based on the three zones such as Pearl River Delta，the Coastal Economic Zone and Northern Ecological Development Zone，the Dagum Gini coefficient method are used to evaluate the spatial balance of water resources in different regions of Guangdong Province. The research findings show that the spatial balance of water resources in different regions of Guangdong Province is mainly due to inter-regional differences. The water resources spatial equilibrium of the Pearl River Delta and the Coastal Economic Zone are relatively poor， the water resources allocation are mainly from the water transfer projects. The water resources spatial equilibrium of the Northern Ecological Development Zone are well balanced， and the water resources allocation is mainly based on the local water resources utilization， which can be used as water sources for other regions. The Dagum Gini coefficient method can provide a reasonable description of differences within and between zones and the contribution of hypervariable density， and can be used as a means of evaluating the spatial equilibrium of water resources. It can provide a basis and direction for optimizing water resource allocation， and it can provide a forceful water security guarantee for improving the coordinated development of regional economy and society.

In order to explore the evolution of hydrological cycle in the agro-pastoral ecotone under changing environment， this paper takes Mu Us Sandy Land as the study area， and data of geological， hydrological， meteorological， and applies artificial water withdrawal to establish a surface （Water and Energy transfer Processes in Large river basin， WEP-L）-groundwater （Visual Modular Finite Difference Groundwater Flow， Visual-MODFLOW） joint model， the model parameters are calibrated and verified by using the monthly surface runoff data of Baijiachuan hydrological station and groundwater table data. The results show that the NSE of the monthly runoff simulation of the WEP-L model calibration and verification period is above 0.40， the R ² is above 0.65， and the relative error is within ±15%， the model is relatively accurate in simulating the monthly surface runoff process in the dry season at Baijiachuan Hydrological Station. Meanwhile， the R ² of groundwater table simulated and measured during the simulation period of four representative wells in the study area simulated by the Visual MODFLOW model is basically above 0.58， the MAE is less than 0.3m and the RMSE is between 0.028~0.265m， suggesting that the established surface water-groundwater model can be used for distributed simulation of hydrological cycle process in the Mu Us Sandy Land. On this basis， the spatial distribution characteristics of surface water-groundwater in Mu Us Sandy Land are further explored. The results show that the surface runoff and groundwater table in different regions of the Mu Us Sandy Land are significantly different， and the groundwater table is low in places with large surface runoff. From 2019 to 2020， the runoff in the Mu Us Sandy Land decreased， but the spatial distribution was basically the same， showing a gradual increase from the west to the east， and the runoff in the southeast corner of the area was the largest. The groundwater table in the area remained almost unchanged from 2019 to 2020， showing that the amount of groundwater recharge and extraction are basically the same. In terms of space， the difference in groundwater table in the adjacent areas of the southeast and northeast corners of the sandy land is relatively large， and the water table drops faster， which is similar to the topographical change. The research results can provide scientific support for agricultural water allocation in the agro-pastoral ecotone， and for the regional water resources planning and management.

Based on the sustainable development concept to consider both preventing groundwater overexploitation and stabilizing winter wheat yield， the region with serious groundwater overexploitation in the Hebei Plain to the south of Beijing and Tianjin is selected as a case study in this investigation， from the viewpoint that multi-water resources allocation must be implemented for irrigation during the winter wheat growing season. Combined with the utilization of flood storage and detention areas after the “23·7” catastrophic flood in the Haihe River Basin， a preliminary discussion was conducted on the role of using flood storage and detention areas to construct surface regulating reservoirs from the following three aspects， i.e.， the utilization of rain and flood resources， the utilization of domestic sewage resources， and the requirement of storage capacity for transbasin water diversion projects.

Limited by the coarse spatial resolution， Gravity Recovery and Climate Experiment （GRACE） satellite data is difficult to be applied in small or medium-sized areas. Therefore， based on the random forest algorithm， the monthly GRACE terrestrial water storage anomaly （TWSA） in central Yunnan from 2003 to 2020 had been improved from 1°×1° to 0.1°×0.1° from two scales， namely grid scale （Random Forest-Grid， RF-G） and regional scale （Random Forest-Zone， RF-Z）， respectively. The downscaling results are compared with the downscaling method based on PCRaster Global Water Balance （PCR-GLOBWB） hydrological model from the perspective of time and space to ensure accuracy. Furthermore， the Empirical Orthogonal Function （EOF） method is used to decompose the orthogonal pattern and analyze the characteristics of the TWSA downscaling results， enabling a deeper understanding of data characteristics and influencing factors. The results show that the RF-Z model outperforms in downscaling TWSA for the central Yunnan region， with the correlation coefficient of 0.99， the Nash-Sutcliffe efficiency coefficient of 0.97， the root mean square error is 6.68mm， and the mean absolute error of 5.22mm. Notably， the downscaled results from RF-Z successfully mitigate gridding artifacts. The variance contribution rate of the first four eigenvectors of EOF decomposition is 91.73%. The first mode is “high in the southwest and low in the northeast”， and its time coefficient has a significant seasonal rule. The second mode presents the distribution of “high in the northwest and low in the southeast” and the corresponding time coefficient shows an obvious decreasing trend. The third and fourth modes respectively present the distribution characteristics of “whole region type” and “high in northwest and low in southeast”. In addition， there is a strong correlation between TWSA and NDVI in the driving variables. This study can provide data support and technical guarantee for water resources management and ecological environment protection in central Yunnan.

The tidal level fluctuations in the estuarine area trigger fluctuations in the water level of the coastal diving layer， exhibiting a non-synchronous fluctuation pattern with the tidal level. This phenomenon has a profound impact on the stability of the bank slope. The varying water levels disrupt the equilibrium and increase the risk of slope instability， posing significant challenges to the structural integrity and long-term stability of the slope. During the ebb tide stage， the groundwater table within the interior of the bank slope tends to be higher than the tidal level. Consequently， this leads to a greater water holding capacity in the saturated area and creates conditions that are more susceptible to inducing bank slope collapse and instability. The higher water levels during this stage increase the potential for instability， posing a significant risk to the structural integrity and stability of the bank slope. In order to address the specific challenges of complex estuaries， this paper presents SUBS， a bank collapse warning model. SUBS is developed by improving the BSTEM （Bank Stability and Toe Erosion Model） and coupling it with SUTRA （Saturated-Unsaturated Transport）， a groundwater model that incorporates unsaturated flow movement. By combining these advancements， SUBS provides a comprehensive and accurate framework for predicting bank collapse events in intricate estuarine environments， contributing to improved bank collapse risk assessment. The research findings show that the fluctuation of groundwater caused by the fluctuation of tidal level in estuarine area has quite a strong hysteretic property. The Factor of Safety of the bank slope and the most dangerous failure surface will change periodically with the tide. And the Factor of Safety will increase during the rising tide， reflecting improved stability. Conversely， during the ebb tide， the Factor of Safety decreases due to the lag in groundwater drainage. Especially during the ebb stage of the spring tide， the water level plummets rapidly， significantly heightening the risk of bank slope collapse. Additionally， the presence of seepage faces on the bank slope further increases the vulnerability to instability. By comparing the stability of homogeneous and composite bank slopes， the results strongly indicate that soil cohesion plays a significant role in determining the stability of the slope. This finding underscores the importance of considering the cohesive properties of the soil when bank slope stability is assessed. The stability of the bank slope is significantly enhanced in the composite structure， where clay is present on the upper part and sand on the lower part. This configuration outperforms the bank slope composed of homogeneous sand with low cohesion. The presence of clay provides increased cohesion， resulting in improved resistance to slope failure and greater overall stability of the composite bank slope. In this context， more attention should be paid to the influence of groundwater level fluctuation. This paper expands the application scope of the traditional BSTEM model by coupling a groundwater model and considering real-time fluctuations in groundwater levels. It introduces a new research method for predicting the slope stability in estuarine areas， thereby enhancing our understanding and analysis of slope behavior in these complex environments.

In recent years， the problem of water shortage has gradually become prominent， and to solve the contradiction between the supply and demand of drinking water resources， the development， and utilization of unconventional water source is especially important. The secondary effluent of the sewage treatment plant can be used as an unconventional water source for drinking water reuse through an advanced treatment. The removal methods of pathogenic microorganisms in the secondary effluent include disinfection， advanced oxidation， media filtration， and membrane filtration. Slow filtration is employed as an advanced treatment way to examine its efficacy in removing opportunistic pathogens （OPs） and dissolved organic carbon （DOC） from the secondary effluent under various operating circumstances （C/N and pH of influent）. Additionally， the OPs removal mechanism of slow filtration and the community structure of microorganisms on its surface are studied. The results demonstrate that slow filtration with biofilm is superior to slow filtration without biofilm in eliminating OPs and DOC under different operating conditions. Under different influent C/N conditions， the increase in C/N helps to improve the removal effect of biofilm slow filtration on OPs， while too high C/N would inhibit the removal of OPs， and the removal effect is greater than that of without biofilm slow filtration， and the optimal C/N is 10， and the removal rates of Pseudomonas aeruginosa， Legionella and Mycobacterium avium are 91.2%， 94.8%， and 93.1%， respectively. Under different influent pH conditions， the removal effect of biofilm slow filtration on OPs in water is greater than that of biofilm slow filtration effluent， and when the influent water is neutral （pH=7）， biofilm slow filtration has the best removal effect on OPs， and the removal rates of OPs under the above conditions are 87.0%， 91.3%， and 84.1%， respectively. Under different influent C/N conditions， the removal effect of biofilm slow filtration on DOC is better than that of no biofilm slow filtration， and the removal first increases and then decreases， and the C/N is the best when C/N is 10， and the removal rate is 53.8%. Under different influent pH conditions， the removal effect of biofilm slow filtration on DOC in water is better than that of no biofilm slow filtration， and when it is neutral （pH=7）， biofilm slow filtration has the best removal effect on DOC， with a removal rate of 31.5%. Under the two optimal conditions， Pseudomonas aeruginosa， Legionella， and Mycobacterium avium are positively correlated with DOC in biofilm slow filtration effluent. When the influent C/N is 10， the biofilm diversity is the highest and the species composition is the most uniform. When the pH value is neutral， the species diversity is higher， while when the pH value is acidic and alkaline， the biomass decreases and the biofilm diversity decreases.Compared with the secondary effluent， the dominant population structure and number of biofilm microorganisms on the slow filtration surface changes to different degrees under the conditions of C/N 10 and pH 7. When C/N is 10， Planctomycetes and Rhizobium are dominant bacteria. At pH 7， the dominant genera are Nitrospirae and Novosphingobium.

A distribution flow method （DFM） and its ecological flow index（DEFI） and evaluation grade standard（DFGS） are proposed to study the ecological flow of rivers on the basis of Multi-probability density estimation. Taking the Yichang section of the Yangtze River as an example， The proposed DFM compared with traditional calculation method of hydrological ecological flow， method of flow evaluation， and calculation result of fish ecological flow， and the changes in river ecological flow satisfaction rate and ecological index score before and after variation are evaluated. Results show that the DFM considers the intra- and inter-annual variations in natural runoff， thereby reducing the influence of extreme flow and uneven flow distribution during the year. The method can meet the actual runoff demand of river ecosystem， is superior to traditional hydrological method， and presents strong space-time applicability and certain application value.Inter-annual changes in wet， normal， and dry seasons should be considered， and the ecological flow level and ecological flow index scores higher or close to those before the variation should be used as the criteria for water resources and ecological flow management.

Clarifying the variation law of water quality in the main stream of the Three Gorges Reservoir after impoundment can provide a reference for water environment protection and management in the reservoir area. Based on the monthly water quality data of multiple sections of the mainstream of the reservoir area from 2004 to 2019， this paper uses Mann-Kendall test method， water quality index （WQI） comprehensive evaluation method and cluster analysis to analyze and study ten typical water quality indicators. The results show that since the impoundment of the Three Gorges Reservoir， the annual average concentration of permanganate index， five-day biochemical oxygen demand， ammonia nitrogen and lead in each section of the main stream of the reservoir area have all met the Class III water quality standards， and the water quality in the reservoir area has generally improved. According to the inter-annual fluctuation characteristics of water quality indicators， it can be divided into three time stages： 2004-2006，2007-2014 and 2015-2019， and the spatial heterogeneity of each stage is different. The concentration of total nitrogen in each section of the reservoir mainstream ranged from 1.3~2.1 mg/L， and the concentration of fecal Escherichia coli group in the section of Cuntan and Qingxichang is 10 735~79 000 A/L， which exceeds the Class III water quality standard as the main pollution index of the reservoir mainstream. The water quality of the Cuntan section is the worst among the six sections， which needs to be paid attention to. The water storage and sediment retention effect of Xiluodu-Xiangjiaba cascade reservoirs in the upper reaches of the Yangtze River will reduce the inflow pollutant flux of the Three Gorges Reservoir and improve the water quality of the mainstream of the reservoir area. The water level rise during the impoundment of the Three Gorges Reservoir by stages is conducive to the improvement of water quality in the reservoir area. The regular operation during the year affects the annual change of water quality in the mainstream of the reservoir area. The water quality law of the section located in the fluctuating backwater area is different from that in the perennial backwater area.

Reservoir-based drinking water sources play an important role in human drinking water safety. The accurate assessment of water quality and accurate tracing of water pollution sources are the necessary basis for refining water quality management in reservoir-based drinking water sources. How to combine water quality assessment and pollution source tracing is still a very challenging problem. Benefit by the extensive application of Absolute Principal Component Score （APCS） and Multivariate Linear Regression （MLR） in environmental pollution assessment and tracing， this paper combines the APCS with MLR to establish a method of APCS-MLR for water quality quantitative assessment and water pollution tracing analysis of a reservoir-based drinking water source. Taking Shanxi Reservoir （total storage capacity 1.824 billion m³） in Wenzhou， Zhejiang Province， China as the study area， continuous water environment monitoring is carried out at 25 fixed monitoring sample sites during 2017-2022 AD， and the water quality dataset of 550 sample sizes including the water quality factors of pH， Dissolved Oxygen， Permanganate Index， Total Phosphorus， Total Nitrogen， Redox Potential， Fecal Escherichia Coli and Turbidity have been obtained. Based on the above basic data， the APCS-MLR method is used to quantitatively evaluate the water quality of Shanxi Reservoir， identify the types of water pollution sources， and quantitatively analyze the distribution and contribution rate of different types of pollution sources. The results show that ① the water quality of Shanxi Reservoir is generally good， but there is a risk of water pollution； ② the main sources of water pollution risk are urban domestic pollution， rural non-point source pollution and soil erosion， and the unknown pollution sources that cannot be ignored；③ the distribution of water pollution sources has significant temporal and spatial variability； ④ water quality factors such as Permanganate Index， Total Phosphorus and Total Nitrogen are mainly affected by rural non-point source pollution and meteorological conditions. Fecal Escherichia Coli is mainly affected by urban domestic pollution， and the contribution of unknown pollution sources to other water quality factors is noteworthy. The analysis shows that the unknown pollution source is most likely from the livestock and poultry industry. This study shows that it is reasonable and feasible to identify the types and contributions of water pollution sources of reservoir-based drinking water sources based on APCS-MLR.

With the rapid development of industry and agriculture， river water pollution problems are becoming more and more serious. The phenomenon of water flow confluence is common in river systems. Due to the complex hydraulic characteristics of the intersection， the influx of highly concentrated pollutants from branch channels can accumulate in the downstream of the main channel， causing river water pollution and seriously threatening the water safety of downstream regions. Aiming at the water quality pollution of the confluence caused by tributary discharge， a two-dimensional hydrodynamic and water quality coupling model of the 90° equal-width open channel confluence is established based on the hydrodynamic and water quality model software Delft3D. The model parameters are calibrated through comparison and verification with physical model experiments in existing studies. The study proposes that the engineering measures of arranging submerged dams near the open channel intersection can intensify the convection of the flow， enhance the mixing of pollutants and reduce the concentration of pollutants， so as to solve the problem of water pollution near river confluences. A total of 14 arrangements of different submerged dam locations， lengths， and heights are numerically simulated. Then the pollutant distribution maps and flow field distribution maps under each working condition has been obtained， and the variation coefficient and extreme value of pollutant concentration in each section are calculated for analysis. The research findings show that the arrangement of submerged dams near the confluence can accelerate the mixing of pollutants， thereby reducing the extreme value of pollutant concentration. The main mechanism for the submerged dams to accelerate the mixing and diffusion of pollutants is that the transverse velocity zone and recirculation zone generated by the submerged dam intensify the flow convection effect， promoting the mixing of pollutants. The arrangement of submerged dams on the right bank of the main channel downstream of the confluence has a better effect on reducing the concentration of pollutants than the arrangement of submerged dams on the left bank. Among the simulated conditions， pollutant concentration can be most significantly reduced when the length of the submerged dam is one-half the width of the river. The higher the submerged dam， the better the effect of reducing the extreme value of pollutant concentration. The coefficient of pollutant concentration variation can be reduced by 46%， and the maximum pollutant concentration value can be reduced by 33% under the appropriate submerged dam arrangement condition compared to the baseline condition without submerged dams. When the submerged dam is arranged across the river width， the generated transverse flow velocity area is located on the bank， which has limited effects on the mixing of pollutants. The research conclusions can provide a scientific basis for pollution control in converging rivers.

It is of great significance for soil erosion control and ecological environment management to study the influence of different land use patterns on runoff and sediment processes in the basin. Based on the measured monthly runoff and sediment data from 1996 to 2003， the SWAT model of Xixian watershed is established. According to the simulation results of SWAT model， the contribution rate of runoff and sediment yield to the whole watershed under different land use types is calculated. Then， the runoff and sediment yield simulation data of each sub-basin of SWAT model are used as the output variables required by the random forest regression model， and the random forest regression model is used to evaluate the importance of different land use types to runoff and sediment processes. The results show that： ① The SWAT model has high accuracy. The decisive coefficient R2 and Nash coefficient NSE of runoff and sediment rate in the regular and verification periods are greater than 0.75， and the percentage of deviation PBIAS is-1， -5.6 and 5.1， 9.6. The model is suitable for runoff and sediment simulation in Xixian watershed； ② The contribution rates of land use types to runoff and sediment processes in the basin are in the order of woodland > dry land > paddy field > grassland and dry land > paddy field > grassland > woodland. ③ The decisive coefficient R2 of each stage of the random forest regression model is basically greater than 0.5， and the fitting effect is better； the order of the importance of different land use types to the runoff and sediment process obtained by the random forest regression model is basically the same as the order of the contribution rate of different land use types to the runoff and sediment process calculated by the SWAT model， indicating that the SWAT model is used to calculate the contribution rate of different land use types to the runoff and sediment process. The accuracy is high. In summary， the contribution rate of cultivated land to runoff and sediment in Xixian watershed is the largest. The method of this study can also be applied to other watersheds to obtain the contribution rate of runoff and sediment of different land use types in different watersheds， and provide a reference for the efficient soil and water conservation in the watershed.

The water environment in rural areas is not only an important source of water for rural residents， but also closely related to agricultural production， sustainable development of rural economy， and farmers’ health. How to improve the water environment in rural areas has become an urgent and important issue to be solved. This paper integrates exogenous incentives theory and organizational trust theory into a unified analysis framework， using 962 household survey data from provinces such as Jiangsu， Anhui， and Shaanxi. Using the Double-hurdle model， the impact of exogenous incentives and organizational trust on farmers’ willingness to participate in water environment governance is empirically analyzed， and the mediating effect of organizational trust is explored to provide a reference for promoting good governance of village water environment. The research results indicate that firstly， exogenous incentives have a significant positive impact on farmers’ willingness and degree of participation in water environment governance. From a multidimensional perspective， both economic and emotional incentives have a significant positive impact on farmers’ willingness and degree of participation in water environment governance. Reputation incentives only have a significant promoting effect on willingness to participate. Secondly， organizational trust has a significant positive impact on farmers’ willingness to participate in water environment governance， but it does not have a significant impact on the level of participation. From a multidimensional perspective， goodwill trust has a significant positive impact on farmers’ willingness and level of participation in water environment governance. And competence trust has only a significant promoting effect on willingness to participate. Thirdly， a further mechanism analysis has found that organizational trust plays a positive mediating effect between exogenous incentives and farmers’ participation in water environment governance decision-making behavior. Based on the above research conclusions， this paper suggests that： firstly， village committees should improve the exogenous incentives mechanism for farmers to participate in water environment governance. The first step is to establish a credit system and punishment system for rural water environment governance， and moderately increase the performance rewards for public welfare positions such as river guards and cleaners. Then， the village committee should regularly carry out “Healthy Family” evaluation activities， actively promote exemplary models of protecting the village environment， and guide village social public opinion by utilizing farmers’ emphasis on personal reputation to enhance their sense of responsibility and honor and shame in protecting the water environment. Furthermore， the village committee should actively explore the unique customs and habits of the village， regularly organize collective cultural and entertainment activities to enhance the cohesion between farmers， and strengthen the relationship between the cadres and the masses to enhance farmers’ sense of belonging to the village. Secondly， grassroots autonomous organizations should strive to enhance their credibility. On the one hand， grassroots governments need to regularly carry out training activities on the professional abilities of village cadres， continuously improve their office skills， and establish a talent reserve system for village cadres to strengthen the organization’s talent team. On the other hand， the village committee should improve the “four discussions and two disclosures” system， standardize the procedures for disclosing village affairs information， safeguard the rights of farmers to know， participate， and supervise， in order to establish a fair and just image of grassroots autonomous organizations. Thirdly， the village committee should enhance farmers’ subjective awareness of public affairs participation. It not only needs to fully leverage the initiative of farmers through regular organization of courtyard meetings and the establishment of opinion boxes， but also avoids the formalization of grassroots election systems， in order to ensure the political participation rights of farmers and reduce their dependence on the government.

Common in the inherently curved river channel， the bridge pier built toward the construction will alter the trend of the water flow movement downstream and negatively impact the stability of the embankment. The hydropower model in the Mike Zero series software is used to numerically simulate the conditions of various construction locations for the cylindrical bridge pier and the pier and the river channel in order to investigate the effects of diagonal bridge pier in the continuous curve， and analyze the impact of bridge piers on water level and flow velocity under various operating conditions. Research indicates when a bridge pier with different oblique angles at different positions in the corner， the height of the maximum water in front of each pier is increasing at the bridge pier diagonal cross-intersecting angle α ranging from 30° to 60°. Additionally， the offset of the oblique pier increases the plane flow velocity of each operating state， and the flow velocity around the bridge pier increases with the size of the bridge pier’s cross section. After the construction of a pier in the central area of the bridge pier， both the horizontal and vertical flow velocities along the longitudinal side of the pier decrease. The decrease in flow rate with the increase in the angle of the bridge pier becomes more evident. However， it is worth mentioning that the horizontal longitudinal rate at the back of the cornering coast and the back of the bumpy area increases to varying degrees， and it consistently remains higher than the flow rate prior to the construction of the pier. The influence of the water flow between adjacent curves has a reverse suppression effect on the development of the lateral circulation structure of the front curve. When the bridge connection section is built in the corner connection section， the loop of the back surface of the pier is smaller than the circulation of the bridge pier in the curve section. These findings have a basis for the design of the river bridge and shore protection engineering.

The side deep groove hole and submersible hole combined fishway studied in this paper is a new type of weir hole combined fishway designed by referring to the vertical slot structure of the vertical slot fishway. The research and application of this type of fishway is still in the initial stage， and the distribution law of hydraulic characteristics in the pool room needs to be explored urgently. In this paper， based on FLOW-3D software， the numerical simulation models of the side deep groove hole and submersible hole combined fishway and vertical slot fishway are established. Based on the results of physical model tests， the boundary conditions and input parameters are modified. The flow field structures of the two types of fishways are compared and analyzed， and the influence of different types of obstacles on the hydraulic characteristics of side deep groove hole and submersible hole combined fishway is explored. The results show that compared with the general vertical slot fishway， the side deep groove hole and submersible hole combined fishway has obvious three-dimensional flow field characteristics， which can provide more migration paths and resting places for fish， but its “ L ” type mainstream structure will not help fish to sense the mainstream direction and thus affect the success rate of fish tracing. Cylindrical obstacles with smooth curved surface are arranged in the combined fishway of side deep groove hole and submersible hole. The flow pattern in the fishway pool is improved， the mainstream velocity gradient is reduced， the turbulent kinetic energy is reduced by about 33.3 %， and the maximum attenuation rate of turbulent dissipation rate is 82.78 %. In the construction of fishway engineering， smooth curved surface should be used to avoid the structural type of edge or cross-section shape mutation.

The purpose of this paper is to study the effect of the subsurface drainpipe with triangular section and pipeless wall on inhibiting water flow around the cross section in unsaturated soil. In this study， the water drainage tests are carried out by using the subsurface drainpipe with triangular section （symbol T1） in indoor soil tank， as well as the subsurface drainpipe with circular section （symbol CK） done as a control test， both kinds of drainpipes are pipeless wall. The MATLAB system is utilized to simulate the process of soil water flowing around pipe section. The experimental results show that the soil water content at the bottom of the drainpipe T1 treatment is less than that of CK treatment， and the soil salt content at the bottom of the drainpipe T1 treatment is more than that of CK treatment， indicating that the inhibitory effect of T1 treatment on soil water flow around drainpipe cross section is better than that of CK treatment. The beginning time of soil water discharging from the outlet of T1 treatment is 3.89 h earlier than that of CK treatment， and there is no significant difference between the two treatments in drainage and salt discharge（p>0.05）. The simulation results reveal the characteristics of the drainage of this kind of subsurface drainpipe in unsaturated soil， which proves theoretically that the water content under the T1 treatment is lower than that of the CK treatment， and T1 treatment has a better inhibitory effect on the flow detour around drainpipe cross section. In unsaturated soil， the subsurface drainpipe with triangular section and pipeless wall can effectively inhibit soil water flow around the cross section than the circular section subsurface drainpipe， which is conducive to the drainage for this king of subsurface drainpipe in unsaturated soil.

The research on agricultural water quota is of great significance for promoting water conservation， rational allocation and utilization of water resources， and improving the effective utilization coefficient of irrigation water. Based on the work of industry water quota compilation in Gansu Province in 2022， this paper revises and evaluates the water quota for vegetable irrigation in typical irrigation areas in Gansu Province. On the basis of collecting and investigating the water consumption data of each typical irrigation area， the agricultural irrigation zones are re-divided according to the natural geographical and climatic conditions in Gansu Province， and the general value and advanced value of the water quota for vegetable irrigation are analyzed and calculated by empirical method， statistical analysis method and analogy method. The research shows that ① based on the precipitation isoline and drought index isoline， the agricultural irrigation zoning method is put forward， which takes geographical zoning and other factors affecting agricultural irrigation water into consideration. Gansu Province is divided into five agricultural zones， which is more in line with the geographical distribution and climate characteristics of Gansu Province than the current zoning， and can better reflect the differences in agricultural irrigation water use between different regions. ②The water quota for different kinds of vegetables in each agricultural irrigation zone is between 27 00 and 9 300 m³/hm². The maximum quota for onions is 3 750 to 9 300 m³/hm²， and the minimum quota for vegetables in solar greenhouse is 2 700 to 5 700 m³/hm². The vegetable quota of agricultural irrigation zones shows three trends： high， medium and low， most of which are located in the middle， and the trend of change is consistent with the characteristics of plant growth and agricultural water-saving. ③ The water quota for vegetables in different agricultural zones varies greatly， which is shown as increasing from the east to the west and from the south to the north. The Hexi Corridor is larger than the eastern Longdong Plateau， and the central Longnan is larger than the southern Longnan， which basically conforms to the distribution law of precipitation isoline and the characteristics of regional farmland irrigation. ④ Using the quantitative evaluation system， it is concluded that the coverage of vegetable irrigation quota in Gansu Province is “reasonable”， the practicability is “strict”， the rationality is “strict”， and the progressiveness is “reasonable”. The revised vegetable quota standard has significantly improved in “four properties”.

The impulse wave is a universally existent hazard induced by landslides nearby water basins. Predicting the characteristics of the impulse waves is of great importance for risk assessment of landslide generated waves. Previous studies often focused on the instant wave parameters and selected several landslides parameters such as thickness and velocity to build predictive models for wave characteristics such as height and amplitude. The time series relations between landslide parameters and wave parameters need to be determined. This paper gives insights into the time series variation of the wave characteristics. Experiments are first conducted by using granular particles， and a time series panel database is built by using experimental data. Then a time series prediction model is established for wave characteristics based on a random coefficient panel data model， and the model is tested with the support of experimental data. The proposed model provides a temporal predictive method， which compensates for the deficiency of conventional models that can only predict the instantaneous wave parameters.

There are many large rivers in China. Under the conditions of internal soil properties and external rainfall discharge， soil and water exchange occurs between soil and river flow on the bank slope， which leads to the instability and slip on the bank slope easily. Many riverbank slopes are binary riverbank structures dominated by silty sand soils， which have prominent security and stability problems. By taking part of the silty sand reaches of the Xiangjiang River as the research object， this paper uses the finite difference software FLAC3D， based on the fluid-solid coupling theory and strength reduction method， combined with the silty sand bank slope topography and soil data of the selected river reach， Rayno protective structure is proposed. A three-dimensional model of bank slope protection is established to study the influence of Raynaud gaspe-Gabion cage structure protection on bank slope stability from the aspects of bank slope stress field， displacement field， shear strain increment and safety factor. Raynaud’s pad produces a large compressive stress on the bank slope soil due to its own weight， which weakens the soil tension， but has no significant effect on the soil stress distribution. The revetment scheme has an obvious protective effect on the horizontal displacement of the bank slope， the maximum displacement is reduced from 0.61 m to 0.19 m， the vertical displacement of slope foot is reduced from 0.17 m to 0.03 m， and the vertical settlement displacement of slope top is reduced from 0.28 m to 0.07 m. Under the protection of Rayon’s pad， the range of shear strain increment of the bank slope is significantly reduced， the effective plastic strain zone is significantly less than that of the unprotected bank slope， and the maximum value of shear strain increment is also smaller than that of the unprotected bank slope， the shear stress of the soil mass is weakened， and the maximum area appears at the foot of the slope and the junction between the silty sand soil layer and the sandy mudstone basement. In this case， the safety factor of the bank slope reaches 1.549. The protective effect is obvious. The safety factor of the bank slope increases with the increase in the laying length of the Rayon pad. When the laying length reaches the boundary between the silty sand soil layer and the clay layer， the Fs value has reached 1.549， which fully meets the protection requirements. When the laying length continues to the top， the safety factor is stable around 1.58. At this time， the protection effect has met the needs of the project. Through simulation， the protection effect of Renault pad scheme on the bank slope under extreme low water level is obvious， and the stability of the bank slope is significantly improved， indicating that the protection scheme is feasible. Moreover， the laying of Renault pads and Gabion cages is easy to operate， good anti-impact performance， long service life， and does not require regular maintenance and maintenance. The protective structure scheme is suitable for the bank slope.

As a fundamental natural and strategic resource， water resources have gradually become a controlling factor limiting the sustained and stable development of regional economy and society. In order to implement water resources as the maximum rigid constraint requirement and realize the rational development and utilization of water resources maximization in the drought-stricken areas of western Guangdong， taking Guangdong water resources allocation project around the Beibu Gulf as an example， based on an analysis of the water consumption change trend from 2012 to 2020 in the project demand area， the multi-level index method， entropy value method and weighted average method are used to construct a rigid constraint evaluation system for water conservation， which is used to study the total water consumption and the rigid constraint degree of each water conservation index at the water supply end and the user end in 2020 and in 2035.The results show that the total water consumption and the water consumption of all industries in the demand area of Guangdong water resources allocation project around the Beibu Gulf in the past decade have shown a slow downward trend， and the water consumption structure has gradually become reasonable. However， the current water conservation level in 2020 is poor. Except for the total water consumption index， the other indicators of the constraint layer do not meet the requirements of rigid water conservation constraints. The design has a strong degree of water conservation rigid constraint in 2035， and the water conservation indicators in the constraint layer meet the evaluation criteria. The comprehensive score of the water conservation indicators in the expected layer is 90.7， and the water conservation rigid constraint level is high. The project design meets the national and Guangdong water conservation rigidity constraint requirements and the primary premise of “saving water first and then transferring water” in water transfer project. However， it should further strengthen the work related to household water conservation， agricultural water conservation irrigation and efficient water conservation irrigation. The research findings can provide a reference for the analysis of water transfer areas and objects， and optimization of engineering design schemes for the Guangdong water resources allocation project around the Beibu Gulf. The established water conservation rigid constraint evaluation system has a reference significance for similar water transfer projects.

In order to study the greenhouse gas emissions from rice and the efficiency of rice production， this paper takes Heilongjiang Province， an important commodity grain base in China， as an example， uses the Chinese official provincial greenhouse gas inventory method based on the IPCC guidelines to estimate the direct and indirect emissions of rice greenhouse gases， and analyzes the change trend of rice greenhouse gases. On this basis， the DEA model is used to analyze the rationality of the input-output structure of rice production. The results show that the total amount of greenhouse gas emissions from rice in Heilongjiang Province show an overall upward trend， with CH₄ accounting for the highest proportion of 87.70% and N₂O accounting for 5.77%. Indirect emissions account for 6.53%. The rice production efficiency value of Heilongjiang Province in 2008， 2009， 2010， 2016 and 2018 was less than 1， the input and output structure was unreasonable， the relative benefit failed to achieve the best， there were different degrees of low input utilization rate and insufficient output value income， and farmers’ income and profits were damaged. The greenhouse gas emission rates of rice in 2008 and 2010 were low， and the implementation of low-carbon measures in the production process was better， achieving less carbon emissions. The research results can provide a scientific reference for rational allocation of rice planting production input factors and reduction of greenhouse gas emissions in Heilongjiang Province.

Considering that the dispatching operation of tidal sluice is greatly affected by the tide， it is difficult to control the flow through the sluice. Based on the mechanism model of the sluice， this paper analyzes the influence of water level （tidal level） on the discharge through the sluice， and then designs a mathematical model for tidal level prediction based on GRU neural network. Combined with the actual demand of Jiangdu East Sluice， the optimal dispatching system of the sluice station is developed. Compared with the measured data， the multi-layer GRU neural network model proposed in this paper can accurately predict the time when high and low tide levels occur. After the software system is deployed， it can well support the operation dispatching project of Jiangdu East Sluice， and has high promotion and application value in similar projects.

The multi-trough aqueduct is a new type of aqueduct structure， which has the advantages of large cross section water flow， good overall workability and small deflection deformation of the channel body， but the channel body is more sensitive to uneven vertical deformation. In view of the fact that this type of structure is still the first in the water conservancy industry in our country， how to establish a multi-trough aqueduct operation safety early warning monitoring index is an important problem in project operation management. At present， domestic scholars have put forward a number of monitoring models about aqueducts， but these models do not give clear monitoring indicators， and do not reflect the modern monitoring concept of “hierarchical monitoring， step-by-step warning”. Therefore， based on the previous research work， this paper proposes taking the non-uniform vertical deformation at the support as the main monitoring index， and the measured value of the reinforcement at the inner wall of the trough as the secondary monitoring index， and the research results can provide a reference for the safe operation of the multi-trough aqueduct.

In order to effectively reduce the overall height of the straight pipe type vertical axial flow pump device， the outlet elbow is optimized. By taking a vertical axial flow pump device model as the research object， this paper designs a variety of schemes with the ratio of the turning radius and diameter of the outlet elbow as the characteristic parameter. The numerical simulation calculation of each scheme is carried out， and the optimal scheme is selected. The reliability of the numerical simulation results is verified by the model test. The numerical simulation results show that when the ratio of turning radius to diameter increases from 0.8 to 1.4， the efficiency of the pump device increases by about 3 %， the local head loss coefficient of the elbow decreases by about 0.3， and the pressure recovery coefficient of the outlet channel increases from 95.77 % to 96.54 %.If the outlet channel elevation is limited， it is recommended that the ratio of turning radius to diameter does not exceed 1.3. The hydraulic losses of guide vanes， elbows and outlet conduits interact with each other. Therefore， to further improve the efficiency of the pump device， the optimization of the outlet conduit should be optimized with the pump as a whole， and even the guide vanes and outlet conduits can be optimized together. At the same time， the local head loss coefficient of the elbow using one-dimensional theory under design conditions can accurately predict the hydraulic loss of the elbow.

The thin-walled steel pipe pile bracket is a temporary support structure commonly used in the construction of large-span aqueducts and other projects. Because its slenderness ratio is relatively large， the buckling instability problem is more prominent. Therefore， the accurate calculation of its structural safety factor is the key in the design. In order to study the effect of stress concentration on buckling instability of steel pipe pile bracket， combined with a large-scale aqueduct project， the beam elements and shell elements are used to establish steel pipe pile bracket models， and the buckling critical load of steel pipe pile bracket under different diameter-thickness ratios and bracket heights are compared and analyzed through the finite element software ABAQUS. The results show that there are obvious differences in the buckling instability modes of steel pipe pile bracket under different models. Because the beam element cannot reflect the local stress characteristics well， the obtained structural safety factor is relatively important， and the calculation result is dangerous. For the thin-walled steel pipe pile bracket， the relative difference of buckling critical loads under the two models is positively correlated with diameter-thickness ratio and initial imperfection. When diameter-thickness ratio is greater than 20， the relative difference between the two is greater than 11.4%. In actual engineering， we recommend using shell element for stability checking.

By using the principle of bionics， this paper treats the front， middle and rear parts of the blade working surface with hemispherical non-smooth structure， combined with the flow field CFD and acoustic field LMS for simulation calculation. The flow field and sound field results of the design flow of a centrifugal pump are compared and analyzed. The results show that the non-smooth structure makes the frictional resistance of the blade smaller， and then effectively reduces the shear stress and turbulent kinetic energy on the blade surface， and the weakening effect is most obvious at the blade entry and exit. At the same time， the vortex strength in the impeller flow channel is significantly reduced， and the internal vortex distribution of the pump is more uniform， which can effectively reduce its turbulent pulsation intensity as a whole， stabilize the flow field and effectively reduce the flow noise. The non-smooth structure blade can effectively reduce the total sound pressure level， among which the optimal noise reduction at the impeller outlet is 3.28 dB and the noise reduction rate is 1.9%. The total sound pressure level at the diaphragm is reduced by 3.11 dB， and the noise reduction rate is 1.82%. In summary， non-smooth blades have a good noise reduction effect compared with smooth blades， and the overall noise reduction rate is about 0.81%~1.90%.

As an important organ for crops to absorb water and nutrients， the quantification of root system is of great significance for water and fertilizer management in the field. However， compared with aboveground parts， the current studies on root system architecture are very limited， especially in saline soils. In this paper， the dynamic changes of sunflower root length density （RLD） in different salt fields （low saline S1， high saline S2） were observed by using minirhizotron based on the experimental data of saline farmland sunflower in Hetao Irrigation District of Inner Mongolia， and the three-dimensional structure of crop roots in each field was simulated by combining root system architecture model （RSA） RootBox. The results showed that RootBox could well simulate the root system of sunflower under different salinity. The simulated RLD values of minirhizotron observation site were close to the measured values， R ² was more than 0.73 and RRMSE was less than 0.28. However， the RLD simulation accuracy of S2 field was relatively lower， and RMSE was 0.84 higher than that of S1 field. Moreover， the simulated average RLD distribution in S1 field was close to the observed minirhizotron RLD distribution， while the difference was significant in S2 field， especially in the 60-90 cm soil layer. These results indicated that the minirhizotron method and root system architecture model could provide support for quantifying the morphological structure of crop roots in saline fields， and the quantitative effect of crop roots in high saline fields was more significantly affected by soil salinity.

In the multi-energy complementary power generation system， the wind-photovoltaic output is unstable and discontinuous， which makes the hydropower units in the system need to change the working condition frequently， which brings challenges to the economy， safety and stability of hydropower station operation. When the unit vibration avoidance strategy is considered in the load distribution of the hydropower plant， the decision variables of the ordinary particle swarm optimization model will become a complex matrix with high dimensionality， mutual coupling and discontinuity. The convergence result of the particle velocity updating process in the model is greatly reduced due to the reduced suitability of the process. In this paper， a bidirectional updating multi-objective particle swarm model is proposed innovatively. Based on the day-ahead hour-level scheduling mode and vibration avoidance strategy of the unit， two objectives of the unit combined crossing number and the sum of the optimal working conditions of the unit throughout the day are optimized. The results show that compared with the ordinary particle swarm optimization algorithm， the calculation speed of the optimization model is improved by 14.7%， and the convergence accuracy range is improved by 4% to 6% on average， which can provide a new theoretical support for the optimization operation of hydropower station with both economy and safety stability.

In order to study the sealing performance of P-type water seal in long-term service， this paper establishes a P-type viscoelastic finite element model of water seal. The evolution of mechanical and deformation characteristics of water seal during long-term service is simulated and analyzed. Firstly， based on the creep experimental data of typical rubber materials， the parameters of Burgers constitutive model and standard linear solid model to describe the creep properties of rubber materials are determined by using the least squares principle. Secondly， the creep experiment of rubber material is simulated in ANSYS， and the feasibility of viscoelastic simulation of water-sealed rubber material is verified by comparing the simulation results with the test results. The comparison results show that the Burgers model can more accurately reflect the creep phenomenon of rubber materials in the viscoelastic process than the standard linear solid model. Finally， in order to evaluate the sealing performance of the long-term service process of P-type water seals， the influence of viscoelasticity， the paper studies reservoir pressure and pre-pressure on contact stress and width of water seal by parameter analysis based on Burgers model.

Hybrid generation of multiple energy sources is an effective way to promote the accommodation of new energies. It is of great significance to enhance the synergy of different energy sources by determining a reasonable size of the renewable power plant within the hybrid system， thereby enhancing the system’s complementary performance. However， the traditional capacity configuration model for the hybrid system has the disadvantage that the complementary operation process is not accurately simulated. This paper proposes an optimal sizing method on the basis of simulating the refined operation process of large-scale hydro-photovoltaic （PV） complementary power plants to determine the PV size. First， a long-term optimal operation model for the hydro-PV system is modeled under each possible PV size， which determines long-term water and energy allocation strategies. Second， a short-term optimal operation model for the hydro-PV system is established to determine a daily power generation plan and the corresponding PV curtailment rate， constraint by the long-term operation strategy. Finally， the optimal PV size is determined based on a cost-benefit analysis model， aiming at maximizing the net present value of the PV plant over its lifetime. Zhongyu hydro-PV complementary project is selected as a case study. Results show that： ① when the installed capacity of PV is below 500 MW， the curtailment rate of PV remained within 2%， but the curtailment rate of PV rises rapidly with the increase PV size； ② when the feed-in tariff is 0.1 CNY/kWh， the net present value of photovoltaic power plants is always negative， and the economy performance is poor； ③ when the feed-in tariff is 0.353 CNY/kWh， the optimal PV installed capacity is 1 900 MW integrated with a hydropower plant with an installed capacity of 1 030 MW， and associated net present value of the PV plant over its life-time ranged from 46.2 to 54.6 billion CNY when the long-term variability of the reservoir inflow is considered.

The vibration signal of hydraulic machinery has the characteristics of strong noise， non-stationary， non-linearity， etc. The effective extraction and identification of the fault characteristic of the vibration signal has an important influence on the fault diagnosis. In this paper， two common vibration faults of misalignment and loosening of hydraulic machinery are simulated by test bench. The fault signal is extracted by variational mode decomposition and Hilbert envelope spectrum analysis. First， use the instantaneous frequency average of the components to determine the number K of variational modal components， decompose the signal， and then the envelope spectrum analysis of the decomposed and reconstructed signals is performed. Studies have shown that VMD can effectively extract the feature quantity of the signal， which is beneficial to the identification of the fault. The difference of the envelope spectrum characteristics of the reconstructed signal under different fault conditions and different degrees of the same fault is compared. It is found that the higher harmonic information is more prominent in the case of misalignment faults， and the higher harmonics increase with the increase of the degree of misalignment. The vibration caused by looseness fault is directional， and the vibration signal is accompanied by inter-harmonics. These vibration fault characteristics can provide reference for intelligent fault diagnosis.

The vibration attenuation characteristics have a great influence on the dynamic behavior of the shaft system of hydro-generator units. In order to accurately describe the vibration characteristics of the shaft system of hydro-generator units under hydraulic excitation， this paper deems it necessary to investigate the vibration attenuation characteristics of the shaft system. Firstly， a method of extracting hydraulic excitation feature based on PSO-VMD is proposed to analyze the vibration characteristics of hydraulic excitation. Then， the vibration transmission models with no bearing shaft unit and the vibration transmission model with no bearing shaft unit are established by wave finite element method. According to the models， the vibration transmission equation of the shaft system of the hydro-generator units is constructed by wave finite element method. And according to the constructed vibration transmission equations of the shaft system， the calculation method of the vibration attenuation coefficient of the shaft system is determined. Finally， the vibration attenuation characteristics of the shaft system are analyzed by an example. The research findings show that the vibration transmission model and vibration attenuation coefficient calculation method of shaft system of hydro-generator units proposed in this paper are feasible and effective， which provides a certain theoretical basis for further in-depth research on the influence of vibration attenuation characteristics on the dynamic behavior of shaft system of hydro-generator units.

The restriction of topographical conditions makes the open channel network become a new way to connect cascade hydropower stations. However， this arrangement has many problems such as complex pipe network， pressure-free coupling and so on. In this paper， the improved pressure gradient method and the global matrix method of open channel network are used to calculate the steady flow and unsteady flow of the hydropower station respectively， and the differences of transient in open channel network between the forward-in and side-out scheme and the forward-in and side-out scheme are discussed. The results show that under steady flow conditions， the forward-in and side-out scheme make the longitudinal open channel in the open channel network play the role of water storage， and the transverse open channel delivers water to the downstream power station. In the forward-in and side-out scheme， the longitudinal pipeline conveys water to the downstream power station and the transverse pipeline distributes the flow. Under the load rejection or load-up condition of the downstream power station， the wave in the forward-in and side-out scheme propagates along the transverse pipeline and to the longitudinal pipelines on both sides when the fork point is passed through. In the forward-in and side-out scheme， the wave propagates along the longitudinal pipeline. When the fork point is passed through， as the water depth increases， the wave propagates from the transverse pipeline far away from the upstream to the transverse pipelines on both sides.

Aiming at the problem that the early warning method based on risk matrix and considering settlement rules is affected by massive cooperative operation data， which leads to poor early warning effect， the risk early warning of man-machine cooperative operation of the hydropower station under deep data fusion is proposed. The closed-loop mode of digitalized cooperative operation is constructed to ensure the stability of risk warning process of digitalized man-machine cooperative operation of hydropower station operation. The maximum confidence gain is calculated， and the features are normalized and combined， so as to build a full-dimensional data deep fusion model for hydropower stations to avoid data loss. Deep fusion data are obtained through sensor nodes， and multidimensional time series are established based on space-time in space and time to provide effective data support for the safe operation of field workers. Based on the results of intelligent perception and recognition of potential risks， a risk early-warning process for man-machine collaborative operation of hydropower stations based on deep data fusion is designed， so that workers can deal with on-site emergencies in time. The risk warning probability of this method is closer to the actual value， which indicates that the warning effect of this method is better.

Aiming at the problems of increasing concurrent users and command sending times， and poor transmission rate and integrity of control commands， an intelligent monitoring system architecture based on domestic equipment was designed. The domestic Godson 2H chip is used to control different devices in the hydropower station equipment unit， collect their operation status data， and transmit the operation status data of the power transmission station equipment unit to the operator work station and monitoring terminal through 100m optical fiber Ethernet and gateway. According to the monitoring program of hydropower station equipment in the operator work station and monitoring terminal， the moving time window is used to divide the sub-time series of hydropower station equipment operation data， and it is fused with the location data of hydropower station equipment to obtain the space-time joint data of hydropower station equipment. The fuzzy c-means clustering method is used to detect abnormal values according to historical fault data， so as to realize the abnormal operation monitoring of hydropower station equipment. The experimental results show that the system has good stability and communication transmission ability in the application process. The collected operation data of hydropower station equipment is relatively accurate， which can effectively monitor the abnormal conditions of sluice hoists in hydropower station units， and the practical application effect is remarkable.

Existing fault diagnosis methods for hydroelectric units either focus on the construction of new fault symptom extraction algorithm based on expert experience， or rely on the machine self-learning algorithm to automatically extract fault symptoms. In order to combine the advantages of the two， this paper proposes a fault diagnosis method for hydropower units based on CNN self-learning and manual experience. The CNN convolutional neural network is used to automatically extract the hidden symptom of hydropower unit. Combined with the artificial symptom in time-domain and frequency-domain commonly used in data analysis of hydropower units. A high-dimensional fusion feature vector is constructed to characterize the vibration characteristics of hydropower units， and the redundant information between features is eliminated by feature screening and dimensionality reduction. Finally， based on XGBoost classification algorithm， a power plant runner room rubbing fault measured data is used to verify that the method can improve the hydroelectric unit fault diagnosis accuracy.

The Additional Mass Method （AMM） has been gradually applied in the study of compaction quality testing techniques for rockfill because of its efficient， accurate and non-destructive characteristics. In this paper， the test parameters and the accuracy of different inversion models of the additional mass method for testing the compacted density of rockfill are investigated， and the optimized test parameters for testing the density of rockfill are obtained. Firstly， the stiffness correlation model （SCM）， phase angular frequency correlation model （FCM） and digital template model （DTM） are established at the test site according to two inversion methods， namely correlation method and contour method， and then the application effect of each inversion model is evaluated at the rockfill dam compacting construction site. With the experiment， the model samples are expanded， and the sample mean errors and inversion relative errors before and after the expansion are analyzed. The results show that the additional mass method has a promising application in rockfill dam compacted density testing， the optimized field test parameters are highly feasible in application， the inversion results of all three models meet the accuracy requirements， among which DTM has the best application in rockfill density testing of panel rockfill dams in the Wuyue Pumping and Storage Project， and the inversion accuracy of the dry density of rockfill compaction is the highest.

Flywheel torque is a key index to measure the rapid response performance of hydropower units， and it is an important basis in the calculation of power station transition process and power system regulation. At present， the load rejection acceleration test method is usually used to measure the flywheel torque of rotating parts of hydropower units domestically to check the design indexes. However， this method has the disadvantages of complex test conditions， safety risks and low measurement accuracy. In view of the operation characteristics of pumped storage units with many operating conditions and frequent switch， this paper puts forward creatively a method to measure the flywheel torque by using time waves of active power and speed during unit’s normal shutdown process from phase modulation condition and by using angular momentum theorem. This method has the technical advantages of easy operation and high measurement accuracy. Besides， it can be conducted simultaneously with the routine debug test or unit’s daily operation， so as to save the test period and labor cost， and avoid the safety risk caused by the load rejection accelerated test method.