Flood forecasting is one of the important non-engineering measures for flood control and disaster reduction in the middle reaches of the Yellow River. In this study， a GRU-Transformer flood forecasting model is constructed by coupling gated recurrent units （GRU） with Transformer machine learning models， and rainfall-runoff simulations are conducted to predict flood events in typical sub-basins of the middle reaches of the Yellow River. The predictive results are compared and analyzed with those of the ANN（Artificial Neural Network） and WOA-GRU（Whale Optimization Algorithm Gate Recurrent Unit） neural network flood forecasting models， with a focus on exploring how to better apply the Transformer model to the field of flood forecasting in order to improve the accuracy of flood forecasting in the middle reaches of the Yellow River. The model is established by using historical observed flood data from 1990 to 2016 in the Gu County Reservoir Controlled Basin. The input data includes rainfall data measured at 24 stations and discharge data at the outlet cross-section， while the output data includes flood events under different lead times. The model is calibrated by using 39 flood cases and validated using 10 flood cases. The results of the study show that the GRU-Transformer model has good applicability in flood forecasting， exhibiting higher predictive accuracy in the 1~6 hour lead time flood forecasting， with NSE values of greater than 0.85 in both calibration and validation periods. Its predictive accuracy is better than the WOA-GRU and ANN models under the same lead time， but decreases to a certain extent with increasing lead times. The GRU-Transformer model is more stable and better at predicting flood peaks， showing excellent performance in predicting small flow flood processes and simulating the recession phase of floods. However， it tendes to underestimate flood peaks with longer lead times. Compared with the WOA-GRU and ANN models， the GRU-Transformer model has better robustness， and its predictive accuracy decreases slowly as lead times increases. Hence， the GRU-Transformer model can be used as one of the better flood forecasting methods， providing new forecasting methods and scientific decision-making basis for flood prevention and control in the river basin.

This paper evaluates the spatial equilibrium status of water resources in Yunnan Province from 2006 to 2022 and 2025 scientifically， and proposes a water resource spatial equilibrium evaluation model based on social network search （SNS） algorithm， mountaineering team optimization （MTBO） algorithm， bi-directional gated loop unit （BIGRU） optimization， and bi-directional long short-term memory （BILSTM） network optimization. First， 15 indicators are selected from three aspects of water resources support， water resources pressure and water resources regulation to build the evaluation index system and grade standard of water resources spatial balance， and the samples are generated by linear interpolation and random selection methods to build BiGRU and BiLSTM fitness function. Secondly， the principles of SNS and MTBO algorithms are briefly introduced. SNS-BIGRU， MTBO-BIGRU， SNS-BILSTM， and MTBO-BILSTM models are constructed by using SNS and MTBO to optimize the number of neurons in the hidden layer of BiGRU and BilSTM and the learning rate （hyperparameter）. The robustness of four models， including SNS-BIGRU， MTBO-BIGRU， SNS-BILSTM， and MTBO-BILSTM， is verified through different sample sizes and 10 consecutive runs. Finally， SNS-BIGRU， MTBO-BIGRU， SNS-BILSTM， and MTBO-BILSTM models are used to evaluate the spatial balance of water resources in Yunnan Province from 2006 to 2022 and 2025， and the evaluation results are compared with those of SNS-Support Vector Machine （SVM）， MTBO-SVM， and fuzzy comprehensive evaluation methods. The results show that： ① the models such as SNS-BIGRU have good recognition accuracy and robustness. SNS and MTBO can effectively optimize the hyper-parameter of BIGRU and BILSTM， and improve the prediction performance of BIGRU and BiLSTM. ② SNS-BIGRU and other four models evaluate the spatial balance of water resources in Yunnan Province from 2006 to 2011 as “unbalanced”， from 2012 to 2013 as “relatively unbalanced”， from 2014 to 2018 as “critical equilibrium”， from 2019 to 2022 as “relatively balanced”， and by 2025， it can basically reach the level of “balanced”. There is a 3-year difference in the evaluation results of the four models compared to SNS-SVM， MTBO-SVM， and fuzzy comprehensive evaluation methods. The model method constructed and proposed in this paper serve as a reference for the spatial balance evaluation of water resources.

The water conservancy industry is promoting digital twins in an unprecedented situation. The basis of smart water management is urgently needed to solve the problem that three-dimensional visualization of water conservancy projects cannot meet the requirements of professional visualization software. In this paper， a three-dimensional visualization platform for water conservancy is built based on technologies such as Cesium， Vue and Springboot. This platform has realized the key application technologies of thematic three-dimensional visualization such as multi-source data fusion， flood discharge and flood evolution， and laid a foundation for later digital twin visualization.

Model parameter calibration is an important way to improve the simulation effect of hydrological models. In order to solve the problems of low initial population quality， prematurity and poor local search ability of traditional genetic algorithm， this paper proposes an improved adaptive genetic algorithm （IAGA） to optimize the parameters of Xin?anjiang model. The Ergodic characteristics of chaos variables are used to randomly generate the initial population and select the best， so as to improve the individual quality of the initial population. Aiming at the evolutionary process of crossover and mutation， this paper designs the discrete coefficient of population objective function to reflect the degree of population dispersion. By using this coefficient， the adaptive adjustment crossover and mutation probability operators are constructed to prevent premature convergence of genetic algorithm. Based on the ring crossover operator， the global search ability of the algorithm is improved. The adaptive non-uniform mutation operator is used to optimize the local search ability of the algorithm in real time and avoid falling into local optimum. The IAGA algorithm， traditional genetic algorithm （GA） and adaptive genetic algorithm （AGA） are applied to the parameter calibration of the Xin′anjiang model in the Qinhuai River Basin， and the performances are compared from the aspects of convergence， time-consuming， stability and effect. The results show that the IAGA algorithm has more excellent optimization ability， better convergence results， higher stability and accuracy. The flood simulation results are better than the GA algorithm and the AGA algorithm. During the calibration period and the verification period， the deterministic coefficients are higher than 0.85， and Nash-Sutcliffe efficiency coefficient are higher than 0.8， which generally meets the second-level standard of hydrological forecasting. The results show that it is feasible to improve the traditional genetic algorithm by using the above comprehensive means， and the improved IAGA algorithm has a good application prospect， which provides an effective way for the automatic calibration of Xin′anjiang model.

A multi-strategy fusion improved Golden Jackal Optimization Algorithm （MGJO） is proposed to address the shortcomings of the Golden Jackal Optimization Algorithm in solving complex or high-dimensional optimization problems， such as being prone to local optima， slow convergence speed， and low computational accuracy. Firstly， by introducing a chaotic mapping strategy to initialize the population instead of random parameters， the algorithm can generate initial solutions with good diversity in the search space and avoid the initial population distribution deviating from the optimal value. Secondly， a nonlinear dynamic inertia weight is proposed to make the search process more realistic， effectively balancing the algorithm′s global and local search capabilities. Finally， the position update strategy of Cauchy mutation is introduced to fully utilize the guiding role of the optimal individual to improve population diversity， effectively exploring unknown regions and avoiding the algorithm falling into local optima. In order to verify the optimization accuracy， convergence performance， and stability of the improved Golden Jackal Optimization Algorithm， eight benchmark test functions with different features are selected for experiments. The results show that among the 8 benchmark test functions， the improved Golden Jackal Optimization Algorithm has achieved optimal results in terms of mean， standard deviation， and optimal value. In addition， the results of Wilcoxon’s sign rank test indicate that the improved Golden Jackal Optimization Algorithm is significantly superior in statistics. Through practical applications， it shows that the Golden Jackal Optimization Algorithm based on multi-strategy fusion improvement can effectively estimate the parameters of the Muskingum Model， and the optimization effect is significantly better than the particle swarm optimization algorithm， the sine cosine optimization algorithm， and the Golden Jackal Optimization Algorithm. This further verifies the effectiveness of multi-strategy fusion improvement and the superiority of the improved algorithm in parameter optimization. This provides an effective new method for more accurate estimation of the parameters of the nonlinear Muskingum Model.

Dam deformation is the visual representation of the state of a dam under the influence of internal and external loads during its operation. Building a high-precision deformation prediction model is of significant importance for dam safety monitoring and operational assessment. Existing dam displacement models have long training times， and their prediction accuracy and generalization capabilities are often suboptimal， making them unsuitable for accurate short- to medium-term displacement predictions. This paper coupled Long Short-Term Memory （LSTM） with the Transformer framework and introduced an improved Invasive Particle Swarm Optimization （IPSO） algorithm for optimization to create the IPSO-LSTM-Transformer （ILT） dam deformation prediction model. Using data from measurement point 11-1 on the vertical axis of the Jinshuitan arch dam as an example， this paper analyzed and predicted deformation time series data from 6，150 data sets. The research results demonstrate that the model's prediction accuracy decreases to a certain extent as the prediction horizon increases， but it maintains good predictive capabilities within a prediction step of 10. Compared to traditional Particle Swarm Optimization algorithms， the ILT model significantly improves the model's optimization precision and convergence speed. When compared to the single-step and multi-step prediction results of RNN， LSTM， and IPSO-Transformer neural network models， the ILT model exhibits higher accuracy and better stability， even when trained with limited data. The research findings provide new technical means for the precise short-to-medium-term prediction of dam displacement during operation.

Dams are important structures that provide various benefits， such as hydroelectric power generation， irrigation， and flood control. However， dam failures can lead to catastrophic consequences， causing significant economic and human losses. Therefore， predicting the potential impact of a dam break is crucial for ensuring the safety of people and property downstream. The width of the breach is a critical factor in estimating the flooded area downstream of an earth-rock dam during a dam break. Traditional empirical formulas developed by the Scientific Research Institute of the Ministry of Railways and the Yellow River Water Conservancy Commission are used to estimate the width of the breach， taking into account the storage capacity， length， and height of the dam. However， these formulas have been found to have significant errors when compared to actual breach widths observed in dam break cases at home and abroad. To improve the accuracy of these formulas， this paper uses an allometric model to fit the data from seven dam break cases， resulting in an optimization formula for calculating the width of the breach. The new formula takes into account the length， height， and storage capacity of the dam， as well as the degree of compaction of the soil in the dam body. The optimized formula has been found to have a maximum error of only 4.5% when compared to actual breach widths， indicating that it is more accurate than the traditional empirical formulas. The optimization formula proposed in this study provides a more accurate method for estimating the width of the breach in earth-rock dam breaks， and can be used to improve the accuracy of calculations for maximum flow rate. The results of this study can also have significant implications for dam safety engineering， as well as for the development of effective emergency response plans in the event of a dam break. In addition， the DBFL-IWHR model is used to simulate the downstream flood evolution and compared with the traditional empirical formula. The DBFL-IWHR model is a two-dimensional hydrodynamic model that takes into account the complex interactions between the water flow and the topography of the river channel. The results show that the maximum flow rate calculated by the traditional formula is lower than that of the DBFL-IWHR model， and that the arrival time of the maximum flow rate in the downstream section is delayed compared to that of the DBFL-IWHR model. This highlights the importance of using accurate models in predicting the potential impact of dam breaks on downstream areas. In conclusion， the optimization formula proposed in this study provides a more accurate method for estimating the width of the breach in earth-rock dam breaks， and can be used to improve the accuracy of calculations for maximum flow rate. Furthermore， the use of accurate hydrodynamic models， such as the DBFL-IWHR model， is recommended for simulating the downstream flood evolution and predicting the potential impact of dam breaks. These findings may have significant implications for dam safety engineering， emergency response planning， and the protection of people and property downstream of earth-rock dams.

Subsurface infiltrating irrigation is a kind of underground micro-irrigation method. The irrigation water is diverted to the soil at a certain depth under the ground through the buried pipe for subsurface infiltrating irrigation，and then the soil capillary action is used to achieve direct water supply to the root zone of crops. This irrigation method is essentially the same as the irrigation process of “Subsurface Drip Irrigation”. Subsurface infiltrating irrigation can effectively improve soil environmental quality and facilitate crop growth， and it is a highly efficient and water-saving irrigation technology with broad development prospects. It is of great significance to research on subsurface drip irrigation for promoting the development of efficient water-saving agriculture. In this paper， the relevant research progress and existing problems are reviewed from the aspects of soil water transport rule， irrigation technology parameters， irrigation system， influence and regulation of infiltration irrigation pipe clogging etc.， and the future research directions are proposed，which may be referred to by scholars in the field of water-saving irrigation research. It is concluded from this review that， compared with the production practice of subsurface infiltrating irrigation， the research on its mechanism is relatively lagging behind， which limits the deep popularization and application of this technology. The main manifestations are as follows： the law of soil water transport under subsurface infiltration irrigation is not clear enough， clogging is still the limiting factor that hinders the application and development of subsurface infiltration irrigation technology， the optimization design of subsurface infiltration irrigation water distribution system needs further research. This paper suggests carrying out a numerical simulation analysis of water infiltration under different irrigation conditions in the future， selecting the appropriate treatment level， studying the main factors affecting the effect of infiltration irrigation， and seeking the optimal combination of irrigation technology parameters. Research on crop irrigation system under the condition of subsurface infiltration irrigation is carried out to form a set of reasonable and perfect irrigation system and test method. Further research should be carried out on the rule of subsurface infiltration irrigation pipe outflow， clogging mechanism and the effective control threshold of key parameters of irrigation water quality when entering the subsurface infiltration irrigation system.

Irrigation is one of the types of land management that has the greatest impact on regional climate， and its impact has been increasing in recent decades. A large number of papers have demonstrated the cooling effect of irrigation， particularly in arid and semi-arid regions. However， the cooling effect in humid regions has been found to be not significant， and the investigation of the cooling effect pertaining to extreme high temperatures has received comparatively less attention.In this study， a sliding window search algorithm is used to investigate the impact of augmenting the proportion of irrigated areas on the occurrence of extreme high temperatures in the Yangtze River Basin based on a global gridded temperature dataset and a historical irrigation distribution dataset. To isolate the climatic effects of various factors in the observed data， the multiple linear regression techniques are employed. Furthermore， a control test is set up by using the WRF model of the coupled irrigation module to perform numerical simulations for verification.The results show that irrigation in the Yangtze River Basin has a cooling effect on extreme high temperatures， and the intensity of the cooling effect depends on the proportion of irrigated area， which becomes more obvious with the increase in irrigated area， but when the proportion of irrigated area exceeds the threshold （0.25~0.30）， the cooling effect gradually diminishes. Numerical simulation experiments verified the results of the analysis based on observed data， but the model would overestimate the cooling effect of irrigation to some extent. Meanwhile， it was found that irrigation could increase soil moisture and latent heat flux and decrease sensible heat flux and soil heat flux， and the cooling effect would be weakened as the proportion of irrigated area increased， the surface moisture increased and the albedo decreased. The results of this research can provide a theoretical basis for the scientific management of agricultural irrigation in the Yangtze River Basin， which is of great scientific significance.

In recent years， extreme weather events have shown multiple and strong occurrences， and extreme hydrological events such as possible maximum floods triggered by extreme weather have posed serious threats to reservoir safety， while the use of conventional flood control scheduling protocols for reservoirs may fail in the face of their threats. Therefore， it is especially important to optimize the regular scheduling protocols of reservoirs and to form emergency scheduling for extreme situations. To address the problem， this paper focuses on the Zipingpu Reservoir， an incomplete regulated reservoir located in the upper reaches of the Min River as the research object， establishes a one-dimensional hydrodynamic model of the river section in the reservoir area based on HEC-RAS， following the “spatial-temporal trade-off” scheduling approach， the optimization principle of “advance pre-release combined with increased release” is adopted， and carries out a study on the scheduling mode of the reservoir in the face of possible maximum floods and the optimization of the scheduling timing with the goal of ensuring the safety of the reservoir and minimizing the downstream risk. It is found that when facing the maximum possible flood with the total influent flow rate of 8 times the reservoir flood control capacity， a reasonable dynamic allocation of the reservoir flood control capacity can be achieved through the combined mode of flood discharge and the joint optimization of the scheduling start and end times， developing an emergency scheduling protocol for the reservoir to cope with the potential maximum flood events. It realizes the reasonable dynamic distribution of reservoir flood control capacity with flood history， and wins more time for reservoirs to complete the flood release task. The optimized scheduling method avoids the hidden danger of conventional scheduling failure， the peak water level in front of the dam during the flooding period is lowered by 18.4 m compared to the original scheduling method， ensure that the water level in the reservoir is always in the safe range； the change of water surface line in the reservoir area is controlled within 14.7 m， which is 55.6% lower compared with the original dispatch， and the overall water level change in the reservoir area is more stable； and the peak reduction rate under the optimized scheme reaches 74%， which minimizes the threat of flooding to the downstream. On this basis， through a further analysis of the definition of reservoir flood control potential， it reveals the reasons for the obvious differences in the flood control effect of reservoirs under the two scheduling methods， and provides new ideas and references for reservoirs to carry out emergency scheduling in the face of extreme floods.

Ponds are essential elements of both natural landscapes and urban environments， serving as green infrastructures and playing a vital role in contemporary water conservation planning. They provide a wide range of ecosystem services that contribute to the overall health and sustainability of the environment. These services include flood regulation， nutrient retention， mitigation of the urban heat island effect， as well as supporting fish production and aquaculture. Evaluating the significance of ponds by examining their characteristics， determining their priority level for governance and protection， and proposing utilization strategies based on their importance levels are crucial steps in understanding and optimizing their ecological service functions. These efforts form the foundation for effective governance and protection of ponds and ensure their continued contribution to the land ecosystem’s service function and overall effectiveness. By analyzing the land use status of Liaocheng City， an assessment is conducted to understand the characteristics and spatial distribution of pits and ponds. Subsequently， an evaluation index system is developed to determine the importance of these pits and ponds in the region. This comprehensive analysis provides valuable insights into the significance of these water bodies and their role in the local ecosystem. It is found that the distance from the main rivers/lakes and reservoirs is conducive to the migration of Amphibian. The number and area of ponds around cultivated land are much larger than other types of land use. The number of ponds in each district and county decreases according to cultivated land， forest land， rural residential land， and urban residential land. The density of pits and ponds is 3~10 /km²， and the main gathering centers are in the northeast of Dongchangfu District， the middle of Dong’e County and the northeast of Gaotang County.The density and importance of ponds show a trend of high in the north and low in the south， and high in the east and low in the west. To make the most of ponds with high importance scores， this paper recommends strategically utilizing them based on their specific morphology and spatial distribution. This may involve implementing measures such as maintaining their natural features， protecting the surrounding vegetation， and ensuring proper water management practices. On the other hand， for ponds with low importance scores， an ecological reclamation approach can be pursued in conjunction with local land comprehensive improvement plans. By implementing these strategies， Liaocheng City can effectively utilize and protect its pit and pond resources. This will contribute to the preservation of the land ecosystem’s service functions and enhance the overall ecological well-being of the region.

Climate change and human activities are important causes of runoff changes in watersheds. The Budyko hydrothermal coupled equilibrium equation is a common tool for runoff change analysis， because it takes into account certain physical causes on the one hand， and the parameters of the equation are simple on the other hand， so it has been widely used in runoff change attribution for a long time. However， the current research and application of Budyko’s formula for time-varying forms still need to be strengthened. Therefore， this paper first analyzes the trend and abrupt change of annual runoff in the study area by Mann-Kendall test and abrupt change test， and then constructs the time-varying Budyko formula based on the principle of hydrothermal coupling equilibrium， including linear， quadratic polynomial and physical mechanism， and uses Nash efficiency coefficient as the evaluation index to verify the most suitable. Finally， the contribution of precipitation， potential evapotranspiration and human activities to the runoff change is calculated， and the attribution analysis of the runoff change in the Liudong River basin is carried out. The results of this study show that the runoff of the river basin has been decreasing in recent years with the impact of climate change， with a significant change in 1997. A comparison of the sensitivity of precipitation， potential evapotranspiration and human activities to runoff show that the decrease in precipitation is the dominant factor in the decrease in runoff， with a contribution of 49%. Meanwhile， with the development of human economy and society and the construction of large water conservancy facilities， the influence of human activities on runoff changes in the basin is gradually emerging， with a contribution rate of about 26%.

The optimal regulation of multi-energy complementary systems helps to take advantages of different power sources. The growing installed capacity of wind and photovoltaic power has brought about the problems of clean energy consumption and grid peak shaving. A bi-level optimal scheduling model of wind， photovoltaic（PV）， hydropower， thermal power and energy storage is proposed to solve the problems. Firstly， considering that there are many variables and constraints involved in the optimal scheduling of multi-energy complementary， the model is processed hierarchically based on the output characteristics and complementary relationship of multiple energy sources， to reduce the complexity of model solving. Then， according to the demand of source-load coordination， clean energy consumption and power generation economy， the model is divided into the upper-level model of Wind-PV-Hydro-Storage joint optimal scheduling and the lower-level model of thermal power unit optimal scheduling. The optimization objectives of upper-level model are the minimum net load variance and the maximum clean energy generation， and the optimization objective of lower-level model is the minimum operation cost of thermal power units. The net load curve achieved by the upper-level model is used as the constraint of the lower-level model. Finally， taking the IEEE30-bus system as an example， the CPLEX solver of MATLAB platform is used to calculate three pre-defined scheduling scenarios. The results show that the anti-peak regulation of wind power and photovoltaic output will expand the peak-valley difference and variance of net load， increase the pressure of peak shavingand reserve of thermal power， and increase the power generation cost and unit loss. The participation of hydropower in multi-energy complementary systems has a significant improvement on the net load fluctuation of the power grid， which can effectively reduce the peaking pressure of the power system. Energy storage can reduce the conflict between smoothing net load fluctuation and improving clean energy generation to a certain extent. The optimal scheduling model proposed can effectively reduce the fluctuation of source and load， promote the consumption of clean energy and reduce the operation cost of the system， which contribute to the low-carbon and safe operation goals of the grid.

Utilizing satellite remote sensing technology for the retrieval of water depth is a crucial method for quickly acquiring water depth information over large areas. However， traditional optical satellite images often suffer from low inversion accuracy due to various factors， including the presence of sediments， suspended particles， and chlorophyll in the water. These constituents alter the color and turbidity of the water， making it challenging to accurately estimate water depth through remote sensing techniques. To mitigate the influence of these water color materials on the accuracy of water depth inversion， a novel approach was proposed， centered around a mathematical model and the use of Sentinel-2 remote sensing imagery. This approach involves analyzing the mathematical relationships between water depth and the surface area of different types of water channels. This method deduces the river surface depth model by generalizing and classifying the river section. It combines the Sentinel-2 remote sensing images to determine the relevant parameters in the mathematical model， and derives an expression that can directly calculate the water depth from the water surface area， which can minimize the influence of water color on water depth retrieval from remote sensing images. To validate the effectiveness of this approach， it was applied to the Xiaoqing River， and the results were compared with ground-truth data. The average absolute error in water depth inversion at two hydrographic stations， Huangtaiqiao and Shicun， was found to be 0.03 meters and 0.23 meters， respectively. These results demonstrate a significant improvement in the accuracy of water depth estimation. The method proves to be more reliable in areas with varying water color and turbidity. It can quickly obtain water body depth information based on satellite remote sensing technology and has promotion and application value.

This paper analyzed the pre-stressing mechanism of the steel wire and the damage process of the pipeline， and proposes a method of PCCP wire broken warning and alarm threshold assessment based on mechanical simulation analysis. The PCCP finite element model was established by ABAQUS program， and the complete construction process including laying bedding， installing pipelines， backfilling in steps was simulated， and the stress state of pipeline prestressing steel wires， steel cylinders and pipe core concrete was calculated under nearly 100 working conditions with different depths of burial and different design working pressures. It was proposed to take the maximum permissible number of broken wires of the pipe core concrete cracked under the action of water hammer as the early warning threshold for the bursting of the pipeline， and the maximum permissible number of broken wires in the limit state of the buried bearing capacity of the pipeline as the alarm threshold for pipe bursting， and analyzed the relationship between the PCCP wire broken warning and the alarm threshold under different working pressures and burial depths.

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.

In order to dynamically analyze the impact of future land use change on the non-point source pollution load in the watershed，this study couples the PLUS land use prediction model with the SWAT non-point source pollution load model，so as to reveal the distribution of non-point source pollution in the watershed under different land use change scenarios．By taking the Dongjiang Lake Basin as the research area，this paper simulates and predicts the temporal and spatial evolution of non-point source pollution under different land use patterns in the historical series of the study area and in the following 2035 by building the SWAT non-point source pollution model and the PLUS land use model．The results show that the SWAT model has good applicability to the Dongjiang Lake Basin．The Nash–Sutcliffe efficiency index of the river runoff in regular and verification periods are 0.80 and 0.71. Meanwhile，the ammonia nitrogen and total phosphorus rates are higher than 0.5 in both periods．The temporal and spatial evolution characteristics，as well as changing trends，of non-point source pollution in the Dongjiang Lake Basin are studied by using long series simulation results．Non-point source pollution in the Dongjiang Lake Basin is affected by natural processes such as precipitation and runoff and land use patterns. From a time perspective，the pollution output load is concentrated during the high-water period with heavy precipitation. The inter-regional change reveals a trend of non-point source pollution first increasing and then decreasing； from the perspective of spatial scale，higher loads of ammonia nitrogen and total phosphorus are concentrated in the northwestern and central sub-basins with larger runoff and scattered farmland. The impact of different types of land use on non-point source pollution is studied in conjunction with the distribution pattern of land use and non-point source pollution．The contribution degree of total phosphorus load is cultivated land > construction land > grassland > forest land >unused. The land use pattern in 2035 is set by using the PLUS land use model under the historical trend scenario and territorial spatial planning， and the simulation and analysis of the response to non-point source pollution are completed on this basis．Under two different land use pattern scenarios，the territorial spatial planning scenario reduces ammonia nitrogen by 2.12 t and total phosphorus by 54.6 t compared with the historical trend scenario．The former scenario is more beneficial to control the non-point source pollution loads in the Dongjiang Lake Basin．The increase in pollution load is caused by the pollution of farmland， the rapid expansion of construction land and the reduction of forest land，and the restricted conversion of forest land and cultivated land plays an important role in reducing the pollution load of the watershed．

In order to explore the influence of the staggered impeller on the pressure fluctuation characteristics of the double entry two-stage double suction centrifugal pump， this paper uses the method of combining experiment and numerical simulation to carry out a research on the same pump with symmetrical impeller and staggered impeller as the contrast scheme， and quantifies the pressure pulsation characteristics of the suction chamber， inter-stage flow channel and volute under three typical working conditions of 0.6Q， 1.0Q and 1.2Q. The results show that： ① in terms of external characteristics， the head and efficiency of the pump with staggered impeller are higher than those with symmetrical impeller at all working conditions， and they can be 2% and 3% higher than those at 1.0Q working condition. ② In terms of pressure pulsation characteristics， for the suction chamber， the influence of staggered impellers on pressure pulsation is small at all working conditions， and the difference of dominant frequency amplitude is less than 2%. For the inter-stage flow channel， the staggered impeller can restrain the pressure fluctuation at all working conditions. For example， the dominant frequency amplitude at the tongue of the inter-stage flow channel can be reduced by 13.5% compared with that of the symmetrical impeller. For the volute， the staggered impeller can improve the pressure fluctuation under all working conditions. For example， the dominant frequency amplitude at the tongue of the volute can be reduced by 31.9% at most. This finding can provide a reference for the application of staggered impeller in double inlet two-stage double suction centrifugal pump.

It is one of the most effective ways to reduce pipe network leakage by controlling pipe network pressure. Traditionally， the pressure reducing valve is only applicable to the pressure management of local pipe network. In this paper， the method of real-time regulation of the pressure reducing valve and the water supply pump station is used to manage the pipe network pressure. Based on the systematic analysis of the response relationship and characteristics between the leakage amount and the node pressure， a hydraulic model of pipe network leakage is established.Taking the water supply network in CYN District of a city in North China as an example， genetic algorithm （GA）， particle swarm optimization （PSO） and whale optimization algorithm （WOA） are used to solve the case， and then the operation effects of these three algorithms are compared and analyzed. The results show that the whale optimization algorithm has better performance for solving the leakage model.

As an important non-engineering measure， the optimal operation of reservoir flood control can reduce the loss caused by flood disasters with little investment and plays a key role in flood control and disaster reduction. In this paper， considering the safety of the reservoirs themselves and the safety of the downstream flood control section， a multi-objective optimal model for real-time flood control operation of reservoirs is established with the objective function of minimizing the maximum flow of the downstream flood control section and minimizing the maximum water level of each reservoir. Based on the “filter operator”， an improved multi-objective Lichtenberg algorithm （MOLA） is proposed， which is used to solve the multi-objective model， and the real-time flood control operation schemes of the reservoirs are obtained， to enhance the practicability of operation solutions. Finally， a comprehensive screening method based on hierarchical clustering and the physical meaning of Pareto front is proposed to screen the scheduling schemes on the Pareto front and select limited ones for the scheduler， to increase the focus of decision-making. Taking the Shiguanhe flood control system of the Huaihe River Basin as an example， this paper applies the multi-objective optimal model for real-time flood control operation of reservoirs. The result shows that the proposed model based on the improved multi-objective Lichtenberg algorithm has high computational efficiency and strong applicability. The gradient analysis method is used to quantitatively analyze the mutual feedback relationship between the maximum water level of Nianyushan Reservoir， the maximum water level of Meishan Reservoir， and the maximum flow of Jiangjiaji flood control section. The results show that the water level change of Meishan Reservoir has a more significant impact on the flow of Jiangjiaji section， and the Meishan Reservoir is a priority in flood risk control of Shiguanhe River Basin. The research results can provide decision-making support for real-time flood control operation of reservoirs.

Wheat drip irrigation technology is the main project of high-standard farmland construction in North China， and it is also an important technical means to deal with the shortage of water resources in the region and ensure national food security. Based on the latest research progresses of drip irrigation technology on wheat at home and abroad and the research results of our group for many years， this paper elaborates the influences of drip irrigation factors such as drip flow， dripping element spacing， drip belt laying distance on soil water distribution， the ways of drip irrigation scheduling on wheat， and the effects of drip irrigation on wheat water consumption characteristics， dry matter accumulations， yield compositions and so on. At the same time， the development trends of wheat drip irrigation in the future are put forward： smart irrigation decision-making and water-fertilizer integration technology that integrates multiple factors such as meteorology， soil and crops， It is hoped these contents would provide theoretical and technical support for accelerating the application and popularization of drip irrigation technology in the main wheat-producing areas in China..

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 recent years， the frequent occurrence of urban waterlogging disasters caused by extreme rainfall due to climate change has posed a threat to urban water safety and sustainable development in China. Accurately grasping the public opinion and emotions in the disaster-stricken areas is of great importance for improving the situational awareness capabilities of emergency management departments in dealing with waterlogging disasters. In today's era of intelligent networks， the increasing importance of social media as a platform for people to voice their problems and suggestions has made it a major carrier of public sentiment and societal opinion， providing a new avenue for obtaining information about natural disasters. A key technical challenge that needs to be urgently addressed is how to quickly extract urban flood disaster information from social media， and how to perform thematic categorization and sentiment analysis of natural disaster information to accurately grasp the thematic categories of regional disaster situations and public opinion trends. Taking Sina Weibo as an example， this article elaborates on the methods of collecting and pre-processing flood disaster data， and constructs a thematic classification and sentiment analysis model of urban flood disaster information based on FastText to accurately capture the thematic categories and public opinion orientations of disaster-stricken areas. The research results， using the “7.20” heavy rain and flood disaster in Zhengzhou in 2021 as an example show that the methods proposed in this article achieve intelligent extraction and analysis of urban flood disaster data on social media. The theme classification model achieves an F1 score of over 0.80 for the classification prediction of the eight predefined categories， and the sentiment analysis model is generally able to accurately predict data labelled as “negative” in sentiment， which indicates that the FastText-based urban flood disaster information theme classification and sentiment analysis model constructed in this article can meet the needs of urban emergency management departments to dynamically grasp the development of flood disasters and public emotions. It holds significant guiding importance for flood prevention and disaster mitigation planning， calming public emotions， and pinpointing rescue efforts in real time.

In recent years， uncommonly severe droughts have attacked many places in Guangdong Province， with long duration， wide impact and serious consequences， which is contrary to people’s general understanding of the water-rich areas in the south. In order to find out the causes， influencing factors and characteristics of drought in Guangdong Province， and effectively identify the weaknesses in drought disaster prevention and control， taking the typical drought-prone counties in Guangdong Province-Chaonan District in eastern Guangdong and Xuwen County in western Guangdong Province as examples， based on the natural disaster risk theory， this paper establishes a drought disaster risk assessment zoning model， which couples the three elements of hazard， vulnerability and defense， and the evaluation index system and calculation method of comprehensive risk index are put forward. The index weight is determined by analytic hierarchy process. The natural breakpoint method is used to scientifically divide the regionalization， and the risk matrix method is introduced to aggregate the drought risk and drought defense and disaster reduction ability to represent the level of drought disaster prevention and control， and the risk influencing factors and risk levels of drought disaster are qualitatively and quantitatively evaluated. The results show that， under the main influence of less natural rainfall and large demand for economic and social water， the comprehensive risk of drought disaster in Chaonan increase from west to east， most towns and streets have moderate drought risks， while the whole area of Xuwen has medium-high and above drought risks， the comprehensive risk of drought disaster in western and central areas is high. If the water supply engineering capacity， river system density and drought-defense investment level are not high， it can be determined that most towns and streets in Chaonan are medium prevention areas， and most towns and villages in Xuwen are key prevention areas. The rationality of the results is verified by typical historical drought events， and some measures and suggestions are put forward for the weaknesses of drought defense in drought-prone counties. The research results can provide technical support for improving the drought-defense and disaster reduction system in typical drought-prone counties in Guangdong Province.

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.

With the development of industrialization and urbanization， untreated domestic sewage， industrial sewage and pollutants of surface runoff in the rainy season are discharged into the river system， leading to the serious urban water pollution. Due to the complexity and variability of the sources of urban polluted water bodies and environmental conditions， the current river restoration focuses on the rapid recovery of water quality， but does not fundamentally clarify the source of pollution， and does not consider the restoration of river water ecosystem damage. It leads to the fact that urban river is characterized with poor ability of self-purification and imperfect biodiversity， meanwhile， it is difficult to maintain and continuously improve water quality. This paper systematically illustrates the development process and inherent science of the concept of near naturalization restoration and urban sponge city. Both of them have separate characteristics， the concept and measures of which have commonality with the urban river restoration. The ecological restoration under the guidance of near-naturalization concept is beneficial to restore the hydrological continuity of river channels， to reshape the meandering and winding landscape of rivers， to increase the biodiversity index， making full use of their original ecological functions and values. Whereas， the concept of sponge city can effectively reduce surface runoff， purify， accumulate， utilize rainwater and alleviate the discharge of pollutants into river or water bodies. They also contribute to the mitigation of flooding risk and improvement of river dredging and drainage functions. In addition， this paper summarizes the near-naturalized and sponge city part from the project carried out in Fuyang City， Anhui Province. Through the combination technology of “source control， pollution interception， dredging， water diversion and management”， ecological restoration makes the near naturalization and sponge city integrated， which also emphasizes the construction of food chain system and greening management in the river channels. The two concepts focus on the restoration of self-purification capacity of the river and the reconstruction of ecosystem integrity， emphasize the treatment and reuse of rainwater resources， achieving the harmonious development of urban ecological restoration and landscape. Finally， to ensure the sound cycle and sustainable development of urban water ecosystem， the paper develops the direction of urban river restoration under the concept of near naturalization and sponge city intersection based on the current advanced environmental remediation and administration of domestic and foreign countries. It mainly includes two aspects： one is that the river restoration should be implemented in combination with the over-all planning of urban areas， making the river channel construction as an organic component of urban landscape； the other one is to gradually establish the evaluation indicators and standard for urban river restoration， including the traditional water quality indicators and those indicators related to the biological habitat and biodiversity.

As a unit hydrograph method widely used in engineering practice， the synthetic unit hydrograph of Guangdong is obtained from the analysis and synthesis of rain and flood data before 1983， which reflects the production-confluence relationship before urbanization in Guangdong Province. However， there are few studies on the evaluation and modification of its applicability in urbanized areas. Taking Jingtian Watershed of Shenzhen City， Guangdong Province as an example， based on the rainstorm and flood records of Jingtian Hydrology Station from 2011 to 2019， this paper evaluates the applicability of the comprehensive unit line in Guangdong Province by using evaluation indexes such as Nash efficiency coefficient， identification index and correlation coefficient， and conducts a sensitivity analysis of important parameters by Spearman rank correlation coefficient method. Based on Latin hypercube sampling method and constrained least square method， the comprehensive unit line method of Guangdong Province is modified. The results show that the Jingtian Basin has experienced rapid urban expansion since the 1980s， and the proportion of impervious surface has exceeded 90%. The comprehensive unit line method in Guangdong Province has obvious shortcomings in describing the storm-flood process in this basin. The two schemes proposed in this paper can improve the simulation effect of the model by determining important parameters and modifying the unit line. Among them， the cross-validation parameter optimization method based on grid search and the unit line correction method based on constrained least square method proposed for small samples show a good simulation performance， and the indexes such as Nash efficiency coefficient， identification index and correlation coefficient are significantly improved， which better reflects the characteristics of production and convergence in Jingtian Basin. Compared with the recommended unit line of the integrated unit line method in Guangdong Province， the modified unit hydrograph method shows the characteristics of larger peak discharge， earlier peak time and smaller total duration， which is more in line with the law of production and confluence of urbanization.

With the guide vane of the pump-turbine as the main research object， the guide vane opening of 11， 33 and 41 mm is selected to analyze the influence of different guide vane airfoils on runaway characteristics of pump-turbine， so as to provide methods and theoretical guidance for the design and optimization of guide vane airfoil of pump-turbine. The results show that the improved guide vane airfoil has a better improvement effect on the "S" characteristics of the unit under three kinds of guide vane openings. After the improvement of the guide vane airfoil， the internal flow state of the unit is improved on runaway characteristics. The velocity streamlines in the guide vane and runner area are evenly distributed， and the concentrated distribution area of vortex core is reduced. After the improvement of guide vane airfoil， the relative value of pressure pulsation amplitude of monitoring points in vaneless area at different openings decreases in different degrees， and the velocity pulsation curve is gentle and the velocity peak value is smaller than before the improvement. The concentrated distribution area of vortex core in the draft tube of the improved guide vane airfoil is reduced， and the unit can operate in a relatively stable state.

Due to climate change and human activities， the runoff characteristics of the upper Yangtze River have changed significantly in recent years， bringing many challenges to the development and utilization of water resources in the upper Yangtze River Basin and the functions of national strategic freshwater resource reservoirs such as the Three Gorges and the upstream reservoir group. Attribution analysis of runoff changes is of great importance to the development and utilization of water resources in the basin. Based on the observed runoff data from 1951 to 2013， statistical methods such as Mann-Kendall test， Spearman test and Pettitt test are used to diagnose the variation patterns of the Three Gorges inflow runoff. Based on the meteorological and land use data of the same period， the causes of the variation of the Three Gorges inflow runoff are further quantitatively analyzed by using the climate elasticity method， the water-energy balance equation and the SWAT. The results show that： ① the inflow runoff of the Three Gorges was significantly changed around 1993， before 1993 the runoff was relatively natural and less affected by climate change and human activities， and after 1993 the runoff changed and was more affected. ② During the study period， the inflow runoff from the Three Gorges decreased significantly， at a rate of 8.8 mm/10 a. Large-scale human activities in the upper Yangtze River were the main cause of the decrease in inflow runoff into the Three Gorges， while the decrease in precipitation and the increase in temperature were important causes. ③ The attribution results of the climate elasticity approach are consistent with the SWAT-based method， while the water-energy balance approach underestimates the impact of human activities on runoff. ④ SWAT takes into account the spatial and temporal changes in land use， can better describe the causes of runoff changes than the traditional “two-stage” method. These results are important to guiding the comprehensive utilization of water resources in the Three Gorges Reservoir and the rational development of water resources in the upper Yangtze River.

Since 1956， the Dongting lake basin has experienced a historical process from shrinkage to development. To investigate the reason behind its evolution during each historical stage and predict its evolution trend， we work out this study based on data of water-sediment discharge， lake-basin water surface area and lake capacity during 1956-2019， in which contribution ratios of sedimentation， lake basin subsidence， reclamation and sand mining on lake-capacity variation are identified using the variable separation method. Results show that the lake-basin water surface area decreased by 1 247.59 km² during 1956-2019， in which the shrinkage of the east lake basin was the most severe， and reclamation within the lake basin was the major driving factor during 1956-1980， whereas the lake-basin water surface area became stable after 1980. Both sediment input and output continuously declined before the impoundment of the Three Gorges Dam （1956-2002）， with a rough sedimentation ratio of 70% in the lake. However， sediment input experienced a remarkable reduction after the impoundment （2003-2019）， with the sedimentation ratio falling to 14%. There was an offset effect among lake-basin subsidence， sand mining and sedimentation when they altered the lake capacity. At present， the lake basin is still in a slow tectonic subsidence， with an average rate of 3 mm/a. As sand minning proceeds， the lake shrinkage slows down. Before 1980， the lake capacity decreased， with contribution ratios of reclamation， sedimentation and tectonic subsidence were -92.7%， -13.2% and 5.9%. However， after 1980， the lake capacity witnessed a shift from declination during 1981-2002 to augment during 2003-2019 and a net declination， with contribution ratios of sedimentation and tectonic subsidence were -107.6% and 7.6% during 1981-2002 and those of sedimentation， tectonic subsidence and sand mining were -11%， 24.8% and 86.2% during 2003-2019. Considering the higher rate of tectonic subsidence than sedimentation after the impoundment of the Three Gorges Dam and the dominance of sand mining in the lake capacity change， the Dongting lake will continuously develop as the new sand mining planning （2023-2027） implements.

Riverbed roughness is an important aspect of river dynamics research， and its quantitative measurement has always been challenging. In this experiment， regardless of the macroscopic undulation of the riverbed， we laid the initial bed surface in a straight channel with non-uniform natural sand and thickened it by gradually increasing the flow rate of water. Laser scanning technology was used to obtain high-resolution bed elevation data after each bed roughening. Statistical theory and variogram function were used to investigate the surface roughness characteristics of riverbeds with varying degrees of coarseness， and to deepen the understanding of their statistical characteristics. The study's main finding is that artificially laid non-uniform sand presents an elevation frequency distribution that approximates a normal distribution. On the contrary， the frequency distribution of the stable rough bed surface formed by the continuous cumulative erosion of different flow intensities shows a slight positive deviation trend. The study found evidence that the increase of flow intensity leads strictly to an associated elevation standard deviation increase. This finding indicates that elevation standard deviation can be used as a reliable indicator to measure the characteristics of riverbed roughness in future studies. The study revealed that the kurtosis of the bed elevation data precisely decreased monotonically with the flow intensity， and that skewness and kurtosis showed a monotonic trend， indicating that they can be used to measure bed roughness. Additionally， the study found that the flow forming the bed surface is anisotropic， and as flow intensity increases， the rough layer breaks and becomes rougher again. This leads to an increase in the base value of the two-dimensional bed elevation variogram. Therefore， the study suggests that the base value of the two-dimensional variogram could serve as another reliable index for evaluating bed surface roughness. In addition， due to the influence of water flow， although the change trend of the characteristic parameters of the average variogram along the flow direction， vertical flow direction and radial profile elevation is consistent， the average variogram base value and golden point value of the transverse section are slightly larger than those of the transverse and longitudinal sections. Conversely， in the radial section， the abutment value and nugget value are considerably smaller than the values in transverse and longitudinal sections. In conclusion， this study enhances our understanding of the characteristics of bed roughness and provides crucial insights into statistical expressions for quantifying it.

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.

Evapotranspiration is a key factor in hydrological and energy cycles， and its spatio-temporal evolution is influenced by various complex factors such as watershed climate， energy， and underlying surface. The influencing factors of evapotranspiration in different climate regions have spatio-temporal differences and different sensitivity characteristics. Studying the spatio-temporal changes in evapotranspiration is beneficial for revealing the response characteristics of hydrological cycles in complex environments， further deepening people’s understanding of water balance in watersheds， and providing theoretical reference for the rational planning and utilization of water resources in watersheds. Based on the SWH dual source evapotranspiration model， the evapotranspiration and its components of the Poyang Lake Basin from 2001 to 2017 are simulated. On the basis of multi-temporal and spatial scale validation， the spatial-temporal evolution characteristics of the total evapotranspiration （ET）， soil evaporation （Es）， plant transpiration （Ec） and evaporation ratio （Es/ET） of the basin are analyzed. Based on the SOBOL sensitivity analysis method， the sensitive influencing factors and actual change causes of the evapotranspiration components of the basin are explored. The results show that the correlation coefficients between the simulated and measured values of the SWH model at the 8-day scale are 0.92 and 0.89 at the station and watershed， respectively， indicating good simulation results. At the 0.05 significance level， the annual ET in the Poyang Lake Basin does not decrease significantly at the rate of 1.0 mm/a， Es decreases significantly at the rate of 2.6 mm/a， Ec does not increase significantly at the rate of 1.7 mm/a， and Es/ET decreases significantly at the rate of 0.28%/a. The spatial distribution characteristics of Es/ET in the basin are high in the middle and low around， with Es/ET in winter>spring>autumn>summer. Except for summer， Es/ET shows a significant downward trend， mainly concentrated in the southern plain of the lake area and the Xinjiang River basin， accounting for 33.86% of the total basin area. Temperature and wind speed are the main sensitive factors affecting changes in ET and Es in the watershed， followed by precipitation and net radiation. Es is also more sensitive to NDVI. The main sensitive factor for Ec and Es/ET at both annual and seasonal scales is the NDVI， and the significant increase in NDVI is the main reason for the changes in Ec and Es/ET in the watershed.

Tetracycline hydrochloride （TCH） is widely used in medical， livestock breeding， and agricultural industries. However， because it is not fully absorbed by humans and animals while used， it enters environmental water bodies with feces and urine. TCH can damage the ecological environment， harm human health， and produce drug-resistant bacteria， posing threats to the environment and human health. Therefore， finding an economical and effective removal method is crucial for water quality safety. Currently， the removal methods for TCH in water mainly include chemical， biological， and physical methods. Compared with chemical and biological treatments， the adsorption method in physical treatments for removing TCH from polluted water bodies has the advantages of low cost， environmental friendliness， high efficiency， stability， and easy operation. In choosing adsorption materials， carbon-based and mineral materials often appear powdery， are not easily recoverable， and carry the risk of secondary pollution. In contrast， gel materials are suitable for removing organic pollutants. Thus， finding an inexpensive adsorbent with good adsorption performance is currently a hot subject. Montmorillonite （MMT） is a clay mineral with a stable crystal structure and high mechanical strength. It has a surface with many permanent negative charges. Due to its low cost， easy availability， and superior adsorption properties， it is commonly used in wastewater treatment to adsorb heavy metal ions， dyes， phenolic compounds， polycyclic aromatic hydrocarbons， etc.， with good removal effects. However， there is currently no research specifically on using MMT for TCH adsorption. Against this background， this paper aims to study the adsorption performance and effects of MMT adsorbing TCH. Through research， it is found that the Freundlich isothermal adsorption model and the pseudo-second-order kinetic model fit well for MMT adsorbing TCH， indicating that its adsorption is multilayered and can reach 87% of the total adsorption amount within 60 minutes. The Langmuir saturation adsorption amount can reach 118.6mg/g. The Gibbs free energy ΔG0 is always negative， indicating that the adsorption of TCH by MMT is a spontaneous process. The calculated enthalpy and entropy changes are both positive， indicating that the adsorption process is endothermic and occurs randomly on the solid-liquid surface. Increasing the temperature promotes adsorption， which is consistent with the conclusions drawn from temperature effect experiments， further indicating that the adsorption process is an endothermic reaction and increasing the temperature is conducive to adsorption. The solution pH significantly affects adsorption performance. As the pH increases from 3 to 10， the adsorption amount first increases and then decreases， with the optimal pH range being 6-8. This is because， under strongly acidic conditions， H+ competes with TCH for adsorption， resulting in a lower adsorption amount of TCH by MMT. As the pH value increases and the H+ concentration decreases， the competitive adsorption with TCH is reduced， so the electrostatic adsorption of TCH by MMT increases. But as the pH continues to rise， TCH gradually transforms into H2TC- and HTC2- forms， creating electrostatic repulsion with negatively charged MMT and causing a decrease in adsorption. Based on the above experiment results and characterization analysis， the mechanism suggests that the adsorption process of MMT on TCH includes both physical adsorption and chemical actions， with the latter being dominant. The Al-O-H group in MMT can form hydrogen bonds with the tricarbamoyl amide and hydroxyl groups on the TCH molecule. At pH < 5， there is also a certain electrostatic attraction. In summary， due to the low cost of MMT， its fast adsorption rate， and high adsorption capacity， it has unique advantages in the adsorption performance of TCH， thus promising a bright application prospect in the actual TCH wastewater treatment.

In order to simulate the operating status of the irrigation networks with pipe conveyance under different working conditions， this paper presents a numerical simulation model based on the mass conservation law and energy conservation law of constant flow. In this model， the equations of hydraulic state are established respectively to indicate the irrigation networks with pipe conveyance by using the bisection method to solve the equations respectively， the simulation results include the actual working points of the main nodes of the pipelines and the outlets， and the actual flow rate， head， power and efficiency of pumps. The case analysis shows that the model converges rapidly under the condition of each rotational irrigation schemes， the simulation results provide an important basis for water management of the system and the optimization of the engineering designs， which reflects a good practical application value.

Based on the knowledge and understanding of modernization of the physical irrigation district and digitalization of the analog irrigation district， this paper analyzes and summarizes the “five major functions” of the construction of modernized digital irrigation district including “Identification system of irrigation district”， “Stereoscopic Perception System”， “Precise Control System”， “Information Exchange System” and “Water Allocation System”. In order to meet the requirements of intelligent water projects and efficient operation and management of irrigation district， to efficiently simulate water flow in canal system， the generalized map of irrigation district with “joint flow process” as input and output is systematically sorted out， and the key application structure system of modernized digital irrigation district is studied and proposed. That is to build an interactive overall structure with “database” as the carrier， “mathematical model” as the support layer， “nine professional applications” as the interaction layer including “organization management”， “project management”， “security management”， “pumping station management”， “water saving and water supply management”， “economic management”， “information management” and “public services” on the basis of “one digital map of the irrigation district”. It is expected to effectively improve the safety， equity， reliability and flexibility of irrigation water supply services.

The water conveyance and power generation system network of cascade hydropower station， which has many types of pipes and joints， is complicated. Traditional calculation programs for the transition process of hydropower station can’t model， determine the topological relationship of pipeline network and calculate it. Aiming at the layout of water transmission and power generation system of series hydropower stations， this paper develops a set of visualization software for modeling and calculation of transition process of multistage series hydropower station based on Qt library. According to the functional requirements of the software and the design idea that each module is independent， the software is divided into three modules： drawing module based on Qt graphics view framework， calculation module based on transient flow and post-processing module for results processing. The three modules are connected with each other， and users manage the three modules through the main interface. Finally， the practicability and correctness of the software are verified by engineering examples.

Towns and cities require wastewater treatment plants to ensure the ecological environment， human health， and sustainable development. It is necessary to predict the future values of the effluent quality indicators of wastewater plants in order to improve the efficiency of urban wastewater treatment plants and optimize energy use. However， due to large number of effluent quality indexes of wastewater plants， the extremely complex reactions involved in the wastewater treatment process， and the high degree of time-series nonlinearity of the data， the mechanistic model based on determining the biochemical reactions and the statistical-based prediction method cannot achieve the desired results. As a solution to this issue， this paper proposes a deep learning-based prediction method for wastewater plant effluent water quality， and a town in Jilin Province has used a CASS process wastewater plant to monitor water quality data at the influent and effluent as the source data， as well as the neural networks combined with the encoder-decoder structure for predicting wastewater plant effluent water quality. The model is also applied to complex environments by adding data on local environmental factors （temperature and precipitation） that affect wastewater treatment. The historical （20 steps） data as the model input to predict the future water quality data. At the same time， to better compare the model performance， this paper divides experiments into short-term prediction （single step） and long-term prediction （20 steps） of two different time dimensions for prediction. Experimental results show that the proposed structure improves the prediction ability of both LSTM and GRU networks， especially the improvement of long-term prediction ability. Based on the ED-GRU model， which has the best prediction effect， the root mean square error （RMSE） of the four effluent water quality indexes of COD， NH₃-N， TP and TN in short-term prediction are 0.755 1， 0.219 7 and 0.073 4， 0.314 6， respectively. The goodness of fit （R ²） is 0.901 3， 0.933 2， 0.916 7， 0.953 2， which can be used to make a better prediction of the local water quality trends. The RMSE of the four indicators in the long-term prediction is 1.720 4， 1.768 9， 0.447 8， 0.831 6， and the R ² is 0.484 9，0.550 7，0.450 2，0.759 5， which can predict the overall trend of future changes in effluent water quality. Compared with the sequential structure GRU， it is predicted that the short-term RMSE will decrease by more than 10%， R ² to increase by more than 2%， and the long-term RMSE will decrease by over 25% and the R ² will increase by more than 15%. Based on the results of this paper， the neural network based on the encoder-decoder structure can make accurate predictions of the effluent quality of wastewater plants and provide technical support for the next step of wastewater treatment process improvement.

In our present stage， agricultural water right trading is dispersed and the scale is smaller， and the market activity of agricultural water right trading is not in full swing. With the contradiction between supply and demand of water resources becoming increasingly tense， agriculture has necessity to stimulate the decisive role of market in water resources allocation， and further create greater trading space for agricultural water rights. Agricultural water rights involve multi-level management systems， but few studies have analyzed the factors affecting the development of agricultural water rights trading from different dimensions in detail， so it is impossible to systematically promote the development of agricultural water rights trading. Therefore， this paper divides the key factors affecting the development of agricultural water rights trading into three dimensions： macro social economy， middle market players and their mutual relations， and micro trading elements. A qualitative analysis is made of the substantive attributes of each factor index in different dimensions and its impact on the development of agricultural water rights trading， and the macro-support for the development of agricultural water rights trading is found. This paper clarifies the development ideas of agricultural water rights trading market， and then focus on the role of micro-trading elements in the process of water rights trading. From three dimensions， it puts forward suggestions on how to strengthen the agricultural water rights trading policy and promote the construction of rural water system connectivity in multiple ways， clarify the role positioning of government and enterprises， and encourage the synchronous transfer of agricultural water rights trading and land to activate the agricultural water rights trading market so as to improve the agricultural water rights trading market to provide the construction foundation and ideas.

The plain river network area has a flat terrain and slow flow velocity， resulting in a limited ability to resist pollution. Therefore， enhancing the connectivity of the water system is crucial for improving the quality of the water environment. This article focuses on the Yuejin polders which has poor water system connectivity in Shengze Town as the subject of research. By conducting water diversion experiments and constructing a hydrodynamic model of the river network in the polders area， the study explores the scheduling and operation rules of water conservancy work， methods of connecting the river network， and the corresponding changes in the water environment. The study utilizes water age as a time scale parameter to measure the connectivity of the water system. It establishes a river network model for hydrodynamics， water quality， and water age in the Yuejin polders. The simulation evaluates the connectivity and water quality improvement in the polders area under five water diversion schemes. Additionally， an evaluation system of pressure， state and response is constructed to quantitatively analyze changes in water system connectivity and the level of water environmental improvement resulting from water diversion. The results reveal that from the perspective of the length of water exchange， the exchange time of water bodies in the main river channels of the research area is within 5 days. The greater the connectivity of these water bodies， the shorter the water age becomes. From the perspective of changes in water quality indicators， during the water diversion experiment， the most noticeable change in the water environment inside the polders is the level of ammonia nitrogen. It shows a strong response to water diversion， and simulation results indicate that water age generally aligns with the concentration of ammonia nitrogen. Enhanced connectivity of water bodies leads to a shorter water age， which aids in reducing ammonia nitrogen levels. From the perspective of water diversion scheme， the uni-source water diversion and uni-region drainage scheme has limited effectiveness in improving the connectivity of the water system within polders， especially in areas with weak water flow in the river network. This scheme also increases variations in water flow within the polders， resulting in spatial differences in connectivity and water quality in the river network. Consequently， local stagnant water areas or dead water areas may be formed. Therefore， the combination of multiple sources of water diversion and multi-regional drainage scheme can enhance the connectivity of the water system and improve water environmental quality.