The calculation of TBM tunnel segment lining structure is an important link in lining design. This paper combines an engineering example in South China to establish the lining structure calculation model using the modified usage method， beam-spring method， and three-dimensional finite element method（3D FEM）， and compares the internal forces and deformations of the lining structure calculated by each method. At the same time， the paper studies the influence of the staggered assembly angle on the lining structure forces. The results show that the maximum axial force and shear force of the structure calculated by each method are close to each other. The order of the maximum bending moment and deformation of the whole structure is as follows： modified conventional method > beam-spring method > three-dimensional finite element method. According to the results， the modified conventional method yields results with high safety reserve， simple calculation， making it suitable for preliminary design of engineering. The three-dimensional finite element method is suitable for accurate calculation and preliminary design check of segments， and can show the mechanical characteristics of the detailed structure of segments. The calculation result of beam-spring method is between other two methods， which is relatively economical and can reflect the stiffness contribution of the joint of segment more accurately than the modified conventional method， and the model is more user-friendly than the three-dimensional finite element calculation model which is suitable for engineering design. At the same time， the beam-spring method has a more obvious staggered assembly effect than the 3D FEM in calculating the maximum bending moment.

To investigate the effect of joint inclination on the dynamic failure mechanism of jointed sandstone， this study conducted dynamic splitting numerical simulations of sandstone containing joints with different inclinations using Ansys/LS-Dyna. The influence of joint inclination on the mechanical behavior， failure mode， and energy dissipation characteristics of sandstone was systematically revealed， and a dynamic splitting damage constitutive model for jointed sandstone was established based on the Weibull statistical function. The results show that， under Brazilian splitting conditions， the peak stress of sandstone increases with the increase in joint inclination， while the peak strain decreases first and then increases. For samples with smaller joint inclinations， splitting failure mainly occurs along the joint direction， whereas for samples with larger inclinations， splitting failure occurs along the loading direction. As joint inclination increases， the degree of damage to the samples decreases， the energy reflection efficiency decreases， and the energy absorption and transmission efficiencies significantly increase. The dissipated energy density of sandstone exhibits a "decreasing-then-increasing" trend with increasing joint inclination， with an inflection point at 45°. Furthermore， the proposed dynamic splitting damage constitutive model was validated and refined using stress-strain curves， and the modified model curves were found to align closely with experimental results， accurately describing the stress-strain characteristics of sandstone with different joint inclinations during the splitting failure process. This study provides important theoretical and technical guidance for underground engineering and geotechnical applications.

The change of temperature stress in high altitude area has a significant influence on the overall bearing capacity of concrete double-curvature arch dam. In order to analyze the overall bearing capacity of the concrete double-curvature arch dam of ZY hydropower station under temperature effects， and ensure the safety design， construction and operation of the project， a three-dimensional nonlinear finite element analysis method of TFINE program was employed to establish a numerical model of the integrated arch dam-foundation system. Firstly， under normal water level conditions， the displacement， stress and yield state of arch dam under temperature decrease and increase scenarios are analyzed， and unfavorable conditions are obtained. Then， under this working condition， the bearing capacity of arch dam is analyzed by overload method， such as arch dam displacement， unbalanced force， complementary energy norm and yield zone volume. The results show that under the action of temperature stress， the safety of the arch dam meets the requirements under the normal water level condition， and the temperature drop condition is a more unfavorable condition. When the overload ratio is 1.2~1.5， the upstream dam heel cracks； when the overload ratio is 4.0~5.0， the dam body is in nonlinear deformation； when the overload ratio is 7.5~8.5， the dam body loses its bearing capacity.

Piping is a typical form of seepage failure in earth-rock dams， and its evolution process is accompanied by internal physical field changes within the earth-rock dam structure. Investigating the relationship between the variations in the internal physical field of earth-rock dams and the evolution of piping is of significant importance for identifying the state of piping progression. In view of this， a multi-field information fusion analysis framework for piping evolution is first constructed based on the multiple physical field information obtained during the operation of earth-rock dams. Building on this foundation， the seepage pressure， temperature， electrical potential， and flow velocity fields during the piping evolution process in earth-rock dams are integrated. By applying normalization and dimensionality reduction techniques， a matrix decomposition fusion method and principal component analysis （PCA） are employed to perform fusion analysis of the multi-field fitting functions. Subsequently， a quantitative characterization function with established correlations is constructed to analyze the logical symbiotic relationships among seepage pressure， temperature， electrical potential， and flow velocity fields. Finally， by analyzing the characteristics of different stages in the evolution of piping， the normalized timeline of piping evolution in earth-rock dams is divided into three stages： （0， 0.481）， （0.481， 0.663）， and （0.663， 1）. These stages correspond to the initial phase， expansion phase， and critical phase of piping evolution， respectively. The proposed method for multi-field information fusion and state identification in the piping evolution process of earth-rock dams offers a valuable reference for seepage safety monitoring and early warning in such structures.

In the early stages of tunnel construction， the lack of shield machine excavation data under different geological strata and working conditions leads to a decrease in the prediction accuracy of shield machine progress prediction models based on big data. Relying on a shield tunneling project in Shenzhen， a single-layer geological EDEM numerical shield model was constructed using the numerical discrete element software （EDEM）. Through simulation， more excavation parameters of the shield machine under different geological strata and conditions were obtained， and the shield machine excavation progress prediction and preliminary optimization of excavation parameters in composite geological strata were carried out based on EDEM numerical simulation parameters. The research results show： ① Modeling single-layer geology and shield simulation based on EDEM is feasible and can accurately simulate the actual situation of shield tunneling in specific single-layer geology； ② Shield machine excavation speed is positively correlated with the cutterhead thrust and cutterhead rotation speed in a non-linear manner， and the cutterhead torque is positively correlated with the cutterhead thrust and cutterhead rotation speed in a linear manner； ③EDEM simulation results can be used for excavation progress prediction models and have good prediction accuracy.

The maximum height of the upstream earth-rock cofferdam of a hydropower station is 62 m， and the height of the slope formed by the cofferdam and foundation pit is 135 m. The earth-rock cofferdam is located on deep overburden layer with a maximum thickness of 71 m. The overburden layer has the characteristics of “low bearing capacity， small permeability coefficient， low shear strength and high compressibility”. In order to ensure the safety and stability of the cofferdam and slope， vibro-replacement stone column is used in design to reinforce the deep overburden layer of the cofferdam foundation. The depth of the designed stone column of a hydropower station far exceeds the existing technology level. It is the deepest stone column applied ever in engineering practice in China on a large scale. In order to solve the problem of ultra-deep vibro-replacement stone column construction and verify the effect of stone column reinforcement and drainage， the ultra-deep vibro-replacement stone column construction equipment and technology are determined through on-site productive tests， and the physical and mechanics parameters such as shear strength， bearing capacity and compression modulus of stone column body and soil between column， permeability coefficient of stone column， etc. are obtained. A set of control methods which can be applied to large-scale construction， quality inspection of vibro-replacement stone column in cofferdam foundation are summarized. This research results can be used as a reference for the design， construction and acceptance of foundation treatment of hydropower engineering projects.

Pile-soil composite foundations， known for their excellent bearing performance， have become a common method for treating deep overburden layers in hydropower projects in southwest China. The combined effect of pile-soil foundations is strong， and one of the challenges in engineering design is efficiently and rapidly evaluating the effectiveness of reinforcement in composite foundations. Based on finite element numerical analysis method， a three-dimensional finite element model of pile-soil composite foundations was established， and a series of numerical tests were conducted. According to the numerical test results， an improved calculation model for the equivalent compression modulus of composite foundations was proposed. The improved model was applied to an actual project to analyze the stress-deformation behavior and stability of sluice and dam structures. The calculation results indicate that the improved composite foundation calculation model outperforms the area-weighted method and is applicable to group pile calculations. The displacement and stress levels of the foundation after treatment are significantly reduced compared to untreated foundations， providing a reference and computational basis for engineering practice.

The existing deformation monitoring models of concrete dams rarely consider the dynamic spatiotemporal correlation of multiple measurement points， thus limiting the prediction accuracy of deformation. To overcome this shortcoming， this paper constructs a dynamic prediction model of spatial deformation of concrete dam based on cluster analysis， long short-term memory （LSTM） network and attention mechanism， which can improve the prediction accuracy of deformation of target measurement point by introducing dynamic correlation factors reasonably. Taking the horizontal displacement monitoring data of several measurement points of a gravity dam as an example， the effectiveness of the model and the importance of spatial dynamic correlation factors are verified by comparing with three other LSTM-based models. Furthermore， the contribution degree of multiple factors to the model output is quantified by two interpretable machine learning algorithms for different measurement points， and the ranking results are consistent with the prior knowledge of dam engineering. The research results can provide reference for promoting the engineering application of intelligent dam deformation monitoring model.

The Jinsha River serves as the main stem of the upper Yangtze River， contributing approximately 50% to the total runoff discharge and 60% to the total sediment load in the upper Yangtze River Basin. Its extensive tributary network and complex sediment sources render its hydrological dynamics highly complex. In recent years， the operation of key cascade reservoirs has significantly altered flow and sediment transport characteristics， necessitating an in-depth analysis of these changes. In this study， hydrological data （1977-2020） from the Xiangjiaba（Pingshan） Hydrological Station in the lower reaches of the Jinsha River were used to investigate sediment transport dynamics during flood events before and after the impoundment of the Xiangjiaba Reservoir and Xiluodu Reservoir. Flood events were extracted from the time series data， and analytical methods， including Mann?Kendall （M?K） analysis， sediment rating curve analysis， and hysteresis pattern analysis methods， were systematically applied. The key findings indicated that a 99% reduction in sediment load occurred during the postimpoundment period， which was primarily attributable to reservoir sediment trapping. The discharge?sediment concentration relationship exhibited fundamental regime shifts. The original robust power-law relationship between water discharge and sediment load was disrupted after reservoir operation. Under moderate and high discharge levels （10 000~13 000 m3/s）， the sediment transport capacity was no longer governed primarily by hydrodynamic forces but was instead constrained by sediment supply limitations. However， this flow range remained the dominant sediment transport range. The sediment rating curves significantly flattened （the coefficient decreased by 87%）， reflecting reservoir-induced flood peak attenuation and changes in the discharge?sediment relationship. Asynchrony analysis of flood events revealed that under natural conditions， sediment source depletion during flood events led to insufficient subsequent supply， causing sand peaks to exhibit predominantly leading asynchrony. After reservoir operation， a notable change in asynchrony characteristics between flood and concentration peaks occurred， with the sediment peak lag pattern becoming dominant， driven by a substantial weakening of hydrodynamic conditions due to elevated reservoir water levels. This study elucidated the mechanistic shifts in water?sediment transport in the lower Jinsha River， thereby providing theoretical foundations for the formulation of reservoir sediment management strategies.

The stilling basin combined with incomplete flaring gate piers has been widely employed in low Froude （Fr） number bottom flow energy dissipation due to its advantages of energy dissipation efficiency， small fluctuation of water surface after jump， and compatibility with conventional auxiliary energy dissipators. While researchers have extensively investigated its energy dissipation mechanisms and general hydraulic characteristics， the characteristics of fluctuation pressure and cavitation on the stilling basin floor need to be further discussed. In this paper， physical model tests and numerical simulations are used to investigate the characteristics of pressure fluctuation and cavitation erosion on the bottom of stilling basin combined with incomplete flaring gate piers and T-shaped piers. The results show that the VOF method coupled with the RNG k-ε turbulence model can better simulate the three-dimensional hydraulic jump characteristics in complex configurations， and the numerical simulation results are basically consistent with the experimental data. Under the condition of low Fr number inflow， the distribution of fluctuation pressure at central axis of flaring gate pier hole and side pier are different. Severe hydraulic jump exhibits intense turbulence at the head of the stilling basin， which rapidly diminishes in the middle and tail sections. The maximum fluctuating amplitude of the bottom slab pressure is within 10% of the time- average pressures， with probability density approximating a normal distribution and distinct low-frequency characteristics. The cavitation number at the measuring points exceed critical thresholds， indicating low probability of cavitation erosion within the stilling basin. These experimental results provide valuable references for the design of similar hydraulic engineering projects in the future.

The linkage effect of diversion water level during the construction diversion of large-scale water conservancy projects has a significant impact on flood control and safety. Existing research mostly focuses on the analysis of single project construction diversion， and the study of hydraulic characteristics of multi-regional collaborative construction diversion is not sufficient. Based on a two-dimensional mathematical model of water flow， taking the section from Qishi navigation junction to Qingnian navigation junction of Pinglu Canal as an example， the variation law of water surface profile in different diversion types of river sections was analyzed， and the linkage effect of water level along the river during multi-regional collaborative construction was explored. The results show that the water level along the river is significantly affected by the diversion method and terrain conditions. At low flow rates， the water level mainly changes with the longitudinal shape of the riverbed. As flow rate increases， the longitudinal control ability of the riverbed weakens， and the river's plane shape and local bends gradually become dominant factors. There are significant spatial differences in the linkage between collaborative construction and water level in different diversion types of areas. Cutting and connecting bends can effectively reduce the water level in the upstream and local river sections， and combined with river channel expansion can further increase the water level drop. However， local bend checkpoints weaken the impact of excavation on water level， leading to a weakened regional linkage effect. The impact of return water caused by changes in tailwater level is jointly determined by collaborative construction and the size of incoming flow. At low flow rates， tailwater changes can be well transmitted upstream and have a wider range of effects， while at high flow rates， they are mainly limited by the cut and curved river sections that are not connected at the end. Based on the above findings， in future similar engineering construction， priority should be given to connecting the curved river section， improving the water level control capability through section excavation， and arranging construction projects reasonably to optimize the flow terrain and strengthen regional synergy. The research results can provide reference for multi-regional collaborative construction diversion optimization and water level regulation decision-making in large-scale water conservancy projects.

The increasing nitrogen input load in the Pearl River Delta urban agglomeration has led to a rising trend in total nitrogen （TN） levels in the Pearl River Estuary. To reveal the spatiotemporal variations of different nitrogen forms and identify the sources of nitrate nitrogen （NO??-N） ， the dominant inorganic nitrogen species， surface water sampling was conducted during both flood and ebb tides in the wet and dry seasons of 2023 across the complex river network of the estuary. Based on the analysis of the spatiotemporal distribution patterns of various nitrogen forms， nitrate sources were quantitatively apportioned using nitrate isotopes （δ1?N-NO?? and δ1?O-NO??） and the SIAR model. Results indicated that nitrate was the predominant form of inorganic nitrogen， with a mean concentration of 1.85 mg/L. Except for a few sampling points affected by upstream cross-border inflows， ammonia nitrogen （NH??-N） and nitrite nitrogen （NO??-N） concentrations were generally low at most monitoring sites， typically below 0.50 mg/L and 0.10 mg/L， respectively. Although higher nitrogen concentrations were observed at some locations during the dry season， their contribution to the annual total load was substantially lower than that during the wet season. The isotopic compositions ranged from +3.08‰ to +10.03‰ for δ1?N-NO?? and from +0.51‰ to +5.12‰ for δ1?O-NO??. Quantitative source apportionment revealed that the primary contributors to nitrate pollution were agricultural sources （44.7%）， followed by domestic sewage （36.4%） and industrial wastewater （18.9%）. No significant differences in contribution proportions were observed between flood and ebb tides； during flood tide， the contributions from agricultural， domestic， and industrial sources were 45.6%， 36.2%， and 18.2%， respectively， while during ebb tide， they were 43.4%， 36.5%， and 20.1%. The significant spatial heterogeneity in nitrogen concentrations and fluxes， along with the identified source characteristics， provides a scientific basis for developing targeted total nitrogen pollution control strategies in the Pearl River Estuary.

Incoming water and sand data is a necessary condition to predict the distribution of sediment siltation in reservoirs， reservoir sand discharge rate and carry out water and sand scheduling. However，for many reservoirs located in small watersheds or constructed decades ago， the monitoring data of their incoming water and sand are scarce， and only the topographic data of different ages and the process of outgoing flow with sand content can be inquired. The lack of information makes the water and sand scheduling and sediment management of reservoirs lack of basic data support， and it is difficult to meet the needs of sediment regulation and analysis， which restricts the in-depth development of related research and management work. In this paper， the water and sand data of Yegoumen Reservoir （Xindu District， Xingtai City）， located on Shahe River， a tributary of the Ziya River in the Haihe River Basin， are taken as an example， and we propose the water volume algorithm of the reservoir and the method of hydrological comparison with the nearby hydrological stations to fit the daily process of the inlet flow and sand content of Yegoumen Reservoir. The daily process data of outflow， water level， evaporation， etc. and the reservoir capacity curve of Yegoumen Reservoir are used to project the daily process of inlet flow. The reference area is determined by analyzing the watershed area， climatic characteristics， and the subsurface conditions， etc.， and the daily process of inlet sand content is fitted by adopting the relationship of sand content-sand delivery rate of the Podi hydrological station with a long series of water and sand observation data in the same watershed. Based on the measured topographic data of Yegoumen Reservoir from 2017 to 2022， the siltation volume in the reservoir area， the outflow water-sand process， and the suspended mass gradation data， the water-sand mathematical model is applied to verify the correctness and rationality of the above fitted daily process of sand content in the inlet flow. The verification results indicate that the daily process of sand content in the inlet flow for the Yegoumen Reservoir shows minimal discrepancies compared to the actual data， both in terms of total sediment validation and the water-sediment process validation. The research results can provide a reliable method for fitting the inlet water and sand conditions of reservoirs in areas with little data， and the method can be used for the fitting of reservoir inflow and sand conditions in small watersheds and other related rivers in the same watershed with measured data from hydrological stations， which has practical application reference value， and has important theoretical and practical significance for the sediment scheduling and safe operation of reservoirs.

Reservoirs primarily designed for flood control frequently employ either a single fixed discharge operation or compensation-based operation in actual scheduling practices. However， The lack of interconnected， coordinated， and unified flood control operations among reservoir groups within river basins hinders the full utilization of hydrological compensation effects and storage capacity compensation effects between reservoirs.Domestic and international scholars have conducted extensive research on joint flood control operation for cascade reservoirs， focusing on methodologies such as Linear Programming （LP）， Nonlinear Programming （NLP）， Dynamic Programming （DP）， and various intelligent algorithms. Nevertheless， due to inherent limitations in mathematical optimization algorithms—particularly the "curse of dimensionality" and poor convergence stability—these approaches have rarely been integrated into practical reservoir operation plans or real-time flood control scheduling systems.This study addresses this gap by deeply analyzing the inherent hydraulic linkages within cascade reservoir systems. We propose a novel， relatively simple and implementable method： the Cascade Reservoir Flood Control with Complementary Storage （CRFC-CS） method， achieved by coupling physical principles with numerical algorithms. Based on graded water level partitioning for the downstream reservoir（s）， a compensation-based control release model for cascade reservoirs is established. This model achieves dynamic inter-reservoir linkage and complementary utilization of flood control storage capacity， effectively addressing flood control scheduling challenges in basins characterized by complex flood regional composition. The CRFC-CS model is computationally tractable with clear and straightforward operational procedures， ensuring strong engineering practicality. It successfully achieves seamless coordination and unification across the flood control planning phase （e.g.， storage allocation， rule formulation） and the entire real-time flood operation phase， effectively resolving the disconnect between planning and execution.To validate its efficacy， the method was applied to flood control operations for upstream reservoirs in the Qingjiang River Basin （a primary tributary of the Yangtze River）. Compared to the conventional fixed discharge operation method， implementing CRFC-CS yielded a 52.5% reduction in the system's maximum flood retention volume while maintaining equivalent flood safety standards. This conclusively validates the practicality and superior performance of CRFC-CS in enhancing storage utilization efficiency and optimizing flood control operations. The method provides an efficient and reliable new solution for coordinated flood control of reservoir groups in complex river basins.

Under the combined influence of climate change and human activities， urban flooding disasters have become increasingly frequent， posing severe impacts on socio-economic development. To effectively address urban flood risks， conducting scientific flood simulation and early warning studies in urban watersheds has become a top priority. This study takes the Wusha River Basin in Nanchang City， Jiangxi Province， as the research area. It constructs the WRF （Weather Research and Forecasting） model and the MIKE SHE/MIKE 11 coupled model to simulate precipitation， river water levels， and runoff processes in the urban watershed， respectively. Firstly， a four-layer one-way nested grid WRF model was developed to simulate a precipitation event in the basin in July 2020. The results show that the WRF model effectively captures the precipitation characteristics of the basin， with a simulation bias （Bias） of -0.3 mm. Secondly， the MIKE SHE/MIKE 11 coupled model was constructed to simulate the rainfall-runoff process in the Wusha River Basin from January 1 to August 26， 2022. Within this framework， the MIKE 11 model was primarily responsible for simulating river water level changes， providing hydrodynamic boundary conditions for the MIKE SHE model. Taking the river water level simulation near the Wanli Station of the Wusha River as an example， the MIKE 11 model achieved a coefficient of determination （R2） of 0.86， indicating its ability to accurately reflect the dynamic trends of river water levels. Meanwhile， the MIKE SHE/MIKE 11 coupled model integrated surface and subsurface hydrological processes in the basin， demonstrating strong performance in simulating the measured runoff at Wanli Station. Over the entire simulation period， the Nash-Sutcliffe Efficiency （NSE） coefficient of the model reached 0.7， with simulated flow rates closely matching observed values. The WRF model and the MIKE coupled model established in this study provide effective technical support for urban flood early warning and disaster risk assessment， holding significant importance for the formulation of urban flood prevention and mitigation strategies.

To achieve the safe and stable operation of reservoirs and the efficient utilization of water resources in the basin， the key lies in clarifying the operation rules and dispatching strategies of reservoirs. To this end， aiming at the problems that traditional neural networks have when simulating reservoir dispatching operation strategies， such as vanishing gradients， getting stuck in local optimal solutions， and difficulty in determining hyperparameters， an improved deep neural network model （TSD） combining the Stochastic Gradient Descent with Momentum （SGDM） and the Tree-structured Parzen Estimator （TPE） is proposed. It has enhanced the accuracy and applicability of the deep neural network model by improving the training method of network parameters and automatically optimizing hyperparameters. Meanwhile， considering the numerous factors affecting reservoir dispatching decisions， the F-test method （FR） and the Mutual Information method （MIR） have been adopted respectively to achieve the optimization of input factors. Further， six simulation methods for reservoir dispatching strategies were constructed based on the Decision Tree model （DT）， Support Vector Machine model （SVM）， and improved deep neural network model： FR-DT， MIR-DT， FR-SVM， MIR-SVM， FR-TSD and MIR-TSD. And case studies were carried out with four reservoirs， namely Ahai， Jin’anqiao， Ertan and Pubugou. The research results show that compared with other methods， the FR-TSD and MIR-TSD methods have larger deterministic coefficients and smaller root mean square errors and mean absolute errors when simulating the dispatching strategies on various reservoirs. This indicates that the simulation effects of the FR-TSD and MIR-TSD methods are better and the accuracy is higher， and they can simulate the dispatching operation strategies of reservoirs more accurately， thus providing decision support for the actual operation of reservoir dispatching. Furthermore， an analysis of the simulation results of different reservoirs under the same method reveals that the simulation effect of the model is influenced by the regulating capacity of the reservoir and the allowable range of water level variation. Reservoirs with smaller regulating capacity and allowable range of water level variation have poorer simulation effects， while those with larger ones have better effects.

Soil salinization is one of the key factors affecting the sustainable development of agriculture in the Hetao Irrigation District. Accurate prediction of soil salinization and sodification trend is an important means to formulate scientific prevention and control measures. Traditional studies usually use the total amount of soil salinity in the root zone as an indicator to evaluate the evolution trend of salinization， while rarely paying attention to changes in ion composition. Due to the different physical and chemical behaviors and migration capacities of different salt ions， soil salts not only changes in total amount， but also change in composition of salt ions under the influence of external forces such as irrigation leaching， evaporation， freezing and thawing. To conduct in-depth research on the distribution and transport patterns of salt ions in different land use types， this paper selects a typical area in the Yichang Irrigation Area of Inner Mongolia's Hetao Irrigation District as the research area. From 2017 to 2019， observations were conducted on the distribution processes of various ions， analyzing the dynamic processes of water， salt， and ions， as well as the characteristics of ion differentiation.The soil moisture content increases with depth due to water infiltration and water-holding capacity， while variability showes an inverse trend， decreasing with soil depth. The electrical conductivity （EC） profile of abandoned cultivated land decreases with depth， with surface accumulation being the main feature of overall salt distribution. The distribution of salt ions in soils of different land types is primarily characterized by highly differentiated Na⁺， Cl^-， and SO₄ ^2- ions. The HCO₃ ^- content is also significant but is relatively uniformly distributed in the soil profile. The contents of Ca²⁺ and Mg²⁺ are noticeably lower， especially in wasteland where both their composition and proportion are minimal. The mobility differentiation of various salt ions is evident. The migration degree and rate of cations are in the order of Na⁺ > Mg²⁺ > Ca²⁺， which correlates with ion migration rates through soil layers. Among anions， Cl^- shows the strongest differentiation， while HCO^3- exhibits weaker differentiation.

Yellow River Pump Stations Face Severe Sand Erosion and Cavitation Issues： Application of Epoxy Carborundum and Polymer Ceramic Composite Coatings for Pump Protection and Repair.The pumps at Yellow River water-lifting stations are severely affected by sand erosion and cavitation. Sand particles in the water and the collapse of cavitation bubbles cause pitting， material loss， and gradual degradation of the pump's flow components. Without protective measures， this can lead to reduced structural strength， decreased water output， lower efficiency， increased energy consumption， and even equipment failures， impacting water supply reliability. This paper analyzes the application of epoxy carborundum coatings and polymer ceramic composite coatings in addressing pump erosion issues， based on the practical experience of pump erosion control at the Hongsibu Pump Station in Ningxia. It explores the characteristics of these coatings in erosion protection， proposes technical approaches for applying epoxy carborundum or polymer ceramic composite coatings to pump bodies， and provides details on application timing， methods， and expected outcomes. Additionally， it suggests applying polymer ceramic composite coatings to pump impellers， outlines relevant technique requirements， and describes the impeller coating effects. Field inspections have shown that the application of epoxy carborundum and polymer ceramic composite coatings in Yellow River water-lifting pump stations can extend the major overhaul cycle of pumps by approximately 1 000 hours and increase their effective service life by more than 100%. The coating protection model introduced in this paper provides technical support for erosion protection in Yellow River pumps.

Based on in-depth research， this study systematically reviews the development history， current status， and existing problems of rural water supply and standardization. It thoroughly analyzes the demand for standardized development in rural water supply and proposes several considerations and recommendations to accelerate progress. The standardization of rural water supply should adhere to a problem-oriented and demand-driven approach， emphasize technological innovation， strengthen deep integration of industry， academia， research， and application， foster and develop new quality productive forces， and leverage the guiding role of standards to unleash innovation potential. Following the principle of balancing development and safety， a full-lifecycle technical standard system should be established， covering planning and design， construction， operation and maintenance， water quality safety， and management services. This system will consist of "2+N+M" standard system. In terms of engineering planning， it is essential to effectively align with strategic plans such as the National Water Network， urban-rural integration， rural revitalization， and rural construction to optimize the overall layout of rural water supply. For engineering construction， adherence to standards must be prioritized to ensure standardized construction of rural water supply projects， establishing and proving rural water supply system that achieves overall optimal performance. Regarding operation and management， upgrading standards is crucial to transition rural water supply toward a modernized management model characterized by specialization， equalization， and degitization， thereby promoting high-quality development in rural water supply.

In response to the limitations of single-criterion allocation in initial water rights allocation in agriculture， this paper comprehensively considers fairness， effectiveness， and rationality in agricultural water rights allocation， and constructs a hierarchical allocation index system consisting of 3 criterion layers and 12 indicator layers using the AHP entropy weight method coupling model. Taking four irrigation districts in Yidu City as an example， empirical analysis of initial water rights allocation in agriculture is conducted. The results showed that the agricultural water rights obtained through the coupling model of AHP-entropy weight method in Xingfu Canal Irrigation District， Daxi Irrigation District， Jiudaohe Irrigation District， and Hongshan Irrigation District were 23.928 2 million m3， 13.226 4 million m3， 7.947 million m3， and 3.501 2 million m3， respectively. The model allocation results were highly consistent with the actual water demand of each irrigation district. This model verifies the importance of multi-criteria comprehensive consideration in the allocation process， overcomes the one-sidedness of a single weighting method， and improves the scientificity of weight and allocation ratio. The results of this study can provide a theoretical basis for the dynamic adjustment of agricultural water rights in irrigation areas in the future.

The Xiaolangdi North Bank Irrigation Project， a crucial part of the Yellow River Basin's modern water network， encounters complex geological issues like slope instability， roof fall， and land subsidence. This study aims to address the need for wide-area surface deformation monitoring in the irrigation area. Distributed Scatterer Interferometric Synthetic Aperture Radar （DS - InSAR） is integrated to construct a "Census Classification + Key Monitoring" stability evaluation system. A total of 813 372 monitoring points were extracted across the study area， revealing an average deformation rate of -14.119 mm/a， with a maximum cumulative settlement of 68.044 mm， and 10 hidden-danger areas were identified. Field surveys show these areas are mainly due to construction disturbance and land leveling， and the deformation is reasonable and stabilizing. The detected risk areas cover key engineering parts with emergency treatment in construction. InSAR inversion indicates the time-series deformation of key parts aligns with construction logs， showing characteristics of “predictable trends but difficult-to-match magnitudes”. This research offers important references for the safe operation of water projects in loess regions and geological disaster prevention in similar projects.

Reinforced concrete structures in hydraulic engineering are exposed to a variety of complex environments. It is thus important to investigate the factors leading to cracking caused by steel reinforcement corrosion， in order to predict structural durability and plan maintenance strategies. In this study， rust-induced cracking of reinforced concrete in the Shaoshan Irrigation District was taken as a case study. A single-bar corrosion model was established based on the PF_CZM phase-field fracture model， and the influences of cover thickness， concrete strength， material heterogeneity， and aggregate distribution on rust-induced cracking were simulated and analyzed. The simulation results resembled the observed modes of cover damage in practice. The results show that the thickness of the protective layer mainly affects the crack morphology of the protective layer. With the increase of the protective layer thickness and the decrease of the steel bar diameter， the angle between the two main cracks increases. However， it has no obvious effect on the displacement of the protective layer when there is obvious damage and obvious cracks， so it has little effect on the durability of the structure. The strength and heterogeneity of the concrete material mainly affect the durability of the structure. With the increase of the strength and heterogeneity of the concrete material， the displacement of the protective layer when obvious damage and cracks appear will increase， but the crack development morphology has no obvious change.

Pumping station technology upgrading is an important part of building a national water network， realizing the goal of “dual carbon”， and integrating water resources， ecology and energy security. Overseas pumping stations have made significant progress in hydraulic design， material application， informatization and energy synergy， which is manifested in the enhancement of adaptability to extreme working conditions， improvement of the level of intelligent operation and maintenance， improvement of the ecological mode of operation and the development of green energy supply system. However， under complex conditions such as high sand content and strong corrosion， there are still problems such as insufficient design accuracy， imperfect failure prediction， unclear ecological response mechanism and limited multi-energy synergy optimization. In this paper， the latest foreign research results and engineering practices are sorted out， and key technologies such as inverse problem and machine learning fusion design， digital twin technology， fish-friendly flow channel and ecological protection measures， and wind-solar storage and complementary evaluation are summarized. It also proposes technical paths for the national water network and the follow-up project of South-to-North Water Diversion， which will provide reference for the modernization of water conservancy infrastructure and the construction of intelligent water conservancy during the 15th Five-Year Plan period.

As a new type of ecological agricultural model， crayfish-rice co-culture has gradually occupied an important position in China's agricultural development. Understanding the variation characteristics of the rice growth environment is of great significance for increasing the grain yield in crayfish-rice fields and ensuring the achievement of double harvests from one water source in crayfish-rice co-culture system. Based on this， this paper reviews the current development status， industrial advantages， and still existing theoretical and technical problems in actual production of crayfish-rice co-culture system in China. Combining with existing literature and research foundations， this article summarizes the research progress on the characteristics of the crayfish-rice symbiotic system and the variation characteristics of the soil environment， field water layer control methods， and biological - ecological environment brought about by the changes in co-cultivation management methods. It also summarizes the impacts of the above characteristic changes on rice growth. Finally， it outlines future research directions from three aspects， including the coupling mechanism of the crayfish-rice co-culture system， the collaborative regulation technology for water conservation， emission reduction， and carbon reduction， and model development， aiming to provide a scientific basis for stabilizing grain production and increasing income in paddy fields under integrated rice-fishery farming and for the efficient utilization of agricultural resources.

Accurate and timely soil moisture inversion is a crucial foundation for implementing precision irrigation management in farmlands， significantly enhancing irrigation water resource utilization efficiency. This study developed enhanced Thermal Optical Trapezoid Model （TOTRAM） and Optical Trapezoid Model （OPTRAM） by incorporating nonlinear dry/wet boundaries and phenological characteristics， using multi-source remote sensing data from Landsat-8/9 and Sentinel-2A/B. The OPTRAM model further accounts for the influence of phenological stages.The accuracy of the enhanced models in soil moisture inversion for arid farmland was then evaluated using measured soil moisture data.The findings of the study demonstrated that the original TOTRAM model exhibited superior performance in comparison to the basic OPTRAM model， with root mean square errors （RMSE） of 0.183 cm3/cm3 and 0.141 cm3/cm3， respectively. The implementation of non-linear dry/wet boundaries resulted in a substantial enhancement in the performance of both models， achieving comparable reductions in RMSE to 0.145 cm3/cm3 （TOTRAM） and 0.126 cm3/cm3 （OPTRAM）. The phenology-integrated OPTRAM model demonstrated optimal accuracy， with a root mean square error （RMSE） of 0.096 cm3/cm3. In summary， the enhanced OPTRAM model exhibited superior precision in the retrieval of soil moisture in arid agricultural soil compared to TOTRAM， while concurrently maintaining the higher spatiotemporal resolution advantages afforded by optical satellite data. This advancement provides critical technical support for precision irrigation management systems.

To explore the effects of applying water-retaining clay on soil aggregate structure and water conductivity in the Loess Plateau， a soil incubation experiment was conducted to systematically analyze the impacts of water-retaining clay with different particle sizes， application rates， and cultivation periods on soil bulk density， soil aggregate distribution and stability， total soil organic carbon， and saturated hydraulic conductivity. Water-retaining clay was applied at three particle size levels （<2、2~5、5~10 mm）， three application rates （5%、10%、20%）， and samples were collected and tested at 0、42 and 84 days of incubation. The results showed that compared with the control group， soil bulk density decreased by 2.8% to 20.2% after applying water-retaining clay， and the soil bulk density generally decreased with the increase of particle size， application rate， and incubation time. At the same time， the application of water-retaining clay significantly increased the content of water-stable aggregates larger than 2 mm， the mean weight diameter （MWD）， and the geometric mean diameter （GMD）. Among them， the proportion of water-stable aggregates larger than 0.25 mm increased by an average of 13.7%， and MWD and GMD increased by an average of 46.44% and 25.13%， respectively. The total soil organic carbon content decreased by an average of 0.561 g/kg. The application of water-retaining clay significantly increased the saturated hydraulic conductivity of the soil and increased with the increase of application rate， reaching a maximum enhancement of 13.49-fold. Overall， the application of water-retaining clay can reduce soil bulk density， improve the stability of water-stable aggregates， and increase the saturated hydraulic conductivity of the soil. The research results can provide a theoretical basis for improving soil structure， stability， and water conductivity in the Loess Plateau.

Permanent magnet synchronous motor （PMSM） as a control object has the characteristics of multivariable， strong coupling， nonlinearity and time-varying parameters. In order to improve the stability requirements of the speed during its operation， this paper combines the particle swarm optimization （PSO） algorithm with PID control method， and uses PSO algorithm to optimize the parameters of PID controller. The experimental results show that the PSO-optimized PID control method achieves faster response speeds， stronger disturbance rejection capabilities， and superior speed stability performance.

The characteristics of water and sediment transport in rivers include hydrodynamic and sediment transport features， which can help analyze the water and sediment movement of rivers and the changes in river geomorphology. The calculation and detection of water and sediment transport characteristics in river channels have important guiding significance for the safety monitoring and dredging of hydropower stations and reservoirs. In the calculation of water and sediment transport characteristics in rivers， empirical analysis of scenarios and energy balance methods require strict information on river parameters. In the calculation of diverse river channel shapes， obtaining hydraulic parameters often proves challenging. Therefore， in order to accurately determine the sedimentation state of the reservoir and evaluate the erosion and sedimentation morphology of the hydropower station channel， the effective shear method was used to calculate the water and sediment transport characteristics of the hydropower station， and the optimized calculation formula was embedded into the Delft 3D model to improve the sediment transport module of the model. Drawing on the optimization scheme of domestic shear force calculation methods， this study removed the difficult to obtain hydraulic radius and slope data of the river channel， and simplified the calculation of effective shear force. And the optimized shear calculation method was integrated into the sediment transport module of Delft 3D， while combining the hydrodynamic module of the model to obtain accurate river sediment carrying capacity data. In the actual measurement and verification of typical rivers in China， the reliability of the Delft 3D model and effective shear calculation method was verified through channel information and indoor calculations. Experiments have shown that compared with other methods， the mean square error of the improved effective shear method is the smallest， at 0.56， and the correlation coefficient is the highest， at 0.83， indicating that the improved effective shear method performs the best in the algorithm. Meanwhile， in the simulation experiments of hydropower stations and river channels， the average absolute error of flow velocity calculation decreased by 0.04， and the relative error decreased by 16.5% after model optimization. In the calculation of sediment concentration， the average absolute error of sediment concentration after model optimization decreased by 0.1kg·m^-3， and the average relative error decreased by 38.2%. The experiment shows that the model constructed in the study has significantly improved the predictive performance of river flow velocity and sediment concentration， exhibiting higher accuracy and reliability. After optimizing the Delft 3D model through effective shear calculation methods， the model exhibits better compatibility. By constructing a calculation method for the sediment carrying capacity of rivers， it is possible to simulate the sedimentation amount of reservoirs in the next 40 years， providing scientific support for the judgment of sedimentation status in hydropower stations and providing data basis for the regulation of reservoirs under hydropower stations. Therefore， the simulation method of water and sediment transport characteristics based on Delft 3D model and effective shear force has practical value in the operation and management of hydropower stations.

Pumped storage units play an important role in power regulation in grids featuring high proportions of renewable energy， and their safety， reliability， and healthy operation are crucial. Health status assessment can effectively obtain the actual operating conditions of the unit， and is an important part of achieving predictive maintenance of the unit. The factors that cause vibration and deflection in pumped storage units during actual operation are highly complex and multidimensional. In order to obtain a practical and highly accurate prediction method for the health status of pumped storage units， this paper introduces the random forest regression algorithm into the field of pumped storage unit operation status assessment， and proposes a new method for evaluating the health status of pumped storage units based on the main curve method. Firstly， an objective and accurate standard health model is established using the random forest regression algorithm. Then， based on the deviation between the standard health value and the measured value at the evaluation time， the reliability of the unit's key equipment operation is evaluated using the main curve method combined with the Hausdorff distance. Finally， the proposed method is applied to the measured data of pumped storage units， and the results verify the accuracy and feasibility of the proposed assessment method.

Pumped storage power stations are important energy infrastructure in China. The water and the sediment in upper and lower reservoirs continuously exchange and interact with each other. The sediment entering the reservoirs leads to reservoir capacity loss， while the fine-grained sediment may cause cavitation erosion in pressure pipelines or abrasion on turbine blades when carried into the power generation system by water. Taking Qichun Huayuan pumped storage power station as an example， based on a one-dimensional mathematical model considering the exchange of water and sediment between upper and lower reservoirs， using long-term hydrological and sediment data， the sediment concentration through turbines and its gradation are studied over a 100-year operational period of the power station， and the abrasion conditions of units are predicted. The results indicate that the daily average sediment content passing through turbines is positively correlated with the daily average suspended sediment transport rate entering the lower reservoir. The greater the sediment transport rate into the lower reservoir tributary， the higher the sediment concentration through turbines， and the coarser the sediment particle size. The occurrence of the maximum daily average sediment content through turbines corresponds to the peak of daily average suspended sediment transport rate into the lower reservoir， with a delay effect in sediment content through turbines following the sediment transport peak. The maximum daily average sediment concentration pumped through turbines is 0.19 kg/m3， and the maximum sediment particle size is 0.031 mm. Due to the low sediment concentration and fine particle size through turbines， the cavitation erosion in pressure pipelines and the abrasion on generating units at Qichun Huayuan pumped storage power station are within a controllable range. To ensure safe operation of the power station， the surface unevenness of pressure pipelines must be strictly controlled during construction， and a comprehensive maintenance of the pump-turbine units is required after approximately 12 000 h of pumping operation. The study can provide fundamental support for the construction and the safe operation of Qichun Huayuan pumped storage power station.

The multi-energy complementary power generation system plays a critical role in the development of clean energy bases and achieving the “carbon peaking and carbon neutrality” targets. This paper introduces a two-layer optimization model for determining the capacity configuration of a water， thermal， wind， and solar multi-energy system that accounts for seasonal fluctuations. The model is designed based on the resource availability and electricity demand of the study area. The outer layer model focuses on optimizing the system’s economic and environmental performance， while the inner layer considers system stability as well as the output characteristics and consumption of clean energy during typical days in wet， normal， and dry seasons. The study uses Gannan Tibetan Autonomous Prefecture as a case example and applies the NSGA-II optimization algorithm for configuration and scheduling research. The findings indicate that the optimal power generation capacity configuration for the multi-energy system consists of 62.55% hydropower， 21.32% thermal power， 9.74% solar power， and 6.39% wind power. The wind and solar curtailment rates during wet， normal， and dry periods are 5.18%， 3.56%， and 0%， respectively. Additionally， the study finds that during the dry season， the combined output of water， thermal， wind， and solar energy fluctuates significantly and incurs high operational costs. These results provide valuable insights for determining the scale and configuration methods for constructing multi-energy complementary new energy bases.

To address the the complexity of wind resource simulation for mountainous wind farms， this study takes a complex mountainous wind farm as an example. Based on existing anemometer tower data near the wind farm， and considering the relative relationship between the terrain shape and the prevailing wind direction， the computational fluid dynamics （CFD） software Windsim 12.0 was employed to establish two digital terrain models with different boundary ranges of the wind farm. Numerical simulations of the flow fields in the wind farm area were simulated， and the power generation results from the two models were compared with the actual power output of the wind farm. The results indicate that， to accurately assess wind resources in complex mountainous wind farm areas， it is essential to avoid insufficient development of numerical terrain flow field simulations and the adverse effects of boundary conditions on internal flow fields during modeling. This study highlights the critical role of digital terrain model construction in wind resource assessment for complex mountainous wind farms， providing a reference for wind resource evaluation and rational utilization in such terrains， as well as technical support and empirical insights for wind energy development in similar environments.

Vibration monitoring of hydropower units plays a crucial role in evaluating unit health status and providing early warnings of deterioration. Accurate prediction of the trend of vibration deflection of unit components can detect the abnormal operation of the unit in advance， and effectively enhance the safety and stability of the unit operation. However， vibration oscillation signals of hydropower units monitored on-site contain noise， and the current methods for predicting the vibration oscillation of hydropower units mostly predict the single position of the hydropower units， leading to incomplete evaluation of the operational stability of the hydropower units， and the interaction among the vibration oscillation of multiple measurement points is not fully considered. To address these challenges， this paper proposes using Cross Graph Neural Networks （CrossGNN） to predict the vibration oscillation signal of multiple positions of hydropower units. CrossGNN is a graph neural network model with linear complexity. The multi-component vibration signals of hydropower units can be interoperable across scales and variables， thus implicitly revealing the spatio-temporal relationship of vibration signals at multiple positions of hydropower units. In order to effectively deal with the noise in time dimension， the adaptive multi-scale identifier （AMSI） is used to construct a multi-scale time series with noise reduction effect. Then a cross-scale neural network is proposed to accurately extract scales with clear trend and weak noise. At the same time， cross-variable GNN is constructed based on the homogeneity and heterogeneity among different variables. By focusing synchronously on edges with higher significance scores and restricting edges with lower scores， the time and space complexity of CorssGNN can be linearly related to the length L of the input sequence， thus effectively improving the prediction accuracy and generality. Finally， taking a hydropower station unit in China as an example， the effectiveness of the proposed method is verified by predicting the vibration oscillation signal of six positions of the unit， which provides a new idea for the vibration prediction of the hydropower station.