To achieve efficient resource utilization of construction waste residue （CWR） and address the issue of effluent pH reduction during the nitrogen removal process in a pyrite-enhanced bioretention system， a bioretention system was constructed using a composite medium composed of CWR and pyrite. This study investigated the impacts of varying dosing of CWR and different compositing approaches for the mixture medium on pollutant removal efficiency by bioretention system. Moreover， an optimal strategy for composite media was determined by analyzing microbial community composition and evaluating by-products control effects. The results demonstrated that the addition of 40% （V/V） CWR into the traditional medium resulted in an enhancement of 8.70% and 9.69% in the removal rates of NH₄ ⁺-N and TP， respectively. Nevertheless， due to alkaline leaching stress， there was a decrease of 5.27% in COD removal rate and emergence of NO₂ ^--N accumulation phenomenon. The integration of media significantly mitigated the alkaline stress effect caused by CWR， leveraged the strong adsorption capacity of CWR for nitrogen and phosphorus， and enhanced denitrification through the use of pyrite as an electron donor for autotrophic denitrification. Consequently， this strategy not only increased the α-diversity of the microbial community but also elevated the relative abundance of nitrifying genera （e.g.， Nitrospira） and denitrifying genera （e.g.， Denitratisoma and Bacilli）， while simultaneously inhibiting the growth of Thiobacillus and Thauera. As a result， the system's pollution removal efficiency was significantly improved， effectively addressing the issue of NO₂ ^--N accumulation in the effluent and achieving better control over effluent pH、TFe and SO₄ ^2- byproducts. Particularly， incorporating 40% （V/V） CWR in the planting layer along with 20% （V/V） in the submerged layer of bioretention system achieved superior decontamination performance with respective removal rates for COD、TP、NH₄ ⁺-N、NO₃ ^--N and TN being 84.49%、96.94%、91.83%、87.11% and 82.13% respectively. Additionally， all concentration levels for by-products remained below permissible limits.

Quantitative assessment of nutrient output and analysis of its change trend in the area where pond renovation is implemented， and study of the impact of pond renovation on water quality purification service function are conducive to the promotion of rural nonpoint source pollution control as well as sustainable development of agriculture. In this paper， Liyang city， a typical county in southern Jiangsu， was selected as the research object， and the InVEST model was used to calculate the water quality purification service function on the basis of the multi-period land use data from 2002 to 2022. Based on the land use change characteristics of the transformation of ponds to cropland and the standardized renovation in the research area， we proposed an improved method for calculating of the total nitrogen （TN） and total phosphorus （TP） outputs by considering the intensity of the pollutants discharged from the tail waters of the aquaculture ponds. Also， the effects of two measures of pond reclamation to cropland and standardized renovation of ponds on the service function of water quality purification was explored. The results were as follows： ① The output of total nitrogen （TN） and total phosphorus （TP） in Liyang City from 2002 to 2022 showed a trend of stabilization followed by a decline. In 2022， the output of TN and TP was 131.99×10⁴ and 11.65×10⁴ kg respectively， which was the lowest level of all the years. ② Statistical analysis shows that in the land use transformation involved in pond renovation， the order of TN and TP output per unit area is arable land＜standardized renovated pond＜non-standardized pond. The implementation of the two measures of "pond-to-farmland conversion" and pond standardization can reduce the output of pollutants in the region， indicating that pond renovation is positively correlated with the improvement of water purification function. ③ Without distinguishing between natural water bodies and aquaculture ponds， the InVEST model alone cannot well reflect the actual trend of water purification function in the southern Jiangsu counties， where aquaculture ponds account for a relatively large area， and it is necessary to combine with the improved method to reconstruct the actual nitrogen and phosphorus outputs. The proposed improvement method can also be applied in similar areas. ④ The measures of returning ponds to farmland and standardized renovation have effectively reduced regional nitrogen and phosphorus pollutant emissions， and the results of the study can provide a scientific basis for the construction of land-use planning and ecological protection patterns that take into account the protection of arable land and the control of water pollution in the southern counties of Jiangsu Province.

The hydraulic retention time of the long-distance water distribution network in rural water supply is too long， and the disinfection dosage of water from the water plant is insufficient to maintain the residual chlorine level at the end of the network， which easily leads to the over-limit of microbial indicators. Increasing the chlorine dosage of water in the water plant will result in a higher chlorine concentration at the near end of the network， which is prone to the generation of disinfection by-products， affecting the safety of water supply quality， and is not economical. Booster chlorination is a disinfection improvement technology for reasonably controlling the residual chlorine concentration. However， an unreasonable dosing scheme is not conducive to controlling the generation of disinfection by-products. This paper optimizes the chlorine dosing control parameters by studying the influence of chlorine dosage and the control node of residual chlorine during booster chlorination on residual chlorine decay and the generation of disinfection by-products. The research results are as follows： The decay rate of residual chlorine in water samples after booster chlorination is significantly lower than that before booster chlorination； booster chlorination leads to a booster increase in the content of trihalomethanes （trichloromethane， dichlorobromomethane， and monochlorodibromomethane） and haloacetic acids （dichloroacetic acid and trichloroacetic acid）； when the total chlorine dosage is the same， booster chlorination can reduce the generation of trichloroacetic acid； when the total chlorine dosage is 3.29 and 2.82 mg/L respectively， compared with one-time chlorination， the decay of residual chlorine is relatively average and slow throughout the reaction time， and the chlorine consumption in 7 days is almost the same； when the initial chlorine dosage is 2.35 mg/L， and booster chlorination is carried out when the residual chlorine decays to a lower concentration （0.09 mg/L） with a booster chlorine dosage of 0.47 mg/L， it can ensure that the residual chlorine concentration meets the standard and effectively control the uniform distribution of residual chlorine， reducing the generation of disinfection by-products. The scientific optimization of chlorination parameters can provide a theoretical basis for booster chlorination， which is conducive to providing safe and high-quality drinking water to users in a more reasonable and economical way， and improving the water supply quality guarantee capacity.

Excessive iron and manganese concentrations in rural groundwater critically threaten potable water safety， while conventional biofiltration systems exhibit inadequate resilience to seasonal fluctuations. However， the seasonal variations in microbial community distribution and their coordination mechanisms during the contact oxidation process remain unclear， which hinders the optimization of this process. A rural water supply plant in southwest Liaoning was studied to analyze seasonal iron and manganese removal performance and microbial interactions. The iron removal rate was about 75% in spring and autumn， and about 83% in summer and winter. Overall， it fluctuates little with the seasons. Manganese removal effect in spring， summer and autumn was not much different， with the removal rate maintained at more than 94%， but dropped to 56% in winter. The changes in filter material morphology and manganese oxidation states in different seasons， and the results showed that the surface wrinkles of manganese sand decreased in winter， resulting in fewer adsorption sites， lowering Mn（III） and Mn（IV） levels and weakening oxidation capacity， thus affecting manganese removal. High-throughput sequencing analyzed microbial community spatiotemporal variations in water samples of Water Plant A. Significant differences were observed between winter and other seasons at class and genus levels. Winter had the highest Alphaproteobacteria abundance， with Sphingomonas as the dominant genus. The Spearman rank correlation method was used to explore the correlation between the dominant genera （top 50） and water chemical parameters. The results showed that the dominant genera Gallionella and Moranbacteria positively correlated with iron and manganese concentrations， while Saccharimonadales and Sphingomonas showed negative correlations. In winter， low-abundance bacteria like Rhodoferax exhibited significant positive correlations. Winter microbiome interaction analysis revealed that Gallionella， Moranbacteria， and Rhodoferax contributed to iron and manganese removal through direct oxidation， organic decomposition， sulfate reduction， and sulfur metabolism.In winter， the reduction of wrinkles on the surface of manganese sand led to insufficient adsorption sites， and the conversion of Mn（III）/Mn（IV） valence states was blocked， and the abundance of synergistic bacteria decreased， which was the main reason for the decrease in manganese removal efficiency. This study reveals seasonal microbial dynamics in contact oxidation systems and their mechanistic roles in Fe/Mn elimination. Through research， the dynamic change rules of microbial communities and the interactions among functional bacteria are revealed， providing theoretical basis and technical support for the improvement of the contact oxidation process and the efficient removal of iron and manganese.

Unmanned Aerial Vehicle （UAV） remote sensing technology presents a multitude of advantages， including cost-effective deployment， rapid responsiveness， versatile and user-friendly operation， superior image quality， and minimal disruption to the environment. It can be used to monitor multiple water quality indicators， such as total nitrogen， suspended matter， turbidity， total phosphorus and chlorophyll， etc.， which is the development trend of river and lake water environment monitoring technology system. To assess the applicability and reliability of this technology for monitoring river water quality， the Xiushui River—one of the five major rivers in the Poyang Lake Basin—was selected as the research subject. A total of 31 samples were collected， and key water quality parameters including suspended solids （SS）， total phosphorus （TP）， total nitrogen （TN）， turbidity （TUB）， and chlorophyll-a （Chl-a） were quantitatively retrieved using remote sensing data obtained from UAV multispectral imaging.The accuracy of monitoring was evaluated through linear fitting， coefficient of determination （R2）， normalized root mean square error （NRMSE）， and mean relative error （MRE）. Furthermore， a comparative analysis along with an economic assessment demonstrated the applicability of UAV remote sensing technology in this context. The results show that：①The remote sensing technology of UAV demonstrates a high accuracy in monitoring water quality parameters such as SS， TP， TN， TUB， and Chl-a. The coefficient of determination （R2） for the linear fitting curves between the inversion values and the measured values ranges from 0.565 to 0.89， closely aligning with a 1∶1 trend line， thereby meeting the precision requirements for water quality parameter retrieval. Among these parameters， Chl-a exhibits the highest accuracy， while TP shows the lowest； thus， they can be ranked in descending order as follows： Chl-a SS TUB TN TP. ②The normalized root mean square error （NRMSE） values for each index fall between 0.1 and 0.3， indicating a moderate preference for goodness of fit. Furthermore， the mean relative error （MRE） for each index ranges from 13% to 24%， which is generally close to the measured values with deviations remaining within a controllable range. ③Additionally， the costs and construction periods associated with UAV remote sensing monitoring are more than 50% lower than those of manual monitoring， indicating that UAV remote sensing technology is a more economical option. This study innovatively uses UAV remote sensing technology to invert river water quality， and verifies the feasibility of UAV remote sensing technology in river water quality monitoring， which provides a new method for rapid and accurate monitoring of river water quality， and has certain practical guiding significance for promoting the development of water environment monitoring technology.

Bio-slow Filter （BSF） degrades the organic matter in the sewage through the biofilm formed by the flow contact between the sewage and the filter material， and combines the physical interception and filtration functions of the filter material to reduce the organic matter content of the sewage and purify the water body. It has the advantages of low energy consumption， high purification efficiency， simple operation and maintenance management. It has strong applicability to the removal of organic matter of rural domestic sewage. To improve the removal efficiency of organic matter of rural domestic sewage by biological slow filter system， the influence of biological slow filter structure and operating parameters on the removal efficiency of organic matter of rural domestic sewage was explored through the design of biological slow filter purification device and sewage purification test. The results showed that the sewage organic matter （COD_cr） removal rate of single river sand filter material with small particle size is better than that of quartz sand or quartz sand river sand mixed filter material. The biological slow filtration purification system with 1.0 m filter material height was filled with quartz sand and river sand mixed filter material according to three layers of “reverse particle size” stratified filling method. Under the conditions of 0.3 m/h filtration rate and 0.3 m overlying water depth， the removal of organic matter （COD_cr） in rural domestic sewage has the best effect. The research results can provide technical reference for the design and operation of rural domestic sewage BSF system.

The construction and operation of water engineering projects pose varying degrees of obstruction to fish migration. Fishways are the primary engineering measure for restoring habitat connectivity. To enhance the effectiveness of fish attraction at fishway entrances， pulsed electric fields（PEF） have been widely applied in guiding and intercepting fish movements； however， the behavioral response mechanisms of fish under dynamic water and pulsed electric field conditions remain understudied. Most existing studies focus on analyzing macroscopic statistical indicators such as interception rates and stunning rates influenced by electric field parameters. The response patterns of fish decision-making regarding perception and returning behaviors under combined effects of water flow and pulsed electric fields are still poorly understood. This study conducted behavioral experiments on adult silver carp （Hypophthalmichthys molitrix） in a dynamic wate rand PEF environment using a large glass flume facility （50 m long， 2 m wide， with a 5 m experimental section）. Based on an orthogonal experimental design， the study investigated the impacts of key external environmental parameters—including flow velocity （0.2~0.8 m/s）， pulse voltage （110~330 V）， pulse frequency （4~12 Hz）， and pulse width （2~10 ms）—on fish perception distance and returning behavior. The results revealed the following： ① Under experimental conditions， the sensing distance of fish ranged from approximately 83 to 178 centimeters. The sensing distance is defined as the perpendicular distance on a horizontal plane from the sensing point （i.e.， the location where the experimental fish first exhibits abnormal swimming behavior） to the line connecting the positive and negative electrodes. The significant factors influencing sensing distance were ranked as flow velocity and pulse voltage， with lower flow velocities or higher pulse voltages leading to longer sensing distances. ② Flow velocity was identified as the critical factor influencing fish returning behavior. Lower flow velocity significantly increased the probability of fish exhibiting turning behavior. ③ Under the experimental conditions， when the flow velocity increased by 0.1 m/s， the probability of fish exhibiting returning behavior decreased to 76% compared to the preceding velocity. Furthermore， when the sensing distance exceeded 103 cm， the fish displayed a stronger tendency to engage in turning behavior.

In order to deal with the possible sudden cadmium pollution， aimed at the actual situation the water supply in a single village in Fujian Province， the waste oyster shells （OS）， which are common in rural areas， were used as raw materials. With the goal of improving the cadmium adsorption performance， ， the modification of OS was carried out. The effects of preparation conditions， such as OS particle size， modifier amount， modification period， and temperature on the static cadmium removal performance of oyster shell modified material （APTES-OS） were investigated. At the same time， in order to avoid affecting the turbidity of the effluent and the loss of materials， and to facilitate the recycling application， APTES-OS was formed， and the dynamic cadmium removal performance of the formed material was investigated to provide a reference for continuous operation in the emergency process. The results of the preparation condition optimization experiment showed that the maximum Cd （II） saturation adsorption capacity of the modified APTES-OS material can reach 44.4 mg/g， at the conditions of 100~120 mesh OS particle size， 0.1 mL/10 g mount of modifier， 8 hours modification time and 90°C modification temperature. The characterization results demonstrated that the modification measures made the surface of OS more uniform and compact， but did not change the calcite crystal structure of OS. At the same time， the N-H characteristic peak appeared on the OS surface， proving that the modified material successfully grafted the amino functional group， which was helpful to improving the chemical adsorption of Cd（II）. When pH＞3.25， the surface of APTES-OS is negatively charged， and it is easy to adsorb positively charged Cd（II）. The dynamic adsorption experiments results of the formed APTES-OS material showed that the penetration time can reach 20 minutes， and the saturation adsorption duration could reach 336 minutes at an inlet flow rate of 3.12 mL/min. The Thomas model could better describe the dynamic adsorption behavior of Cd（Ⅱ） on the molding material. The results of the study indicated that the modification measures greatly improved the cadmium adsorption performance， and the formed material had a good continuous operation effect. The study provides a potential water purification material for dealing with possible cadmium pollution and a reference for continuous operation in emergency process， and it also offers new ideas for the resource utilization of OS.

Combined supporting structures consisting of steel set and shotcrete are widely used in underground tunnels when the geological conditions are poor. However， there exist many difficulties in conducting nonlinear finite element analyses for the steel set due to its small size and dense arrangement. Therefore， according to the mechanical properties of the steel set， a four-node isoparametric element model of the steel set structure was proposed， and its mechanical action was simulated by stiffness superposition. Based on the Mises yield criterion and the secondary plastic flow model， an elastoplastic constitutive model was established to simulate the yielding and hardening behavior of steel set. The elastic damage constitutive model was used to simulate the damage softening behavior of concrete， and finally， a nonlinear numerical simulation method for the combined supporting structure of steel set and concrete was formed， which is verified to be reasonable by a planar circular tunnel example. This method was used to investigate the force characteristics of the combined supporting structure， and the results show that： when the surrounding rock pressure is small， the concrete is in an elastic state so it has a high bearing capacity and is the main bearing structure； when the surrounding rock pressure is large， the concrete undergoes compression damage， and the excess stress is transferred to the steel set， resulting in a significant increase in the stress of the steel set， and the steel set evolves into the main bearing structure； reducing the spacing between steel sets can to some extent reduce the steel set’s stress， slow down the development of concrete damage， and enhance the supporting effect of the combined supporting structure.

A dam deformation prediction model based on Successive Variational Mode Decomposition （SVMD） and Informer is proposed to address the challenges of nonlinearity and instability in dam deformation. The dam displacement sequence is firstly decomposed by SVMD to avoid frequency overlapping and mode mixing. Then the weights of the influencing factors are calculated by Random Forest（RF） algorithm for each modal component respectively， and the key factors are screened out. The corresponding Informer model is constructed for each component for prediction， and the hyperparameters of the Informer model are optimized by using Grasshopper Optimization Algorithm （GOA）. Finally the prediction results of each component are reconstructed to obtain the final displacement prediction results. The validation results based on a domestic project example show that the SVMD-GOA-Informer model is better than other commonly used models in terms of accuracy and stability of displacement prediction.

This paper is based on the optimization project of the Hanjiang， Rongjiang， and Lianjiang river systems connection， addressing the seismic design issues of shield tunnels that traverse soft soil and liquefied areas. A numerical simulation approach was employed to conduct performance analysis and comparison of design schemes for the seismic behavior of shield tunnels. The results indicate that the established numerical model can effectively simulate the dynamic behavior of shield tunnels in soft and liquefied soils. Comparing the designs with and without an inner lining， as well as shallow-buried and deep-buried schemes， it was found that the inner lining scheme reduced the maximum values of bolt stress and joint opening in the tunnel segment by 49.0% and 59.1%， respectively. Furthermore， the maximum settlement displacement for the deep-buried scheme decreased by 3.66 cm， representing a reduction of 23.4%. Ultimately， it is recommended to choose the deep-buried design scheme with an inner lining.The above research provides a reference for the design of similar projects.

Landslide dam is a natural dam body formed by geological disasters such as earthquakes， landslides， and mudslides. Its geometric shape and particle size distribution are significantly different from those of earth rock dams. The landslide dam that accumulates naturally has not been artificially compacted， with a loose internal structure and a large randomness in particle size distribution. Under the influence of the potential energy difference between the upstream and downstream water levels， landslide dams are prone to collapse， posing a serious threat to the safety of downstream residents' lives and property. Conducting indoor physical model experiments is an important means of studying the mechanism of landslide dam failure. This article relies on a water tank test device to design seven sets of physical model test schemes with different particle order structures， aiming to summarize the characteristics of dam failure and sedimentation of landslide dams with different particle order structures by observing the seepage characteristics during the water storage stage and the failure mode during the dam failure stage. The research has found that landslide dams have two forms of erosion during the water storage stage： internal erosion of the dam body and downstream slope erosion. The formation of seepage channels is closely related to the size of pores between particles. In overflow failure， downcutting erosion is a necessary condition for widening development， and the starting flow velocity of dam particles determines the type of dam failure mode， which in turn affects the magnitude of peak flow. The fine-grained structure dam has a fast water storage time， and overflow failure occurs before a seepage channel is formed through the dam. The medium-grained structure dam has a relatively stable seepage channel， which can effectively reduce the shear strength of water flow， but it is also easy to cause the loss of dam particles. The main manifestation of dam failure mode is seepage failure. The erosion layers of the landslide dam with positive and negative grain structure are distinct， and the bedding structure of the siltation area is clear. The difference in vertical positive and negative particle order structure mainly depends on the vertical position distribution of the fine particle layer and the coarse particle layer， and the sedimentation zone presents an opposite particle accumulation distribution in the vertical water flow direction. The position of fine and coarse particles in the horizontal positive and negative particle sequence structure determines the duration of dam failure， and the sedimentation area presents an opposite particle accumulation distribution in the direction of water flow.

In order to meet the need of energy dissipation in long distance and high-drop pipeline water transmission project， and make up for the shortcomings of existing energy dissipation wells with large shaft height and low energy dissipation ratio in high head and small flow， a horizontal orifice plate energy dissipation well composed of closed section with built-in orifice plate and open section connected to the atmosphere is proposed. Through physical model test， the influence factors of energy dissipation such as aperture， number of holes， plate shape， number of plates and water depth in open section are analyzed， and the law of energy dissipation of energy dissipation well is explored. The physical model test shows that the aperture is the main factor affecting the energy dissipation effect of the orifice plate energy dissipation well. When the flow rate is constant， the smaller the aperture， the larger the orifice flow velocity， the larger the head loss and the higher the energy dissipation ratio. For the orifice plate energy dissipation well with one flat plate， when the orifice flow velocity is 6.50 m/s， the energy dissipation ratio is 71.17% and the head loss is 3.78 m. When the total hole area of the orifice plate is constant， the number of holes has basically no effect on the energy dissipation effect of the energy dissipation well. In the case of two holes， the energy dissipation effect of curved plate energy dissipation well is slightly better than that of flat plate energy dissipation well. The number of orifice plates has significant influence on the energy dissipation effect of energy dissipation wells. The more the number of plates， the larger the head loss and the higher the energy dissipation ratio. When the flow rate is constant， the water depth in the open section has no effect on the head loss of the energy dissipation well.

As a common type of soft rock， muddy siltstone deteriorates significantly under the coupled action of dry-wet cycles， often causing subgrade engineering problems. Therefore， it is crucial to study the mechanism of strength deterioration of muddy siltstone under dry-wet cyclic conditions. In this paper， a series of dry-wet cyclic strength deterioration tests were conducted on muddy siltstone. Based on the mineral composition analysis， a GBM-PFC numerical model of rock was constructed considering different mineral components and their contents， and numerical simulations were carried out. Combining the macro- and micro-structural deterioration characteristics of muddy siltstone， a strength deterioration evolution model was established. The results indicate that the GBM-PFC model can more accurately simulate the impact of dry-wet cycles on the deformation process of the rock， especially in terms of micro-crack evolution. As the number of dry-wet cycles increases， the rock strength deteriorates significantly. The micro-crack evolution process can be divided into four stages： zero growth， initiation， rapid growth， and post-peak stages. The crack angles are mainly concentrated between 60°~120° and 200°~300°， predominantly tensile cracks. These tensile cracks mainly occur in quartz minerals， while shear cracks are primarily found in clay minerals and quartz. When the sample is destroyed， the low-stress zone is concentrated in the debris blocks， while the high-stress zone is concentrated in the intact blocks. During the deformation process of the sample， boundary energy is mainly converted into strain energy and cementation energy. Under the influence of wet-dry cycles， clay minerals undergo dissolution and disintegration， with the internal nucleation of micro-cracks and micro-fractures， which intensify as the number of cycles increases.

To enhance the utilization rate of sludge and address the problems of low strength and high compressibility， this research employs basalt fiber （BF） in combination with calcium carbide slag （CS） and ground granulated blast-furnace slag （GGBS） for sludge solidification， with the anticipation of enhancing its mechanical and durability properties. The mechanical properties are analyzed through conducting unconfined compressive strength （UCS） tests， the Brazilian test （splitting tensile test， STS）， permeability tests， and dry-wet cycling tests. The response surface method （RSM） is utilized in conjunction with statistical principles to optimize the experimental batch formulation， considering CS-GGBS content， BF content， and length as influencing factors， with the 7-day UCS as the response value. The results indicate that the optimal formulation is 20% CS-GGBS， 1.2% BF， with a BF length of 18 mm， and the most significant improvement in early strength is observed. The significance of the influence on the response value is in the order of BF content CS-GGBS content BF length. BF enhances the STS of solidified sludge， reduces the permeability coefficient， and strengthens the resistance to dry-wet cycles. At the conclusion of 28 days of curing， the STS of the sample with a length of 18 mm and a content of 1.2% BF is the maximum， reaching 498.65 kPa， and its durability coefficient increases.

Traditional methods of water resource allocation and control in irrigation districts often focus on a single model， neglecting the complex coupling relationship between the check gates and the turn-out gates， making it difficult to comprehensively address the multi-scenario demands in practical irrigation districts. In response to this deficiency， this paper proposes a coupling model integrating water distribution and control， which is applicable to water distribution plans in multiple scenarios. The model initially presets the water distribution scheme and conducts dynamic adjustments and optimizations based on the hydraulic characteristics of the uniform flow zone and the backwater zone in the Integrator Delay （ID） model， in combination with the location of the offtakes， until the scheduling strategies of the check gates and the turn-out gates are mutually matched with the target water levels. The model selects multiple water distribution indicators and control indicators to conduct a comprehensive evaluation of the schemes under different scenarios. The application of the model to the Bojili Irrigation District verifies that through the linear quadratic regulator （LQR） control method， the frequency and amplitude of gate regulation can be effectively reduced， enhancing the stability and safety of canal operation. This model offers a new thought for the water supply and distribution management of irrigation districts， not only optimizing the allocation efficiency of irrigation water supply but also significantly improving the management level.

Based on the principles of multiple linear regression， and incorporating multicollinearity diagnostics， stepwise regression， and error analysis， an optimal regression model method is proposed to identify the optimal combination of independent variables and select the most relevant field measurement data. This method enables more accurate inversion analysis of the three-dimensional initial in-situ stress field. Taking a pumped storage power station as a case study， combined with field-measured in-situ stress data and a three-dimensional numerical model， the optimal regression model method is applied to perform an inversion analysis of the in-situ stress field. The research results indicate that the optimal regression model method can eliminate relatively insignificant linear independent variables and overcome the issue of multicollinearity among the independent variables. The method successfully identifies the optimal combination of tectonic movement patterns that form the initial in-situ stress field， and excludes outlier data that fall outside the judgment criteria， leading to the derivation of a linear regression equation. Compared to the results obtained from traditional multiple linear regression methods， the optimal regression model method yields smaller regression errors and higher computational accuracy. It provides a more accurate simulation of the initial three-dimensional in-situ stress field， and the inversion results can be applied to subsequent cavern engineering design and simulation calculations.

Aerodynamic resistance represents the mass transport capacity of atmospheric turbulence in water-heat exchange， and its accuracy is important for modelling and estimation of land surface water-heat exchange. However， due to the absence of data of atmospheric stability， the existing studies usually estimate aerodynamic resistance based on the neutral stratification hypothesis， which would result in considerable uncertainties. Therefore， based on data at 187 global stations and the Monin-Obukhov similarity theory， Penman-Monteith equation， Thom model and nonlinear regression methods， this study constructed an aerodynamic resistance estimation model， which considers the effects of atmospheric stability and vegetation characteristics， and investigated the ecohydrological implications of the aerodynamic resistance estimation model based on comparing the estimated potential evapotranspiration using different aerodynamic resistance estimations. Results showed that： ① the mean equivalent aerodynamic resistance at the 187 flux stations was 44.6±24.6 s/m， while those estimated using the traditional method was 125.1±22.7 s/m， which considerably overestimated aerodynamic resistance； ② the land surface factors including canopy height（h_c ）， Leaf Area Index（LAI）， Normalized Difference Vegetation Index（NDVI） and Enhanced Vegetation Index（EVI） could express most of the variabilities in the aerodynamic resistance coefficient （R ²=0.81）， based on which the estimated mean aerodynamic resistance at the 187 stations was 57.8±51.9 s/m， which is significantly improved compared with the traditional method； ③ the potential evapotranspiration （PET） based on traditional aerodynamic resistance methods considerably underestimated PET （y=0.55 x）， while those based on the aerodynamic resistance coefficient model were very close to the truth （y=1.15 x）， especially in land surfaces with high canopy heights， such as deciduous broad-leaved forests， evergreen broad-leaved forests， and mixed forests，where the traditional method overestimated PET dramatically. These findings would be valuable for evaluating the interactions among land surface and atmosphere and for estimating water-heat exchange.

The Sixth Coupled Model Comparison Program （CMIP6） data is often employed to evaluate potential global-scale changes in climate variables. However， it is less efficacious in projecting changes at the regional level. The Ili River Basin in Xinjiang Uygur Autonomous Region of China （IRBC）， characterized by significant elevation variation and complex terrain， gives rise to considerable discrepancies in data analyses based on limited number of meteorological stations. Consequently， reliable meteorological data are essential for climatic and hydrological research. This study develops CMIP6 data into a new multi-model ensemble dataset by four approaches： reliability ensemble average （REA）， convolutional neural network （CNN）， random forest （RF）， and Bayesian model average （BMA）. Additionally， we employed performance indicators such as the Taylor Diagram， Taylor Skill Score （TSS）， and Kling-Gupta Efficiency （KGE） to identify the method with the best simulation effect on precipitation and temperature in the study area. The results demonstrate that the BMA dataset exhibits the most effective simulation of precipitation patterns across a range of extreme precipitation indices. In calibration period（1961-1999）， the annual total precipitation when daily wet day amount 95th percentile （R95PTOT） is the highest. In the validation period（2000-2014）， BMA's rank sum ratio （RSR） is 1.1， ranking first， indicating that its comprehensive simulation effect is the best. The KGE results of annual maximum consecutive 1-day （Rx1day） and 5 day precipitation （Rx5day）， and R95PTOT are 0.032， 0.39 and 0.52， respectively， which are all higher than the values obtained from other datasets. In the average temperature simulation， the RF dataset performed the best. The standardization deviation （SD）， the center root mean square error （CRMSE）， the correlation coefficient （r） and TSS in the calibration period are 1.005， 0.088， 0.996 and 0.49， respectively. These values represent the most favorable outcomes compared to other datasets. Similarly， the RF also outperformed others during the validation period， with a RSR value of 1.18. The findings of this study assess the efficacy of various approaches in simulating meteorological data within the study area. This can provide a usable method for the analysis of meteorological data in future scenarios and provide a scientific foundation for the management of meteorological disasters and water resources in the IRBC.

With the intensification of global climate change and rapid urbanization， watershed flood risks are becoming increasingly prominent， with land use change serving as a key driving factor profoundly affecting watershed hydrological cycles. This study focuses on the Zhuozhou section of the North Juma River Basin （approximately 588 km2）， which is located at the piedmont of the Taihang Mountains with a unique trumpet-shaped topography and multiple river confluences. The Zhuozhou flood disaster caused by the “23·7” extreme rainfall in 2023 highlighted the urgency of related research. Based on land use change analysis from 1990-2020， a MOP-PLUS-HEC-HMS coupled model framework was constructed to systematically simulate and evaluate the evolution of land use patterns under four development scenarios in 2035 （natural development， economic development， ecological protection， and farmland protection） and their comprehensive impacts on flood processes. K-Means clustering method combined with dynamic time warping algorithm was employed to identify rainfall patterns， comprehensively analyzing the impact mechanisms of different rainfall patterns on flood characteristics. The results show that from 1990 to 2020， farmland area in the study region continuously decreased by 17.4% while impervious surface area dramatically expanded by 3.9 times， with the most intensive land use conversion occurring during 2000-2010. The 2035 multi-scenario simulations indicate that the ecological protection scenario is most beneficial for flood risk mitigation， reducing peak flow by 0.06%~0.20% under various return periods， while the economic development scenario increases peak flow by 0.11%~0.40%. Peak flow differences under different rainfall patterns can reach 5%~20%， and as rainfall return periods increase， the relative impact of land use changes on peak flow gradually weakens. The constructed coupled model framework demonstrates good accuracy （PLUS model Kappa=0.87， HEC-HMS model NSE0.8）， providing scientific basis for sustainable development and flood risk management in the Zhuozhou section of North Juma River Basin. The study recommends adopting an “ecology-first” land use planning strategy and offers important reference value for land use planning and flood prevention in similar watersheds.

With climate change anomalies and increasing human activities， drought events have become widespread， frequent and concurrent， causing significant losses to the society. In order to analyze the effects of climate change and human activities on the evolutionary characteristics of hydrological drought in the upper Fen River， based on the 1980-2016 hydrological data of Lancun station in the upper Fen River， the smoothness of measured runoff and natural runoff was analyzed. And a generalized additive model was used to construct a non-smooth standardized runoff index. The changes of hydrological drought characteristics were analyzed by combining with the travel theory， which quantified the contribution of climate change and human activities to the hydrological drought characteristics. The results show that the natural runoff series exhibits smoothness， while the measured runoff has significant non-smoothness. The non-stationary standardized runoff index constructed in this study has high accuracy and can better capture the changing characteristics of hydrological drought. There were significant changes in hydrologic drought frequency， duration and intensity during the anthropogenic impact period （1980-2016） compared to the relatively natural period （1956-1979）. Climate change was the main driver of changes in hydrologic drought frequency and intensity， while human activities had a significant impact on the shortening of drought duration. This study provides new methods and ideas for hydrological drought analysis and theoretical support for drought management and disaster prevention and mitigation in the upper Fen River region.

In-depth exploration of the balanced relationship between water resources and socio-economic development is an important support for refining the “Four Waters and Four Determinations” initiative， which is of great significance for realizing sustainable use of water resources and promoting high-quality social and economic development. To support the ecological protection and high-quality development of the Yellow River Basin， taking the Yellow River Basin in Shandong Province as the research object， an index system of water-socio-economic high-quality development is constructed， and the development level and spatial equilibrium of the water-socioeconomic high-quality development system and its subsystems during 2013-2022 are analyzed in detail by using the five-element correlation number and coupling coordination degree model. The obstacle index of spatial equilibrium of the system is identified according to subtraction set pair potential. The results show that：①The water resources carrying capacity of nine cities along the Yellow River in Shandong province shows a fluctuating upward trend， mainly affected by precipitation change. The index of high-quality development level of social economy increases steadily， but the difference between regions is obvious. ②The variation trend of sub-system equilibrium is similar to that of the development level. The equilibrium degree of water resources system shows a spatial pattern with Jinan city， Zibo city and Tai 'an city as the core， and its spatial equilibrium degree fluctuates greatly， but the overall increase is small.The socio-economic high-quality development system shows a pattern of "high in the north and low in the south"， and the spatial equilibrium degree shows a stable growth trend. ③The equilibrium degree of the water resources-socio-economic high-quality development system in each city fluctuates and rises. On the whole， the composite system develops towards spatial equilibrium， and the main obstacle of the system spatial equilibrium is the per capita water resources. Cities should focus on reducing the load of water resources. The research results can provide reference for coordinating the contradiction between supply and demand of water resources， fine management of water resources and precise regulation of social economy.

River runoff has certain spatial and temporal variability under the influence of different environmental factors， which increases the difficulty of river runoff prediction. In this study， we constructed a GCN-LSTM model by combining graph convolutional neural network （GCN） and long short-term memory network （LSTM） from the spatio-temporal relationship of runoff. In this model， the spatial correlation between sites and the dynamic changes of time series are fully considered， which can improve the accuracy of flow prediction. The optimal model is selected by comparing the simulation effects of the GCN-LSTM model with those of the GCN and LSTM models alone， and a study of the effect of hyperparameter combinations on the simulation effects is carried out using the optimal model. The results show that the GCN-LSTM model has the best prediction effect on river runoff， followed by the LSTM model， and the worst is the GCN model. The optimal combination of hyperparameters of the GCN-LSTM model is 64 hidden layers， 1400 training rounds， Leaky-ReLU activation function， and a learning rate of 0.007. The increase in both the number of training rounds and the learning rate had a significant positive impact on the prediction results， and the joint increase in the number of training rounds and the learning rate improved the results of the GCN-LSTM model more significantly. Compared to the number of training rounds， the choice of activation function has a greater impact on the prediction results. Leaky-ReLU significantly improves the prediction effect of the model， while the Sigmoid function is the least effective. Therefore， the choice of hyperparameters has a crucial impact on the performance of the model. By choosing an appropriate combination of hyperparameters， the effect of the GCN-LSTM model can be significantly improved to ensure stable and efficient optimization during the training process. The results will provide technical support for river runoff prediction.

The key reservoirs of the basin not only supply water for local industries， but also undertake the important task of allocating water resources within the basin， such as long-distance water replenishment to ensure ecological base flow or minimum discharge flow at downstream sections. The rational determination and application of drought-warning water levels are of great significance for basin drought prevention and mitigation. Taking integrated scheduling requirements of water resources in the whole basin into account， the phased drought-warning water levels for the key reservoirs were calculated. And a set of methods was proposed to evaluate the early warning capability and water supply guarantee capacity of these drought-warning water levels and optimize them. On this basis， to study water supply strategies during dry years， these drought-warning water levels were used as indicators for initiating drought response and water supply restrictions. Moreover， with the objectives of minimizing the cumulative water deficit index and remaining water storage ratio， an optimization model of reservoir dispatching was proposed to optimize water demand on wide-shallow damage principle. The non-dominated sorting genetic algorithm（NSGA-Ⅱ） was applied to solve the model， obtaining the optimal reduction coefficients. Applying the methods to Baise Reservoir in the Pearl River Basin， the results show that the calculated drought-warning water levels of the reservoir exhibit strong early warning capability for dry years in both the upstream watershed and the Yujiang basin. The early warning initiation rates for moderately dry years are 80% and 73%， respectively， while for extremely dry years， the initiation rates are both 100%. Storing water above the drought-warning level by the end of the flood season can basically ensure normal water supply for years with inflow frequency less than 75%. The optimal reduction coefficients of water demand for the Long’an and Guigang sections during drought periods are 1.0 and 0.79， respectively. In this scenario， the uniformity of water shortage within the year increases for dry years， with the numbers of months experiencing severe water shortage at Long'an and Guigang sections decreasing by 25% and 21%， respectively. Additionally， the guarantee rate of minimum discharge flow at Long'an section is improved. The research can provide reference for calculating the drought-warning water levels of key reservoirs in the basin and formulating water supply strategies during drought periods.

Central China has a typical temperate and subtropical monsoon climate， 60% of which is mountainous， and the spatial and temporal characteristics of atmospheric precipitation and water vapor sources are very complex. By searching the literature on precipitation hydrogen and oxygen isotopes and water vapor sources in central China （Hunan， Hubei and Henan） in recent years， the isotopic characteristics of precipitation in central China and its related aspects are sorted out and summarized， and the future research on the stable isotopes of hydrogen and oxygen of atmospheric precipitation in central China is prospected. The results show that the precipitation isotope compositions in central China show seasonal variations of low summer and high winter in time， which fully reflect the precipitation effect of the distribution of hydroxide stable isotopes； there is a spatial trend of decreasing from south to north， and the areas of high precipitation hydroxide stable isotope values are mainly located in low-latitude and low-elevation areas such as eastern Hunan and eastern Hubei， and the high-elevation mountainous areas such as western Hubei and western Henan are the areas of low values. The slopes of the local atmospheric precipitation lines are closer to the global and national atmospheric precipitation lines， but there are different degrees of deviations in the intercepts of each region， with imbalanced isotope fractionation in wet and rainy regions in Hunan and Hubei， and strong secondary evaporation under the arid and low rainfall clouds in Henan. Precipitation is the main factor affecting the isotopic composition of atmospheric precipitation in central China， and there are inverse temperature effects and elevation effects in some regions. The water vapor of atmospheric precipitation in central China is mainly influenced by the oceanic air masses carried by the southwest monsoon and southeast monsoon in the summer half of the year， while the atmospheric precipitation air masses in the winter half of the year mainly come from the interior of the Asian-European continent and local evaporative water vapor. The above results provide a theoretical basis for the study of the ecohydrological cycle process in central China， and provide scientific guidance for the rational regulation of regional water resources.

In order to explore the effect of different inlet guide vane number on unsteady operation of axial flow pump unit under low flow condition， Reynolds-Averaged Navier-Stokes （RANS） equation and SST k-ω turbulence model were used for three-dimensional steady calculation， and inlet guide vane schemes with different blade numbers were selected for comparative analysis. The results show that under the condition of large flow and designed flow， the inlet guide vane will increase the hydraulic loss of inlet passage section slightly， and has little influence on the head and efficiency of axial flow pump. Under the condition of low flow rate， the inlet channel flow section of the axial flow pump without inlet guide vane has flow backflow and a wide range of reflux vortex， which causes the inlet channel blockage and energy loss. After adding inlet guide vane， the hydraulic loss of inlet passage section is significantly reduced， and the pump head and efficiency of axial flow pump are greatly improved. The inlet guide vane with 5 blades has the most obvious effect on the head and efficiency of axial flow pump. With the decrease of flow rate， the inlet guide vane can restrain the return flow field at the inlet of the axial flow pump， weaken the prerotation action， and improve the flow disorder degree in the inlet flow channel. In engineering applications， it can improve the unsteady operation of the axial flow pump device under low flow condition.

The joint optimal operation for sewage pumping stations is of great significance to improving the quality and efficiency of urban sewage system operation and management. Based on the model predictive control （MPC） method and the mechanism model of drainage system coupling heuristic optimization algorithm， a joint optimal scheduling decision-making system for sewage pumping stations was developed to meet the diversified needs of sewage overflow control， energy conservation in pumping station operation and convenient maintenance. The urban drainage network model－storm water management model（SWMM） was used to construct the hydrodynamic and water quality model of sewage system， and the optimal scheduling model was established based on particle swarm algorithm （PSO）. The two-stage screening mechanism was used to ensure that the global optimal feasible solution was found. The total energy consumption of pumping stations and the complexity of the control scheme before and after optimal scheduling was compared， providing a scientific basis for the integrated scheduling of sewage system plant network.

During the partial-load operation of pump-turbine， the amplitude of pressure pulsation in the vaneless space between guide vanes and runner is extremely high， and it contains abundant frequency components， including the high-frequency pulsation under the effect of rotor-stator interaction， and the low-frequency pulsation formed by the vortex rope of the draft tube. The high-amplitude pressure pulsation during the partial load operation of the pump-turbine significantly affects the operation stability of the pumped storage units. To explore the variations of the flow field， amplitude-frequency characteristics， formation mechanism and propagation law of pressure pulsation in the vaneless space， the internal flow characteristics and pressure pulsation of the pump-turbine under 50% load power generation conditions at different unit speeds from the perspective of the weak compressibility of water were investigated in this paper. Combined with the model test data， the disparity between compressible and incompressible simulations in the study of pump-turbine’s pressure pulsation characteristics is compared. By analyzing the influence of the pressure pulsation propagation effect caused by the water flow compressibility on the numerical simulation， it is discovered that considering the weak compressibility of the flow is more precise in caturing the middle- and low-frequency pressure pulsation components in the vaneless space.

Under the drive of the “dual carbon” goals， hydro-wind-solar multi-energy complementary systems have become an important solution for decarbonization China's power system. However， most existing research focused on regulation reservoirs， neglecting the complementary operation of hydro-wind-solar systems with daily regulating reservoirs. This paper used the Duobu Hydropower Station and surrounding wind and solar power stations as research cases， constructed a short-term optimal scheduling model for hydro-wind-solar complementarity， and used dynamic programming to solve it. The typical daily water level changes， unit start-stop status， and load distribution of the hydropower station had been analyzed. The simulation results were compared with the actual operation results to verify the model effectiveness. The results showed that in typical days of non-flood season， the fore-bay water level decreased firstly and then increased， with only unit 1 and 2 operating. In typical days of flood season， the water level basically remained at the normal water level， with all units operating. The average power generation benefit by optimized scheduling in March 2023 was 3.052×10⁵ kWh， compared to 3.013×10⁵ kWh by historical actual operation， increasing the efficiency of power generation by 1.28%. The research results have important practical value for guiding the complementary operation of water-wind-solar power in the Duobu Hydropower Station.

Steel spiral cases in pumped-storage power plants （PSPPs） bear cyclic internal water pressure， thus posing fatigue damage risks to the encasement concrete， affecting the durability of the composite structure. The currently commonly used numerical simulation method based on the damage mechanics framework cannot solve the above problems. In this context， a representative meridian-cross-section of a water-filled and pressure-maintained spiral case structure in the Yangjiang PSPP was modeled using the ABAQUS code. The damage mechanics model based on the continuum medium and the linear elasticity fracture mechanics model based on the extended finite element method （XFEM） were adopted to study the damage and cracking behavior of the encasement concrete as well as the stress distribution characteristics of the steel spiral case. The results show that similar distribution patterns of the concrete damage and crack propagation were observed with the two calculation methods， and the calculated stresses in the steel lining were also in good agreement， which verifies that the fracture mechanics based on the XFEM can reliably simulate the damage to and cracking of the surrounding concrete of the spiral case structure. This work provides a practical method for fatigue analysis and life prediction of the concrete in spiral case structures.

The prediction of the vibration trend of hydroelectric units is related to the safe and stable operation of the units. However， since the vibration signals of the units do not possess the characteristics of stability and linearity， the accurate prediction of the vibration trend of hydroelectric generating units poses a significant challenge. Thus， this paper presents a prediction model for the vibration trend of hydroelectric units based on HHO-VMD-BiGRU. Firstly， the parameters of VMD decomposition are determined using the Harris Hawk Optimization（HHO） algorithm， and then VMD decomposition is carried out. Each decomposed modal component is normalized separately， and a BiGRU model is established for its prediction. Finally， the predicted results are inversely normalized and superimposed to obtain the final prediction result of the vibration trend of the generating unit. In this paper， a comparative experiment is designed based on the data of a certain hydropower station unit in China. The results show that the proposed model has relatively high prediction accuracy and can be used in actual engineering.

Digital technology has brought new development opportunities for reservoir resettlers， but the digital divide has limited the improvement of its digital ability. By simulating the micro data of resettlers in the Three Gorges Reservoir Area in Hubei Province， this paper discusses the mechanism of digital technology in bridging the digital divide with the help of social networks. The study finds that digital technology entrepreneurship provides resettlers with a new way to get rich， and social networks play a key role in the adoption and diffusion of digital technology. Especially under the promotion of national policies and later support projects， resettlers continue to deepen the application of digital technology through imitation and innovation. Social networks promote the adoption and dissemination of digital technology by enhancing resettlers' social recognition of digital technology. In addition， this paper further analyzes the influence of factors such as interaction distance and technology diffusion scope on technology adoption and diffusion， and reveals the role of these factors in the process of digital technology adoption and diffusion. Finally， it puts forward relevant suggestions that the government of the reservoir area should make use of the structural characteristics of social networks and the leading role of elite resettlers to promote the wide spread of digital technology， enhance the digital ability of resettlers， and help resettlers to narrow the digital divide.

The stability of isolated grid operation is an important prerequisite for ensuring power supply and accelerating grid recovery. This article focuses on the control strategy of isolated grid operation of impulse hydropower units group. Firstly， a refined simulation model of Pelton hydropower stations group in Nujiang region of Yunnan Province was established. By modeling and simulating the isolated grid of impulse hydropower units， adjustment parameters that can achieve good transition process quality were sought. And through the simulation of the process of connecting to the isolated grid， the control strategy and adjustment parameters for the isolated grid operation of impulse hydropower units group were formulated. Finally， testing verification was conducted on site based on the optimized control strategy and adjustment parameters. The test results show that after optimizing the operating parameters and control strategies of the impulse hydropower unit governor in isolated grid operation， the various indicators of the transition process from large grid to isolated grid operation are superior to the technical standards of isolated grid operation. The optimization of operating parameters and control strategies for isolated grid is of significance for improving the frequency stability of impulse hydropower stations in response to isolated grid operation， as well as for enhancing the anti-interference ability and safety defense performance of regional power grids.