In order to reveal the co-evolution mechanism of water-energy-food-ecology （WEFE） system security and economic resilience in the Beijing-Tianjin-Hebei urban agglomeration， this study used the panel data of 13 prefecture-level cities in the Beijing-Tianjin-Hebei region from 2007 to 2022 to construct a three-dimensional evaluation framework of pressure-state-response， and systematically analyzed the characteristics and influencing factors of regional coupling spatial network from 2007 to 2022 by comprehensively using the coupling coordination degree model， modified gravity model， social network analysis and secondary assignment procedure. By quantifying the nonlinear correlation between resource constraints and economic resilience， this paper aims to break the limitations of traditional single-factor research and propose a differentiated networked governance path， so as to provide theoretical support and decision-making basis for urban agglomerations to break through the path dependence of "resource consumption for growth" and realize sustainable development of ecological priority. The results show that from 2007 to 2022， the average coupling coordination degree of the WEFE system security and economic resilience in Beijing-Tianjin-Hebei increased from 0.38 to 0.48， but regional differences expanded significantly， and the spatial pattern evolved from a “core-periphery” fragmented structure to a “multipolar network” form. While the number and density of network associations are increasing， the correlation and stability still need to be optimized： Beijing and Tianjin form technology capital spillover through the “siphon-radiation” effect， and intermediary cities such as Shijiazhuang and Baoding play the role of “structural holes” to promote peripheral integration； Geographical proximity significantly strengthens network association， while population quality， government efficiency， technological innovation， openness level and climate risk differences have inhibiting effects on network formation. Based on this， this study proposes to promote the multi-directional circulation of elements by constructing a dynamic monitoring and three-level governance structure， implementing a core node feedback mechanism and reward fund to promote network collaboration， and establishing a cross-domain collaboration， talent sharing and climate adaptation mechanism， so as to realize the differentiated networked governance of the coupling of WEFE system security and economic resilience in Beijing-Tianjin-Hebei.

The conventional reservoir operation diagram， constrained by static regulation frameworks and linear assumptions， demonstrates limited capacity in characterizing dynamic coupling mechanisms and nonlinear constraints within cascade reservoir systems. To address this， based on the theory of system dynamics， this study built a simulation model for early flood-season storage scheduling in mega reservoirs. Taking six cascade reservoirs （Ludila， Guanyinyan， Wudongde， Baihetan， Xiluodu， and Xiangjiaba） in the middle and lower reaches of the Jinsha River as the case study， the dynamic coupling path among water level， reservoir capacity and flow rate was analyzed through system dynamics feedback loops and stock-flow architecture. The study coupled optimization scheduling techniques using LOOKUP functions and IF-THEN-ELSE conditional statements， which characterized nonlinear relationships including water-level-reservoir capacity curves and hydropower unit output constraints， achieving multi-objective dynamic simulation of coordinated reservoir impoundment operations. The Research results indicated that the system dynamics model could accurately depict the dynamic and nonlinear characteristics of the impoundment operations， and its simulation results were highly consistent with those of optimal operation schemes. Under various hydrological scenarios （wet， normal， dry， and extremely dry years）， the Nash-Sutcliffe Efficiency （NSE） values for the reservoir operation water levels exceed 0.99， and the NSE values for the reservoir discharge processes surpass 0.97. The mean absolute error （MAE） values for reservoir operation water levels have not exceeded 0.11 m， while the root mean square error （RMSE） values have not surpassed 0.28 m. For reservoir discharge simulations， the MAE values are below 54 m3/s， and the RMSE values are less than 171 m3/s. Compared with the conventional operation scheme， the system dynamics simulation scheme can increase the multi-year average hydropower output by 2.495 billion kWh/a （an improvement rate of 3.21%）， reduce the spilled water volume by 1.435 billion m3/a （an improvement rate of 15.61%）， and decrease the average computation time for the joint operation of mega reservoirs from 6 hours to 5 seconds. The results not only thoroughly demonstrate the accuracy and reliability of the simulation model， but also provide scientific and technical support for the joint operation of mega reservoirs.

Flood forecasting is one of the most important non-engineering countermeasures in flood prevention and disaster reduction， providing significant social and economic benefits. Due to the complexity of floods and the limitations of human understanding， flood forecasting results are often inevitably compromised by various sources of uncertainties such as inaccuracies in input data， imperfections in model structure and misestimations in model parameters. To provide more reliable flood forecasts， this paper employed the model averaging based on game theory （GMA） to integrate the effects of different model structures， used the system differential response （SDR） to deal with the errors of input precipitations. The flood correction models based on GMA and SDR were constructed based on the ideas of “correction first， then combine” and “combine first， then correction”， that is， GMA-SDR and SDR-GMA. The proposed models were applied to the Wuxigou catchment and catchment above Laoshikan reservoir. Results showed that： ① The Xin’anjiang model， HBV model and vertically hybrid yielding model all exhibited good applicability in the study areas， with deterministic coefficients exceeding 0.80. GMA outperformed the individual hydrological model and contributed to improved forecasting accuracy. In comparison， the accuracy improvement effect of SDR was more obvious than that of GMA. ② The proposed models had more substantial improvements in flood forecasting accuracy， increasing the average deterministic coefficient of event-based flood forecasts in the study areas by approximately 10% and 14%， respectively. The superior performance of the GMA-SDR method indicated that the systematic differential response error correction of the coupled system of multiple hydrological models as a whole was an effective and comprehensive correction pathway. The proposed flood correction models coupling GMA and SDR can fully integrate the forecast information of multiple hydrological models， and has better correction accuracy and reliability.

The Yangtze River is China′s strategic water source. To further study the the Yangtze River Economic Belt′s conservation and intensive water resource utilization and strengthen water resource reutilization， the utilization process is divided into two stages： social production and sewage treatment. Using a two-stage network SBM-DEA model， the study measures and analyzes the water resource utilization efficiency， both stage-by-stage and overall， for 11 areas in the Yangtze River Economic Belt（YREB） from 2011 to 2022. The Theil index and Moran′s I are further employed to analyze the spatiotemporal differentiation of efficiency. The results show that： ①From 2011 to 2022， the average water resource utilization efficiency in the YREB exhibited a “W”-shaped fluctuation， with a mean value of 0.62， indicating substantial room for improvement compared to the efficiency frontier. The changes in sewage treatment efficiency closely mirrored the overall efficiency trends， suggesting that the sewage treatment stage plays a key role in determining water resource utilization efficiency. ②The spatial distribution of efficiency has shifted from a saddle-shaped pattern—high in the east and west， low in the middle—to a stepwise structure that increases from west to east and from upstream to downstream， reflecting significant spatial disparities. The Theil index decomposition indicates that the overall disparity is primarily driven by intra-regional differences within the upstream， midstream， and downstream regions， with the upstream region being the dominant contributor over the long term. From 2013 to 2022， the contribution rate of the downstream region increased by an average of 16.03% annually， and in 2021-2022 surpassed that of the upstream region， becoming the main source of intra-regional disparity. ③Between 2011 and 2015， water resource utilization efficiency in the YREB was spatially random， but since 2016， a positive spatial correlation has emerged. High-high agglomeration areas have mainly been concentrated in Jiangsu， Zhejiang， and Shanghai， while low-low agglomeration areas have appeared in Yunnan and Guizhou. Over the study period， the number of agglomeration areas gradually declined， revealing that regional synergy remains unstable， and greater efforts are needed to enhance coordination and improve water resource utilization efficiency across the region.

Floods are among the most common natural disasters worldwide， and accurate flood forecasting is essential for disaster prevention and emergency management. Traditional flood forecasting models often face limitations in capturing complex rainfall patterns and peak flow characteristics. To address these challenges， this study proposes a Long Short-Term Memory （LSTM） model enhanced with a multi-head attention mechanism and a customized Floss loss function. Taking the Yongjiang River Basin in Nanning City as a case study， we collected rainfall and flood peak data from 15 historical flood events between 2008 and 2024. Using a sliding window approach， we expanded the dataset into 320 training samples. To improve the model′s generalization and convergence performance， K-fold cross-validation was applied during training. In addition， Particle Swarm Optimization （PSO） was used to automatically tune key hyperparameters such as network structure and learning rate. To mitigate the risk of underestimating flood peak levels， we designed the Floss loss function， incorporating a penalty term for underestimation and a water-level-based weighting scheme to enhance sensitivity to high water levels. In the testing phase， we compared LSTM models with and without multi-head attention mechanism under the Floss loss setting， and further evaluated the impact of different loss functions—including Huber、 MAE、 MSE and the proposed Floss—on predictive performance. The results indicate that： ①The attention mechanism significantly improves predictive accuracy， reducing the test RMSE by 41.6% from 1.9642 to 1.1462 compared to the baseline model. ②The Floss loss function， through its underestimation penalty （β=1.206 9） and water-level weighting （α=1.0）， effectively reduces underestimation errors， achieving a lower RMSE（1.1462） than Huber（1.1834）， MAE （1.1864） and MSE （1.2313）. ③The attention-based LSTM model using Floss shows no underestimation in three independent flood events， with maximum errors within 1.15 meters. These findings demonstrate that incorporating attention mechanisms and a tailored loss function can significantly enhance model accuracy and robustness， offering new methodological and technical support for intelligent flood forecasting.

Numerical modeling of river flood evolution plays a crucial role in flood risk management and disaster prevention strategies. However， the interaction of water flow over the wide-shallow river is complex， and the applicability and accuracy of traditional hydrodynamic models needs to be further explored. Wide-shallow main stem of the Nenjiang River is characterized by intricate riverbank formations and highly concentrated water management infrastructure. To address the above-mentioned issues， the Fulaerji-Jiangqiao stationof the Nenjiang River was selected as the study area， and high-resolution terrain and geomorphological datasets were utilized to depict the impact of topography and embankments within the river on water flow evolution. On this basis， a two-dimensional flood evolution simulation model of the selected study area was constructed by the TELEMAC-2D. The simulated discharges obtained from the TELEMAC-2D model were then discussed and compared with those from the MIKE21 model during the flood season. The results showed that the built TELEMAC-2D model had satisfactory performance on flood modelling. The simulated inundation area was consistent with actual flood coverage observed in the concurrent remote sensing imagery. Also， the modelling results could effectively reflect the water-blocking effects of inner embankments and local microtopography on flood routing within the river channel. For different flood events， the relative errors of the flood peak flow at the gauged stations were all less than 20%. Furthermore， the coefficient of determination between the simulated and measured discharge series for most flood events was above 0.9. The modelling results of the TELEMAC-2D model were comparable to those from the MIKE21 model. The simulated flood process sequences from these two models exhibited similar trends in flood onset and recession stages， and both were consistent with the measured flood hydrographs. Additionally， the floodplain flow threshold for the studied river reach was determined to be approximately 1 100 m3/s， and the model demonstrated satisfactory performance in modelling both floodplain and non-floodplain flood events of different magnitudes. The results indicated that the TELEMAC-2D model had satisfactory modelling capability and was suitable for flood routing in wide and shallow rivers.

Global climate change has altered precipitation patterns in various regions， affecting the abundance of surface and groundwater resources， and subsequently impacting hydrological processes. Exploring the characteristics of runoff changes under different climate change scenarios can provide key basis for scientific management of watershed water resources and accurate assessment of flood risks， which is of great practical significance. This article takes the Juanshui River Basin in the upper reaches of the Lushui River as the research object， constructs a SWAT （Soil and Water Assessment Tool） model to simulate the daily runoff process of the basin， and uses precipitation data from four typical climate scenario models （SSP1-2.6、SSP2-4.5、SSP3-7.0 and SSP5-8.5） based on EC-Earth3-Veg、FGOALS-g3 and MRI-EMS2-0 products to simulate the future runoff process of the study area and analyze the characteristics of future water resources changes in the basin. The results indicate that the selected CHM-PRE reanalysis precipitation dataset can effectively drive the SWAT model to simulate daily runoff processes in the watershed. The R²， NSE， and PBIAS for the calibration period and validation period are 0.70~0.89、0.64~0.88 and -3.9~-30.4， respectively. The error in the calibration period is mainly caused by precipitation input. The runoff process in the research area is mainly influenced by surface runoff， confluence， groundwater recharge， and river seepage. With the increase of greenhouse gas emissions， future rainfall will gradually increase. In the SSP1-2.6， SSP2-4.5， SSP3-7.0， and SSP5-8.5 scenarios， future annual average rainfall will be 1 728~1 885、1 628~1 764、1 561~1 817 and 1 697~1 914 mm， respectively. Future annual average runoff will be 239~276、222~249、208~261 and 239~281 million m³， respectively. Greenhouse gas emissions will increase the interannual variability of rainfall and runoff in the watershed. When the future development mode is SSP5-8.5 scenario， the maximum daily runoff in the future will show a significant increase trend （P<0.05）， significantly increasing the risk of flood disasters in the watershed. The research results of this article provide important guiding significance for water resource management and hydropower resource development in the long-term planning level year of the study area.

Precipitation is a key input variable in the simulation of ecosystem water yield services and plays a central role in the hydrological cycle of ecosystems. With the advancement of remote sensing technology， multi-source remote sensing precipitation products have provided abundant data support for simulating watershed ecosystem water yield services； however， their precision and applicability require further validation and evaluation. Therefore， this study takes gauge station precipitation data as reference to systematically evaluate six different remote sensing precipitation products over the Xiangjiang River Basin and their performance in simulating water yield services using the InVEST model. The results show that： ① The MSWEP and GSMaP precipitation products exhibit strong correlation with ground-based observations （mean PCC≈0.70） and high detection capability （MSWEP： POD>0.80； GSMaP： POD>0.75）， along with low error metrics （RMSE<7.82 mm and 9.05 mm； MAE<4.56 mm and 4.91 mm； FAR<0.36； CSI>0.57）. ② Under simulations calibrated using the optimal parameters for each precipitation product， the model driven by ANUSPLIN-interpolated gauge precipitation data yields the smallest simulation errors （NRMSE=0.11 annually， 0.12 seasonally） and better performance （PCC≥0.90； KGE=0.89 and 0.88， respectively）. ③ Using the InVEST model parameters calibrated from ANUSPLIN-interpolated precipitation as a reference， the simulation capabilities of each remote sensing precipitation product were compared. Results show that MSWEP and GSMaP successfully reproduce water yield variations at both annual （PCC>0.85； KGE>0.72） and seasonal scales （PCC>0.88； KGE>0.86）， whereas CHIRPS and IMERG exhibit substantial biases （PBias>31%； KGE<0.60）. ④ Compared to ANUSPLIN-interpolated precipitation， the InVEST-simulated annual water yield driven by all six remote sensing products tends to be overestimated， while seasonal water yield exhibits significant differences in temporal allocation and spatial variability. The findings of this study provide a basis for applying remote sensing precipitation products in water resource change monitoring and water yield service assessment， facilitating the development of scientifically sound water resource management strategies and promoting the conservation and efficient utilization of water resources.

Reservoirs are critical infrastructure for watershed water resource management. The water storage and release processes of reservoirs directly influence the efficient utilization of water resources. Accurately monitoring changes in reservoir storage is of great significance for understanding operations of reservoirs and their impact on watershed water resources. Synthetic Aperture Radar （SAR） satellites and optical remote sensing satellites provide an effective means for accurately monitoring reservoir storage， due to wide coverage and high accuracy. However， the extraction of water bodies from SAR images is affected by the incidence angle effect. The reservoir storage results vary and the accuracy is reduced due to differences in water body extraction. Thus， this study focuses on the Maoergai and Qiaoqi Reservoirs in the Minjiang River Basin. A regression-based correction model was developed using Sentinel-2 optical imagery to reduce the impact of incidence angle effects on water surface area extraction from Sentinel-1 data. Then， an area-storage model was applied to fit reservoir storage based on area extraction results， using in-situ storage measurements. Finally， a consistency evaluation of the retrieval outcomes was performed. The results indicate that the combination of Sentinel-1 and Sentinel-2 data enhances observation frequency， improving the continuity of inundation area and storage observations， achieving continuous weekly monitoring. Orbital-specific correction reduces inter-orbital discrepancies， and improves the fitting accuracy of the area–storage capacity model. The fitted model accurately represents the relationship between water surface area and reservoir storage. Both reservoirs in the study area have a storage capacity exceeding 100 million cubic meters， consistent with the operational characteristics of multi-year regulation reservoirs. Both reservoirs released water earlier than usual in response to emerging drought conditions in the Yangtze River Basin during the 2022 flood season. This method provides reliable technical support for intelligent management based on remote sensing of reservoirs as well as the monitoring of unregulated reservoirs.

Ecological base flow plays an important role in ensuring the ecological security of rivers， maintaining the stability of river morphology and maintaining the health of aquatic habitats. In this study， four watersheds in the Xi'an section of the northern Qinling Mountains were taken as the research area. Based on the monthly flow data of four hydrological stations—Maduwang， Qinduzhen， Heiyukou and Laoyukou in the study area from 1973 to 2019 and the meteorological data of nine meteorological stations in the same period， the Brachymystax lenok tsinlingensis was used as an indicator species. The ecological base flow and ecological base flow guarantee rate were calculated by the ecological depth-velocity method， and the results were compared with the results of three hydrological methods of Tennant method， Texas method and ABF method to evaluate the applicability and reliability of each method. At the same time， combined with precipitation， potential evapotranspiration（ET ₀） and standardized precipitation evapotranspiration index （SPEI）， the characteristics of climate and drought changes in the basin were evaluated， and the correlation between ecological base flow guarantee rate and climatic factors was discussed. The results show that the study area shows a trend of drought， but the change trend is not significant. The intra-annual and inter-annual fluctuations of hydrological station flow are large， and the flow of Maduwang station shows a significant downward trend. The ecological base flow calculated by the ecological water depth-flow velocity method is close to the result of the Tennant method at Heiyukou station， where the Brachymystax lenok tsinlingensis is found. The Texas method seriously underestimates the ecological base flow， while the ABF method has a high calculation result， which may cause pressure on water resources management. The combination of ecological water depth-velocity method and Tennant method can improve the applicability and reliability of ecological base flow calculation. The order of ecological base flow protection rate from high to low is： Texas method， ecological water depth-flow velocity method， Tennant method and ABF method. The ecological base flow guarantee rate was significantly correlated with ET₀ and SPEI， and the correlation increased with the increase of SPEI time scale， indicating that the ecological base flow guarantee rate in the study area was susceptible to drought. The research results can provide scientific basis for the ecological environment protection of Qinling Mountains.

For water-scarce northern rivers， cascade reservoirs are often constructed to impound upstream and inter-regional water， to restore and expand the flood storage area， wetlands， artificial lakes， and to restore the groundwater level in the basin to provide sufficient ecological water. In order to maximise the positive effects of damming on the survival of biological habitats， this paper takes six waterbird species in the Fen River Basin as the target birds， and selects the middle reaches of the Fen River gradient storage hydraulic dam as the research object， and makes use of the habitat suitability model to optimize the original design of the storage scheme， and puts forward the optimal storage scheme by considering the Weighted Usable Area（WUA） of the waterbirds' habitat on the basis of the guaranteeing effect of the water storage. The results of the study show that the optimized WUA during the dry water period is 37.1% higher than the original scheme， which can provide a wider range of suitable habitats for the migration of Fen River migratory birds in winter. The improvement of habitat suitability in the upstream section of the hydraulic dam control area was significant. Under the storage scenario corresponding to the maximum WUA， the high suitability area is mainly distributed in the middle and upper reaches of the pre-dam area. In order to enhance the universality of the optimal design of the water storage scheme of the terrace lock and dam， the numerical calculation results were combined to propose the improvement measures for the water storage scheme setting of hydraulic dams with different conditions. The results of the study can provide a reference for the hydraulic regulation of typical northern rivers with water shortage in the dry season.

The mechanisms underlying algal bloom suppression in response to rainfall-induced multi-dimensional and multi-factor changes in aquatic environments remain unclear. This study conducted high-frequency monitoring of three intermittent rainfall events in September 2023 in the Xiangxi River Reservoir Bay， categorized as Type Ⅰ rainfall（short-duration， high-intensity）， Type Ⅱ rainfall（long-duration， low-intensity）， and Type Ⅲ rainfall（long-duration， moderate-intensity）， to investigate the influence of rainfall sequences on bloom dynamics and phytoplankton succession. Results indicate that during the rainfall period， microscopic examination identified 93 genera of phytoplankton belonging to 10 phyla. The dominant species in Cyanophyta were Microcystis and Pseudanabaena； in Bacillariophyta， the dominant species were Cyclotella and Fragilaria； and in Chlorophyta， the dominant species was Chlorella vulgaris. Rainfall type strongly influenced bloom responses， exhibiting a three-phase pattern： following Type Ⅰ rainfall， chlorophyll-a （Chl-a） concentration dropped sharply by 73.7% before rapidly returning to pre-rainfall levels； after Type Ⅱ rainfall， Chl-a showed a fluctuating downward trend； and during and after Type III rainfall， Chl-a remained at low levels below 5 μg/L. Phytoplankton community composition responded distinctly to the three rainfall types： Cyanobacteria dominated during Type I and Ⅱ events， whereas the proportion of Bacillariophyta （diatoms） increased significantly after Type III rainfall， indicating a shift from cyanobacterial to diatom dominance. Diversity indices analysis showed that both species richness and community diversity declined following rainfall. Correlation analysis revealed that key environmental factors shaping phytoplankton structure included water temperature， dissolved oxygen， pH， conductivity， water level， and flow rate. The cumulative effects of intermittent rainfall， through the synergistic action of environmental stress induced by earlier rainfall events， contributed to bloom suppression. These findings provide a theoretical basis for utilizing artificial rainfall regulation as a strategy for algal bloom control.

Dams obstruct fish migration upstream and pose risks for fish moving downstream. To enhance the ecological connectivity of rivers， extensive and in-depth research has been conducted abroad on the risks to fish navigating dams， as well as upstream and downstream passage technologies. Compared with international studies， domestic research in China has largely focused on upstream fish passage technologies， while studies on the evaluation， design of downstream passage channels， and protective measures for fish are quite lacking. With China's growing emphasis on natural ecology， the restoration and reconstruction on river habitats and fish migration routes gradually commence， and the design， construction， and research of downstream fish passage routes become imperative. Conducting a comprehensive review research about the current state of safety research for fish navigating downstream through dams abroad， this paper highlights the main risks posed by dams to fish moving downstream， and details fish-friendly downstream passage channels or methods， including their principles， characteristics， and operational requirements. It discusses safety barrier types and layout strategies designed to be placed upstream of the diversion channel to prevent fish from entering the turbine and to guide them towards the entrance of the bypass， and compares the usage scenarios and limitations of different behavioral barriers （electric， acoustic， visual， and bubble barriers）. Finally， it summarizes the existing issues and challenges in current research on downstream fish passage through dams， and offers the following recommendations for future domestic research： ① Develop geometric and hydraulic design standards for downstream channels； ② Conduct long-term monitoring of fish navigating downstream through dams； ③ Focus on the performance and applicable conditions of downstream fish passage technologies and facilities； ④ Adopt a cross-disciplinary collaborative approach.

The aim of this paper is to explore the spatial distribution of ecosystem services， the trade-offs and synergistic relationships among ecosystem services， and the key factors driving the changes of these services in the Han River Basin. Five ecosystem services， namely， habitat quality （HQ）， water yield （WY）， carbon storage （CF）， soil conservation （SC）， and net primary productivity （NPP）， were selected for analysis， and the synergies and trade-offs among them were assessed using Spearman’s method， and the XGBoost-SHAP model was adopted for the analysis of driving factors. The results showed： ① Each ecosystem service showed significant imbalance in spatial and temporal scales. Temporally， water production and soil retention showed a trend of decreasing and then increasing， habitat quality showed a trend of increasing and then decreasing and then increasing， and net primary productivity and carbon storage showed a trend of continuous increase. Spatially， water production was more affected by rainfall presenting a larger yield in the eastern region， while the other four ecosystem services generally showed smaller values in the east. ② Water yield showed obvious trade-offs with the other four services， especially with carbon storage， while the other four services mainly showed synergistic effects. ③ Rainfall is the main natural factor influencing water yield， while elevation has a significant effect on net primary productivity， habitat quality and carbon storage， and slope is a key determinant of soil conservation.

The silica sand storage reservoir， as a novel Sponge City infrastructure， achieves technological breakthroughs in urban stormwater management through nature-based approachs. Combining theoretical analysis with case studies， this study systematically analyzes the self-purification mechanism， water storage and purification mechanism， and breathable oxygen enrichment principle of silica sand reservoirs. It further explores their structural and functional characteristics， with empirical validation through the engineering implementation of the silica sand storage and self-purification system at the lakebed of Beijing′s Longtan West Lake Park. Research results demonstrate that the reservoir establishes a purification system integrating “desert aeolian sand skeleton + biological filter pond functions”， achieving efficient micron-level filtration of stormwater （suspended solids removal rate ≥95%）. Through structural design of breathable and impermeable materials and natural dynamic mechanisms， it realizes non-powered oxygenation （dissolved oxygen 8~10 mg/L） via temperature difference-driven micro-circulation， facilitating bidirectional exchanges of airflow， substances， and energy among the atmosphere， water body， and soil. This significantly enhances water self-purification capacity while addressing technical limitations of traditional reservoirs such as sedimentation issues and high maintenance costs. Engineering practices confirm that the system effectively mitigates combined sewer overflow pollution， with effluent water quality consistently meeting Class IV limits of the Environmental Quality Standards for Surface Water. Annual rainwater resource utilization reaches 930 000 m3， achieving localized retention of 85% rainfall runoff within the watershed. This research provides theoretical foundations and technical support for stormwater management in Sponge City construction， offering significant practical implications for optimizing urban water environments.

Light non-aqueous phase liquids （LNAPLs） are typical persistent pollutants in subsurface environments， and their migration mechanisms within the water-gas-NAPL multiphase system represent a core scientific challenge for targeted prevention and control of groundwater contamination. The migration process of LNAPLs in the aquifer is usually controlled by the dynamic changes of the groundwater level. The fluctuation of the dynamic water level in the unconfined aquifer may significantly affect the migration and release of LNAPLs. However， the multiphase flow redistribution mechanism under the influence of the regional water table still needs further exploration. Therefore， in response to the above scientific issues， a method based on multi-point continuous water level data was employed to quantify the process of changes in the direction of the water table. Groundwater dynamics and multiphase flow theory were integrated by constructing a multi-field and multi-phase flow coupled model including water phase， gas phase， LNAPL phase， flow field and chemical field， so as to evaluate how the variation of the direction of the water table affects the migration and distribution of LNAPLs， systematically revealing the control mechanisms by which the dynamic evolution of the groundwater table morphology governs LNAPLs migration and transformation. The results show that： ① The variation in the direction of the water table affects the migration trajectory of LNAPLs， and there is a positive correlation between LNAPL migration and the direction of the water table. If the direction of the water table becomes gentler（morphological slowing）， the migration speed of LNAPLs will slow down， with the migration rate of LNAPL decreasing by 38.2%. ② If the direction of the water table becomes steeper （morphological steeper）， the migration speed of LNAPLs will increase. ③ The variation in the direction of the water table affects the change in LNAPL saturation. If the direction of the water table becomes gentler， the change in LNAPL saturation is relatively small； If the direction of the water table becomes steeper， the change in LNAPL saturation is relatively large. ④ The variation in the direction of the water table affects the change in the temperature field. Under the variation of the water table， the mixing of the lower and upper water bodies will make the water temperature near the water table more uniform. The temperature gradient decreased from an initial 0.35 ℃/m to 0.18 ℃/m. ⑤ The variation in the direction of the water table affects the distribution of the dissolved and volatile phases of LNAPLs. With the change of the water table， the change rates of the dissolved and volatile phases of LNAPLs become slower， the rate of change of the dissolved phase concentration decreased by 42%， and the volatilization flux dropped from 0.15 d^-1 to 0.09 d^-1. This study aims to reveal the impact of the variation in the direction of the water table on the migration of LNAPLs in contaminated sites.

In order to study the pressure fluctuation and the transient stress characteristics of the flow passage during the shutdown process of centrifugal pump， the numerical simulation of the shutdown process of the pump was carried out based on the transient calculation results of the pump station， and the transient stress and deformation of the impeller were discussed by using the unidirectional fluid-structure interaction method. The calculation results show that the pressure at monitoring points in the passage are greatly affected by rotor-stator interaction during the shutdown process. The pressure fluctuation in the bladeless area shows a large amplitude at the corresponding impeller rotation frequency（50 Hz） and its harmonics frequency， while the amplitude rapidly decreases in the fixed guide vane inlet area at the same frequency. The pressure fluctuations at monitoring points on the blade pressure surface and suction surface show a large amplitude at the guide vane passing frequency（89 Hz）. As the opening of the guide vanes decreased， the combined effect of the clogging effect of the high-speed water ring in the vaneless space and the complex vortices in the impeller cause a sharp drop in flow rate. The water flow inside the impeller becomes turbulent and vortices appear in the runner inlet and the fixed guide vane area， resulting in low-frequency and high amplitude pulsating pressure. The maximum equivalent stress during the shutdown process occurs at the junction of the blades and the upper or under cover plate， and the maximum deformation occurs at the cover plate near the impeller outlet. The deformation gradually increases from the center to the edge. The maximum equivalent stress value is 121.3 MPa， and the maximum deformation is 0.26 mm.

Pumps are common equipment in modern industrial and agricultural production， and their operating environments are often characterized by significant noise， which complicates data-driven fault identification. Research indicates that graph neural networks have a distinct advantage in extracting fault features from noisy signals. By transforming one-dimensional signals into graph-structured data， hidden fault information within the signals can be revealed. However， the reliability of fault identification largely depends on the construction strategy of the input graph. In response to this， this paper proposes a robust graph construction strategy and feature extraction method that is resilient to noise. The graph construction phase embeds node information using short-time Fourier transform and establishes edge relationships through cosine similarity， ensuring that the feature space within the samples is adequately described. Next， an optimized graph pruning method is proposed， which enhances the noise robustness of the input graph while also reducing computational pressure. Furthermore， an improved GraphSAGE network model is employed to perform layer-wise feature extraction on the constructed input graph， and a SoftMax classifier is used to assign fault labels to each sample. Data collection and method validation are conducted using an axial flow pump test platform， demonstrating the reliability of the proposed method for multi-component fault identification in noisy environments.

To investigate the influence of thermodynamic effects on cavitation flow characteristics， this study adopted two thermodynamic correction methods to modify the Zwart-Gerber-Belamri cavitation model. Numerical simulations of cavitation around NACA0015 hydrofoil were compared with experimental data. Results demonstrate that the modified cavitation models show good agreement with experimental results and can effectively predict thermodynamic effects on cavitation. Thermodynamic effects induce temperature reduction in cavitation regions， suppressing cavitation development， with their influence intensifying as temperature increases. The Fourier’s law-based correction model exhibits superior performance in modification effectiveness. Flow loss analysis based on entropy production theory reveals that velocity gradient-induced entropy production dominates the total entropy generation， accounting for over 97%. Thermodynamic effects improve flow field structures and reduce turbulent fluctuations， thereby decreasing energy loss. However， temperature gradient-induced losses remain negligible compared to those caused by velocity gradients.

In order to avoid resonance in the operation of centrifugal pump rotor， based on the principle and method of modal analysis， a three-dimensional model of air and water rotor system was established by using finite element software. The vibration characteristics， stress distribution and fatigue failure of centrifugal pump rotor system during operation were discussed from three aspects： modal analysis， calculation of critical speed and fatigue characteristic analysis. The research conclusions are as follows： The blade passing frequency is 37.5 Hz， while the first and second order natural frequencies of the centrifugal pump rotor system in water are 60.78 and 60.81 Hz respectively， so the possibility of resonance of the centrifugal pump in the working process is small. The first-order critical speed and second-order critical speed of the rotor system are 592.6 and 627.4 r/min respectively， which is much larger than the rated speed， so the centrifugal pump rotor system is stable and reliable， and will not resonate during operation. According to the fatigue characteristic analysis of rotor system， the maximum stress value of blade and pump shaft is below the safe allowable stress limits， which meets the requirements of strength design. Under the action of stress amplitude， any position of the pump shaft structure can withstand 10⁹ maximum cycles， and there is no high cycle fatigue failure under low stress during normal operation.

To enhance the operational scheduling efficiency of drainage pump stations and reduce energy consumption， a decision support system （DSS） for optimizing the scheduling of drainage pumping stations was developed， taking the pumping station group in Wuhan Economic & Technological Development Zone as the research object. The system includes four functional modules： data management， model management， scheduling management， and operation statistics. It supports real-time monitoring， scheduling plan generation， and multi scheme comparison， and relies on the AI water management platform to achieve remote access and intelligent management. By synthesizing multi-source data with a dynamic programming optimization model， it coordinates dual regulation mechanisms （variable speed and blade angle） in pump units to maximize average efficiency during non-emergency drainage. During the 2024 flood season， the system successfully optimized unit operation plans. Notably， the Donghu Low Discharge Pumping Station′s efficiency achieved a 17.17% increase in non-emergency drainage phases， reducing energy consumption while meeting flow requirements. This provides a practical solution for refined scheduling of drainage pump stations.

To study the influence of adding an external fairing structure on the hydrodynamic performance of low-velocity hydraulic turbines， this paper proposes a parabolic external structure to enhance the turbine′s power generation efficiency. The computational fluid dynamics （CFD） method and Fluent simulation software were used to conduct a comparative analysis of the turbine′s hydrodynamic performance before and after adding the external structure. The results show that adding the external structure significantly improves the stability of the flow field in the turbine's working area. Based on this， the influence of different upper-to-lower axis ratios of the external structure on the flow field characteristics and impeller performance was further investigated. It was found that adding an external structure with an axis ratio of 19∶21 optimized the water flow uniformity， maximized the impeller′s power coefficient， and enhanced the turbine′s stability and power generation efficiency.

A collaborative optimization method based on orthogonal experimental design and CFD numerical simulation is used to study the changes in tailpipe pressure and vorticity before and after optimization of a bulb tubular turbine. Taking the bulb tubular turbine of the Burqin Power Station in Xinjiang as the research object， a 3-factor 4-level orthogonal experimental scheme was constructed for blade angle， guide vane opening， and operating head. The sensitivity patterns of each factor on unit efficiency and tailpipe recovery coefficient were explored through range analysis method. Combined with three-dimensional numerical simulation analysis of the entire flow channel， the evolution process of the tailpipe flow field before and after coordinated optimization was analyzed. The results showed that： The blade angle had a dominant effect on efficiency （range 30.59）， while the guide vane opening had a significant effect on the recovery coefficient of the tailwater pipe （range 0.074）. The recovery coefficient of the tailwater pipe of the bulb turbine under the optimal combination （A₄B₄C₁） reached 0.858， an increase of 11.9% compared to before optimization. After optimization， the peak vorticity of the tailpipe decreased， and the uniformity of flow velocity at each section was improved. This can provide reference for collaborative optimization research of bulb tubular turbines.

The Guanbu Pumping Station supplies water in two directions： to the Xiajiashan Pumping Station and to the Hexi Reservoir. The head difference between these directions forces the system to rely on valve throttling for flow distribution， causing energy losses exceeding 28% of the pump head and cavitation risks during low-water-level operation. To address these issues， the system was redesigned into two independent one-way pipelines equipped with variable-frequency drives for flexible regulation. An evaluation model was developed based on hydraulic characteristics and operational constraints to analyze energy efficiency and optimal scheduling before and after the retrofit. Results showed that efficiency toward Hexi remained nearly unchanged， whereas the Xiajiashan direction avoided throttling losses， improved energy efficiency by 2.7%~10.2%， and eliminated cavitation risks. The findings provide a valuable reference for energy-saving retrofits and operational optimization of similar pumping stations.

The overburden of the cofferdam foundation at the Lawa Hydropower Station contains a 50 m-thick lacustrine sediment low-liquid-limit clay layer， characterized by large thickness， low bearing capacity， low permeability coefficient， and low shear strength. Rapid filling and loading of the cofferdam generate excess static pore water pressure in the saturated cohesive soil of the foundation， reducing soil shear strength and causing stability issues for the 130m-high combined high slope formed by the cofferdam and foundation pit excavation， as well as significant deformation of the cofferdam. Through research and field tests， ultra-deep gravel piles with a depth of 70 m were used for the first time to reinforce the soft foundation， accelerating soil drainage and improving the deformation modulus and shear strength of the composite foundation. This paper focuses on the key technical issues encountered in the analysis of slip resistance and deformation stability of the composite foundation. It is recommended to use the limit equilibrium method for slip stability calculations， with shear strength indices determined according to different components and calculation conditions. For saturated cohesive soils， the adverse effects of excess pore water pressure should be noted， and the time-history variation of excess pore water pressure should be analyzed. The shear strength of the composite foundation can be obtained through area-weighted analysis， and the composite permeability coefficient can be derived based on the similarity principle of consolidation degree. This paper introduces the foundation treatment scheme and construction of the Lawa cofferdam， providing reference for similar projects.

The deterioration of mudstone strength in the excavation unloading damage area under the action of wetting-drying cycles is the main cause of slope and foundation instability in mudstone area. Mudstone in Badong area is selected as the research object. Through triaxial loading and unloading test and nuclear magnetic resonance analysis， the evolution law of macro-mechanical properties and micro-pore structure of mudstone damaged by unloading under wetting-drying cycles are studied， and the deterioration mechanism of mudstone damaged by unloading under wetting-drying cycles are revealed. The results indicate that under the influence of wetting-drying cycles， the internal porosity of unloading-damaged rock samples increases， yet the rate of increase progressively diminishes； the impact of wetting-drying cycles on the micromechanical structure of mudstones gradually wanes. During the wetting-drying cycles， the pore distribution within the rock samples exhibits an evolutionary characteristic where small and medium pores gradually transform into larger pores. With the increase in the number of wetting-drying cycles， the strength and elastic modulus of the rock samples gradually decrease， and the cracks gradually increase when the rock samples are damaged， showing significant degradation characteristics. Establishing the relationship between the damage degree of the micromechanical structure of mudstones， the macroscopic mechanical degradation degree， and the number of wetting and drying cycles enables cross-validation and prediction between macroscopic and microscopic parameters. Under unloading conditions， cracks develop within the mudstone， and when water enters the mudstone through these cracks， the clay mineral particles absorb water， leading to swelling and disintegration. The repeated wetting-drying cycles cause damage to the structural system of the mudstone， which is the fundamental reason for the deterioration of its mechanical properties.

This study investigates the sealing failure of high-head gate seals， revealing the influence mechanism of the drop effect on sealing performance through constitutive characteristic testing and mechanical modeling of the water seal. Based on the sealing mechanical model considering the drop effect， the P_max-P'_action relationship and the τ_intrinsic-Δ_ultimate are used to characterize the effectiveness of the water seal from the perspectives of mechanical pressure-bearing performance and material constitutive performance， respectively. Among these， the τ_intrinsic - Δ_ultimate is more operationally useful for clarifying the impact of the drop effect on the sealing effectiveness of the water seal. The correlation characteristics of the experimental data indicate that the τ_intrinsic-Δ_ultimate generally decreases with an increase in compression ratio ε and shows a significant drop effect when ε > 15%， resulting in a sharp decline in the sealing effectiveness of the water seal. This finding provides important reference data for predicting the ultimate pressure-bearing performance of in-service high-head gates.

Due to the significant scale differences in rockfill gradation， common methods for image segmentation on particles often suffer from over-segmentation or under-segmentation， struggling to meet the requirements of engineering applications. Therefore， this paper proposes a contour extraction method integrating multi-scale visual measurement. Firstly， images of the paved rockfill are collected. Then， to address the problem of uneven segmentation scales caused by large particle size spans of rockfill， an integrated multi-scale visual measurement model is constructed in combination with Mask R-CNN， presenting an accurate approach to extract the contours of stones in different sizes. Based on the extracted results， a model is established to reconstruct the three-dimensional shape of particles and calculate the gradation， enabling fast evaluation of the apparent gradation of rockfill materials. Field experiments exhibit that this method provides high-precision identification of large-span particle sizes and can effectively support quick assessment of rockfill gradation on site.

To address the inefficiency and low accuracy of manual inspections for ant nest hazards in hydraulic engineering， this study proposes an intelligent detection method for drone images based on an improved YOLOv7 model. By integrating SENet channel attention mechanisms into three feature layers of the YOLOv7 backbone network， the model’s capability to extract features of ant nest targets is enhanced. An augmented dataset containing 1，445 drone images of embankment ant nests was constructed for model training. Experimental results demonstrate that the improved model achieves precision， recall， and mAP values of 91.2%、95.4% and 91.5%， respectively， representing improvements of 2.7%、3.2% and 3.4% over the original model. This effectively mitigates missed detection issues caused by weak geometric features in ant nest images. An intelligent recognition system developed with PyQt5 enables the engineering application of the model， supporting image and video input alongside multi-dimensional result visualization， thereby providing an effective solution for intelligent inspection of embankment ant hazards.

To investigate the nonlinear dynamic response characteristics of deep soft soil sites subjected to near-field ground motions， 30 pairs of near-fault pulse-like and non-pulse-like ground motions were selected from the NGA-West2 database. Numerical simulations were conducted for three KiK-net strong motion stations with different site classifications （Category C， D， and E） using time-domain nonlinear analysis methods， investigating the influence of ground motion pulse characteristics on site nonlinear dynamic response. Results indicate that the near-fault pulse characteristics of ground motions exhibit significant influence on the nonlinear dynamic response of deep soft soil sites. The maximum response spectrum amplification factor under pulse-like ground motions reaches 2.26， which is 17.9% higher than that under non-pulse-like ground motions. Furthermore， the peak amplification factor of pulse-like ground motions increases with the softening of the site conditions， with the peak amplification factor in deep soft soil sites being 43.8% larger than that in hard soil sites. A predictive equation， which uses the ratio of ground motion predominant period to site natural vibration period as the predictor variable， was developed for predicting peak amplification factors of deep soft soil sites subjected to the near-fault ground motions. The proposed predictive equation can predict the maximum amplification factors of response spectra accurately， providing practical guidance for evaluating the nonlinear dynamic response characteristics of deep soft soil sites under near-field seismic motion.

Based on a TBM-driven tunnel of a water resource allocation project， a three-dimensional finite element numerical analysis model integrating segment lining， pea gravel， and surrounding rock was established to simulate the entire construction process. This study investigates the influence of pea gravel backfilling timing on the load-bearing characteristics of the segment lining. The results indicate that： ① As construction progresses， the surrounding rock pressure gradually releases. The backfilled pea gravel layer forms an integrated load-bearing structure with the surrounding rock and lining， jointly bearing excavation-induced loads from the surrounding rock. The excavation-induced load on the lining increases and stabilizes as the tunnel face advances. ② During water injection and pressurization， tensile stresses generated by internal water pressure are partially counteracted by excavation-induced compressive stresses. ③ Internal water pressure is predominantly borne by the surrounding rock and segment lining. ④ Under the initial geostatic stress field， pre-compressive stresses induced by excavation in the lining exhibit maximum values at the waist zone and minimum values at the top and bottom. Advancing pea gravel backfilling effectively enhances pre-compressive stresses in the lining， reduces overall tensile stress during operation， and improves the safety margin against concrete cracking. Considering the safety margin for lining bearing capacity （safety factor ≥1.2） and procedural constraints of double-shield TBM construction， it is recommended to perform pea gravel backfilling optimally within a range of 12 to 14.3 m from the tunnel face.

The process of landslide deformation will change the law of force transfer and distribution， and the stability coefficient will also change in the process of its gradual deformation and failure. Therefore， it is of great significance to study the evolution characteristics of slope stability with deformation. According to two failure forms of landslide （push type and traction type）， the characteristics of force distribution along the slide surface are analyzed. Through in-depth analysis of the dynamic evolution characteristics of the unstable region， critical state region and stable region of the sliding surface during the progressive failure process of the slope， based on the understanding of the characteristics of the stress and strain discontinuity of the sliding surface of the slope and the research on the characteristics of stress distribution in different zones of the sliding surface， the concepts of failure rate， failure ratio and failure area ratio are introduced to describe the characteristics of the landslide at different deformation stages. Furthermore， the concepts of current stability coefficient and friction resistance change coefficient are put forward， and the evaluation methods of multi-parameter stability evaluation indexes such as comprehensive sliding force-anti-sliding force method （CSRM）， comprehensive displacement method （CDM）， main thrust-main tension method （MTM or MPM）， tensile failure method （TFM） and surplus displacement method （SDM） are introduced. Based on the understanding of the mechanism of landslide failure， a new analysis method is derived based on the established shear stress model and the traditional strip method. Taking the landslide of Zhangjiazhuang Section of Lanzhou-Xinjiang Railway as an example， the analysis results show that both the survey results and the critical state block obtained by the above analysis method are the 15th block， and the calculated displacement results are close to the measured values. The comprehensive evaluation method can reasonably and scientifically reflect the whole process of progressive failure of landslides， providing a basis for studying the mechanical evolution of landslide disaster.