Addressing the issue of insufficient flood forecasting accuracy during the Meiyu period (June 18-28) in the Fenshuijiang River Basin, this paper investigates the practical application and improvement method of coupled "Xin'anjiang + Muskingum" hydrological model. Based on the observed rainfall and reservoir operation data, the evaluation of forecasting precision for peak discharge, runoff depth, and time-to-peak was conducted through relative error analysis. The accuracy of the model was verified by comparing the measured values with the predicted values in combination with the deterministic coefficient (D_DC). The forecast effect was optimized by correcting the runoff yield and concentration parameters of the Xin 'anjiang model and the flow routing parameters of the Muskingum model. The results show that after parameter adjustment, the peak discharge relative error is below 15%, runoff depth error is low 40%, time-to-peak deviation is within 2 hours, and D_DC values exceeds 0.85; However, there is still a lag in the forecast during the concentrated period of heavy rainfall. The correction coupled model significantly enhances flood forecasting accuracy during the Meiyu season, offering reliable support for reservoir operation decisions. In the future, it is necessary to further optimize the dynamic coupling mechanism between the input of rainfall spatio-temporal distribution and the parameters of river routing parameters.

In recent years, frequent heavy rains have made Zhengzhou city suffer from the hazards of urban waterlogging. Identifying the spatiotemporal distribution characteristics and driving forces of waterlogging can help improve the current flood-prone situation in Zhengzhou city. Based on the waterlogging data of Zhengzhou from 2020 to 2024, the standard deviation ellipse method, autocorrelation method, kernel density estimation method, and optimal parameter geographic detector were used to systematically analyze the spatiotemporal distribution characteristics of waterlogging points and their driving forces from multiple scales. The results show that the annual distribution of waterlogging points in Zhengzhou is uneven; Spatially, the the focus of waterlogging is located in the old urban area, with significant clustering of waterlogging points at different scales, especially with the strongest spatial clustering within a 3km scale; There is a significant scale effect in the explanatory power of driving factors, with socioeconomic and urban construction driving factors having the greatest explanatory power at different scales, and the combined effect of factors significantly surpasses the independent effects of single factors.

The video image flow monitoring technology has been applied in hydrological monitoring and irrigation area monitoring. Due to the limitation of received light, video image flow monitoring method has limitations in monitoring at conditions of night and low light. The thermal imaging was used to increase the spectral applicability of video flow measurement and compensate for the low applicability of video flow measurement under night conditions. By using a visible light and thermal imaging double-sided camera device mounted on a drone, the flow velocity field inversion results of visible light and thermal imaging camera devices under conditions of visible light and night were compared with the flow velocity monitoring data. The results show that under the condition of sufficient visible light during the day, the inversion effect of visible light video image flow velocity is better, and the accuracy error can reach within -5% except for a few monitoring points; Due to the limitation of its resolution, thermal imaging camera has a certain ability to capture natural tracers on the river surface, and has the ability and potential to invert the flow velocity field on the river surface. If missing particles of cold ice are added to the river section, the monitoring accuracy of thermal imaging at night can be significantly improved. Except for one monitoring point, the relative error of monitoring accuracy is 8.4%, and the accuracy of the other three monitoring points is relatively high, all around -1%. The research results can provide important references for improving the monitoring accuracy of video velocity measurement under conditions of nighttime and low light.

To enhance the application value of precipitation observation data in public meteorological services, this study investigates a quality control method for precipitation data based on multi-source meteorological data and machine learning models. Based on the meteorological station data, multi-source integrated analysis products, meteorological radar, and satellite products, as well as the XGBoost model, a multi-source collaborative quality control method for precipitation data was developd by comprehensive scoring. The accuracy of this method was evaluated using the artificial error implantation technique. The results indicate that when random precipitation anomalies are implanted, the detection rate of erroneous data is 0.85; When errors are implanted at different precipitation levels, the detection rate of erroneous data is 0.79. After collaborative quality control, the average error between the precipitation data to be tested and neighboring meteorological stations is reduced by 15%, and the correlation coefficient is increased to 0.7-1.0. Therefore, this method can effectively identify suspicious precipitation data, which can provide strong data support for meteorological disaster prevention and mitigation.

To analyze the daily-scale spatiotemporal process of the persistent extreme drought in Sichuan and Chongqing in 2022, the daily-scale drought index was calculated based on the ERA5-Land meteorological data from 2018 to 2022. Three-threshold tour theory was used to identify persistent extreme drought events in the Sichuan-Chongqing Region in 2022. The duration, intensity, and frequency of the drought across different terrain types were extracted, and the spatial heterogeneity of drought processes was revealed. The results show that the majority of pixels in the Sichuan-Chongqing region were subjected to two drought events in 2022 and the worst of the drought occurred on 22 August. The average duration of persistent extreme drought in Sichuan-Chongqing region during the summer was 67 days, with the longest duration being 159 days and the shortest being 17 days, showing a increasing trend from west to east. The earliest drought started on 16 June and the latest on 28 August. The correlation between drought severity and drought duration reached 0.98, and their trends were consistent. In different terrain areas, the first type of drought process occurred in spring, with an average of 3.5 drought events, an average total duration of 166 days and an average severity of 193.63. The second type of drought with no drought in spring occurred on average 2.2 times, with an average duration of 120.6 days and an average severity of 136.27, which is only 70.38% of the first type. The research results can provide theoretical basis and technical support for regional daily drought monitoring.

Drought disaster is the combined effects of disaster-causing, socioeconomic and environmental factors. The textual information of historical drought disasters in China was used to classify drought disaster. The method of hotspot analysis was employed to identify prone areas of drought disaster. Based on three elements of hazard, exposure, and vulnerability, the risk assessment of drought disaster was investigated. The results show that three types of key information including water and rainfall conditions, drought severity and social impact extracted from drought disaster texts were well applied to their classification. During the period of 1949-2020 in China, it experienced an average of about 170 drought disasters per year, with mild, moderate, and severe droughts accounting for 52.4%, 27.6%, and 20.0%, respectively. The prone areas of drought disaster mainly occurred in Henan, Shanxi, Shaanxi and Inner Mongolia etc. The levels of the hazard, exposure and vulnerability in Henan, Hubei and Shandong accounted for the higher or above. The levels of drought disaster risk in Henan, Hubei, Sichuan, and Shandong, as the major grain producing areas, were the higher or above. The results of the study can provide a reference for drought disaster mitigation.

Agricultural drought risk assessment is the prerequisite for agricultural drought risk management. Crop growth is highly vulnerable to threats from natural disasters such as droughts, floods, and typhoons, with drought-induced losses accounting for over 50% of the total agricultural natural disaster losses. Based on the regional natural disaster system theory, this study constructs an agricultural drought disaster risk assessment indicator system comprising three components of hazard, vulnerability, and exposure. A total of 22 indicators including annual precipitation were selected. The study adopts county-level administrative regions across China as research units and integrates the fuzzy comprehensive evaluation method to establish the agricultural drought disaster risk assessment framework. The results indicate that the spatial distribution of drought hazard is significantly correlated with annual precipitation, showing a trend of higher hazard in the northwest and lower in the southeast. Provinces with the highest vulnerability include Heilongjiang, Guizhou, and Ningxia, while Guangdong and Zhejiang exhibit the lowest vulnerability due to their strong economic resilience and low disaster impact indices. Henan, Hebei, Heilongjiang, and Ningxia demonstrate higher comprehensive drought risk ratings owing to high agricultural exposure levels. In contrast, regions such as Qinghai, Tibet, Fujian, and Zhejiang exhibit the lowest risk levels due to smaller agricultural scales or abundant water resources. This research can provide a basis for targeted agricultural disaster prevention and mitigation strategies.

To investigate the three-dimensional spatiotemporal propagation characteristics of meteorological drought, based on the CN05.1 gridded data and standardized precipitation index (SPI) during the period 1961-2021 in China, a spatiotemporally continuous event identification method and hierarchical clustering algorithms were applied to classify different propagation patterns of spatiotemporally continuous meteorological droughts and analyze their characteristics. The changing characteristics of events in future climate scenarios were discussed. The results indicate that the spatiotemporal continuous meteorological drought events distribute widely with significant variations in their movement distances, ranging from localized areas to nearly half of China. Three propagation patterns are identified based on movement distance and direction. The Type 1 and Type 2 events are characterized by long duration and large affected areas but occurring less frequently. The Type 3 events occur more frequently, have shorter durations, and affect smaller areas. Under future scenarios, the total number of spatiotemporally continuous drought events is projected to increase, while their duration and intensity are expected to decrease. Both the maximum and total affected areas are likely to expand.

Scientific classification and evaluation of groundwater level funnels is an important basis for the treatment and protection of groundwater overexploitation. Based on the actual situation of groundwater dynamic analysis, evaluation and management in China, this paper put forward the basic provisions, evaluation indexes, classification standards and evaluation methods of influencing factors for the division of deep and shallow funnels. At the national level, the classification and evaluation criteria of groundwater level funnels have been unified. Taking the Beijing-Tianjin-Hebei region as the research object, this paper systematically analyzed the impact of the comprehensive control of overmining in North China since 2019 on the evolution of funnel. The results show that compared with 2018, the shallow funnel presented a stable type in 2023 , while the deep funnel presented a reduced type. The area of the deep funnel was reduced by about 99%, and the water level in the center of each funnel was obviously rising. Based on the XGBoost integrated learning model, the development and change of the shallow funnel in the Beijing-Tianjin-Hebei region were mainly influenced by human factors, followed by meteorological factors. Among them, groundwater exploitation, accumulated precipitation and ecological water recharge of rivers and lakes have the most significant impacts, with impact contributions of 23.1%, 23.0% and 15.2%, respectively.

To address the shortcomings of existing water safety evaluation methods in terms of scientific indicator selection and accurate weight allocation, this study focuses on the optimal selection of indicators and optimization of weight assignment, starting from five aspects of flood control, drinking water, water use, river and lake ecology, and socio-economic security. The key indicators are selected through correlation analysis, principal component analysis, and information sensitivity analysis. The combined weight method, integrating entropy weight method, analytic hierarchy process, projection pursuit model, and cloud model, is used to solve the indicator weights, which are then optimized by simulated annealing. Finally, the cloud model is employed for comprehensive evaluation, with an application case in Chenzhou City, Hunan Province. The results show that the indicator optimization identified 22 key indicators, including industrial recycled water rate and per capita water resource availability; The correlation between the weights obtained by the simulated annealing algorithm and indicator information sensitivity is the highest (R²=0.744 2), indicating a more reasonable weight distribution; The water safety status of Chenzhou City from 2016 to 2022 was generally basically safe, with a continuous improvement trend. The results validate the effectiveness and applicability of the proposed model, which provides new methodological support and practical guidance for urban water safety evaluation.

The Gan-Yue Canal is an important component of the third vertical Zhejiang-Jiangxi-Guangzhou channel in the national high-level waterway network "four vertical-four horizontal-two networks" planned by the National Comprehensive Three-dimensional Transportation Network Planning Outline. Whether the canal shipping water can be guaranteed is one of the important questions that must be answered clearly. Starting from the general situation of the Ganjiang River and Beijiang River basins involved in the Gan-Yue Canal and the basic situation of water resources development and utilization, according to the prediction of the number of gates passing through the Gan-Yue Canal and the layout scheme of the ship lock, the daily average theoretical water consumption calculation of the ship locks of each cascade hub of the canal was carried out so as to calculate the shipping water consumption and water shortage of the Gan-Yue Canal. Combined with the "Jiangxi Water Network Construction Plan", the combination scheme of normalized daily water supply of step-by-step cyclic water lifting + emergency water supply of Jifu Reservoir ( Chongxian Dam Site ) was recommended. This paper holds that the scheme of taking corresponding measures, such as water-saving technology for locks, step-by-step water lifting, and water replenishment for reservoirs, can meet the water supply demand of the cascade of water shortage hubs and solve the problem of insufficient shipping water resources in Gan-yue Canal Project. Finally, the research directions for deepening the water supply guarantee plan of shipping have been proposed.

Water body health assessment is an important tool and key means for diagnosing the functional status of ecosystems. In view of the ecological characteristics of river-type reservoirs, taking Xiluodu Reservoir as an example, a multi-dimensional health evaluation system integrating water environment, water ecology, sediment environment and water dynamics has been constructed. The framework comprises four subsystems of water environment, water ecological structure & function, sediment environment, and hydrodynamics. Nine specific indicators (under 6 criteria) including water quality, trophic status, phytoplankton, organic pollution, heavy metal pollution, and flow velocity, are chosen for quantitative evaluation. The results show that the reservoir's comprehensive health index in 2023 was 80.9, indicating an overall "Good" status. Significant spatial heterogeneity exists, upstream areas consistently outperformed mid-downstream sections, where reduced flow velocity elevates algal bloom risks, warranting management attention. While the water and sediment environments were relatively favorable, constrained hydrodynamics and low phytoplankton biomass were the key limiting factors for ecosystem health. The assessment results align closely with the observed ecological conditions, demonstrating the framework's practical applicability for health evaluation in similar river-type reservoirs.

Currently, urban wet weather overflow pollution has become one of the key factors restricting the improvement of urban water environment quality. Conducting research on the traceability of overflow pollution is of great significance for revealing the output patterns of pollutants and achieving precise control of overflow pollution. This study systematically monitored the overflow sewage at an overflow outlet of the Qinghe River in Beijing and the surface runoff in the nearby area in July 2024. Three-dimensional excitation-emission matrix fluorescence spectroscopy (3D-EEM) combined with parallel factor analysis (PARAFAC) was employed to trace the sources of dissolved organic matter (DOM) in the overflow sewage. The results indicate that the pollutant concentration in surface runoff is higher than that in overflow sewage at the initial stage of rainfall. However, as the rainfall continues, the pollutant concentration in surface runoff gradually decreases and eventually becomes lower than that in overflow sewage. Three fluorescent components are detected in the overflow sewage, namely, the fulvic acid-like component C1, the mixed component C2 of aromatic protein-like substances and humic acid-like substances, and the tyrosine-like component C3, accounting for 37.20%, 49.29%, and 13.51% of the total fluorescent components, respectively. The traceability analysis further reveals that pipeline sediments contribute the most to the DOM in overflow sewage, representing its primary source.

Chlorophyll-a is a key indicator for assessing lake water quality, but traditional point-based water quality monitoring has limitations. Remote sensing technology can provide large-scale and dynamic water quality monitoring. Therefore, utilizing multispectral remote sensing technology and considering the spectral band characteristics of the Sentinel-2 satellite, three-band and four-band chlorophyll-a concentration inversion models were constructed based on ground-measured data. The leave-one-out cross-validation method was adopted to validate the model accuracy. The optimal model was applied to monitor the chlorophyll-a concentration in Chaohu Lake from 2019 to 2023. GIS spatial analysis and statistical methods were combined to systematically analyze the spatiotemporal variation characteristics of chlorophyll-a concentration in Chaohu Lake. The results showed that the three-band model based on b₄/b₅/b₇ achieved the highest inversion accuracy. For the Sentinel-2A and Sentinel-2B three-band models, the determination coefficients (R²) were 0.763 and 0.766, the mean relative errors (M_MRE) were 16.87% and 16.66%, and the root mean square errors (R_RMSE) were 4.26 μg/L and 4.22 μg/L, respectively. Spatiotemporal analysis revealed that over the past five years, the chlorophyll-a concentration in Chaohu Lake exhibited significant spatial heterogeneity characterized by higher levels in the west and lower levels in the east, and seasonal fluctuations characterized by higher concentrations in summer and autumn and lower concentrations in spring and winter. An overall decreasing interannual trend was observed, and the inversion results were consistent with the water quality monitoring data for Chaohu Lake. The improved chlorophyll-a concentration inversion model established in this study demonstrates good accuracy and strong applicability. The proposed research method is feasible and effective, providing robust technical support for the monitoring, evaluation, and management of inland Type II water bodies such as Chaohu Lake using remote sensing.

To investigate the impact of vegetation on the motion characteristics of porous jet flow, the Realizable κ-ε turbulence model was adopted to analyze the influence laws of the jet-cross-flow velocity ratio and jet spacing on the motion characteristics of the momentum jets arranged in series in vegetated river channels from the aspects of flow velocity distribution, vortex morphology and jet trajectory, respectively. The results show that vegetation inhibits the horizontal expansion of the jets and promotes their vertical spread. At low jet-to-crossflow velocity ratios, the front jet suppresses the vertical diffusion of the rear jet, while at high jet-to-crossflow velocity ratios, the shading effect of the front jet on the rear jet is significant, allowing the rear jet to diffuse to higher positions. This study can provide theoretical guidance for the design and optimization of wastewater discharge in vegetated channels.

To investigate the influence of guide vane height on downstream helical flow in a guide-vane swirl generator, numerical simulations and physical experiments were combined. Five swirl generator models with varying guide vane heights were designed to systematically analyze circumferential velocity distribution, streamwise evolution of mean circumferential velocity, and helical flow attenuation characteristics. Results indicate that the downstream circumferential velocity follows a counterclockwise rotational distribution. With increasing guide vane height, the distribution regions of circumferential velocity and angular momentum were observed to expand significantly, resulting in enhanced helical flow intensity. The mean circumferential velocity was found to decay exponentially along the streamwise direction, though its attenuation rate showed minimal dependence on guide vane height. At a fixed downstream cross-section, the mean circumferential velocity increased with guide vane height, but this growth rate decreased progressively. When the height exceeded 35 mm, further increases had negligible effects on velocity enhancement, suggesting optimal swirl generation at 35 mm. These findings provide a theoretical foundation for the structural optimization of guide-vane swirl generators.

The river water surface profile serves as a fundamental basis for the construction of hydraulic engineering structures including levees, sluice gates, and pumping stations. In recent years, the river regime in the Middle and Lower Reaches of the Dongjiang River has changed greatly, and the extreme storm surges occur frequently in estuaries, resulting in a rising trend of the design tidal level. To study the water surface profile of the middle and lower reaches of the Dongjiang River and delta river network area under the new situation of changing boundary conditions, a one-dimensional hydrodynamic mathematical model is built based on MIKE11 software with the latest measured terrain data and design tide level. The floods in June 2022 and June 2020 are used to calibrate and verify the model. The water surface profiles of the middle and lower reaches of the Dongjiang River and the delta river network areas are calculated. The maximum water level error of calibration and verification of the model is within 0.1 m, and it can simulate the hydrodynamic conditions well. That the undercutting of the middle and lower reaches of the Dongjiang River leads to a downward trend in the water level under the same flow, and the rising design tidal level leads to the rise of water level in the lower reaches of the river network area.The change of water surface profile is in line with the actual situation. The research results can provide reference for the engineering design of embankment, water gate and pumping stations in the Dongjiang River and delta network river area.

Currently, the method of preventing siltation of water intakes in mountain rivers is a passive measure, i.e., allowing the unit to be shut down and then manually dismantling and cleaning the filter elements. This method is inefficient and time-consuming with poor safety. A new type of rotary filter is proposed to address the problems of easy clogging and high maintenance cost of traditional basket filters. FLUENT was used to establish a three-dimensional water flow mathematical model to simulate the changes in the flow and pressure fields inside the filter under the conditions of clear and muddy water, and the head loss of the traditional basket filter and rotary filter was analyzed. Compared with the traditional basket filter, it shows that the rotary filter can effectively slow down the silt fall, improve the water capacity of the filter, and effectively extend the working time of the filter. The study can provide design reference and theoretical basis for the improvement and optimization of water intake filters in mountainous rivers.

The CSGR dam of Shaping I-stage is the first application of cemented sand gravel and rock dam construction technology in the main project of large hydropower station, and its supporting design system still has many technical points to be improved. In this paper, theoretical analysis, physical tests, numerical simulation and engineering research methods were used to study the structure and structural design of the CSGR dam. The results show that the section of the CSGR dam is determined comprehensively according to the foundation conditions and dam building materials, and the single safety factor method is recommended for structural calculation; The zoning of the dam body should be divided according to functional requirements, and the rich slurry cemented sand gravel and rock can be used as the anti-seepage protective layer on the dam surface; Generally, the dam body is not provided with longitudinal and transverse joints, and transverse joints can be provided when the building layout needs and the construction strength is restricted; The anti-seepage protection layer of the dam should be equipped with transverse joints; Waterstop shall be set at the contact part between the dam transverse joint and the river to protect the internal CSGR; Temperature control measures may not be taken for the CSGR dam. The research results have accumulated valuable experience for the application of the CSGR dam construction technology in large and medium-sized projects.

The presence of near-field fracture clusters plays a critical role in governing the mechanical behavior of fracture initiation during hydraulic fracturing processes. This study systematically investigates the mechanical properties and fracture propagation mechanisms in granite through uniaxial hydraulic fracturing tests, acoustic emission monitoring, and digital image scanning techniques. Statistical analysis of the experimental data shows that near-field fracture clusters induce significant reductions in fracture initiation pressure, acoustic emission activity, and energy dissipation, all of which follow an exponential decay pattern. When fracture density exceeds two cracks, the attenuation rate of the cracking pressure has decreased significantly, indicating a diminishing influence of fracture quantity on pressure reduction. Fracture surface morphology exhibits statistically significant variations under different fracture cluster configurations, with fractal dimension demonstrating a positive correlation with fracture density. The increasing complexity of fracture surfaces with higher fracture density is characterized by a negative linear relationship between fractal dimension and initiation pressure.

In recent years, pumped storage power stations have developed rapidly, and their construction often faces the problem of mixed utilization of soft and hard rock. Soft rock has poor lithological properties, exhibiting significant breakage during construction. Whether mixtures of soft and hard rock can meet the requirements for dam strength and permeability characteristics requires further investigation. Field rolling compaction tests were conducted on soft and hard rockfill materials for a proposed pumped storage power station in Anhui Province, China, to investigate their physical, mechanical, and permeability characteristics under different compaction parameters. A comprehensive test scheme was designed to compare the compaction outcomes under combined conditions of roller weights (22 t and 26 t), water contents (5% and 10%), lift thicknesses (0.6 m and 0.8 m), and number of rolling passes (6, 8, and 10). A novel tensile direct shear test method was employed to measure the in-situ shear strength indices of the compacted rockfill and to identify the compaction parameters meeting the design requirements. This approach bridged the gap between laboratory tests and field conditions, offering a direct basis for reevaluating dam slope stability. The results showed that under identical compaction parameters, the dry density, permeability coefficient, and shear strength of the mixture containing 50% carbonaceous sericite phyllite were slightly lower than those of the sericite phyllite mixture. The dry density of the mixtures increased with the number of compaction passes, showing a convergent trend. Increasing the roller weight and reducing the lift thickness significantly improved the compaction quality. Regarding particle breakage characteristics, breakage occurred mainly in the surface layer of the lift during compaction, while the rockfill at deeper locations experienced minimal breakage due to the encapsulating effect of finer particles. The sericite phyllite mixture primarily experienced breakage of large particles, whereas the carbonaceous sericite phyllite mixture underwent repeated breakage in the surface layer during compaction, resulting in a powdery texture after compaction. Under a lift thickness of 80 cm, the strength parameters obtained using a 22 t vibratory roller with 10 compaction passes were essentially identical to those obtained using a 26 t vibratory roller with 8 passes. Based on the test results and considering both on-site construction quality and efficiency, it is recommended that for the sericite phyllite mixture, the construction parameters should be a lift thickness of 80 cm, a water content of 10%, and compaction with either a 22 t vibratory roller for 10 passes or a 26 t vibratory roller for 8 passes per lift.

This study focuses on the modification effect of incorporating polypropylene fibers to enhance the mechanical properties of self-compacting hydraulic concrete. It systematically investigates the influence patterns of fiber parameters (length and dosage) and curing time on its compressive strength, failure strain, and microstructural evolution. Experimental programs with varying polypropylene fiber parameters (length and dosage) and curing durations were designed. Multi-scale analysis was carried out through macroscopic mechanical testing and microstructural characterization techniques. At the macro level, standard compressive strength tests and failure strain measurements were conducted to analyze the mechanical response to different parameters. At the micro level, scanning electron microscopy (SEM) and computed tomography (CT) scanning techniques were employed to investigate the synergistic mechanisms between fibers and hydration products. Polypropylene fibers significantly improved the mechanical performance of the concrete through “crack bridging” and “energy dissipation” mechanisms. When the fiber dosage reached 0.8%, the compressive strength increased by up to 80.3% compared to the control group. Both compressive strength and failure strain initially increased and then decreased with increasing fiber content. Short-cut fibers exhibited the best performance due to their superior dispersion uniformity. Microstructural analysis revealed that the fibers and hydration products formed a dense three-dimensional network, effectively delaying the failure process. However, fiber agglomeration occurred when the dosage exceeded the optimal level, which weakened the overall mechanical performance. A self-compacting hydraulic concrete mix design incorporating 0.8% fiber dosage and short-cut fibers can significantly enhance the mechanical performance. The synergistic effect between fibers and hydration products is central to performance improvement, while balancing fiber dosage and dispersion is essential to prevent agglomeration. This research provides a theoretical foundation and practical guidance for improving the mechanical performance of self-compacting hydraulic concrete in hydraulic engineering applications.

In order to solve the problem of large early autogenous shrinkage and high cracking risk of the UHPC, the effects of expansive agent and shrinkage reducing agent on the early autogenous shrinkage of the UHPC were studied. The effects of single expansive agent, single shrinkage reducing agent and their combination on the autogenous shrinkage of the UHPC were tested, and the microstructure of the products was analyzed. The results show that both expansive agent and shrinkage reducing agent can reduce the early autogenous shrinkage of the UHPC, and the shrinkage reducing effect of the combined admixture is more significant than that of the single admixture. When mixed alone, the more the amount of expansive agent is, the better the shrinkage reduction effect is. The optimal dosage is 8%, and the addition of 1.5% shrinkage reducing agent has the best effect on reducing autogenous shrinkage. When the expansive agent is added alone, the pores of the UHPC matrix are filled, the structure is denser, and the ability to resist shrinkage deformation is enhanced; When the shrinkage reducing agent is single-doped, the porosity and pore size of the matrix are smaller than those of the Blank group, and the autogenous shrinkage can be reduced under the appropriate dosage. When the expansive agent and the shrinkage reducing agent are mixed, the size of the AFt crystal is smaller than that of the single-doped expansive agent group but larger than that of the single-doped shrinkage reducing agent group, the structure is denser, indicating that the both of these play a synergistic role in shrinkage reduction.

In order to deeply study the micromechanism of polypropylene steel-like fiber permeable concrete, the CT scanning technology was used to scan the specimens, and a visualization model of the pore structure was established through three-dimensional digital reconstruction technology. Based on the image analysis method, a comparative study was carried out on the morphological evolution characteristics of the internal pore system of the material before and after fiber modification. The results show that the addition of polypropylene steel-like fibers can effectively improve the strength of the specimens, but it will inhibit the water-permeability performance of the specimens. The porosity of each layer of the specimens is stable in the range of 15% and 20%, and the connected pores account for more than 97% of the total pores. In the specimens without added fibers, the number of large pores is small, but their volume proportion is large. After adding fibers, some large pores are transformed into medium-sized pores and the connectivity between pores is inhibited, thus changing the pore structure.

The excavation construction of large underground cavern chambers is prone to induce the relaxation of the surrounding rock unloading. Generally, in-situ testing methods are used to determine the relaxation depth during the construction period, but there is a lack of effective means to estimate the relaxation depth during the survey and design stage. Firstly, the characteristics of surrounding rock unloading relaxation in cavern groups are analyzed, and it is pointed out that the adjustment of the stress field is the direct cause driving the macro-mesoscopic evolution of surrounding rock and the decline of bearing capacity. At present, borehole acoustic testing technology and acoustic change rate indicators are mostly used to identify the surrounding rock relaxation depth. The surrounding rock relaxation depth of underground powerhouse for the built hydropower station is generally within 5 m. Then, a quantitative analysis method for rock mass excavation unloading relaxation is established considering damage and deterioration effects, and quantitative indicators and criteria for the evolution of surrounding rock unloading relaxation are proposed. Finally, the assessment of surrounding rock unloading relaxation is carried out for actual projects. It is found that the proposed method and criteria can further quantitatively analyze the degree of surrounding rock disturbed by excavation on the basis of traditional plastic zone indicators, so as to realize more accurate and targeted cavern support design.

In view of the problem that it is difficult to determine the optimization parameters of rock material yards and mine blasting in water conservancy projects, the traditional methods mainly rely on empirical formulas and experimental adjustments. To solve this issue, this study proposes a parameter optimization method that integrates an improved whale optimization algorithm (GWOA) with back propagation (BP) neural network. A GWOA-BP model was developed with optimization objectives focusing on explosive consumption per unit, borehole spacing, and row spacing. Comparative analysis was performed using measured blasting data of a certain project in Yunnan Province. The results indicate that the GWOA-BP model outperforms the conventional BP model in terms of prediction accuracy and stability, with error metrics significantly reduced. This research offers a novel technical approach for optimizing blasting parameters in simliar projects.

Analyzing the safety of the dam is of vital importance for maintaining their safe operation. Relying on the high asphalt concrete core rockfill dam project of the lower reservoir of a planned pumped storage power station, the mechanical characteristics tests of rockfill materials in transition layer, upstream rockfill area and downstream rockfill area were carried out. The Duncan E-B model and rheological model parameters of rockfill materials were measured. On this basis, the three-dimensional nonlinear stress-deformation finite element calculation of the dam was carried out. The safety of the dam was demonstrated from the aspects of dam body, core wall and cutoff wall. The results show that under the normal water level, the extreme settlement value of the dam is -22.29 cm and the settlement rate is 0.28%. The major and minor principal stresses of the dam are 1.38 MPa and 0.54 MPa, respectively. The extreme values of core wall displacement along the river, dam axial displacement and vertical displacement are 11.55 cm, -3.70 cm/3.63 cm and -21.46 cm, respectively. The extreme value of principal tensile strain is -0.8%. The extreme displacement values of the cutoff wall along the river, the axial direction and the vertical direction of the dam are 1.32 cm, -0.11 cm/0.02 cm and -0.54 cm, respectively. The extreme values of major and minor principal stresses are 6.82 MPa and -1.20 MPa respectively. After rheology and wetting are taken into account, the extreme value of dam settlement is -35.00 cm, and the settlement rate is 0.44%. The extreme values of core displacement along the river, dam axial and vertical displacement are 13.65 cm, -4.97 cm/4.77 cm and -33.01 cm, respectively. The comprehensive analysis results indicate that the distribution and extreme value of stress and deformation of the dam are reasonable, and the tensile strain of asphalt concrete core wall and the tensile stress of concrete wall in dam foundation are not beyond the standard value, so it can be judged that the dam can meet the requirements of safe operation.

To reveal the influence of aftershocks on the failure process of gravity dams, the Jinanqiao gravity dam is chosen to perform the investigation. The impact of reservoir water was simulated by using Westergaard additional mass. The elastoplastic damage model was adopted to simulate the nonlinear characteristics of the concrete material of the dam body, and the nonlinear failure process of the dam body under the action of a single main shock and main aftershocks was calculated. The results show that the failure pattern of the dam body under the main aftershock is consistent with that under the single mainshock. The failure areas are mainly concentrated at the dam heel, the upstream and downstream folded slope, and the downstream dam surface. The aftershock effect will cause the further development of the main earthquake damaged area and significantly increase the cumulative plastic dissipation energy of the dam body. The cumulative plastic dissipation energy caused by aftershocks gradually increases with increase of the PGA. After the PGA reaches 0.45g, the contribution of aftershocks to the cumulative plastic dissipation energy gradually stabilizes at around 30%. In terms of seismic performance, the ultimate seismic bearing capacity of the dam body is in the range of 0.50g and 0.55g under the action of a single main shock, while under the action of the main aftershock, it decreases to 0.40g-0.45g.

Tailings dams are formed through long-term accumulation of tailings, featuring complex stratification and non-uniform permeability coefficients. To obtain representative permeability coefficients that reflect their overall permeability characteristics, a novel inversion method was proposed. Optimal Latin Hypercube Sampling (OLHS) was used to obtain uniformly distributed samples of permeability coefficient combinations for tailings dams. These samples were then input into a finite element model for forward analysis to obtain corresponding samples of water heads at monitoring points. The two sets of samples were combined to form a dataset. A nonlinear mapping relationship from the permeability coefficients to the water heads at monitoring points was established using the Kernel Extreme Learning Machine (KELM). The hyperparameters of the KELM were optimized using an Improved Animated Oat Optimization (IAOO) algorithm, which integrated Latin Hypercube Sampling for population initialization, centroid opposition-based learning, and an adaptive optimal-seeking boundary mechanism. An inversion model for the permeability coefficient of tailings dams based on OLHS-IAOO-KELM was thus established and subsequently applied to a practical engineering case. The permeability coefficient values obtained through the inversion model were reasonable. The relative errors between the calculated water heads from forward seepage analysis and the measured water heads at the seven monitoring points did not exceed 2.08%, meeting the engineering accuracy requirements. Furthermore, the potential distribution of the seepage field in a typical cross-section of the tailings dam conformed to general patterns. Compared with other models, the inversion result of the proposed model exhibited the smallest errors. The proposed model demonstrates high accuracy and robustness, and possesses practical value for the inversion of permeability coefficients in tailings dams.

Computational fluid dynamics (CFD) method was used to numerically simulate the two-phase flow on stepped spillways to investigate the initiation mechanism of self-aeration in stepped spillways and clarify the impact of step length on the self-aeration characteristics of stepped spillways with non-uniform step lengths, including concave, convex, random, and semi-uniform step length configurations. Compared with the traditional uniform steps scheme, the results show that both concave and convex configurations prove unsuitable for rapid initiation of self-aeration, leading to a 6.4% and 7.0% posterior shift in the aeration inception points. Although random step configuration promotes the development of turbulent boundary layers to some extent, the inherent uncertainty in their step length arrangements induces excessive surface fluctuations. The semi-uniform step scheme can significantly move forward the position of the initial aeration point (by 18.8%) while ensuring a relatively stable flow state, which has a broader application prospect.

In response to the challenges of significant water hammer protection difficulty at the terminal section of long-distance water conveyance projects and the complexity of dynamic regulation for pressure extremes, The characteristic line method for transient flow calculation was used to investigate the impact characteristics of dynamic closure of different branch line valves on pipeline pressure control during pump shutdown. Research demonstrates that in terminal water hammer protection for long-distance water supply pipelines, implementing a multi-unit one-way surge tank system with coordinated stepwise protection achieves good protective effect. When adopting a phased closure strategy for mainline-branch line valves, accelerating the closure of one branch valve can enhance protective performance. Reducing the cross-sectional area of one-way surge tanks can reduce the final water level of the towers, enabling dynamic regulation of pressure extremes without affecting the minimum pressure. The study elucidates the collaborative wave-dissipation mechanism between multi-tank joint protection and branch valve closure coordination. An optimal water hammer protection solution is proposed that balances engineering safety and economic benefit. These findings provide theoretical basis for designing long-distance water conveyance systems in complex terrains.

The effective utilization of digital simulation technology for the synergistic optimization of secondary water supply systems and urban main water supply systems has emerged as a critical necessity in the water supply sector. This optimization aims to achieve leakage control in pipelines and reduce energy consumption while aligning with carbon neutrality objectives. This study presents a comprehensive approach that incorporates the sum of water charges and electricity costs as the objective function, leveraging a combination of EPANET 2.2, MATLAB, and the EPANET-MATLAB Toolkit. We propose an optimization model that employs the Cuckoo Search Algorithm to facilitate the real-time scheduling of pump operations and inflow rates within the secondary water supply system. The proposed optimization model was validated through application to a small-scale water supply network. The results show that the total costs reduce 3.5% over a 24-hour period, with water charges decreasing by 0.63% and electricity costs decreasing by 9.9%. The developed optimization model serves as a significant reference for the future advancement of green, safe, and intelligent water supply management practices.

To enhance operational efficiency and safety of low-lift, high-flow vertical shaft tubular pumping station, taking a large-scale pumping station in Tianjin for an example, the optimization design of inlet and outlet flow passages was conducted by the CFD numerical simulations. The practical aspects including flow passage head loss, velocity uniformity, motor chamber space, and hoisting equipment capacity were studied. By considering the characteristic flow rates and lift of the pumping station, optimal combinations of hydraulic models and flow passages were selected. The overall energy performance of the pumping station system was simulated to evaluate its applicability and efficiency. The design scheme was further validated through physical model tests. The results demonstrate that inlet flow passage schemes J1 and J2 exhibited favorable velocity uniformity and head loss characteristics, with scheme J1 showing marginally superior performance. For outlet flow passages, schemes C1 and C2 displayed comparable performance, though C2 offered a more rational equipment layout due to its shorter transition section. The combined scheme J2+C2 proved suitable for low-lift, high-flow pumping stations when considering motor chamber dimensions and gate design. Ultimately, the TJ04-ZL-06 hydraulic model (impeller diameter of 4 m, rotational speed of 88.9 r/min, blade installation angle of -6°) was recommended, ensuring safe and efficient operation across the specified lift and flow rate ranges.

To study the vibration characteristics when the steel flow channel of the pumping station interacts with unsteady turbulence, this article establishes a fully coupled vibration analysis model of pump room-pump-water system with steel flow channel using ADINA software. The law of fluid pressure pulsation in the entire flow channel is studied. The time history and frequency spectrum characteristics of the vibration displacement of the steel flow channel structure are analyzed. The results show that fluid pressure pulsation in the steel flow channel is generated at the impeller and transmitted to the inlet and outlet channels, respectively. The vibration characteristics of the steel flow channel structure are similar to the pressure pulsation of the fluid, indicating that the vibration of the steel flow channel is mainly affected by the interaction between the water pressure pulsation caused by the rotation of the impeller and the pipe wall of the flow channel.

The hydraulic performance in the suction pool of the pump house directly affects the safe and stable operation of the circulating pump. A physical model was established based on the actual project of a pump house for power plant. The effects of combinations such as the height and quantity of the diversion piers and diversion walls in the forebasin and suction pool of the pumping station, as well as the submerged depth of the water blocking breast wall, on the hydraulic performance of the suction pool in pumping station were studied through physical model experiments. The results show that no rectification measures are taken in the front pool and suction pool of the pump house, reflux vortex appears in the suction pool, and vibration noise occurs in the circulating pump. The double row diversion pier is arranged in the suction pool to increase the bottom elevation of the retaining wall in the suction pool of the pump house, while reducing the height of the second row diversion pier. The uneven distribution of flow velocity in the suction pool of sections G and H and the weighted average angle of flow velocity increase the most. The rectification effect in the suction pool of the pump house is the best. The research results can provide reference for the rectification measures in suction pool of similar pump house.

Aiming at the problems of excessive vibration, high noise and low efficiency existing in the same-speed reverse power generation of Huaiyin No.2 Pumping Station, a scheme including a four-quadrant frequency converter, a bypass system and protection setting is proposed, and its mechanism of action in the reverse power generation process is analyzed. The three-stage architecture of the four-quadrant frequency conversion system provides a topological basis for bidirectional energy flow. The interlocking mechanism of the bypass system solves the safety problem of multi-condition switching. The hierarchical protection system realizes the risk control of the whole life cycle of equipment. The vibration online monitoring system and energy efficiency curve comparison are used to verify the effect. The results show that under the four-quadrant frequency conversion speed reduction power generation mode, the vibration amplitude of the impeller chamber is reduced by 78.11%, the power generation efficiency is increased by 45.05%, and the noise is reduced by 10 dB. Various performances are significantly improved, which provides theoretical support for the standardization of reverse power generation technology in low-lift pumping stations.

An improved hybrid prediction model SSA-BP based on intelligent optimization algorithms was developed to address the complex nonlinearities and uncertainties inherent in slope displacement prediction in reservoir areas. This methodology effectively overcomes the limitations of the traditional BP networks, such as slow training speed and susceptibility to local optimum so as to improve the accuracy and robustness of slope displacement prediction. Through the global optimization of initial weights and thresholds using the Sparrow Search Algorithm (SSA), convergence and adaptability of the model was improved. The proposed model was trained using five-month real-time displacement monitoring data obtained from the Zhangjiawan slope. A comparative performance analysis was conducted between the SSA-BP model and BP networks optimized by genetic algorithm (GA) and particle swarm optimization (PSO). The results demonstrate that the SSA-BP model achieves rapid convergence within 24 iterations, significantly outperforming the comparative models. Evaluation metrics including root mean square error, mean absolute percentage error , and coefficient of determination (R²) reveal superior performance of the SSA-BP model. This research presents a reliable and efficient intelligent approach for accurate and robust slope displacement prediction in reservoir area.

Anomaly detection in gravity dam monitoring data is critical for dam safety assessment. To overcome limitations of existing methods in pattern identification and feature extraction, this paper proposes a hybrid anomaly pattern detection method based on VMD-SSA-KMeans-iForest. By introducing variational mode decomposition (VMD) to optimize the decomposition process, the accuracy and robustness of feature extraction is significantly improved. Furthermore, an anomaly detection framework is established by combining K-means with isolation forest. This method is applied to the identification of abnormal data of the W gravity dam. The results demonstrate that the proposed method achieves a 2.5% improvement in anomaly detection accuracy while effectively distinguishing between anomalies caused by structural damage and those resulting from instrument failure,which provides more reliable technical support for the safety assessment of gravity dams.

This study aims to comprehensively evaluate the safety status of earth-rock dams.The seepage conditions of the earth-rock dam were calculated using the equivalent method in conjunction with Autobank software. The dam slope stability analysis and seismic safety evaluation were performed using the Bishop method. The results indicate that the maximum daily leakage of the dam accounts for only 0.25% of the total reservoir capacity, which is relatively low. Additionally, the infiltration line is below the design value, and the infiltration ratio drop at the escape point is within permissible limits, indicating no risk of seepage damage. The safety coefficients for anti-slip stability of both the upper and lower slopes exceed the minimum values specified in the regulations, confirming that the dam slope stability meets the required standards. These findings provide a scientific basis and technical support for the safety management and future maintenance of reservoir dams, ensuring the high-quality development of water conservancy projects.

In response to the problem of traditional machine vision technology requiring specialized targets to assist in measuring dam surface settlement in complex terrain, this study proposes a machine vision measurement technology for dam surface settlement using the natural patterns or natural features (such as bedrock, mountain body, etc.) of the existing objects on the dam surface as markers. A fixed point region image registration method that simplifies the projection model has been developed. By deriving and simplifying the estimation of the projection model, the application scenarios of the model have been extended, and the image can be effectively corrected. An accelerated robust feature transformation algorithm is integrated to extract the features of natural markers, accurately match the image feature lattice, and then calculate the average pixel displacement of the markers. By obtaining the proportional relationship between pixel distance and physical distance, the true displacement of the markers can be calculated. The experimental results show that within a monitoring distance of 70 m, the measurement accuracy is in the range of -1.00 mm and 1.00 mm, effectively solving the problem of low-cost wide area monitoring of dam surface settlement, which can be applied in practical engineering.

This paper focuses on the renovation project of Jianzhong Pumping Station in Hebei Province. The computational fluid dynamics (CFD) technology was used to optimize the rectification measures of the forebay of the side-inlet axial flow pump, as well as the inlet and outlet flow passages, and simultaneously predict the energy performance of the pump unit. Based on the CFD optimization of the inlet and outlet flow passages of the pump unit, a model test study of optimization scheme for pump unit was carried out. The test results show that the efficiency of the pump unit reaches 73.8% under the design lift, which is basically consistent with the prediction conclusion of the CFD method. This study indicates that when optimizing the flow passage design of the axial flow pump unit, giving priority to using the CFD technology to select the optimal schemes for the inlet and outlet flow passages of the pump unit and then verifying through the model test of the pump unit can greatly save the investment cost and accelerate the project progress, providing a reference for similar projects.

In the operation of hydroelectric generating unit, thrust bearings generate a considerable amount of residual heat due to load-bearing, friction, and other factors. Poor heat dissipation performance of lubricating oil can give rise to the tile burning phenomenon, thus causing massive economic losses. Nanoparticles can not only improve the lubrication characteristics of lubricating oil but also enhance the heat transfer process of lubricating oil. Accordingly, through numerical simulation, this study examined the heat dissipation enhancement effect of lubricating oil in thrust bearings when reinforced by nano-copper oxide particles with different concentrations (0.1wt%, 0.3wt%, 0.5wt%). The results demonstrate that the addition of nano-copper oxide can enhance the heat dissipation efficiency of lubricating oil, and the most favorable heat dissipation effect is achieved when the concentration of nano-copper oxide is 0.5wt%.

Under single-nozzle operating conditions, the radial force of the runner for large-scale impulse turbine abnormally increases, severely affecting shafting stability. This study establishes a dynamics model of the bearing-rotor system incorporating the runner, main shaft, and bearing supports. The critical speed and vibration mode characteristics of the shafting system were calculated by using COMSOL Multiphysics software. And then the transient response characteristics under different radial hydraulic thrust forces were analyzed. The results indicate that the first-order critical speed of the unit shafting is 534.49 r/min, meeting the design specification requirements. The radial hydraulic thrust under single-nozzle operation can be considered as a constant radial force. The centroids of shaft orbits in all guide bearings exhibit displacement under radial hydraulic thrust, with the maximum offset observed in the turbine guide bearing. Analysis reveals that during single-nozzle operation, the resultant radial force on the water guide bearing concentrates on the one side, fluctuating within approximately ±1.5° relative to the jet direction. This research can provide reference for structural optimization and operational control of impulse turbine units under special operating conditions.

The joint optimal operation of multi-source gate-dam groups is the key to balance multiple objectives like water level, water quality, water efficiency, and costs in water network scheduling. This study focuses on the cascade scheduling system of the Suqian Yellow River Old Course. Considering water level control, water quality compliance, cost reduction, and efficiency improvement, a multi-source gate-dam joint scheduling optimization model was established by coupling a hydrodynamic-water quality model with the NSGA-Ⅱ algorithm. Using the mechanism of "scheme generation-process simulation-effect evaluation-feedback optimization", the Pareto optimal solution set was iteratively solved. The comprehensive optimal scheduling solution was determined by the entropy weight method. The results show that the significant multi-objective conflicts among water level, water quality, efficiency, and cost in the study area; The cost and efficiency are inversely constrained; The relationship between water quality and water level is non-monotonic; There is a positive synergy interval between efficiency and water level; The cost and water quality mutually restrict each other; The proposed model can effectively balance these four objectives, with the comprehensive optimal solution yielding values of 0, 0.09, 0.24, and 0.12, respectively, achieving integrated optimization compared to single-objective solutions. The proposed method can provide crucial support for solving optimal scheduling problems involving multiple water sources, projects, and objectives.

Small hydropower has the characteristics of small capacity, multi-point distribution and strong basin correlation. The traditional follow-up power generation mode is disorderly, and the flexible and adjustable value of small hydropower groups has not been fully utilized. The evaluation and optimization of adjustable capacity is the key to support the peak regulation of power grid and the accommodation of wind, solar and electricity. Based on the runoff prediction of small hydropower groups in the basin, it is proposed that the output corresponding to the maximum power generation flow of the current water level of small hydropower is the upper limit of adjustable output, and the output corresponding to the ecological installed capacity is the lower limit. The adjustable capacity interval of small hydropower is determined, and then the adjustable capacity optimization model of small hydropower groups in the basin is constructed and an improved particle swarm optimization algorithm is proposed. Taking the five series runoff power stations of Liangqian, Dayan, Kongtou, Fancuo and Gaotang in Jinxi River Basin as an example, the rainfall-runoff process simulation is carried out to analyze the coupling relationship between the storage capacity of small hydropower group and its power generation and inflow flow, and the optimal output and adjustable output interval of small hydropower group in the basin are optimized. The results show that after optimization, the adjustable capacity interval is increased, the upper limit of the adjustment capacity is increased by 12.1 %, and the actual output is increased by 14.6 % compared with that before optimization. The optimized output mode can support the power grid to adjust the output of small hydropower in a larger interval, which can provide decision support for the power grid dispatching department to tap the flexibility value of small hydropower resources and give full play to its peak regulation and consumption capacity.

To systematically investigate the impacts of wind and solar power integration on medium-to-long-term optimal scheduling of the Qingjiang cascade hydropower stations, a multi-objective optimization model for coordinated hydro-wind-solar operation was established. The objective function was reconstructed through objective transformation integrated with penalty mechanisms and solved using the progressive optimization algorithm (POA). Case studies demonstrate that the model simultaneously ensures system power generation while achieving complementary coordination between cascade station operations and renewable power output. Through analysis of complementary coordination effects and reservoir level variations, operational pattern modifications for the Qingjiang cascade reservoirs were extracted: following renewable integration, storage/discharge strategies should be prioritized for adjustment during wet/normal years based on inflow characteristics. This adaptation reserves additional storage capacity to flexibly accommodate complementary coordination requirements with renewables while fulfilling power generation demands.

After the operation of Wudongde, Baihetan, Xiluodu and Xiangjiaba hydropower stations (XJB), the channel conditions in the lower reaches of the Jinshajiang River have been greatly improved, which prompts the ships in this section of the river to increasingly develop towards larger sizes. When encountering the dry inflow from the Jinshajiang River, the water depth of the channel from Xiangjiaba to Yibin River is shallow, and the passage of large cargo ships is difficult, which affects the shipping efficiency of the river section. By analyzing the relationship between the loading capacity of the main ship types and the discharge from XJB, the optimal seaworthy discharge of the river section is obtained. Combined with the actual operation of the ships at the wharf, a tidal shipping scheduling model was established by intermittently releasing the seaworthy flow of XJB, and a variety of schemes were proposed to simulate the calculation. The results show that the XJB can increase the navigation time of large ships, increase the average cargo volume of a single ship by 16%, and increase the power generation head by 0.31 m, and has a positive impact on promoting the exchange of water bodies in the reservoir area. The research results can provide references for regional shipping scheduling management.

The spur dikes are widely applied in marine and estuarine engineering projects, and its surrounding local sediment scouring and silting characteristics directly affects the safety and stability of the project. Existing studies primarily rely on physical experiments or empirical prediction formulas, lacking a deep understanding of the flow structure and sediment transport patterns. Based on the software Delft3D, this paper presents a numerical simulation of the local sediment scouring and silting characteristics of spur dikes under clear water conditions and performs reliability verification. The sediment scouring and siltation characteristics of single dam and spur dike are compared. The diversion characteristics, local bed shear stress and local sediment scouring and siltation patterns of the spur dikes are analyzed, and the impact of dam length and flow velocity is discussed. The results show that the when the spur dike spacing decreases by 40 m, the maximum dimensionless shear stress increases from 2.56 to 7.48. An increase of flow velocity further expands the flow diversion range and the density of streamlines, with the maximum dimensionless shear stress rising from 3.17 to 5.60; The increase is approximately 76.7%, and the area percentage of high shear stress zones increases from 20.27% to 34.44%. Additionally, when the spur dike spacing is reduced by 20 m, the maximum scour value at the dam head increases by approximately 45.89% to 59.92%; When the flow velocity increases, the maximum scour value increases by about 13.41%, while the scour pit area expands and the sediment deposition area spreads. This study can provide theoretical support for optimizzation design of spur dikes.

As a "last resort" for flood control, the effectiveness of flood control projects in flood detention area is crucial for accurately assessing the overall flood control capacity of the area. Based on a one- and two-dimensional coupled hydrodynamic model and scenario analysis method, the effectiveness of flood control projects was evaluated by simulating the flood evolution process in the Xiaoqing River flood-diversion area. The results show that by simulating floods for different recurrence periods before and after the construction of flood control projects and comparing the different evolution results of floods in watercourse and on the surface, the effectiveness of flood control projects can be analyzed in detail, and the overall flood control capacity of the flood diversion area can be effectively evaluated; Three of the flood control projects currently being implemented in the Xiaoqing River flood diversion area in Beijing can achieve the expected flood control effects. Specifically, Project A can effectively protect the flood control safety of the left bank of the Dashijiang River; Project B can facilitate the rapid passage of released flood from the Danning Reservoir through the railway culvert in the flood diversion area; Project C ensures that the discharge of the Xiaoqing River during flood diversion does not exceed 500 m³/s, meeting the requirements of flood control. The proposed method can quantitatively analyze the effect of flood control projects and is of great significance for guiding the planning and construction of flood control projects in flood detention areas and the safety assessment of these areas.

The environmental characteristics of ultra-high altitude areas will affect the air flow and heat exchange process of the ventilation and cooling system of the generator motor, which will lead to the reduction of the cooling effect of the generator motor. In this paper, the key influencing factors of ventilation and cooling system of generator motor in ultra-high altitude environment are analyzed by mathematical model. Based on the finite element simulation, the ventilation and cooling system model of the generator motor is established and quantitatively designed considering the flow field, temperature field and conjugate heat transfer conditions. Finally, the optimal design measures of the ventilation and cooling system of the generator motor under the condition of ultra-high altitude are put forward. The research results provide a theoretical basis for the efficient and stable operation of generator motor in ultra-high altitude environment, which can effectively promotes the technological progress and development of the related industries.