In the context of global warming， the advancement of vegetation spring phenology due to rising temperatures is well documented. Climate warming also leads to increases in soil moisture （SM） deficit and vapor pressure deficit （VPD）. However， as necessary water conditions for vegetation growth， their effects on vegetation spring phenology remain unclear. Therefore， based on the solar-induced chlorophyll fluorescence （SIF） data set， this study extracted the parameters of the start of the season （SOS） of vegetation in spring in China from 2001 to 2018 through the Polyfit-derivative method， the double-logistic Maximum Curvature method and the Timesat method. Secondly， the VPD values of the study period were calculated by using the China meteorological forcing dataset and Penman formula. Finally， Teil-Sen Median trend analysis， Mann-Kendall test and sensitivity analysis were used to clarify the spatio-temporal variation rules of SOS， VPD and SM， and to reveal the influence mechanism of spring SM and VPD on SOS. The results show that： ① SOS first gradually delays with the increase of latitude， and starts to fluctuate steadily at the north of 35°N， with an average SOS on the 130th day of the year； ② In spring， SM and VPD showed a large area of non-significant drying trend， soil moisture decreased at a rate of 0.037 m³/（m³?10 a）， VPD increased at a rate of 0.34 hPa/10 a， and SOS showed a large area of non-significant advance trend at a rate of 5.1 d/10 a. ③ SOS in arid areas were most sensitive to the changes of SM and VPD in spring， and with the decrease of SM gradient in spring， the importance of VPD to SOS gradually increased， and the importance of SM gradually decreased. This study is important for understanding and predicting the response of vegetation growth to the change of water conditions under the background of global warming， and for formulating policies to deal with climate change， and can provide scientific basis for ecological environment construction in China.

As the mother river of Northeast China， assessing the value of water ecosystem services of the Songhua River Basin is of great significance to the sustainable development of the Songhua River Basin ecosystem. Using 2020 as the base year， this paper adopts the InVEST model method， market value method， equivalent factor method， apportionment method and other evaluation methods to quantitatively assess 12 indicators of the Songhua River Basin， including water resource supply， fishery products， hydroelectric power generation， river sand mining， water conservation， water purification， carbon sequestration and oxygen release， biodiversity， soil preservation， recreational tourism， inland shipping， and scientific research and education.The results show that the total value of water ecosystem services in the Songhua River Basin in 2020 is 590.732 billion yuan， accounting for about 43.12% of the GDP of Heilongjiang Province in 2020. The value of regulating function accounted for 72.32% of the total value of water ecosystem services， taking the first place； the value of supporting function and service function accounted for 10.63% and 12.20%， respectively； and the value of providing products was the smallest， only 4.84% of the total value. This paper scientifically establishes the evaluation system of water ecosystem service value in Heilongjiang Province， which provides scientific basis and data support for accelerating the construction of compensation mechanism and proposing practical ecological compensation countermeasures.

Climate change and human activities have increasingly significant impacts on the ecological health of the Dawen River. To maintain the stability of river ecological health， it is crucial to carry out ecological flow evaluation. This study focuses on the the Jinan section of the Dawen River Basin， utilizing multi-source remote sensing data to extract water body area information. A fitting equation is constructed from the water body area and the measured flow， to determine the ecological water body area corresponding to the basic ecological flow. Ecological flow evaluation is then conducted based on remote sensing data. Research results show that，from 1985 to 2021， the water body area of the Jinan section in the Dawen River Basin is 41.84 km²， and the water body area shows an increasing trend， of which seasonal water bodies account for 32% and permanent water bodies account for 68%. Among the six water body indices， EWI and NDWI are suitable for the Jinan section of the Dawen River basin， with an accuracy of 90%. Through linear fitting analysis， the ecological water body areas of the Chenbei and Maxiaozhuang watersheds are 13.98 km² and 18.49 km² respectively. The ecological flow guarantee rates from 1985 to 2021 are 65% and 42% respectively. Affected by natural factors and human factors， significant changes in the ecological flow guarantee rates were observed around 2004， increasing from 43% and 7% to 83% and 73% respectively， and reach 100% by 2020. Cross wavelet and wavelet coherence spectrum analysis results show that the water body area is positively correlated with the climate factors of precipitation and average humidity， negatively correlated with average wind speed， and has no significant coherence with average temperature. Precipitation and average humidity are the main factors affecting changes in the water body area. Among land use factors， changes in water body area are mainly affected by the area of cultivated land and grassland， showing a negative correlation. Based on the different water body areas ratio in the basin， it is determined that the ecological water body area of Xueye Reservoir is 10.82 km²， the ecological water level is 228.97 m and the ecological storage capacity is 102 million m³. The research results can provide technical support for ecological flow evaluation， supervision and dispatch in the Dawen River Basin.

This article focuses on the influence of blade inlet at different positions on the hydraulic performance of centrifugal pumps. NM150-250/30 centrifugal pumps are taken as the research object， and a combination of experimental testing and CFD numerical simulation is used to analyze and explore the external characteristics and internal flow field of centrifugal pumps. SOLIDWORKS software is used to establish three different impeller models， TurboGrid is used for Hexahedron mesh generation， and CFX19.2 is used for steady numerical simulation. The research found that as the blade inlet of the centrifugal pump extends forward towards the impeller inlet， the head and efficiency values of the centrifugal pump also increase under the design conditions. Moreover， under low flow conditions， the flow head curve of the centrifugal pump shows a saddle zone similar to that of a mixed flow pump， and the pump efficiency rapidly decreases and the high efficiency zone is narrow. As the position of the blade inlet continues to extend forward， the inlet reflux generated by the flow under low flow conditions continues to increase， the centrifugal pump saddle zone expands， and the flow state deteriorates.

In an effort to suppress cavitation in low-specific speed centrifugal pump， a method of changing the axial angle of slotted blade was proposed， and three oblique slotted blade schemes were designed. By using numerical simulation methods to compare the experimental results of centrifugal pumps， analyze the effect of blade oblique slotting on the suppression of cavitation in centrifugal pump. The simulation results show that the oblique slotted blade with an axial angle of 5° has the most significant cavitation suppression result on low-specific speed centrifugal pump， and the fracture head is increased by 0.281 m. The oblique slotted blade suppress the development of cavitation in the flow field of the centrifugal pump impeller， and the maximum reduction in cavitation volume is 67.25% during the severe cavitation stage； The oblique slotted blade optimize the flow field structure of the impeller， reduces the low-pressure area at the impeller inlet， and reduces the turbulent kinetic energy in the impeller channel.

The rational layout of spur dikes has a significant impact on the flow structure， patterns of fluvial erosion and deposition. In addition to serving as a protective measure for riverbanks， these dikes also play a role in promoting the formation of various riverbed features， such as deep pools and shallow shoals nearby. These unique characteristics create a rich habitat for aquatic organisms， thereby enhancing ecological sustainability and development. Using the computational fluid dynamics （CFD） technique and the RNG k-ε model for parameter calibration and verification， this study undertakes a rigorous investigation into the hydrodynamic properties and the fluvial erosion-deposition processes occurring in the vicinity of spur dike units with diverse deflection angles situated at the concave bank of a 180° bend. The results indicated that， in relation to energy dissipation and water level fluctuations， the spur dike with a 90° deflection angle exhibited the most prominent characteristics， yielding the greatest water level disparities and the most significant energy losses. The spur dike exhibiting an upward deflection angle occupied a secondary position， whereas the spur dike with a downward deflection angle demonstrated the least noteworthy effects. Furthermore， a positive correlation was identified between vortex intensity and the degree of riverbed erosion and deposition. Counterclockwise vortices contributed to deposition， whereas clockwise vortices were prone to cause erosion. In terms of the distribution of shear stress， the scope and magnitude of the intense shear stress zones formed at the head of the spur dike and on the opposite bank exhibit a distinct pattern where the spur dike with a 90° deflection angle shows the largest impact， followed by the upward deflection spur dike， and the downward deflection spur dike demonstrates the smallest impact. So， the selection of deflection angles for spur dikes significantly influences riverbed scouring and deposition， water flow characteristics， and ecological outcomes. It is crucial to scientifically and rationally design and arrange spur dikes to achieve a balance between controlling riverbed scouring and deposition， preserving ecological balance in river channels， and ensuring the safety of engineering projects.

As a relatively stable component of river runoff， baseflow is also the main source of runoff during dry season in arid and semi-arid areas， which is of key significance to the optimal allocation of water resources and the maintenance of ecological environment in the basin. The accuracy of baseflow separation results has a great influence on the prediction of hydrological processes in the basin and the investigation of baseflow change rules. As an important tributary of the middle reaches of the Yellow River， the Fen River is related to the economic development of the whole middle reaches area， and the study of baseflow change of the Fen River can effectively characterise the change mechanism of the baseflow in the middle reaches of the Yellow River， so it is particularly important to select the appropriate separation method. There are many baseflow separation methods， among which numerical simulation method is widely accepted in practical application because of its objectivity， repeatability and ease of operation， as well as efficient and convenient processing of long series of lengthy and complicated data. Based on Jingle hydrologic station daily runoff data from 2006 to 2014， eight commonly used numerical simulation methods are used to separate the base flow， and the intra-annual and inter-annual variation characteristics of the runoff are analyzed. The characteristics are analyzed from three perspectives： the base flow index of instability coefficient， standard deviation and coefficient of variation； we also study the correlation of base flow index in typical years of base flow and runoff process. To test the validity of the base flow separation results， three indexes are selected：Nash-Sutcliffe efficiency coefficient， the average relative error and the correlation coefficient. The results show that： The Chapman filtration method， the Chapman-Maxwell filtration method and the Eckhardt filtration method proved to be the most suitable methods for separating base flow at the Jingle hydrological station. The calculated BFI values are 0.491， 0.495 and 0.496 respectively. The results of the study provide technical support for the study of baseflow separation and change rule of baseflow in the middle reaches of the Yellow River， and provide scientific basis for the rational use of water resources in the middle reaches of the Yellow River and better construction of the local ecological environment.

Located in the northwestern region of Yunnan Province within the Lancang River Basin， the HD Reservoir area features a high-mountain canyon terrain with complex engineering geological conditions， hosting numerous landslides that pose significant monitoring challenges. In order to enhance monitoring of the CYP landslide in the HD reservoir area， this study utilized 28 descending and 24 ascending radar images from the Sentinel-1A satellite between July 2020 and July 2021. The SBAS-InSAR technique was employed to analyze and obtain the temporal deformation rates of the CYP landslide in both ascending and descending tracks. The results indicate that the maximum deformation rate in the Line of Sight （LOS） direction of the CYP landslide is -150 mm/a， with a cumulative maximum vertical deformation of -172 mm， indicating continuous sliding. By comparing and analyzing the temporal monitoring results of the ascending and descending tracks with the existing GNSS monitoring data， it was found that the vertical deformation extracted from the descending track analysis results in the CYP landslide area exhibits a high degree of consistency with the GNSS vertical deformation， aligning well with the actual situation， which can provide valuable insights for landslide identification and early warning systems. Furthermore， comparative analysis of temporal deformation with reservoir water levels and rainfall revealed a close correlation between the deformation of the CYP landslide and reservoir water levels， as well as rainfall in the area.

Reservoir flood control scheduling is crucial for effectively reducing flood disasters and ensuring the safety of lives and property. This process is a multi-stage， nonlinear， high-dimensional engineering problem with complex constraints and interdependent decision variables. To improve the efficiency of solving the optimal scheduling problem of reservoir groups and fully utilize their coordinated flood control capabilities， this paper proposes an Improved Sand Cat Swarm Optimization Algorithm （SCSO）. The algorithm incorporates the Cubic chaotic mapping strategy to enhance the dispersion and uniformity of the scheduling plan. Additionally， the whale algorithm's spiral search strategy is introduced to improve the population's local and global search capabilities， and the sparrow algorithm's warning mechanism is integrated to boost global search ability in later stages. The algorithm's accuracy is validated using classical test functions and rank sum tests. Results demonstrate significant improvements in the convergence speed and accuracy of the improved Sand Cat Swarm Optimization （ISCSO） algorithm. For the first time， this algorithm was applied to the optimization and scheduling of flood control in reservoir groups. A maximum peak shaving criterion model was established at flood control points， and the joint flood control scheduling system for five reservoirs in the middle and lower reaches of the Yellow River was studied. Comparative analyses were conducted with the original Sand Cat Swarm Optimization （SCSO） and the Dung Beetle Optimization （DBO） algorithms. The peak flow rate at control points obtained by the DBO algorithm was 21 274.3 m3/s， with a peak shaving rate of 46.62%. The SCSO algorithm yielded a peak flow rate of 21 248.6 m3/s， with a peak shaving rate of 46.68%. The ISCSO algorithm achieved a peak flow rate of 20 687.1 m3/s， with the highest peak shaving rate of 48.09%. These results indicate that the ISCSO algorithm achieves the best peak shaving performance for reservoir flood control scheduling， effectively shifting downstream peaks and ensuring the safety of downstream rivers and flood control points. The findings of this research provide new insights and methods for optimizing flood control scheduling in reservoir groups.

With the economic and social development of the Han River basin， the pressure on the water environment and water ecology has increased， and the implementation of the water diversion project from the Yangtze river to the Han River may lead to further changes in the quality and quantity of water in the Han River. Therefore， it is of great significance to carry out simulation analysis and prediction of water quality and water quantity in the middle and lower reaches of the Han River before and after the water diversion project， in order to control the pollution of water bodies in the basin. In this paper， we predicted the water quantity and quality response of Huangjiagang-Wangfuzhou section after the diversion of water by using the segmented Muskingum method and one-dimensional and two-dimensional water quality models. The results show that： ① After the river diversion project adopts the year-round uninterrupted water diversion method to divert water， the flow of the Huangjiagang-Wangfuzhou river section increases， and the increase of flow in the summer flood is higher than that in the fall flood， and the increase of flow in the Wangfuzhou section is slightly higher than that in the Shenwan section； ② Before and after the water transfer， the average monthly total phosphorus concentration in Shenwan section reached the water quality standard of Class II， and the average monthly total nitrogen concentration was within the standard of Class IV-V. The growth rate of various water quality indicators under Scenario 2 was 2-3 times that of Scenario 1. Compared with before the water transfer， the total phosphorus concentration in Scenario 1 increased by a maximum of 4.68%， and the total phosphorus concentration in Scenario 2 increased by a maximum of 13.45%. This was followed by total nitrogen， with a maximum increase of 1.15% for scenario 1 and 3.44% for scenario 2； ③ Monthly total phosphorus concentration in the flood season at Wangfuzhou section before and after the water transfer reached the water quality standard of Class II， and the total phosphorus concentration increased in dry water years after the water diversion while the concentration decreased slightly in abundant water years. Overall， the variation of water quality in dry water years is greater than that in abundant water years， and the variation of each water quality indicator is not much different in the two scenarios.

In the southeastern coastal areas of China， complex flood disaster factors and compounded terrain features often lead to poor flood discharge in watersheds， resulting in flood disasters. Therefore， it is essential to establish a flood simulation model suitable for the characteristics of this watershed and formulate effective flood control and disaster reduction measures through flood mitigation analysis. By utilizing watershed digital elevation data， river network data， land use data， etc.， a hydrodynamic-hydraulic coupled model simulating the flood process in a coastal hilly-plain composite watershed is established to explore methods for reducing flood risk based on engineering scheduling. The Datian Port watershed in Linhai City， Zhejiang Province， is selected as the study area， taking into account watershed characteristics such as hilly convergence， reservoir discharge， tidal fluctuations， initial river channel water levels， and floodgate discharge. Model boundary conditions are designed to simulate the flood evolution process and inundation situation in the study area under different design floods and engineering scheduling influences. The results indicate that the established model can effectively simulate the flood evolution process in the composite watershed of hills and plains. For key flood-prone areas， adjusting the initial water level in the river and controlling flood tide gates in the watershed effectively alleviated flood inundation in the downstream main urban area and Ling Lake scenic area of Datian Port. The downstream engineering scheduling delayed the relief effect on flood inundation in the northeast area of the Datian Port watershed， bordering the hills. Scenario simulation results provide data support for the pre-assessment， prediction， early warning， and contingency planning of flood disasters in the study area， laying a foundation for the further advancement of urban flood control and plain drainage projects and offering solutions for flood disasters caused by multiple disaster factors in coastal hilly-plain composite watersheds.

In order to gain a deeper understanding of the changing law of water-sand relationship in the Jialing River， based on the annual runoff and sediment load data of Beibei Hydrological Station at the outlet of the Jialing River from 1965 to 2022， the Mann-Kendall test， double cumulative curve method and the physical genesis method were used to diagnose the variation points of water and sediment relationship， and the marginal distribution function and Copula function of the runoff and sediment load were preferred through the AIC， BIC， and RMSE， and the optimal Copula function was determined， and the water-sediment joint distribution model of the Jialing River basin was established. The established model was then used to calculate the probability of water and sediment abundance and depletion encounter， joint and co-occurring recurrence periods in the basin， and then to compare and analyse the univariate and joint variables design values of water and sediment. The results show that： ① The water and sediment relationship changed abruptly in 1989， and the water and sediment correlation before the change was stronger than that after the change. ② The optimal marginal distributions of the water and sediment series in 1965-1989 are Logn， and the optimal joint distribution model of water and sediment is the Gumbel Copula model， while the optimal marginal distributions of runoff and sediment in 1990-2022 are Gamma and GP respectively， and the optimal joint distribution model of water and sediment is the Frank Copula model. ③ The synchronous probability of the two stages of water and sediment sequences is 59.77% and 61.14% respectively， both of which are greater than the asynchronous probability， and the probability of occurrence of the extreme cases of “abundant water and sediment depletion” and “depleted water and sediment abundance” is extremely low， which indicates that there is a large correlation between the probability of water and sediment， and the water and sediment conditions are relatively stable. ④ The design value of the joint variable is larger than the univariate one， and the design value of runoff and sediment load calculated by the joint distribution of the two variables is more reliable. The joint recurrence period of water and sediment is concentrated near 2 years， and the majority of the co-occurrence recurrence period is less than 50 years. By exploring the characteristics of the joint change of water and sand in the Jialing River basin， this study can provide a reference for water and sand regulation， disaster prevention and mitigation in the basin.

Rapid urbanization has led to changes in land use patterns and runoff characteristics， resulting in frequent urban waterlogging problems. Predicting the future land use changes and exploring the evolution of urban waterlogging risk can provide reference basis for improving urban disaster prevention and reduction planning. This article takes Nanjing as an example and uses the FLUS model to predict the land use patterns in 2030. Combining the MaxEnt model and risk assessment index system， the main influencing factors of urban waterlogging risk and their contributions are identified. Moreover， the waterlogging risk pattern and its evolution under the land use scenarios are analyzed. The results indicate that： ①The main characteristics of land use changes in Nanjing are a decrease in cropland and an increase in construction land. It is estimated that the cropland area in Nanjing will decrease by about 2.6% and construction land will increase by about 4.81% between 2020 and 2030； ② Indicators such as land use type and distance from roads have a high contribution rate to the distribution of waterlogging risk in Nanjing， while indicators such as the number of days with daily precipitation exceeding 50mm and total precipitation have significant importance. ③ The proportion of high-risk areas in Nanjing in 2010， 2020， and 2030 was 4.77%， 5.37%， and 5.94%， respectively. The high-risk areas are mainly distributed in the central urban areas along the Yangtze River， with the high-risk areas in Gulou District， Qinhuai District， and Xuanwu District accounting for over 50% of the total in 2030； ④ With the change of land use pattern， there is a 23.36% probability that medium-high-risk areas will be transformed into high-risk areas， and a 21.74% probability that medium-risk areas will be transformed into higher risk areas. Overall， the risk level shows an increasing trend.

To address the demand for full-day water demand forecasting in water supply enterprises， a parameter tuning method for water demand forecasting based on the dual closed-loop control theory and adaptive machine learning is designed and developed. The method innovatively introduces the ratio of daily and 15-minute variation coefficients， and triggers the dual closed-loop control processes to adjust output deviations when the preset error threshold is exceeded. Through the analysis of actual water supply data from a water company in Guangdong Province， the application of this parameter tuning method has achieved a 15% increase in prediction accuracy and approximately a 1.2% improvement in model stability compared to traditional forecasting methods in forecasting daily water supply. These results suggest that the model can effectively enhance the accuracy and stability of water supply forecasting， providing a more precise tool for water supply scheduling and resource management， and holds significant practical application value in the development of urban smart water management.

The initial in-situ stress of rock mass is an important part of underground engineering research. Relying on the large-scale underground plant project， the three-dimensional hydraulic fracturing method and the conventional hydraulic fracturing method were used to measure the in-situ stress of hole ZK1 in the tunnel and surface hole ZK2 respectively to obtain the initial in-situ stress of rock mass. Based on the measured data， the three-dimensional numerical simulation method was used to calculate the in-situ stress field inversion， and obtained the distribution law of the in-situ stress field in the required engineering area. The results show that the initial in-situ stress can be effectively obtained by the hydraulic fracturing method， and the underground stress obtained by the three-dimensional hydraulic fracturing method is more accurate and can be confirmed by the vertical hole test data. The calculated value of in-situ stress obtained by numerical simulation is consistent with the measured value. The layout of plant tunnels is reasonable， and the probability of rock burst in the engineering area is low. The field in-situ test results and the regression in-situ stress field distribution rules can provide effective scientific support for engineering design.

The numerical simulation of model I stress intensity factor for SENB specimens with different aspect ratios was carried out by using finite element software ABAQUS. The research explores the effect rules of fulcrum friction on the dimensionless stress intensity factor Y _I and the dimensionless T stress T* of SENB specimens. The results show that the values of Y _I and T* increase gradually with the increase of the aspect ratio of the specimen， and the increase of the friction coefficient leads to the decrease of Y _I. When the sample with small length-to-width ratio is subjected to fulcrum friction， T* will decrease and the fracture trajectory will be more stable. Through the compacted clay mode I fracture test， the experimental results with and without the fulcrum friction effect are compared， and the accuracy of the numerical simulation is verified.

In order to study the method of determining the control conditions of energy dissipation and anti-scouring of sluice， the actual project of Tongcheng Sluice is taken as an example. Based on the optimization model， this paper adopted numerical simulation method to select 5 gate openings respectively in the design condition and the check condition of energy dissipation and to calculate the energy dissipation and anti-impact.The maximum single width energy passing through the gate is determined by analysis to find the most unfavorable working condition of the sluice during operation. After the model is optimized， the calculation length of the upstream section of the rear sluice was selected as 90m， the downstream section of the anti-scour slot was 40 m， the mesh division form was the local encrypted mesh based on coarse mesh and the turbulence model was RNG k-ε. Based on this model， the final calculation and analysis shows that， when the sluice opening was 4.0 m under the energy dissipation design condition， the processed energy of the single width of the sluice reached the maximum. Under this condition， the upstream water level was 10.1 m and the downstream water level was 5.6 m， which was the control condition of energy dissipation and anti-scouring of the sluice. The research content of this paper broke the traditional idea of taking the sluice discharge condition as the most unfavorable condition， which can guarantee the safe operation of the sluice. It had good engineering application value and can provide reference for determining the design conditions of energy dissipation and anti-scouring in sluice engineering.

Considering that the statics/dynamics analysis about the large emersed radial gate are always over-simplified by previous investigations， in this paper， the static and dynamic characteristics of single gate and gate-dam system are analyzed and compared in detail using the ANSYS finite element software. A finite element model（FEM） of gate-dam system considering seal friction， supporting hinge system and prestressed anchor cable is established based on the instantaneous opening condition of spillway radial gate of a hydropower station. The research results show that： in terms of statics， the two sides of the water seal have little influence on the stress distribution of the steel structure components in the gate， with a maximum difference of 14.08%； Also， more reasonable stress distribution of fixed hinge is obtained from gate-dam system comparing with that of single gate； Besides， the anchor block affects the overall displacement of the gate prominently， and the degree of effect can be sorted as： the overall displacement of the single gate < the integrated displacement of the gate dam without the prestressed anchor cable < the overall displacement of the gate dam with prestressed anchor cable. In terms of the dynamics analysis， frequency of the gate structure is reduced by the water seal when fluid-structure interaction effect is taken into account； And the prestressed anchor cable has little influence on the dynamic characteristics of gate-dam system.

To explore the suitable mode of reclaimed water irrigation for sunflower in Hetao Irrigation District， this paper set up five groups of Yellow River water （H）， which included T1 （HHH）， T2 （HZZ）， T3 （ZHZ）， T4 （ZZH） and T5 （ZZZ）， and reclaimed water （Z） irrigation modes for the key growth stages of sunflower （emergence-squaring stage， squaring-filling stage and filling-waxy stage）， and the mulched drip irrigation technology was applied to carry out the two consecutive years field experiment. The results showed that， the Yellow River water amount applied for treatments followed T5<T2<T4<T3<T1， while the reclaimed water amount applied for treatments followed T1<T3<T4<T2<T5. The reclaimed water and Yellow River water irrigation had no significant effect on the 0~40 cm soil pH inside and outside the film. The higher of the reclaimed water irrigation quota， the greater of the soil salinity variation inside the film， and the content of typical heavy metal elements in soil and grains. The corresponding alternate irrigation mode of T2 treatment was more conducive to promoting the growth of sunflower， increasing grain yield， and increasing the content of crude protein and crude fat in grains than other irrigation methods； However， the contents of arsenic， lead， cadmium and chromium in soil and grain of T3 treatment were lower than other treatments. Compared with T1 treatment， the Yellow River water applied amount was saved by 100~120 mm， and the grain yield， biomass， crude protein and crude fat content of grain were increased by 4.34%~7.19%， 6.20%~6.68%， 9.25%~20.50% and 7.39%~13.37%， respectively. Short-term reclaimed water irrigation will not lead to the excessive content of heavy metal elements in sunflower grains and 0~100 cm soil after sunflower harvest. In order to save water and control salt， increase production and improve quality， this paper suggests that the corresponding alternate irrigation mode of T3 treatment is the suitable reclaimed water irrigation mode during sunflower growth period in Hetao Irrigation District. The results of this study can provide theoretical guidance for the safe and efficient application of reclaimed water for sunflower cultivation in Hetao Irrigation District of Inner Mongolia.

Rock weirs are common low-head hydraulic structures in small and medium-sized rivers， and the biofilms formed by riverine microorganisms on their surfaces affect the river environment. Current studies mainly focus on the microbial characteristics in biofilm coated on the river bed stones， but less attention has been paid to biofilms on the surface of rock deposits such as rock weirs. Based on high-throughput sequencing technology， the microbial community composition in biofilms coated on a rock weir in a natural small and medium-sized river is investigated. Also， the effect of different aquatic environmental factors around this structure on the microbial community is studied through correlation analyses. The results show that： ① The hydrodynamic conditions vary in different areas around the rock weir， while the water physicochemical properties around the weir are similar； ② The diversity of microbial communities in biofilms on different areas of the weir surface is different， with the lowest being at the weir crest， followed by the upstream weir surface， and the highest being at the downstream weir surface； ③ The composition of microbial communities in biofilms on different areas of the weir surface is similar， with the dominant phylum being Proteobacteria， but the dominant genera in biofilms on the weir crest are different from those in other areas. ④ Various aquatic environment factors around the weir affect the community structure of microorganisms in the biofilm on weir surface， with the effects of flow velocity， water depth and dissolved oxygen reaching the level of significance. The results of this study reveal the microbial community characteristics of biofilms on the surface of rock weirs in natural small and medium-sized rivers， which can provide a certain basis for understanding the ecological benefits of rock weirs.

This study takes the drainage system of Zhengpu Port New District in Ma'anshan as a representative case to explore the application of urban drainage system design based on the combination of storage algorithms and SWMM models. Established in 2012， Zhengpu Port New District is positioned as a modern port logistics area， a modern port industrial area， and an integrated urban area， with an important strategic development function. Firstly， the study collects geographical， climatic， and drainage system data of the new district and applies storage algorithms based on water balance to analyze the drainage system and its scale. Then， the optimized plan is applied to the SWMM model for dynamic simulation and analysis of rainwater runoff processes. The research shows that to achieve the flood control design standard of no water accumulation in a 20-year rainstorm， the study area needs an external drainage pump station with a total design flow rate of 111.9 m³/s. After deducting the total flow rate of the existing three pump stations， an additional 30.5 m³/s of external drainage flow rate is required. The results of this study provide a scientific basis for drainage and disaster reduction and drainage system renovation in the northern part of Laoxia River in Zhengpu Port New District， contributing to the development and people's livelihood of the new district. Meanwhile， this research method can serve as a reference for urban drainage system design application studies based on the combination of storage algorithms and SWMM models， promoting the development of urban drainage system design.

With the continuous development of information construction in water conservancy engineering， implementation of smart water conservancy and digital twin continues to deepen. BIM technology has been introduced into the operation and management system of water conservancy engineering to realize the characteristics such as management visualization and real-time data. In order to accurately display the internal flow status of the pump device in the operation and management of large pumping station， while reducing computational costs and time， a idea of joint application of BIM and CFD technology is proposed based on the operation and management system of Xifeihebei Station. By conducting CFD calculations under a large number of operating conditions in advance， and processing the calculation results into the required characteristic cross-sectional flow status charts， a flow status charts database for different operating conditions is built， and then the closest flow status chart is selected and displayed based on the real-time operating conditions. The research result has been applied in the operation management system of Xifeihebei Station， providing an example for similar engineering applications.

The construction of water resources projects has changed the hydrological situation of downstream rivers and adversely affected river habitats. Under the engineering background of the whole river canalization of the Jialing River， the slow-flowing river section formed by the cascade navigation and hydropower project will not be able to provide suitable drifting conditions for drifting fish eggs， which will sink and die， and the fish resources will shrink. This paper proposed an ecological scheduling program for the Lize navigation and hydropower project in response to the problem of impeded hatching of drifting fish eggs in the main stream of the Jialing River. Firstly， a one-dimensional hydrodynamic model was established from Tongzihao navigation and hydropower project to CaoJie navigation and hydropower project， and the reliability of the model was verified； Secondly， the flow rate threshold for drifting fish egg hatching was determined， according to which the ecological scheduling plan for the Lize navigation and hydropower project was formulated； Finally， the economic benefits loss due to ecological water discharge was calculated according to the scheduling rules of the Lize navigation and hydropower project. The results show that the correlation coefficient between the one-dimensional hydrodynamic model simulation results and the actual runoff is 0.88， and Nash efficiency coefficient is 0.78， which can effectively reflect the simulation of the flow velocity change process of the simulated river section. The minimum underflow of 1 550 m³/s on the first day， 1 820 m³/s on the second day， 2 000 m³/s on the third day， 2 400 m³/s on the fourth day， 1980m³/s on the fifth day， and 1 550 m³/s on the sixth day of the Lize ecological scheduling is formulated， which can meet the flow rate requirements of drifting fish spawn； when the natural runoff cannot be met， the Tingzikou Reservoir is required to cooperate in joint eco-operation. This study may provide technical support for ecological scheduling studies that consider the hatching needs of drifting fish eggs.

To thoroughly investigate and comprehend the multifaceted response of river morphology and hydrodynamic characteristics to extreme floods in a branching river section， a comprehensive study was conducted on the Qingyuan Lunzhou section， which represents the lower reaches of the Beijiang River. This study employed a combination of field research， riverbed evolution analysis， and numerical simulation methods to systematically examine and elucidate various aspects， including the water flow characteristics， intricate changes in riverbed deformation patterns， sediment particle size distribution dynamics， and overall water level fluctuations during the once-in-a-century flood in the June 2022 flood event. The results indicated that during the “22·6” flood， the main stream of water shifted to the left due to the inertial effect， causing significant damage to the infrastructure in the Lunzhou Island. Moreover， after the water discharged from the canyon， a decrease in flow velocity and sediment carrying capacity led to severe sedimentation in the island head area and the right branch of the river， while the left branch experienced scouring. Additionally， differences in flow velocity between the island head area and the left and right branches resulted in variations in sediment particle size distribution. The sediment particle size in the island head area was notably larger compared to that in the left and right branches of the riverbed. Following the “22·6” flood， the elevation of the riverbed led to a significant increase in water level compared to before the flood. Moreover， the diversion ratio of the left branch increased. Specifically， under an inflow of 5 000 m³/s， the upstream water level of the island head rose by almost 1m， and the diversion ratio of the left branch augmented by approximately 16% compared to pre-flood conditions.

Based on one-dimensional water hammer theory and combined with an engineering example， the selection of the flow characteristics of the end control valve of gravity flow system with wide-range flow variation is numerically studied from three aspects： the influence of flow characteristics of control valve on its steady-state opening-degree， the determination of the most unfavorable flow conditions of valve-closing water hammer， and the influence of flow characteristics of contrive valve on valve-closing water hammer. And the flow characteristics of linear type， parabola type and equal percentage type are compared. The results show that： ① The equal percentage flow characteristic is more conducive to the stable operation of the control valve under the low flow condition. Under this condition， the steady-state opening-degree of the equal percentage type control valve is larger， which can avoid cavitation and vibration caused by too small opening. ② The most unfavorable flow condition of the valve-closing water hammer should consider the minimum initial flow condition， under which the water hammer pressure of the input point of the control valve is largest because of the largest initial pressure and the shortest closing time. ③ The equal percentage flow characteristic is more conducive to reducing the control valve-closing water hammer pressure. Under the same initial flow rate and valve closing rate， the control valve with equal percentage type flow characteristics has a larger initial opening-degree， a longer actual closing time， and a smaller change gradient of flow coefficient in the small opening-degree range， so the extreme value of the valve-closing water hammer pressure is smaller， which is more conducive to pipeline safety.

In order to address the significant manual costs incurred during template measurements due to prism placement and manual observations， as well as to mitigate the safety hazards associated with working aloft， this paper proposes a vision-based AI-driven continuous template automatic measurement approach. Employing an image total station as the primary sensing device， the method utilizes machine vision algorithms to replace manual observation methods for the automated detection and measurement of continuously rising templates at dam construction sites. This approach enhances the efficiency of dam construction layout and reduces the workload for measurement personnel. The method incorporates concentric circles with numerical markings as collaborative targets to replace prisms， and employs a circle center detection algorithm based on cross ratio invariance for precise identification and positioning of measurement points. Additionally， a DP controller is applied to achieve accurate alignment of the image total station. Experimental measurements were conducted at the TB dam pouring site using the image total station Leica TM50I for automated measurements. The results demonstrate that within a testing distance of 70 to 131 meters， the error between this method and traditional manual measurements is within 5 mm.

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

Dredging in rivers and lakes can cause sediment suspending and make water turbid. In order to control the environmental pollution by dredging， attempts have been made to use bubble curtains to block the sediment， and on-site and indoor experiments have been conducted. Comparing the changes in sediment concentration at fixed measuring points with and without bubble curtains， the interception effect of bubble curtains on natural sediment and kaolin particles was explored. Based on this， the concept of turbidity interception rate by bubble curtains was proposed. The spatial and temporal variations of sediment concentration behind the bubble curtain were measured， and the influence of aeration rate per unit width on the turbidity interception rate of the bubble curtain was analyzed. The experimental results show that the bubble curtain has a certain turbidity interception effect， its turbidity interception rate being 0.8 for natural sediment and over 0.4 for kaolin particles. With the increase of the aeration rate per unit width， the turbidity interception rate of bubble curtains increases and then decreases. The bubble curtain has good applicability in controlling the diffusion of dredging sediment and， especially when used in combination with silt curtains， can further reduce the diffusion amount of suspended sediment while allowing free passage of ships in the dredging area.

The Three Gorges Hydropower Station has 34 units with a total installed capacity of 22 500 MW. It is a key power source for the backbone power grid of State Grid Corporation of China′s “West-to-East Power Transmission” project and “North-South Interconnection” project， supporting the safe and stable operation of the grid. However， the annual maintenance work at the Three Gorges Hydropower Station is complex and highly uncertain due to the large number of equipment， diverse unit models， and varied demands for equipment technological upgrades. Additionally， the workload for manual operations is significant. To address these challenges， a maintenance planning platform has been developed based on the SpringBoot microservices architecture. The platform includes the Three Gorges Hydropower Station Operation Scheduling and Optimal Maintenance Arrangement System. It provides a hierarchical operational service framework for decision-makers， managers， implementers， and operators at the power plant. This platform enables comprehensive digital management and control of the yearly maintenance planning， execution， feedback， and adjustments for the equipment at the Three Gorges Hydropower Plant. Furthermore， considering different maintenance requirements and prioritizing safety and stability during the maintenance process， multiple maintenance plan options have been proposed and optimized. Currently， this platform effectively serves the routine maintenance scheduling work at the Three Gorges Hydropower Station.

In order to further improve the efficiency of resistance-type turbines and reduce their influence on the liquid conveying capacity of pipelines， the influence of impeller design parameters on their performance was analyzed by single factor test method， and four key parameters and their value ranges were selected. Then， the response surface method was used to design the test scheme， and the function relationship between the key design parameters and the efficiency and head loss was fitted by the least square method， and the regression model is obtained. Finally， MOPSO algorithm was used to optimize the regression model， and the optimal impeller parameters was obtained. The results show that the average efficiency of the optimized resistance-type turbine is increased by 4.053%， and the average head loss is reduced by 0.679%.

To solve the problem that deterministic streamflow forecast can not provide the uncertainty measurement of streamflow forecast and is difficult to give full play to the forecast value， this paper proposes a Vine copula-based Bayesian Transition Forecast （VCBTF） model to obtain the probability forecast result by post-processing the deterministic runoff streamflow results. Firstly， the ensemble results of the streamflow forecast were obtained through a variety of hydrological forecasting empirical models. Secondly， the ensemble Kalman filtering technology was used to fuse the ensemble results of the forecasted streamflow into the posterior forecast results. Finally， the VCBTF was used to post-process the fused streamflow forecast results to quantify the uncertainty of the runoff forecast and obtain the probabilistic forecast results of the flow. Taking Lianghekou Reservoir with multi-year regulation capacity in the Yalong River Basin as a case study， the medium and long-term streamflow probability forecast is carried out. The results show that： ① The VCBTF model is superior to the deterministic runoff forecast model in terms of Root Mean Square Error， Mean Absolute Error and Nash-Sutcliffe efficiency index， and the Qualified Rate of forecast is increased by at least 2.7%； ② The average value of continuous probability ranking score index of the VCBTF model is 104.54 m³/s， which is better than that of the GPR model with 106.92 m³?/s， and the α-index of the VCBTF model is higher than 0.89 and better than the corresponding result of the GPR model， indicating that the probabilistic forecast results based on the VCBTF model have higher reliability； ③ The average value of the Percentage of measured points contained in the Unit Confidence Interval of the VCBTF model is 2.2， which is better than that of the GPR model with 1.87， indicating that the probabilistic prediction results of the VCBTF model have a higher concentration. Therefore， the VCBTF model proposed in this paper can more effectively reduce the forecast uncertainty of streamflow， and provide more reliable forecast interval information. It can provide strong technical support for the optimal operation of cascade reservoirs in the basin.

The strain localization failure problem of geotechnical granular materials widely exists in engineering design applications. Its main manifestations are strain localization at the mesoscale and shear band generation at the macroscale， and their microscopic mechanism is still currently unclear. In order to systematically study the formation and evolution of strain localization in particle aggregates， a true triaxial test with designated plane strain loading path is simulated using discrete element method （DEM）， which provides thorough insights into the material geometry， motion， and mechanical information of granular materials on both micro- and macroscopic scales. To identify the optimal feature quantity for characterizing strain localization characteristics， micro indicators such as particle temperature， fluctuation displacement， and local dilatancy angle are compared with each other. It is found that the fluctuation displacement has better correlation with other parameters in characterizing strain localization， so it is selected as the strain localization characterization variable. In order to quantify the specific axial strain level from the onset of strain localization in particle aggregates to the completion of development， the Moran’s I is introduced to statistically analyze the spatial distribution characteristics of displacement fluctuation， and the shear band development interval of particle aggregates during the elastic-plastic transition stage is determined. Furthermore， before the strain localization of particle aggregates fully developed， the spatial distribution and the probability density function （PDF） evolution of displacement fluctuation indicates that the plasticity out of research region ceases to evolve in the transition stage， while the plasticity in research region increases in the mode of percolation. Finally， a cluster model describing strain localization on mesoscopic scale is obtained through clustering analysis based on the spatial distribution of displacement fluctuation. This model can link the formation and development of macroscopic shear bands in particle assembly with the microscopic plastic development of individual particles， depicting the evolution process of particle sample from onset of strain localization on mesoscopic scale to fully developed macroscopic shear bands.

In order to explore the level of benefits， evolution patterns， and obstacle factors after the implementation of key soil and water conservation projects in the Gansu section of the Yellow River Basin， an evaluation index system for the comprehensive management benefits of soil and water conservation was constructed based on the theme framework of "water and soil conservation， ecology， economy， and society". The entropy weight TOPSIS and coupling coordination model were used to quantitatively evaluate the spatiotemporal evolution process of the comprehensive benefits of soil and water conservation in 9 cities and prefectures of the Gansu section of the Yellow River Basin from 2000 to 2021， as well as the coupling coordination between subsystems. The obstacle degree model was introduced to identify the obstacle factors for improving the comprehensive benefits of soil and water conservation. The results show that from 2000 to 2021， the comprehensive management benefits of soil and water conservation in the Gansu section of the Yellow River Basin have been increasing year by year， transitioning from an extremely deteriorating state in 2000 to a good state in 2021； There were significant spatial differences in the benefits of comprehensive soil and water conservation management among the 9 cities and prefectures. Lanzhou， Baiyin， and Pingliang had higher benefits of comprehensive soil and water conservation management， but the gap between cities and states showed a good trend of narrowing year by year； The development level of water and soil conservation， ecological， economic， and social benefit systems all showed an increasing trend year by year， and the development level of ecological benefit systems lagged behind that of water and soil conservation， economic， and social benefit systems； The coupling coordination degree of the comprehensive management benefits system for soil and water conservation in the 9 cities and prefectures showed an increasing trend year by year， transitioning from a stage of mild imbalance to a stage of good coordination， and the spatial performance of the 9 cities and prefectures were relatively balanced； The main obstacles to the improvement of comprehensive soil and water conservation benefits in the Gansu section of the Yellow River Basin are the water production modulus， surface runoff depth， plant carbon sequestration， plant oxygen release， and per capita total power of agricultural machinery. Research has shown that the comprehensive management benefits of soil and water conservation in the Gansu section of the Yellow River Basin have become increasingly apparent over time， and the overall direction is constantly developing towards health， coordination， and balance. At the same time， there is still significant room for improvement in the comprehensive management of soil and water conservation and modernization of agricultural production conditions.

Taking Jiexi County， Jieyang City， Guangdong Province as the research object， this paper used the time series Sentinel-1 data of the second half of 2021 to anylize the time series backscattering coefficient characteristics and inter-class differences of different covers on cultivated land such as rice， corn， pond water surface， uncultivated， woods and vegetables in the measured samples. The results showed that the optimal polarization mode of crop classification in Jiexi County was VH polarization， on which， a model for the classification of cultivated land crops based on long short-term memory network （LSTM） was constructed. The model accuracy reached 90%.The spatial distribution of rice， corn， pond water， uncultivated land， forests and vegetables in the study area was extracted based on the model， providing a new remote sensing technology for monitoring cultivated land types in cloudy areas.

Net cage aquaculture has a significant impact on the regional water environment， and studying the changes in water quality parameters in net cage aquaculture areas is of great practical significance for understanding the impact of regional aquaculture on the water environment. This article uses GF-1WFV data to construct an inversion model for the total suspended solids concentration in the net cage aquaculture area， which has grown exponentially in the Manwan Reservoir area in recent years. The results indicate that the model has high accuracy， with an average relative error of 9.65% between the inverted values and the measured values， and a root mean square error of 0.33mg/L. Based on the constructed inversion model and satellite imagery， the total suspended solids concentration in the Manwan net cage aquaculture area was inverted， and the variation patterns of total suspended solids concentration in the reservoir area and different net box positions were analyzed. Research has found that the variation pattern of suspended solids concentration in the Manwan reservoir area and different positions of net cages is basically consistent. The total suspended solids concentration in net cages has not shown any abnormalities due to the phenomenon of local “delineation” in aquaculture， but is lower than the overall suspended solids concentration in the reservoir area. This is mainly because the variation of total suspended solids concentration is mainly affected by precipitation， surface runoff， water flow velocity， etc. Net cage aquaculture can reduce its impact on the total suspended solids concentration in local “delineation” areas. This study has certain reference significance for understanding the changes in total suspended solids concentration in the Manwan reservoir area and net cage aquaculture area. In the future， a multi-source remote sensing data remote sensing estimation model for water quality parameters will be developed for understanding the changing patterns in water environment in the Manwan net cage aquaculture area.

When the regulating valve operates under high flow rates and high pressure differentials， cavitation phenomena are prone to occur in the throttling area， resulting in abnormal vibration and noise in the valve body， and even damage to the valve body. Taking the DN200 flow-pressure-regulating plunger valve as the research object， based on the Siemens LMS data acquisition system， the underwater noise signal of the regulator valve is measured at different openings and cavitation numbers， and the root-mean-square （RMS） value of the underwater cavitation noise is calculated. The cavitation number-noise curves at different openings are plotted， obtaining the initial cavitation number， sustained cavitation number， and some openings also determine the obstructed cavitation number. The results indicate that the flow control valve exhibits better resistance to cavitation at smaller openings. As the valve opening increases， both the initial cavitation number and sustained cavitation number increase rapidly initially but then increase slowly after 70% opening， following a parabolic growth pattern. The results of the study provide certain guidance for determining the characteristic cavitation coefficient curve， monitoring cavitation status， optimizing vibration reduction and noise control design， and ensuring the safe operation of flow-pressure-regulating plunger valves.

In order to improve the safety and stability of hydropower unit operation， monitor the unit's operation status in real time， and accurately and efficiently determine the probability of the rotor grinding fault of hydropower units， a fault determination model based on the combination of subjective-objective combined weighting method and fuzzy theory is proposed. Firstly， the symptom indexes corresponding to the rotor grinding fault are extracted， and a “fault - symptom index” judgment structure system is constructed. Secondly， the Analytic Hierarchy Process （AHP） and Technique for Order Preference by Similarity to an Ideal Solution （TOPSIS） are used to obtain the subjective and objective weights of each symptom index， and the comprehensive weights are calculated based on the maximum extreme difference combination method. The Gauss threshold method is used to determine the limit value of oscillating signs， and the industry standard is used to determine the limit value of temperature signs. The deviation degree of hydropower units is determined based on the limit of signs， and the mapping function of “deviation degree-membership degree” is constructed， and the membership degree judgment matrix is obtained. The fault judgment matrix is obtained by combining the membership decision matrix with the comprehensive weight， and the fault probability is reflected according to the maximum membership degree of the fault judgment matrix. Based on the actual operation data of the SK hydropower station， the fault judgment model of rotor grinding fault is verified， and the judgment results are consistent with the actual fault situation.

The external water pressure of lining is of great significance to the determination of lining thickness and drainage scheme of water-rich deep buried tunnel. The existing research often ignores the analysis of the influence of macroscopic geological conditions on the seepage field， which leads to the lack of reliability evaluation of the external water pressure estimation results and lining design schemes of deep buried tunnels. Based on the Qinling Water Conveyance Tunnel Project of Hanjiang-to-Weihe River Diversion Project， this paper generalizes the deep-buried tunnel in the water-rich area into three representative macro-geological environment models under the watershed， the mountainside area and the river， and studies the influence law and mechanism of geological conditions and engineering measures on the seepage field of surrounding rock and the external water pressure of lining. The results show that： ① The seepage direction of groundwater around the watershed tunnel is mainly vertical under the condition of the same height of groundwater at the top of the tunnel and impermeable lining. The seepage direction of groundwater around the tunnel under the river is mainly horizontal. The external water pressure reduction coefficient of the watershed tunnel， the tunnel near the mountain area and the tunnel under the river increases in turn. The reduction coefficient of external water pressure of tunnel under watershed increases with the increase of buried depth， which is 0.72，0.77 and 0.84 respectively. The reduction coefficients of the external water pressure of the mountain tunnel and the river tunnel are almost unchanged， which are 0.91， 0.91， 0.93 and 0.95， 0.96， 0.96， respectively. ② After the same drainage measures are taken， with the increase of buried depth， the reduction coefficients of external water pressure of watershed tunnel are 0.15，0.42，0.64 respectively， and the pressure reduction effect is the best. The external water pressure reduction coefficients of the tunnel near the mountain and the tunnel under the river are 0.48，0.67，0.77 and 0.63，0.80，0.83， respectively， and the pressure reduction effect gradually deteriorates. ③ When the buried depth of the tunnel is 1 200 m， the reduction coefficients of external water pressure of the watershed， mountainside and river tunnel are 0.43~0.73， 0.67~0.89 and 0.80~0.95 respectively with the increase of the permeability coefficient of the surrounding rock， which shows the regularity that the external water pressure increases with the increase of the buried depth of the tunnel. The research results are universal， and the rationality of water pressure resistance design of tunnel lining in water-rich area can be evaluated from the regularity of macroscopic hydrogeological conditions of tunnel and reduction coefficient of external water pressure.

Long distance tunnels are commonly used to cross complex terrains. The combination of the Drilling and Blasting method （DB）， and the Tunnel Boring Machines （TBM） method for excavation in long tunnels on the plateau can fully leverage the flexibility of the DB method and the efficiency of the TBM method， but it also increases difficulty in schedule management. This paper considers the challenges of long tunnel construction on the plateau， such as long excavation durations， complex geological condition， low air pressure， and low temperature. Based on the studies on excavation simulation models of the DB method and TBM method， the paper examines the duration and impact of switching between the DB and TBM excavation method. It then establishes a simulation model for the excavation progress of long tunnels on the plateau using a combination of the DB method and TBM method， expressing it in the form of a duration function and control flow. Case studies demonstrate that this model can be applied to the situation of simultaneous multiple working-faces in both construction adit and main tunnel， and it can accommodate complex construction boundary conditions of the DB and TBM excavation. The research can provide support for excavation progress management in long-distance tunnels for water diversion， highways， railroads， and other projects in plateau regions.

Evapotranspiration （ET） is a crucial link in water circulation. It plays an important role in the global water cycle and surface energy balance， and has significant impacts on climate， ecosystems， and water resources management. Therefore， the quality of evapotranspiration data is crucial for the precise management of global water resources. This study conducted accuracy validation and spatiotemporal comparison of three ET products in the Northern Hemisphere， selecting the ET products that is more suitable for the Northern Hemisphere， providing suggestions for strengthening the combination of remote sensing and ground observation research. Using the monthly average measured data from FluxNet2015 flux sites to verify three ET products， it was found that PML_ V2 product has the highest accuracy in the Northern Hemisphere， followed by GLDAS， and finally MOD16A2， with correlation coefficients R of 0.66， 0.57， and 0.56， respectively； The root mean square error （RMSE） is 2.46， 5.68， and 12.42 mm/month， respectively； The average biases are 14.36%， 16.86%， and 35.02%， respectively. The GLDAS ET product has the ability to monitor daily scale ET， and the consistency between the daily average estimated value and the measured value at the flux tower site is high. The correlation coefficient R is 0.74， and the RMSE and Bias are 1.62mm/day and 27.90%， respectively. Overall， on the time scale， all three ET products can simulate the seasonal changes in the Northern Hemisphere， with higher summer evapotranspiration and lower winter evapotranspiration. The three ET products in summer all have overestimation phenomena on different land cover types， and the simulation results in other seasons are better than the ground observation values. Among them， MOD16A2 performs the worst， and the overestimation phenomenon is the most obvious. In addition， during the period from 2001 to 2020， except for arid areas， the spatial distribution of the three ET products was relatively consistent in most regions， with a correlation coefficient R greater than 0.6. This study provides scientific recommendations for selecting suitable ET data sources for conducting evapotranspiration studies in the Northern Hemisphere by evaluating the uncertainty and product quality of different ET products.