Hanjiang River basin is the water source of the middle route of the South-to-North Water Diversion Project. Affected by multiple factors such as water diversion， climate change and increasing water consumption within the basin， significant hydrological changes have occurred in the downstream of Danjiangkou Reservoir. To ensure regional water resource scheduling， management and security， it is of great importance to study the non-stationary evolution patterns and impacts of the runoff series. In this study， Mann-Kendall trend test， Pettitt mutation test and GAMLSS model were used to analyze the trend change and mutation characteristics of runoff series from 1960 to 2020 at Huangzhuang Hydrological Station in the middle Hanjiang River. And based on some typical indicators， including standardized runoff index （SRI）， occurrence frequency of low water level and indicators of hydrologic alteration （IHA）， we reveal the change characteristics and impacts on abundance and depletion in the middle Hanjiang River under non-stationary conditions. The results indicate that： ①The stationarity of runoff series in the middle Hanjiang River is broken. The annual runoff at Huangzhuang Hydrological Station， as well as the runoff during the dry season （January to March） and the runoff during storage period at the end of the flood season （September to November）， all display significant non-stationarity. And in the time-varying model based on GAMLSS， the optimal non-stationary models of three runoff series with a covariate of time t follow the LOGNO， GA， and LOGNO distributions， respectively； ②The annual runoff of Huangzhuang Hydrological Station is decaying and the probability of a dry year increases. The runoff increase during the dry seasons and decrease during flood seasons in a year. Both the annual mean water level and the monthly mean water level decrease significantly. The lowest navigable water levels decrease by 0.78 m after the operation of the South-to-North Water Diversion Project. The number of low-flow pulses， the duration， and the number of reversals are moderately altered. More attention should be paid on the impacts of multi-timescale evolution of runoff in the middle Hanjiang River. The results of the study can provide scientific basis and reference for the design of hydraulic projects， water resources scheduling and management and ecological flow regulation in the middle Hanjiang River.

In light of the current challenges in managing flash flood disasters in small and medium-sized basins， it is imperative that improvements to hydrological models take into account the vegetation cover of the underlying surface. further clarify the runoff generation and routing characteristics of the watershed， thereby enhancing the accuracy of forecasting and early warning systems. This study builds upon the traditional TOPMODEL， selecting the Gaotian River Basin and Pajiang River Basin in Qingyuan City， Guangdong Province as the research areas. It selects 15 flood events from the Gaotian River Basin （1975-2013） and 15 flood events from the Pajiang River Basin （1971-2002） for simulation. The coefficient of determination is employed as the objective function， and the SCE-UA optimization algorithm is utilized for parameter calibration and validation. This analysis explores the feasibility of incorporating the curve number （CN value） and generalized unit hydrograph theory to enhance the model's runoff generation and routing module. The results indicate that the average coefficients of determination for the calibration and validation periods improved from 0.74 and 0.75 to 0.82 and 0.80 for the Gaotian and Pajiang River Basins， respectively， demonstrating enhanced simulation accuracy compared to the traditional TOPMODEL. According to the "Hydrological Information Forecasting Specification GB/T 22482-2008，" the model achieved pass rates of 80% and 100% for the two study areas， indicating its capability to accurately capture peak flow rates and their occurrence times， along with a high reliability in simulating total runoff for the selected flood events. Moreover， the generalized unit hydrograph， as a model not yet widely utilized， requires further validation in additional practical applications. The multi-event flood simulation results presented in this study not only contribute to the validation of the model but also provide important data support and theoretical foundations for investigating the relationship between generalized unit hydrograph parameters and the characteristics of watershed underlying surfaces， thus promoting its widespread application in the field of hydrological analysis.

With the rapid development of renewable energy sources （RES） such as wind and solar power， their proportion in the power grid continues to increase. Coordinating the relationship between high-penetration RES and the output of conventional power stations has become a critical issue in power grid scheduling. Taking a regional power grid that integrates RES like wind and solar， as well as cascaded hydropower stations （CHSs）， as the research object， this study investigates the medium-to-long-term compensatory peak regulation scheduling of CHSs in response to the varying outputs of RES and other hydropower stations under an integrated water-wind-solar framework. Sequential compensatory peak regulation scheduling models are established with different calculation periods of years， months， and ten-days， and calculation intervals of month， ten-day， and day. The Discrete differential dynamic programming successive approximation （DDDPSA） algorithm is applied to solve these models. A case study conducted on the Guangxi Power Grid， which has a high proportion of RES， shows that compensatory peak regulation scheduling between CHSs and RES can fully leverage the advantages of both， enhancing the grid's medium-to-long-term compensatory peak regulation capabilities. This approach provides decision-making support for optimizing the compensatory peak regulation operation of CHSs in regional power grids with high-penetration RES， contributing to improved scientific management of the power grid.

To explore the operational rules embedded in the historical operation data of pumped storage power stations， this paper first analyzes the correlation between the output of pumped storage power stations， load， and clean energy output. A cloud model is then employed to convert quantitative data into qualitative cloud concepts. Using the Apriori algorithm， strong association rules between the output of pumped storage power stations， load， and clean energy output are extracted. Subsequently， the cloud reasoning method is applied to simulate the daily output process of the pumped storage power station. The Heimifeng Pumped Storage Power Station in the Hunan Grid is used as a case study to validate the effectiveness of the proposed method. By utilizing the extracted strong association rules for different time periods， we simulate the daily output of the pumped storage power station with the largest peak-to-valley difference on each month through cloud reasoning. The results indicate that， under the simulated output， the peak-to-valley difference and the standard deviation of the residual load are smaller compared to the actual operation. This demonstrates that the cloud reasoning method based on association rules is effective， producing reasonable results and offering valuable reference for practical applications.

In the construction process of large-scale water conservancy and hydropower projects， after the excavation and commissioning of underground tunnels or caverns， the underground tunnels or chambers will undergo time-dependent changes from brittle to ductile behavior and fracture propagation in the deeply buried brittle surrounding rock. To realistically reflect the time effect of brittle rocks and combine it with actual engineering， this paper takes the typical brittle rock marble as the research object and starts from its typical mechanical characteristics and brittle-ductile transformation characteristics. Using the Hoek-Brown constitutive model， the full stress-strain curves of samples under different confining pressure triaxial test conditions， as well as the peak strength， residual strength， and post-peak characteristics of marble were studied. It is proved that the Hoek-Brown constitutive model in FLAC3D can well simulate the brittle-ductile transformation characteristics of brittle rocks. The stress corrosion （SC） model encoded in FISH was reproduced in the built-in Hoek-Brown constitutive model of FLAC3D. Taking the tailrace bifurcated pipes of the water conveyance system of the Shahe Pumped Storage Power Station as the research object， the stability analysis of the surrounding rock under normal operating conditions and the stress deformation analysis of the support structure were completed. Based on this， the time-dependent fracture propagation behavior of the rock considering SC was studied， revealing the brittle-ductile transformation characteristics and time-dependent fracture propagation characteristics of the surrounding rock of the water conveyance system of the pumped storage power station， which is of great significance for the design and safe operation of pumped storage power stations.

In hydropower stations， the water leakage from the plant wall is collected through the catchment pool and then discharged by the drainage pump. Due to the serious calcification of the water quality， it is easy to lead to the scale blockage of the inlet filter screen of the drainage pump， which affects the operation condition of the pump， and even burns the motor. Due to the location of the diversion tunnel where the water collection pool is located deviates from the core operation and management area of the hydropower station， there are few daily inspection arrangements， so it is necessary to identify the blockage degree of the inlet filter by an automatic way. In this study， computer vision technology was introduced， Canny algorithm was used to extract the edge outline of the inlet filter screen of the pump， and then the pore color component was separated by HSV color model. Finally， the color Euclide distance was used to cluster the pixel points of the filter screen， and the number of pore pixels was counted to obtain the pore pixel area. Using this scheme， the pore area of the inlet filter screen of the pump is measured and calculated regularly， and the results are reported to the control center， which is convenient for the transportation and inspection personnel to intervene in time to clear the blockage. The scheme was practiced in a hydropower station， and the results show that this study can effectively detect the scale and blockage degree of the inlet filter screen of the drainage pump.

Hydropower units operate under harsh conditions for extended periods， leading to more frequent abnormal vibrations and gradual fatigue and wear， which cause unit performance degradation. To ensure the safe and stable operation of the units， it is crucial to accurately and intuitively reflect their operating conditions of the hydropower unit and predict future degradation. This provides important information for unit condition maintenance and repair. This paper proposes a method for predicting unit degradation trends based on fused health indicators and VMD-Informer. First， a KAN health model is constructed to fit the mapping relationship between operating parameters and vibration values. Then， by comparing the health model values with the measured vibration values under different indicators， multiple degradation sequences are obtained. A genetic algorithm is used to optimize multiple degradation sequences to obtain fused degradation indicators， taking into account the advantages of multiple indicators to achieve accurate assessment of unit status. Subsequently， the fused degradation sequences are decomposed into multiple components using Variational Mode Decomposition （VMD）. Finally， the Informer prediction model is used to perform multi-step prediction on each decomposed component， and the final prediction result is obtained by reconstructing the predicted components， thus achieving accurate assessment and prediction of the unit's operational status. Case analysis shows that the proposed method can generate reliable degradation trends， while the prediction can learn both the long-term trends and local characteristics of the degradation trend sequences， resulting in higher prediction accuracy.

The flow performance and characteristics of the main water inlet ball valve of the pumped storage unit are affected by various factors such as the type of valve core， valve core opening， and flow channel structure. The flow state at the valve core may affect the cavitation performance of the ball valve， further causing vibration and even cavitation damage to structural components such as the valve core and seal. In this paper， a numerical simulation model of the flow field considering the clearance of the main water inlet ball valve is established. Based on the Realizable k-ε turbulence model and Zwart Gerber Belamri cavitation model， a comparative analysis is conducted on the flow performance and flow characteristics of ball valves under different opening degrees and inlet pipeline structures. The analysis results indicate that： The flow coefficient of a ball valve is positively correlated with its opening degree， while the flow resistance coefficient is the opposite. The opening degree of the ball valve at 45° is the turning point of the flow resistance coefficient. That is， when the opening degree is less than 45°， the flow resistance coefficient of the ball valve decreases significantly with increasing opening degree， and tends to stabilize when the opening degree is greater than 45°. Among several different inlet angles of ball valves， the flow performance is optimal when tanθ=1/6， and the cavitation performance is improved. Its initial cavitation number decreases by 1.42% compared to tan θ=0. The flow field analysis results show that there are significant differences in the pressure and velocity distribution inside the ball valve at different opening degrees， and the jet phenomenon in the outflow direction is obvious at small opening degrees. However， when the inlet angle is different at the same opening， the difference in flow field distribution is relatively small， and the main reason for the difference in distribution is the difference between the inflow direction with valve body clearance and valve core channel angle caused by different inlet angles.

The bidirectional operation of inlet/outlets of pumped storage power stations must meet the requirements of smooth flow and minimal head loss. So， hydraulic optimization of inlet/outlets is crucial for the safety and efficiency of stations. Some low-head stations adopt layouts with open-air powerhouses， where inlet/outlets are closely linked to the draft tubes. Due to the influence of the elbow section of the draft tube， the problem of uneven flow is obvious， so a new shape needs to be proposed. Taking a certain station as an example， CFD simulations were conducted to carry out research and found that the original inclined side inlet/outlet scheme was connected to draft tubes. Due to the centrifugal forces， the main flow within the diffusion section of the original oblique lateral inlet/outlet deviated， resulting in inadequate flow evaluation parameters. Starting from the principle of advanced flow allocation， a solution involving additional baffles was proposed to improve the flow pattern. To further optimize the flow pattern， an innovative shape combining the advantages of lateral and vertical shapes was proposed， with its sensitivity analyzed. The special shape parameters that ensured uniform flow were given. This shape has reference value for the design of the inlet/outlet of pumped storage power stations with open-air powerhouses.

Based on the upper reservoir face rockfill dam of a pumped storage power station， the analysis methods and safety control standards of the ultimate seismic capacity of the concrete-face rockfill dam （CFRD） are expounded from the aspects of permanent deformation of the dam body， seismic stability of the dam slope， tensile fracture resistance of dam body and seismic safety of face slab. The seismic wave overload method is used to calculate the three-dimensional seismic response of the dam under different peak accelerations， and the ultimate seismic capacity of the CFRD is quantitatively analyzed based on the indexes such as the seismic subsidence rate at the top of the dam， the cumulative duration when the minimum safety factor of the slope is less than 1.0， the cumulative slip， the deformation gradient of the dam after the earthquake and the stress of the face slab. Through in-depth and comprehensive analysis， the following conclusions can be drawn： the dam has strong seismic resistance， and its ultimate seismic resistance is between 0.55~0.60 g. The calculation and analysis results provide reference for scientific evaluation of seismic safety of CFRD and reasonable formulation of seismic reinforcement measures.

For the study of incident plane SV wave three-dimensional oblique intake tower structure dynamic response and dynamic water pressure change rule， a finite element model of the three-dimensional system of water intake tower—reservoir water—foundation is established. Based on viscoelastic artificial boundary and three-dimensional wave equation of SV wave， the equivalent nodal load of SV wave at different incidence angles is derived， and the ground motion response of the structure at different incidence angles is investigated. At the same time， it is compared with P wave vertical incidence. The results show that the stress and lateral displacement of the intake tower decrease first and then increase with the increase of the SV wave incidence angle， while the vertical displacement increases with the increase of the SV wave incidence angle. The dynamic water pressure on each facing surface increases with the increase of SV wave incidence angle. When SV wave 0° vertical incidence and 30° oblique incidence （close to the critical incidence angle）， the safety and stability of the intake tower are affected. Compared with the vertical incidence P wave， SV wave is more harmful to the structure of water intake tower. Therefore，this paper carried out analysis of dynamic response of intake tower structure under SV wave oblique incidence， which provides certain reference value for similar projects.

Long distance pressurized pipeline water transmission has become one of the most popular water supply methods. The excess water head in the pipeline usually has a certain impact on the safe operation of the pipeline. The spiral ladder energy dissipation device is a kind of energy dissipation device in the pressure pipeline with simple structure and easy installation， which can effectively reduce the excess water head in the process of water transmission. This paper mainly adopts numerical simulation method to study the energy dissipation efficiency and flow field characteristics such as velocity， pressure and flow line distribution under different ladder spacing conditions from qualitative and quantitative perspectives. The results show that the disturbance of the cross plate structure and ladder plate in the device to the water flow produces strong turbulence， mixing and internal shear. It produces obvious wake afterwards. The overall pressure reduction along the pipeline indicates that the energy dissipation effect is significant. The flow field generally presents obvious regional characteristics before， during and after the energy dissipation device. The spacing of ladder plates affects the turbulence degree of the flow at each ladder plate and the total length of the flow process by changing the flow velocity distribution at each ladder plate and the total length of the energy dissipation device. And then the energy dissipation efficiency is affected. Under various spacing conditions， the energy dissipation efficiency caused by local head loss increases with the increasing flow rate. There are differences in the variation law of the energy dissipation efficiency with the ladder plate spacing under different flow conditions， but they all present a maximum value when the ladder plate spacing is 8 times the ladder plate thickness. Research results reveal the correlation between the spacing of ladder plates and the energy dissipation efficiency to a certain extent， and provide a certain theoretical basis for the practical use of the energy dissipation device.

In order to investigate the relationship between pore structure and permeability of sulfate-amended saline soils improved by wind-deposited sand， we analyzed the pore distribution evolution characteristics of saline soils before and after improvement based on CT scanning， extracted the pore network model to carry out the seepage analysis， and established the permeability prediction model based on the fitting of parameters characterizing the pore distribution. The results show that different from the stable distribution of the original sample， the total porosity and connectivity of the sand-doped sample along the height direction are significantly lower than those of the original sample， and the total distribution of the porosity shows a symmetric distribution of ‘inverted V’； the permeability of the modified sulfate saline soil shows a power function relationship with the porosity and fractal dimensions， and the connectivity predicts the permeability of the soil. The fitting accuracy was higher than that between total porosity and permeability， followed by total porosity， and the correlation between fractal dimension and permeability was lower.

The mechanical property of unsaturated soil is different from that of saturated soil， because pores are occupied by both the gas and water. The description of the mechanical properties of unsaturated soil is an important research topic. In this papar， a liquid bridge model is established with micro and meso mechanism considered. Combined with the linear model describing the contact behavior of soil particles， a model of unsaturated soil is proposed in discrete element method. Based on the proposed model， the triaxial compression test of unsaturated fine-grained soils is simulated with constant suction and the stress-strain relation is discussed. Furthermore， a constitutive model of unsaturated soil is proposed under the elastoplastic framework based on the effective stress and state parameters. This model is verified with simulational results. It is found that the discrete element model can discribe the phenomenon that the strength and volume shrinkage of unsaturated fine-grained soils increase with net confining pressure increasing， and can describe the phenomenon that the strength and dilatancy of unsaturated fine-grained soils are greater than that of dry fine-grained soils significantly. It is also found that the strength and volume shrinkage of unsaturated fine-grained soils in the gas-connected state increase with the matric suction decreasing （i.e. the saturation degree increasing）， and the influence of matric suction on the strength and volume shrinkage of unsaturated fine-grained soils gradually decreases with the net confining pressure increasing. The constitutive model can describe the evolution of unsaturated fine-grained soils with net confining pressure and matric suction correctly， and the calculated results of the constitutive model can better reflect the discrete element simulation results.

The prediction of reservoir bank collapse width is one of the important research issues in water conservancy and hydropower engineering. The empirical diagram method is based on the final stable slope shape of the bank slope to predict the bank collapse width， which does not reflect the bank collapse process of the bank slope， and the physical and mechanical properties of the rock and soil mass of the bank slope are also less considered， so there are often large prediction errors in practical engineering applications. Based on this， this paper proposes a prediction model of bank collapse width based on limit equilibrium theory， and analyzes the key parameters of the model. The results show that the value of the underwater accumulation coefficient has a great influence on the prediction results of bank collapse width， and the optimal underwater accumulation coefficient value increases with the increase of bank height and water depth. In contrast， the slope angle has little influence on the width of the bank collapse， mainly affecting the width of the first bank collapse， and has little effect on the width of subsequent bank collapse. With the increase of the slope of the bank slope， the width of the bank collapse shows a fluctuating upward trend. At the same time， the suitability of the prediction model is verified by comparing the predicted width of typical loess bank slope with the field survey results.

The filling quality of earth-and-rock dams is directly related to the operational safety of dams， and the current commonly used density detection method of water filling method is time-consuming， inefficient， poorly accurate and susceptible to the influence of human factors. In this paper， a volume measurement method of rockfill dam inspection pit based on handheld 3D laser scanner is proposed， which can rapidly scan various types of inspection pits and accurately calculate the volume of inspection pits， and effectively solves the problems of low efficiency and large error of volume measurement in the water filling method. In the application example of compaction quality inspection of 315 m high dam in Shuangjiangkou， the maximum relative error of six groups of compaction index inspection results obtained by this method is only 4.08% compared with the traditional water filling method， which fully proves the effectiveness and accuracy of this method in compaction quality inspection.

As an important means of ecological restoration， returning lakes to lakes can restore lake ecosystems， improve flood control and drainage capabilities， and improve water quality conditions by removing the enclosures and reshaping the lake bottom topography in lakes and ponds. Based on the plain river network runoff model， coupled with the river network hydrodynamic model， after model generalization， boundary conditions， underlying surface runoff distribution and model calibration verification， this paper embeds the hydrological data of the Lixiahe area to simulate the flood retention effect of four different reclamation and return schemes for the lakes and ponds in the Lixiahe River in Xinghua City during the Lixiahe flood in 2006. The four retreat schemes are： return of all lake areas， restoration restoring of 153.32 km² of lake free water surface； return of lakes and ponds with an area of more than 10 km²， restoration of 95.96 km² of lake free water surface； return of 50% of all lake areas， restoration of 76.66 km² of lake free water surface； return of 50% of lake areas with an area of more than 10 km²， restoration of 47.98 km² of lake free water surface. The simulation results of four different lake retreat schemes in the model show that when the lakes and ponds in the Lixiahe Lake area of Xinghua City are cleared and the waterlogging is retained， the river network water level in the Lixiahe area will be effectively reduced during the flood season， and the water level， water depth and water storage capacity of the lakes and ponds in the Lixiahe Lake area of Xinghua will be significantly affected. The results of this paper show that there are certain differences in the flood retention effects of different lake retreat schemes. The larger the area of the lakes and ponds to be retreated， the more obvious the impact on the water level of the river network during the flood season. When all 20 lakes and ponds are retreated， the overall water level of Xinghua can be reduced by about 0.19 m， and the water levels of typical stations such as Yancheng， Funing and Qintong will also be reduced to a certain extent. Due to the participation in the regulation of the external river network during the flood process， the highest water level and water depth of the lakes and ponds in the Lixiahe Lake area of Xinghua generally increased by more than 1.0 m compared with before the retreat， and the water storage capacity also changed consistently and the maximum storage capacity was close to 1 times the original storage capacity. Therefore， the retreat and lake restoration can effectively reduce the risk of flood detention， and it is necessary to carry out the retreat and lake restoration in the entire Lixiahe Lake area of Xinghua City.

This study takes Luoma Lake as the research area， utilizing Sentinel-2 satellite imagery， in-situ water quality data， and spectral data to construct remote sensing inversion models for water transparency and suspended sediment concentrations. The models were developed using both statistical methods and machine learning techniques. The performance of both models in water quality inversion was comprehensively compared， and the optimal model was selected for an in-depth analysis of the spatial distribution characteristics of water quality in Luoma Lake. The results indicate that： ① The correlation analysis between Sentinel-2 equivalent remote sensing reflectance and water quality parameters show that the correlation of band combinations is significantly improved compared to single bands. The transparency has the highest correlation with B3/B4 （0.85）， and the suspended matter concentration has the highest correlation with B5/B4 （0.68）； ② Compared with the statistical regression-based inversion model， both water transparency and suspended sediment concentration achieve higher inversion accuracy using machine learning models. The optimal inversion model for transparency （testing set： R2=0.85， RMSE=7.25， MAE=5.25） and suspended sediment concentration （testing set： R2=0.87， RMSE=3.36， MAE=2.49） are both GA-XGBoost models； ③ The inversion results for Luoma Lake indicated that suspended sediment concentrations are higher， and transparency is lower in the northeastern nearshore areas， possibly due to ongoing human activities such as fish farming； ④ A long-term analysis of inversion results from 2018 to 2022 revealed significant seasonal characteristics in the water quality of Luoma Lake. Suspended sediment concentrations were higher， and transparency was lower during the spring and autumn seasons， while suspended sediment concentrations decreased， and transparency increased in winter. During the 2018-2020 period， both suspended sediment concentrations and transparency showed small fluctuations within a certain range， with only a few significant fluctuations driven by seasonal or weather factors. In 2021 and 2022， the removal of embankments and fishing nets in the northern part of Luoma Lake caused sediment disturbance， leading to increased suspended sediment concentrations and decreased transparency.

In recent years， the risks associated with antibiotics as a typical emerging contaminant in karst water environments have drawn considerable attention. This study， taking the karst water system in Jinan as a case study， employs a suite of analytical techniques including hydrochemical analysis， cluster-principal component analysis， hydrogen-oxygen isotope technology， the Risk Quotient （RQ）， and Joint Probability Curves （JPCs）. On the basis of classifying the hierarchy of the Jinan karst water system， the study analyzes the distribution characteristics of quinolone antibiotics in karst water flow systems of different hierarchies and assesses the potential risks to ecology and human health. The findings are as follows： ① Within the spring area， aquifers develop a three-tiered groundwater flow system ranging from local to intermediate to regional， with the concentration of antibiotics showing a significant difference across these levels， decreasing as the circulation depth increases， indicating that their distribution is controlled by the flow systems of different hierarchies； ② The single-risk entropy method reveals that the local groundwater flow system has a relatively high ecological risk level， posing a moderate health risk to adolescents and infants. In the intermediate to regional groundwater flow systems， only a few sites exhibit mild ecological risks， with generally low human health risks， posing only a limited threat to infants； ③ The multi-tiered risk assessment method， which takes into account the sensitivity differences among the majority of species in the entire spring area water ecosystem， finds that only the maximum risk product of Norfloxacin （NOR） is within the low-risk range， while the risks of other antibiotics are negligible. The results provide a basis for the protection of karst water systems in northern regions.

In order to explore the effects of different initial densities of aquatic plants and different plant combinations under the same density conditions on the removal of nitrogen， phosphorus and chemical oxygen demand （COD） in aquaculture wastewater， three common aquatic plants， Hydrilla verticillata， Ceratophyllum demersum and Myriophyllum aquaticum， were used as experimental objects in this study. The effects of different initial densities （1.25， 6.25 and 12.5 g/L） of H. verticillata and M. aquaticum on the removal of nutrients in aquaculture wastewater were compared. The results showed that under the same initial density conditions， H. verticillata exhibit higher efficiency in removing nitrogen， phosphorus， and COD compared to M. aquaticum. And the increase of initial density of both species was beneficial to the removal of nitrogen， phosphorus and COD， but it would lead to the decrease of relative growth rate （RGR）. When the concentration of H. verticillata was 12.5 g/L， the removal efficiency of TP， TN， NH₄ ⁺-N and COD was 89.21%， 75.66%， 94.61% and 88.87%， respectively. In the same density （10 g/L） combination experiment， one， two， and three aquatic plant combinations were used. The results showed that using a single aquatic plant led to a higher RGR compared to combinations of 2 or 3 species， while the combination of the three species has the lowest RGR. The removal efficiency of nitrogen and phosphorus by single-species treatment of H. verticillata and C. demersum was better than that of the combination of two and three species， while the removal efficiency of COD by three-species combination was better than that of the combination of two and three species. Linear regression showed that RGR of aquatic plants was significantly positively correlated with the removal rates of TP， TN， NH₄ ⁺-N and COD based on the weight. With the increase of RGR， the removal rates of carbon， nitrogen， and phosphorus based on weight significantly increase. In summary， in order to maintain a high nutrient removal efficiency in aquaculture water， it is necessary to optimize plant density management and species combination during the restoration process.

A healthy water balance status is a crucial guarantee for achieving regional sustainable development. This papar synthetically considered the interactive relationship between water resources， ecological environment， and socio-economic aspects in karst landscape watersheds， and selected 15 evaluation indicators to construct a multi-dimensional evaluation index system for water balance health in karst landscape watershed from four dimensions： natural water budget balance， socio-economic supply and demand water balance， ecological landscape supply and demand water balance， and the balance of water use between socio-economic and ecological landscapes. The analytic hierarchy process and the entropy weight method were integrated to calculate indicator weights. Taking the Lijiang River Basin as a case study， the health status of the water balance from 2013 to 2021 was evaluated based on the TOPSIS model. The obstacle degree model was used to quantitatively diagnose the key obstacle factors affecting the health degree of water balance， and the optimization countermeasures of water balance in the basin were proposed. The results indicate that the overall health degree of the water balance in the Lijiang River Basin presents an upward trend， and the evaluation results in 2019 and 2020 are rated as healthy. Affected by factors such as evaporation， precipitation， and precipitation concentration degree， the health degree of water balance in the Lijiang River Basin decreased by 0.09 in 2021. The health status of natural water budget balance， socio-economic water supply and demand balance， and the balance of water use between socio-economic and ecological landscapes criterion layer shows a fluctuating upward trend. The health status of ecological landscape water supply and demand criterion layer has decreased， indicating that there is a phenomenon of economic and social water use crowding out ecological landscape water use in the Lijiang River Basin. The main obstacle factors affecting the water balance health of the Lijiang River Basin are development and utilization rate of water resources， maximum storage capacity of reservoirs， precipitation concentration degree， and evaporation. During the study period， the obstacle degree of the natural water budget balance criterion layer was the largest. Therefore， enhancing the water resource regulation capacity and water use efficiency is of great significance for improving the water balance health level of the Lijiang River Basin.

Against the backdrop of global warming and increasing urbanization， great challenges have been brought by extreme rainstorms to existing urban drainage systems. To cope with urban flooding， deep tunnel drainage systems are increasingly used in large cities， and the dropshaft is an important component of the drainage system. In order to analyze the influence of inclination angle of baffles on the hydraulic characteristics of the symmetric dropshaft in the deep tunnel drainage systems， a three-dimensional turbulence mathematical model based on the Realizable k-ε model and the VOF method was established in this paper. The inclination angles of baffles were set to 0°， 8°， 10°， and 12° at the dimensionless flow rate （Q^* ） from 0.056 to 0.168 to simulate the flow regime， velocity distribution， pressure distribution， and energy dissipation rate of the shaft. The results showed that with the increase of baffle inclination angle， the flow regime showed a transition from wall-impacted flow to critical flow and free-drop flow， the backwater height between the baffles decreased and the percentage of air rised. The discharge increased. The water oscillated less between the baffles and the degree of mixing was reduced， resulting in increased water flow velocity at the edge of the baffles. The pressure of shaft walls mainly consists of hydrostatic pressure and dynamic pressure， and the former is the main influencing factor. As the inclination angle increased， the pressure decreased accordingly. The influence of the inclination angle on the energy dissipation rate of the shaft changed with the flow rate. The overall energy dissipation rate of the shaft was lower for the large flow rate than that of the small flow rate. When the flow rate was small， the water dropped directly onto the baffles， the energy dissipation rate decreased with the increase of the baffles inclination angle. When the flow rate was large， water flow directly hit the opposite wall， which reduced the effectiveness of energy dissipation. The energy dissipation rate increased first and then decreased with the increase of the baffles inclination angle for large flow rate. This research can provide a reference to the design of the baffle inclination angle of dropshafts in the deep tunnel drainage systems.

In engineering practices such as reservoir dredging and irrigation using water diverted from the Yellow River， coarse pebbles often enter the pipelines. When transported under high sediment concentration， these coarse particles increase energy consumption in the pipeline system， reduce transportation efficiency， and are prone to causing blockages at pipeline bifurcations. Clarifying the motion and energy consumption mechanisms of coarse particles in high sediment concentration flows within bifurcation pipelines is crucial for enhancing sediment discharge efficiency and ensuring engineering safety. This article integrates the latest research trends on the hydraulic transport of coarse particles in sediment-laden water flows through bifurcation pipelines， both domestically and internationally. It systematically summarizes the complex hydraulic characteristics within bifurcation pipelines， particularly at the junctions between the main and branch pipes， including pressure drop variations and flow field characteristics. Furthermore， it explores the energy consumption mechanisms and the motion mechanisms of the transported medium when the medium varies within the pipeline. This provides valuable insights for optimizing pipeline design， improving transportation efficiency， and achieving energy conservation and emission reduction. Based on current research findings， a combination of model experiments and fluid-solid coupling CFD-DEM numerical simulation technology is employed to investigate the key parameters of transported materials， such as different coarse particle sizes， high sediment concentration flow velocities， and sediment concentrations. Additionally， it explores the motion mechanisms of coarse particles and the variation patterns of head loss under common pipeline layout conditions， including various inflow and outflow forms， outflow angles， and overall reverse slope angles at bifurcation pipelines. Revealing the energy consumption mechanisms of transporting materials in bifurcation pipelines for high sediment concentration water flows， improving the solid-liquid volume fraction identification algorithm， and utilizing GPU parallel computing technology to enhance the computational efficiency of CFD-DEM numerical simulations will be the future research focus in this field.

The combined effects of sand mining and waterway improvement projects alter flow partition ratios of branching channels within bifurcated reaches. This affects hydrodynamic conditions of shipping channels and poses risks to navigation safety. In order to investigate impacts of sand mining in the north branch and Yilu waterway development in the east branch on hydrodynamics of adjacent shipping channel located at the distal end of Zijiang River， we adopt data of riverbed terrain and hydrology in 2021 and 2023 to establish a planar 2D numerical model of water flow motion， from which hydrodyanmic changes within the shipping channel under different topographic and hydrological conditions are simulated. Results show that water flow conditions within the shipping channel of the north branch hardly changes after the implementation of the two engineering projects. The maximum water-level decrease in the northern branch waterway is 0.01 m during dry season after sand mining. During flood season， the maximum increases of flow velocity and lateral flow velocity are 0.08 m/s and 0.06 m/s， and the flow-partition-ratio growth is 1.22%. The shipping water depth declines by 0.57 m throughout the north branch under the implementation of the Yilu waterway development project. This will not affect the normal navigation in the north branch and hardly hinder ships to enter the east branch at the Maojiaokou diversion node. Because bars and beaches around the mining area may be scoured during flood season after sand mining， protection projects are suggested to be built. The findings are applicable to the planning of sand mining schemes within bifurcated reaches located at intersection areas between rivers and lakes.