Branching channels are common in nature. After the construction of the upstream reservoir hub， the downstream clear water scouring causes the riverbed armoring of the branching channel to become normal. Therefore， it is of great significance to study the laws related to the riverbed armoring of the branching channel under the action of clear water. Through the flume test， it is found that in the dynamic process of the damage and formation of the armoring layer in the branching river bed caused by clear water scouring， the bed-load transport rate presents a fluctuating change of first increasing and then decreasing. And with the increase of flow， the peak value of the transport rate increases， the occurrence time is advanced， and the formation time of the armoring layer is shortened. The armoring degree of the main branch is higher than that of the branch， and the increase of discharge intensifies the damage of armoring layer， resulting in the overall increase of sediment diameter and the reduction of particle size distribution. In addition， the erosion and deposition of riverbed topography are significant. The main branch erodes violently and the branch deposits， and there is a dynamic balance between the flow and the riverbed topography.

The tidal level in tidal river sections is influenced by multiple factors， including river hydrodynamics， astronomical tides， and meteorological conditions， with complex physical mechanisms that make precise forecasting challenging. This study develops a tidal level forecasting model on integration of mechanism-based and data-driven approaches. The Non-Stationary Harmonic Analysis Model （NS_TIDE） analyzes the seasonal and periodic characteristics of tidal level changes， accounting for the underlying mechanisms. This model provides a baseline for tidal level forecasting， ensuring the rationality of the predicted tidal level trends. The data-driven model， DRSN-LSTM， is constructed using Deep Residual Shrinkage Networks （DRSN） and Long Short-Term Memory Networks （LSTM）. It captures the impacts of multiple influencing factors on tidal levels and generates amplitude values for tidal changes. An Adaptive Genetic Algorithm （AGA） is employed to couple and optimize the forecasting results of the NS_TIDE and DRSN-LSTM models. The proposed model was applied to the entrance of the Qinhuai New River in the Yangtze River basin. By comparing the forecasting performance of NS_TIDE， DRSN-LSTM， and the coupled model under different forecast periods， the results demonstrate that the coupled model not only adheres to the physical laws governing tidal level changes but also simulates the effects of multiple influencing factors on tidal amplitude. For a 24-hour forecast period， the Root Mean Square Error （RMSE） for hourly forecasts in non-flood and flood seasons were 0.15 m and 0.18 m， respectively. During typhoon events， the average accuracy rate for forecasts with errors within ±0.30 m exceeded 80%. The coupled model exhibits high accuracy and practicality， ensuring the scientific validity and precision of hydraulic engineering operations in tidal rivers.

In the construction of the cofferdam foundation reinforcement project at the Qiantang River estuary， a common practice is to first construct a vertical geotube groin to reduce the scouring effect of water flow on the main body of the cofferdam. However， under the complex hydrodynamic conditions of the estuary， severe local scouring of the riverbed near the geotube groin head occurs， leading to rupture of the bagged structure and loss of fill material， which results in the damage of the dam and severely impacts the construction progress. To address this issue， this study proposes a method of constructing a mixed clay-geotube groin （hereafter referred to as the mixed groin） by filling the groin head with clay. A series of flume tests were conducted to compare the changes in water flow， sediment transport， and riverbed changes around the geotube groin and the mixed groin under both steady flow and unsteady flow conditions. The results indicate that under steady flow conditions on a fixed bed， the flow velocity near the mixed groin head is generally higher than that of the traditional geotube groin. However， as the water depth increases， the difference in flow velocity between the two decreases. In addition， the range of low flow velocities behind the mixed groin is generally larger than that of the traditional geotube groin. Under unsteady flow conditions on a mobile bed， the maximum scour depth at the head of the traditional geotube groin is significantly greater than that of the mixed groin. The scour pit near the head of the traditional geotube groin tends to be narrow and deep， while the scour pit near the head of the mixed groin has a wider and shallower shape. Within the length of the dam， due to the reduction in flow velocity behind the dam， sediment deposition occurs. The sediment accumulation behind the mixed groin is significantly thicker than that behind the traditional geotube groin. The use of a mixed groin instead of a traditional geotube groin can effectively reduce the depth of scour pits at the groin head under the complex hydrodynamic conditions of the estuary. It addresses the damage problem caused by the tearing of the pipe bag at the groin head， thereby extending the service life of the dam. Additionally， the mixed groin promotes better sediment deposition behind the dam， which raises the elevation behind the groin. It accelerates the construction progress of the longitudinal cofferdam and reduces construction costs. The findings of this study provide a practical and feasible improvement scheme for the construction and protection of geotube groin in cofferdam projects in estuarine areas.

Tidal channels are essential conduits for material exchange between terrestrial and marine environments. They play a vital role in shaping the morphology of mudflats， stabilizing wetland shorelines， and supporting the migration and distribution of nutrients within wetland ecosystems. As critical components of the hydrodynamic system in mudflat regions， the evolution and development of tidal channels are directly linked to the health and stability of wetland ecosystems. This study takes the tidal channels of the Liaohe River Estuary Wetland as the research focus. Using ArcGIS technology， the temporal dynamics of tidal channel structures were analyzed from 1985 to 2019. The research examined the evolutionary characteristics of tidal channel erosion and development and employed gray correlation analysis to quantify the key driving factors influencing tidal channel changes. The results of the analysis reveal a significant trend of tidal channel degradation in the Liaohe River Estuary Wetland between 1985 and 2019. The characteristics of tidal channel erosion development show that the complexity of the tidal channel network has decreased. Although the number of tidal channels increased over the years， their total length experienced a marked decrease. Connectivity between channels weakened considerably， especially the 4th and 5th level tidal channels have gradually disappeared. The overall degradation was manifested by the retreat of tidal channel heads， which advanced at an average rate of -0.22 km per year. These changes have undermined the ecological functions of tidal channels， reducing the mudflat’s capacity for material exchange with external environments.The study shows that with the gradual expansion of the scale of marine aquaculture， the natural tidal hydrodynamics in the wetland tidal flat area has been disturbed， the formation of tidal channels has been weakened， and the degradation of tidal creeks has intensified. The change of tidal dynamics is an important natural driving force in the evolution of tidal channels， and plays a decisive role in their development. The degradation of tidal channels is driven by a combination of human activities and natural factors. Among them， the rapid expansion of mariculture and the tidal hydrodynamics are the key driving factors.

The water surface profile is a necessary basic parameter for the planning， design， research， construction， and management of water-related projects such as water conservancy， hydropower， transportation， and shipping. The rationality and calculation accuracy of its results are crucial. There are many factors that affect the calculation results of water surface profiles， such as river topography， hydrological boundaries， calculation models， river roughness， and so on. The discrete analysis of the model， adjustment of calculation parameters， selection of roughness， differences in boundary values， and generalization of simulation of water-blocking structures all affect the calculation results of the water surface profile. In this paper， the influence of the density of river section layout on the calculation results of water surface profiles in trapezoidal and natural river channels is focused on， which can provide reference for the reasonable layout of calculation sections in water surface profile calculations. The higher the density of the cross-section， the higher the calculation accuracy. However， due to the need to consider the calculation of Froude number and efficiency， the cross-section cannot be infinitely densified. The research results indicate that for straight trapezoidal river channels， the sensitivity of cross-sectional density to the calculation results is relatively small， with only a slight impact on the calculation results. The maximum deviation of the river water level calculated at 200 km is only 0.008 4 m， approximately 0.000 04 m/km. It can be considered that for regular cross-section straight river channels， a spacing of less than 1km between cross-sections is sufficient to meet the calculation accuracy requirements. Generally， a spacing of 3 times the width of the river is sufficient to meet the calculation accuracy requirements. For natural river channels， cross-sectional density has a significant impact on the calculation results. As the cross-sectional density increases， the amplitude of water level deviation gradually decreases in each operating condition. For working conditions where the distance between sections is greater than 5 times the average river width， the change in section density does not significantly improve the calculation accuracy. However， when the distance between sections is reduced to 2-3 times the average river width， the calculation accuracy can be significantly improved. To ensure calculation accuracy， the cross-sectional density should be controlled within a range of 2 times the width of the river as much as possible.

The three outlets of the Jingjiang River are regarded as the crucial connection between the mainstream of the Yangtze River and Dongting Lake， directly influencing the evolution characteristics of the mainstream and lake area and the adjustment of the river-lake relationship. In recent years， the back-flow phenomenon has frequently occurred at the outlets along the Jingjiang River. Especially in 2023， 56 days of back-flow were recorded at the Mituosi station of Taipingkou， which accounted for 8% of the total annual runoff at that station. This paper collects the daily flow and water level data from five stations at the three outlets along the Jingjiang and the Nanzui station at the southern end of the water system. It focuses on the backflow phenomenon in 2023 and analyzes the causes from multiple aspects. The results show that the erosion of the Songzi River combined with the sand mining activities has led to an increase in the flow capacity of the Songdong River. Under low-discharge conditions， the water flow from the Songdong River to the Hudu River， which is the main reason for the increased number of reverse flow days at the Mituosi station in 2023. Moreover， during the dry season， the small water surface gradient and weak hydrodynamic conditions between the North and South sluices of the Hudu River， along with the rapid decline of the water level in the mainstream， have facilitated the occurrence of backflow. In 2023， the runoff volume of the Yangtze River basin was relatively low， and the daily flow process at the Zhicheng station frequently entered in and out the discharge range where the backflow phenomenon occurred， resulting in a significantly increased number of backflow days at the Mituosi station.

This article is based on numerical simulation and systematically studies the hydraulic characteristics， energy dissipation characteristics， and scouring characteristics of the diffusion-type inclined stepped spillway and the smooth spillway in a certain engineering project. The results show that when using the smooth spillway， the energy dissipation rate reaches 35.43%， and the maximum scour hole depth of the downstream is 27.28 m， with good agreement between simulation results and experiments. At the same flow rate， the stepped spillway enhances the swirling and air entrainment of the water flow through the steps， improving the energy dissipation effect along the channel. Compared to the smooth spillway， the water depth in the stepped sections increases by 8% to 35%， the flow velocity decreases by 15% to 22% on different cross sections， and the energy dissipation rate increases by 19.37% to 24.4%， significantly reducing the downstream horizontal jump distance and scour depth. At the same time， the results indicate that the step height has a minor effect on the energy dissipation rate， the water depth at the end of the step， and the flow velocity at the spill.

The uneven distribution of hydrological monitoring networks has resulted in a lack of long-term available streamflow monitoring data in most watersheds worldwide. However， traditional hydrological models and single machine learning models have poor simulation accuracy and generalization capability when simulating runoff in data-scarce watersheds. This study proposes a SWAT-LSTM-Transformer （SLT） coupled modeling framework that integrates physical mechanisms with data-driven approaches， implementing cross-basin knowledge transfer through transfer learning and innovatively introducing a rainfall-based peak flow identification correction method to enhance daily runoff simulation performance in data-scarce watersheds. Using the Hanjiang River Basin （a data-rich basin） as the source domain， a multi-feature input set was constructed， which includes seven hydrological variables simulated by SWAT （actual evapotranspiration， infiltration， surface runoff， etc.） and five meteorological factors （rainfall， temperature， etc.）. The SLT model demonstrated excellent simulation performance in both training and testing periods， with Nash-Sutcliffe efficiency （NSE） coefficients reaching 0.96 and 0.95， respectively. To address the streamflow data scarcity in the target domain of the Wusha River Basin（a data-scarce basin）， a cross-basin transfer learning strategy was designed： based on hydrological similarity analysis， the parameters of the pre-trained SLT model from the Hanjiang River Basin were transferred to the Wusha River Basin's SLT model， incorporating rainfall-based peak flow identification correction for runoff simulation at the Wanli station. Results show that the SLT model performed well in streamflow simulation at the Wanli station， achieving NSE values of 0.86 and 0.73 for the training and testing periods， respectively. Soil infiltration， rainfall， surface runoff， and soil moisture content significantly influenced the SLT model’s simulation performance. The established SWAT-LSTM-Transformer coupled model provides a viable approach for runoff simulation in data-scarce watersheds.

As an important water resource supply region in China， the Yellow River Basin spans several provinces with complex and diverse terrain and climate types. In recent years， the impacts of global climate change have become increasingly significant， and the climate system in the Yellow River Basin has also shown noticeable trends of change. To evaluate the spatiotemporal variability of precipitation， temperature， evaporation， and potential evapotranspiration across the upper， middle， and lower reaches of the Yellow River Basin from 1960 to 2022， this study developed a comprehensive evaluation index system for spatiotemporal variability， which includes two criterion layers—time variation and spatial variation—encompassing 15 evaluation indicators. The entropy-weighted fuzzy TOPSIS model was then applied to conduct a comprehensive assessment of the time， space， and spatiotemporal variability of key meteorological factors in the Yellow River Basin.The results indicate that the spatiotemporal variability of meteorological factors in the Yellow River Basin is significant. The time variability， spatial variability， and spatiotemporal variability scores for precipitation， temperature， evaporation， and potential evapotranspiration in the upper， middle， and lower reaches are mostly moderate， with generally low levels of variability in all three dimensions. However， there are notable differences in the variability of different meteorological factors across different regions. Overall， the spatiotemporal variability of various meteorological factors varies greatly across regions. However， evaporation exhibits similar spatiotemporal variability in the middle and lower reaches， and potential evapotranspiration shows consistent spatiotemporal variability across all three regions， indicating that these meteorological factors have undergone similar degrees of change in different parts of the basin. Additionally， from the upstream to the downstream， precipitation shows a trend of increasing variability initially and then decreasing， temperature and potential evapotranspiration display a continuous decreasing trend， while evaporation shows a trend of decreasing variability initially and then increasing.

The uneven temporal and spatial distribution of water resources constitutes a crucial bottleneck restricting regional sustainable development， particularly in the water-deficient plain areas of northern China. The superimposed effects of climate change and human activities have exacerbated the contradiction between water supply and demand. In this paper， in response to the multi-dimensional regulation requirements of regional water resources and based on the dual water cycle theory， a water resources optimization allocation model integrating the “multi-water sources-multi-objectives-multi-factors” synergy is constructed. This model systematically integrates multiple water sources such as surface water， groundwater， reclaimed water， and transferred water， comprehensively considers multi-dimensional objectives encompassing economy， ecology， and society， and couples multiple essential factors including water balance， water quality constraints， and water use efficiency. It innovatively establishes a “time-space-structure” trinity water resources allocation framework. The research breaks through the traditional allocation mode， based on the spatio-temporal coupling relationship between surface river runoff generation and convergence and groundwater recharge and discharge. It coordinates the characteristics and service functions of water resources development and utilization in different dimensions， and analyzes the elements and processes of multi-water sources （upstream water， reclaimed water， rain and flood water， transferred water）， multi-objectives （ecological water replenishment， ecological landscape， farmland irrigation， flood control and drainage， etc.）， and multi-factors （regional water production and overland water flow characteristics， marginal cost of water conservation， industry water use guarantee degree） for water resources optimization allocation. Through multi-dimensional scenario simulation， the evolution laws of the water resources system are revealed. Taking the water-deficient plain city of Langfang in northern China as an example， through analyses of supply and demand balance and water consumption balance， it is predicted that the water demand in 2030 will be 1.185 billion cubic meters， with a water shortage of 0.044 billion cubic meters and a water shortage rate of 3.71% under the premise of ensuring the sustainable development of Langfang's economy and society， which can ensure the normal realization of the urban and rural ecological water network function. The multi-dimensional regulation technology system proposed in this paper establishes a “quantity-quality-efficiency” coordinated control mechanism， providing a replicable and promotable technical approach for resolving the tight water resource constraints and enhancing the water ecosystem service function in the water-deficient plain areas of northern China.

Quantitative analysis was conducted on endogenous physical clogging characteristics in aquifer media during artificial groundwater recharge， with four experimental schemes designed using a customized column apparatus to quantitatively investigate and quantitatively analyze hydraulic head difference， recharge flow rate， permeability， and particle size distribution. The results show that after 1 524 hours of continuous operation， a 26.46% reduction in the total hydraulic head difference was recorded across the sand column， with the upper section showing a more pronounced reduction of 54.34%. The recharge flow rate decreased from 438 mL/min to 322 mL/min （36.02% reduction）. The overall permeability coefficient declined by 8.0% in the entire medium， while a 35.0% decrease was recorded in the upper section. The relative permeability evolution conformed to by the Bi-Gaussian model， demonstrating that the asymmetric behavior of relative permeability characterized by rapid pre-peak enhancement followed by gradual post-peak attenuation. In terms of space， the endogenous physical clogging of the medium was spatially concentrated in the upper-middle section of the sand column. This was caused by the movement and accumulation of 0.075~0.25 mm particles from the upper segment under kinetic energy， resulting in localized clogging. The relative permeability was observed to be highest in the upper section at recharge stabilization， but lowest in the upper-middle segment， with a 10.94% increase in hydraulic head difference. The mass fraction of 0.075~0.25 mm particles in the clogged zone increased by 6.48% compared to the initial state. Systemic reductions in total hydraulic head difference and permeability were induced by this localized clogging. Permeability decline commenced at 37 days of recharge， with significant clogging observed at 60 days. The clogging zone was located 42 cm from the artificial recharge point. The severity of endogenous clogging was found to be governed by the particle size distribution and uniformity coefficient of the porous media. Particles within the 0.075~0.25 mm range were identified as the dominant factor that triggered endogenous clogging mechanisms. Through multidimensional cross-validation of experimental protocols， the reliability of the results was systematically verified. This study is proposed to serve as a technical reference for site selection in artificial groundwater recharge projects.

In recent years， the frequency and intensity of extreme drought events in Hunan Province have shown an increasing trend， leading to a progressively severe regional drought situation. In this context， conducting a scientific drought risk assessment is of great significance for regional drought early warning and water resourcs management. Using the monthly precipitation data from 83 meteorological stations in Hunan Province from 1960 to 2021， the Standardized Precipitation Index （SPI） was selected as a quantitative index of meteorological drought to explore the spatio-temporal evolution characteristics of drought in Hunan Province. Taking the county-level administrative areas as the evaluation units， risk factors including vulnerability， exposure， and resilience were used to identify the meteorological drought risk in Hunan Province， and a comprehensive evaluation model of drought risk was established. Traditional Markov chains and spatial Markov chains were applied to explore the characteristics of drought risk transition and spatial spillover effects in Hunan Province. The results showed that： ① the SPI-12 series in the past 60 years showed an upward-downward-upward trend， with significant abrupt changes detected in 1984， 1993， 2002 and 2014. ② The spatial patterns of drought duration and severity were generally consistent， with longer duration and relatively higher severity observed in northwestern and southern parts of Hunan. ③ The risk of meteorological drought in Hunan Province showed an increasing trend， and high-risk areas were concentrated in Hengyang， Yongzhou， Zhuzhou， Zhangjiajie， central and eastern Shaoyang， and northern Xiangxi Autonomous Prefecture. ④ Drought risk transition in Hunan Province fluctuated in time， and generally maintained or shifted to lower risk level in space. Transition of drought risk in neighboring regions had the characteristics of geographic agglomeration and synergy， among which synergistic downward areas were mainly concentrated in Shaoyang， Hengyang， Zhuzhou， Xiangxi Autonomous Prefecture， and the southern parts of Huaihua and Yongzhou. The results of the study can provide a reference for drought mitigation and drought risk management in Hunan Province.

As a major agricultural country， China is highly dependent on water resources. Analyzing the spatial pattern characteristics of China's water footprint intensity can contribute to the sustainable development of its water resources. Based on panel data from inter-provincial China between 2015 and 2023， the spatial correlation characteristics of water footprint intensity were analyzed using exploratory spatial data analysis and the spatial Durbin model， after calculating the water footprint intensity of each province. The results show that： ① the average annual water footprint in China exhibits significant polarization， with the maximum value in Guangdong and the minimum value in Xizang， showing a difference of 110.333 billion cubic meters； ② Between 2015 and 2023， the water footprint intensity of each province fluctuated to varying degrees， with the largest fluctuation in Xizang and the most pronounced fluctuation occurring in 2020； ③ In the calculation of the water footprint， agricultural and livestock products account for the largest proportion， reaching 69.7%. The proportions of the industrial product water footprint， domestic and ecological water footprint， and grey water footprint are 9.5%， 11.6%， and 9.1%， respectively. ④ ESDA analysis revealed a significant spatial dependence in water footprint intensity. HH agglomeration types are predominantly located in the northeast and central-western regions， HL agglomeration is mainly found in the non-coastal areas of the east， LH agglomeration includes only a few regions each year and is unstable， while LL agglomeration is primarily distributed in economically developed areas along the east coast. ⑤ The spatial econometric model of water footprint intensity indicates that sustained economic development can effectively reduce water footprint intensity， and there is an “inverted S-shaped” curve relationship between per capita GDP and its square root， cube root， and water footprint intensity. Therefore， based on an understanding of the spatial correlation patterns of China's water footprint intensity， the government's active promotion of economic development is conducive to improving water resource utilization efficiency， and strengthening the coordinated development of water-saving technologies between regions is an effective way to enhance water resource utilization efficiency.

Due to the complex landforms and special hydrogeological conditions intertwined in karst areas， the process of runoff changes is complex and intricate. The inherent relationship between runoff， rainfall， and underlying surfaces presents significant differences compared to non-karst areas. Traditional analytical methods face many limitations when faced with such complex geographic spatial contexts， making it difficult to clarify the trend of runoff changes， which in turn constrains the rational development and efficient utilization of regional water resources. Therefore， in order to explore the characteristics of runoff distribution and changes in karst watersheds， as well as their response relationship with climate change and underlying surface changes， this paper takes the Wuyang River Basin as the specific research object， relies on rainfall and runoff data from 2005 to 2017， and uses geographic detectors and geographic weighted regression models to analyze its spatiotemporal trends and runoff response factors. The research results show that： ① The rainfall and runoff in the Wuyang River Basin exhibit a gradually increasing trend on an interannual scale， and the spatial distribution characteristics are significant， with values in the eastern region significantly higher than those in the western region. This spatial pattern is closely related to the topography of the basin， water vapor transport pathways， and other factors. ② Rainfall is the dominant factor， with explanatory power of 0.557 and 0.616 for the spatial distribution of runoff in 2005 and 2015， respectively， followed by land use type and lithology. The explanatory power of NDVI （Normalized Difference Vegetation Index） and slope is relatively weak. ③ With the passage of time， high-intensity human activities intertwined with natural factors， causing changes in the spatial pattern of NDVI， slope， land use， and lithology factors in the study area. In 2015， nearly half of the regions showed a positive correlation between these factors and runoff， significantly affecting the spatial distribution trend of runoff. This study provides scientific support for understanding the hydrogeological conditions and efficient utilization of water resources in the Wuyang River Basin， and also serves as a reference for similar research in karst areas.

A fair and reasonable compensation benefit sharing scheme is conducive to mobilizing the enthusiasm of each member reservoir to participate in joint operation， and is of great significance for improving the overall power generation of reservoir groups and realizing the full utilization of hydropower resources in the basin. Compared with the traditional single index method and comprehensive index method， the asymmetric Nash negotiation model not only fully considers various characteristic indicators such as the installed capacity and guaranteed output of the power station when solving the cooperative game problem of compensation benefit sharing， but also improves the problem that the solution results are subjective due to artificial weighting. Therefore， this paper introduces the asymmetric Nash negotiation model to solve the compensation benefit sharing problem of the joint dispatching of three cascade reservoirs of Xiluodu， Xiangjiaba and Three Gorges. Firstly， the weight of each reservoir is determined by objective weighting methods such as DIDF method， and then the negotiation break point determined by comparative methods such as comprehensive index method is used as input and the model is solved according to K-T conditions to get the compensation benefit allocation scheme. The apportionment scheme was evaluated by entropy weight TOPSIS method and the progress of the apportionment scheme was solved by asymmetric Nash negotiation model， single index method and comprehensive index method. The results show that the progress of the apportionment scheme obtained by the asymmetric Nash negotiation model is generally higher than that obtained by the single index method and the comprehensive index method. The optimal allocation scheme is the solution of asymmetric Nash negotiation model. The asymmetric Nash negotiation model can not only reflect the characteristics of the reservoir more fully， but also avoid the subjective problems caused by artificial weights， constructors and other steps， and the compensation benefit allocation scheme is more fair and reasonable. It is beneficial to mobilize the enthusiasm of member reservoirs to participate in the joint operation of reservoir groups.

Aiming at the freezing and thawing damage observed in dispersive soil canal slopes with high groundwater levels in seasonal frozen regions， we systematically investigated the frost-heave and thawing deformation characteristics of dispersive soils under varying initial conditions of temperature， moisture， and stress. The results indicated that： ① During the freezing process， as the temperature decreased， the freezing front of the dispersive soil advanced downward， and moisture within the soil migrated toward the freezing front， leading to ice formation. Ice layers and lenses were primarily distributed within the 1/2 to 2/3 depth range of the maximum frozen depth. ② The pore water pressure within the soil exhibited distinct periodic fluctuations in response to temperature changes， accompanied by a significant hysteresis effect. ③ Under identical conditions， as the dry density increased， the frost heave rate increased， the thaw settlement rate decreased， and the cumulative freeze-thaw deformation was reduced. ④ External water supply significantly influenced the frost heave process. Under conditions with external water supply， the frost heave rate of dispersive soil was 3 to 4 times higher than that without external water supply. ⑤ After three freeze-thaw cycles， greater overburden pressure resulted in a lower frost heave rate and a higher thaw settlement rate， indicating that overburden pressure effectively suppressed frost heave deformation. Based on the research findings， it is recommended that the anti-frost design of dispersive soil channel slopes in seasonal frozen regions should prioritize the impact of external water supply. Comprehensive measures， including thermal insulation， soil replacement， drainage， dry density control， and optimization of protective structure thickness， should be adopted to enhance frost resistance.

Mohr-Coulomb strength criterion does not consider the effect of the intermediate principal stress when calculating the ultimate or non-ultimate earth pressure of the soil behind the wall， and the calculation results are conservative. According to the conversion relationship between the passive earth pressure coefficient and the soil internal friction angle under the limit state of Mohr-Coulomb criterion， the soil internal friction angle corresponding to the different strength criteria is obtained. Then， the analytical formula of the non-limiting active earth pressure behind the retaining wall under the T-displacement mode is established after considering the soil arch effect behind the wall and the shear stress between soil layers. After comparing the calculated results with the test results， the relevant influencing factors were analyzed. The results show that： ①The calculated earth pressure of the retaining wall based on the Mohr-Coulomb criterion is significantly greater than the test results， and the horizontal earth pressure distribution of the retaining wall based on the SMP criterion and the Lade-Duncan criterion is in good agreement with the test data. The earth pressure distribution based on the AC-SMP criterion and the generalized Mises criterion is less than the actual earth pressure distribution， and the gap is large. ②In the non-limiting state， there are some differences in the soil φ ₀ and β ₀ obtained by different strength criteria behind the wall， but with η gradually approaching 1， the changes of φ_m and β_m are consistent. ③In the process of the soil behind the wall developing from the static state to the limit state， as the displacement ratio η gradually approaches 1， the resultant earth pressure acting on the retaining wall becomes smaller and smaller， but when the retaining wall produces the same displacement， the non-limiting earth pressure drop amplitude will become smaller and smaller.

The concrete casting volume of the pressure regulating tower bearing platform for large-scale water diversion project is large， and temperature cracks caused by concrete hydration heat is one of the important factors that endanger safety of the structure. Due to the arrangement of water cooling pipe inside the bearing platform， the distribution of temperature field inside the structure is more complex， making it difficult to carry out theoretical calculations. So， a three-dimensional finite element numerical analysis method was adopted in this paper， combined with actual conditions of the project site， to study distribution characteristics and evolution law of the temperature field of regulating tower bearing platform with water cooling pipe inside. It is found that the temperature field is centered on the cold water pipe， and rise gradually towards the surroundings， and the temperature peak appears in the middle of the adjacent cold water pipe. The temperature gradient is small in the middle of bearing platform and larger at the edge， and the risk of temperature cracks is relatively high. Through the comparative analysis of temperature field with or without water cooling effect considered， it is obviously found that with water cooling pipe set inside， all indicators meet the temperature control requirements in the specifications.

To solve the bolt’s axial stress and shear stress at the bolt-rock interface as well as to reveal the force characteristics of fully grouted rock bolts. Based on the local equilibrium conditions of the infinitesimal body， the incremental format of the governing equation of the bolt-rock interface was established， which was solved by the idea of finite difference method， and then a numerical solution model for fully grouted rock bolts was formed. This method was used to deeply investigate the influence of surrounding rock deformation， bolt length， and bolt radius on the bolt’s force characteristics， and some results were obtained as follows. The failure of the bolt is manifested as the shear damage of the bolt-rock interface near the excavation surface， and with the gradual increase of the rock deformation， the range of the shear damage of the interface is increased， the bolt’s axial stress is increased， and the neutral point is moved towards the internal rock. The bolt length has a critical value， increasing the bolt length will have little influence on the bolt force after exceeding the critical value. Increasing the bolt radius can reduce the bolt’s axial stress， but the interfacial shear stress will increase， and the shear damage will aggravate.

In this paper， the effects of polyvinyl alcohol（PVA） fiber， polypropylene（PP） fiber and a new concrete anti-cracking viscosity reducer on the deformation performance （autogenous volume deformation and drying shrinkage） and anti-cracking performance （plate cracking and temperature-stress test） of hydraulic concrete were studied. Considering their influence on workability and compressive strength of concrete， the improvement effects of anti-cracking viscosity reducer and fiber on deformation and anti-crack performance of hydraulic concrete were comprehensively evaluated. The results show that the anti-cracking viscosity reducer is compounded with expansion components， and the expansion efficiency of early hydration reaction can effectively reduce the shrinkage and deformation of concrete. The fiber can limit the propagation and expansion of plastic cracks， thus effectively improving the early crack resistance of concrete. When PVA fiber was mixed with anti-cracking viscosity reducer， the autogenous volume deformation of concrete showed “expansion” before 7 days at the initial hydration stage. As the volume of concrete tends to be stable， the autogenous volume deformation of concrete decreased by 104% and the shrinkage deformation decreased by 34%. The plate cracking test was extended to 48 hours without cracks， the second zero stress time of temperature-stress test was delayed by 35 hours， and the cracking temperature drop was increased by 16.5 ℃. With the guarantee of workability and mechanical properties of concrete， the composite application of anti-cracking viscosity reducer and fiber has the best effect. The deformation and crack resistance of hydraulic concrete have been significantly improved.

When deep-buried tunnels traverse complex geological structures， particularly wide fault zones， the issues of water inrush and mud outburst become critical under high external water pressure. The permeability characteristics of the surrounding rock are the key factors influencing the seepage stability of tunnels. This study investigates the Baifeng section of the deep-buried tunnel in the Yangtze-to-Han River Diversion Project， employing a three-dimensional transient seepage numerical simulation to evaluate the impact of tunnel excavation on the regional seepage field and the effectiveness of pre-excavation seepage control measures.The results indicate that without any pre-excavation measures， the tunnel crossing the Baifeng fault faces significant risks of water inrush and mud outburst. Pre-grouting measures can reduce the water inflow by 70% and increase the external water pressure by 90%， keeping the permeability gradient of fault rock masses below 6； however， the maximum permeability gradient within the grouting concrete can reach 66. Pre-drainage measures can reduce the external water pressure by 35% while increasing water inflow by 64%， with a risk of seepage failure in the fault gouge zone during excavation. When combining pre-grouting and pre-drainage measures， the water inflow increases by 54%， and the external water pressure decreases by 32%， with permeability gradients in the fault rock mass controlled within allowable limits. Nonetheless， higher permeability gradients occur at the ends of pre-drainage holes， necessitating the implementation of anti-filtration measures to prevent seepage failure.

Restricted by factors such as poor natural reservoir formation conditions and weathering of the bedrock of the reservoir basin， the construction of reservoirs in mountainous and hilly areas is faced with prominent anti-seepage treatment problems. The horizontal seepage prevention of the whole reservoir basin geomembrane is often adopted， and the influence of random defects and aging of geomembrane on reservoir leakage is one of the key problems to be considered in reservoir design. Combined with the upper reservoir project of a pumped storage power station in Jiangxi Province， the hydrogeological condition analysis and three-dimensional seepage field fine simulation in the reservoir dam area were carried out， and the influence of random defects and aging of the geomembrane at the bottom of the reservoir on the leakage of the reservoir was systematically evaluated. The results show that the size and location of the geomembrane defects at the bottom of the reservoir have a certain degree of influence on the leakage of the reservoir， and the defects located at the overlap between the dam panel and the geomembrane have the greatest impact on the leakage. At the same time， the random aging of the geomembrane will also cause a significant increase in the leakage of the drainage corridor at the bottom of the reservoir. When the aging area accounts for 50% and the anti-seepage performance decreases by 2 orders of magnitude， the leakage of the reservoir will increase by 10%， and the influence of the aging of the geomembrane can not be ignored.

Due to the concealment of the underwater environment， it is difficult to reasonably evaluate the damage pattern of the rockmass as well as the crushing efficiency when performing underwater mechanical rock breaking. In order to study the damage regularity and crushing efficiency of the rockmass under different construction conditions， the dynamic finite element method is used to simulate the rock breaking process of underwater siltstone. The results show that： when hydraulic crushing hammer is used to drill underwater siltstone， the surface of the rockmass will form a funnel-shaped crushing zone. With the intrusion of the brazing rod， the expansion of the damage is mainly concentrated in the vertical direction. Due to the obstruction of the water， the attenuation of the propagation of the stress in the rock body is faster， so that the crushing of the underwater rockmass is only 65% of that of the rock on land on average. The four influencing factors of the water depth（0~10 m）， the uniaxial compressive strength of rockmass （30~120 MPa）， the impact power （10~90 kJ） and the chisel distance（0.3~1.0 m） are analyzed to get the crushing volume of the rockmass with the changing regularity of the influencing factors. Based on the simulation results， the prediction formula of the crushing volume is obtained through three-dimensional surface fitting， and the error is less than 20% when compared with the field test.

To fully optimize the consumption of renewable energy by cascade hydropower stations and enhance their peak shaving capability， this study proposes the expansion and integration of pumped storage units into existing cascade hydropower stations by utilizing the upstream reservoir capacity， thereby forming a cascade hybrid pumped-storage hydropower station without altering the current operational conditions of the cascade hydropower system. To achieve this， a capacity optimization model for the hybrid pumped-storage hydropower station retrofit within operating cascade hydropower stations is developed， aiming to determine the optimal installed capacity of the hybrid pumped-storage units. Given the presence of numerous nonlinear constraints in the formulated model， direct solution approaches are computationally challenging. Therefore， piecewise linearization， three-dimensional variable linear interpolation， and the Big-M method are employed to convert the nonlinear model into a mixed-integer linear programming （MILP） model， which is then solved using the Gurobi commercial solver. The case study results indicate that the capacity of the two proposed pumped-storage schemes are two 90 MW pumped-storage units and two 190 MW pumped-storage units， respectively. Compared to conventional cascade hydropower stations， the hybrid pumped-storage hydropower station demonstrates higher power generation revenues， with increases of 0.22 billion CNY and 0.44 billion CNY under different schemes. These findings validate the effectiveness of the proposed model and solution methodology.

To improve the consumption of renewable energy and promote the efficient development of the energy system， this paper proposes an optimized scheduling method for the complementary power generation system of wind power， photovoltaic， battery and pumped storage power stations that takes into account the uncertainty of wind and solar power. In response to the uncertainty of wind and solar power output， this article comprehensively considers the uncertainty of wind and solar power output as well as the energy storage characteristics of pumped storage power stations and batteries. A distributed robust optimization scheduling model for peak shaving demand was established by generating typical output scenarios using WGAN-GP （Wasserstein Generative Adversarial Network with Gradient Penalty） method and K-means algorithm. The model aims to minimize the operating cost of the system， taking into account the hydraulic constraints and unit operation constraints of pumped storage power stations， and using the Column and Constraint Generation（C&CG）algorithm for solution. The results of the case analysis show that this strategy can effectively reduce the impact of power grid load fluctuations and wind and solar output fluctuations， and can further improve the efficiency of renewable energy consumption.

Using the state degradation assessment technology of hydropower units is helpful to grasp the state development trend of hydropower units and prevent early faults. In this paper， based on the chaotic system analysis method， a health model reflecting the dynamic characteristics of hydropower units is established in the reconstructed phase space to realize the degradation assessment of hydropower units. Using the online monitoring time series data under massive health status， the nonlinear correlation between the state monitoring variables is analyzed， and the state monitoring variables finally used for modeling are selected. The multivariable phase space reconstruction of the condition monitoring variables is carried out， and the mathematical model of the phase point trajectory motion is established in the reconstructed phase space to restore the dynamic characteristics of the hydropower unit system. Based on the phase point trajectory motion data model， the iTransformer-based unit health model is established to realize the state degradation assessment of hydropower units. In order to verify the effectiveness of the method， taking the on-line condition monitoring data of a hydropower unit as an example， the mean square error of the model proposed in this paper is 0.465， and the coefficient of determination is 0.901， which is better than the four different models used for comparison， verifying the effectiveness of the proposed model.

To facilitate the consumption and absorption of wind and solar resources， China has proposed the development of integrated river basin wind-solar-hydro （WSH） energy bases. The bundled transmission of wind， solar， and cascaded hydropower has emerged as a prevailing trend； however， the intraday variability of wind and solar power poses challenges to the operational patterns of cascaded hydropower stations and the secure operation of the power grid. Against this backdrop， this study constructs a short-term optimal scheduling model for multi-energy complementarity and uses a WSH energy base in the Dadu River Basin as a case study to investigate the impacts of wind and solar integration on source-load matching and cascaded hydropower stations under different typical daily scenarios. The results reveal that： ①Wind and solar integration has negligible effects on source-load matching during typical wet and normal water season days. ②During dry season days， when the wind-solar proportion exceeds 26.18%， ecological flow constraints necessitate the curtailment of 1.615 9 million kWh of photovoltaic power to maintain high source-load matching. ③While wind and solar integration enhances total system generation， it reduces hydropower output by 200、200 kWh and 74、900 kWh in the wet， normal， and dry seasons， respectively. ④The integration affects hydropower operational patterns， with impacts decreasing downstream along the cascade， the controlling reservoir experiencing the most significant influence and lower-tier stations being less affected. These findings provide a reference for optimizing multi-energy complementary scheduling strategies in WSH energy bases.

To enhance the efficient integration of renewable energy， the optimized scheduling of joint power generation from reservoir groups has become increasingly significant. Existing research on generation scheduling primarily focuses on maximizing power generation efficiency， often overlooking the constraints posed by the delivery capacity of cascade power stations. In response， this study introduces a scheduling model for joint power generation from reservoir groups that accounts for flow limit constraints. The outer layer of the model employs the Dynamic Programming Successive Approximation （DPSA） method， while the inner layer allocates output among the units based on installed capacity. Using the typical autumn days in 2020 of the Three Gorges-Gezhouba and Qingjiang cascade power stations as research cases， a comparison is made with actual operational scheduling processes. The results indicate that under conditions without flow limit constraints， the joint scheduling plan for the Three Gorges-Gezhouba and Qingjiang cascade power stations can achieve the highest power generation efficiency. However， with the implementation of flow limit constraints， the proportional increase in system generation compared to the actual scheduling plan decreases by 0.73%， with increases for the Three Gorges and Qingjiang cascade power stations dropping by 0.72% and 0.81%， respectively. This underscores the significant impact of flow limit constraints on the maximum generation capacity of source power plants， highlighting that the rational allocation of output of each power plant unit is critical for ensuring the safe and stable operation of the power grid. The method proposed in this paper provides both theoretical justification and practical guidance for the joint power generation scheduling of cascade reservoirs.

Resource analysis is a core business in hydropower engineering design， but relying entirely on manual methods is inefficient， cumbersome， and prone to errors. To address this， this study has systematically developed a similarity recommendation algorithm for quota semantic analysis， enabling rapid localization of appropriate quotas， and proposed a bidirectional mapping model for quota parameters， achieving automated analysis of these parameters. For design-related business， a quota configuration system that integrates prior and posterior knowledge is established based on a tree-shaped knowledge structure， and a technique for differentiating and decomposing resources and integrating them through summation is developed to construct a resource analysis system that is adaptive to statistical cycles. Application analysis shows that the system significantly reduces manual working hours， is easy to track and verify， and is user-friendly. The application of this system will provide strong support for the intelligent design of hydropower engineering.

The prediction of photovoltaic output is crucial for power system management and the complementary scheduling of hydro， wind， and solar energy. However， research on photovoltaic output prediction considering the spatiotemporal correlation of photovoltaic stations is still relatively limited. This article proposes a multi-site spatiotemporal correlation photovoltaic output probability prediction method based on interpretable deep learning， aiming to improve prediction accuracy and provide richer decision support information. Firstly， a single-site photovoltaic output prediction model based on Bidirectional Gated Recurrent Unit （BiGRU） was established. Based on this， considering the spatiotemporal correlation of neighboring sites， a joint input matrix was constructed to propose a multi-site photovoltaic output prediction model. Combining K-means clustering and kernel density estimation， a photovoltaic output probability prediction model was established， and the deterministic and probabilistic prediction performance of photovoltaic output considering the spatiotemporal correlation of sites was evaluated. Finally， to explain the prediction mechanism of the model， the key input factors that affect the model prediction results were identified using the Shapley Additive exPlans （SHAP） method. Taking 10 photovoltaic power plants in Washington State， USA as an example， the results showed that： ①Compared with the single-site model， the multi site photovoltaic power output prediction model improved the average RMSE index of each plant by 6%， 12.2% and 15.5%， and the average MAE index by 3%， 13% and 17.2% in the deterministic prediction of one step， three steps and five steps in advance， respectively. The joint input of neighboring stations considering spatiotemporal correlation significantly improves the prediction accuracy. ②The comprehensive evaluation index of probability prediction shows that compared with the single-site model， the multi-site model has improved the CRPS range by 14%， 6% and 27% respectively in the probability prediction of one step， three steps， and five steps in advance. The probability prediction results obtained by the multi-site model are generally better than those of the single-site model and are reliable. ③SHAP analysis shows that neighboring stations have a significant impact on output prediction. The model constructed in this article can automatically learn the spatiotemporal correlation between stations and use the spatiotemporal information between stations for prediction， with better performance than models that only consider single station information.

In order to fundamentally solve the problem that the traditional resettlement mode based on agricultural resettlement is difficult to solve the long-term livelihood of landless peasants， the long-term compensation and resettlement mode of reservoir resettlement has been gradually applied in China. The evaluation of the implementation effect of this resettlement mode is helpful to improve the long-term compensation mechanism of reservoir resettlement and protect the legitimate rights and interests of immigrants. Based on the characteristics of long-term compensation and resettlement， this paper constructs an evaluation index system of implementation effect， and determines the weight of evaluation index based on network analytic hierarchy process. This method considers the mutual influence between each index and is closer to the actual situation. There are few studies on the application of mutation progression method in the existing literature on the evaluation of reservoir resettlement effect. In this paper， the mutation progression method is used to construct the evaluation model of long-term compensation and resettlement effect of reservoir resettlement. Taking 6 sample villages with long-term compensation and resettlement and 4 sample villages without long-term compensation and resettlement in Baishi Hydropower Station of Guizhou Province as an example， the resettlement effects are ranked. The results show that the implementation of long-term compensation is helpful to improve the resettlement effect of reservoir resettlement. The evaluation results are consistent with the field survey data， which can be used to evaluate the resettlement effect of other similar projects.