In order to explore the effect of freezing-microwave method for purifying sewage quality， this study designed an experiment of indoor freezing wastewater， combined with microwave rapid thawing， and the melted water was collected at five times intervals （i.e. T1~T5）. The results show that： ① The microwave thawing of 17 min can completely melt the sewage ice， and the efficiency is much higher than that of the natural thawing process （14.5 h）. ② The microwave treatment of the first 8 min （T1+T2） melts 40% of the total water and removes more than 59.18% of the physical and chemical index content and 64.57% ion content in the sewage. The chromaticity， turbidity and yellow flocculent precipitation of sewage were significantly reduced. ③ In the final aquatic products obtained by microwave thawing for 17 min， the concentration ratio of total alkalinity， HPO₃， PO₄ ^3-， COD_Mn， SiO₂ and H₂SiO₃ is between 0.20 and 0.41， and the maximum concentration ratio of TDS to total hardness is only 0.16. The concentration ratio of eight conventional ions in K⁺， Na⁺， Ca²⁺， Mg²⁺， Cl^-， SO₄ ^2-， HCO₃ ^- and NO₃ ^- wastewater is only between 0.05 and 0.20. The concentration of As is close to 0. ④ The results of principal component analysis （PCA） showed that the purification effect of TDS and total anions was the best when freezing-microwave method was used to purify sewage water， and the principal component comprehensive scores Y were 4.55 and 3.65， respectively. In general， combined with freeze-thaw process and microwave rapid thawing， sewage treatment can be realized quickly and efficiently.

Reservoir sediment contains a large amount of inorganic matter. After treatment， it can be used to produce building materials. This article uses a curing agent to solidify reservoir sediment and prepare artificial aggregates. The optimal dosage of the curing agent is studied through orthogonal experiments （the dosage of the curing agent is based on the dosage of the reservoir sediment）. The results are： 8% sodium silicate， 6% gypsum， 3% polycarboxylate superplasticizer， and 0.05% triethanolamine （hereinafter referred to as SRPT）. Then， the optimal SRPT was added as an additional curing agent to prepare artificial aggregates and their performance were investigated. The results show that the maximum compressive strength of the aggregate with the optimal SRPT group added is 7.31 MPa， which is 44.2% higher than that of the group without curing agent. The 1-hour water absorption rate is 9.34%， and the bulk density is 937 kg/m³. This article uses SRPT curing agent to solidify reservoir sediment and prepare artificial aggregates， which can make high-value use of reservoir sediment and meet the regulatory requirements. The research results provide new ideas for the utilization of reservoir sediment in hydraulic engineering.

The entrainment effect of water intake from river-type water source pumping stations can have adverse impacts on the early-stage fish resources within the river. This study conducted physical model experiments on the entrainment effect at the water intake of the Jin Gang Tuo Pumping Station in the Yangtze River， using different water intake schemes. The results indicate that the height of the steel plates on both sides of the water intake box and the arrangement direction of the diversion pipes can influence the entrainment effect. The low-side plate scheme exhibits the most pronounced entrainment effect， with the resulting average lateral and vertical flow velocities being approximately 1.4~1.8 times higher than those of the high-side plate scheme. Moreover， it has a more significant decelerating effect on the flow velocity in the longitudinal direction， leading to a 30% average decrease in the original longitudinal flow velocity of the river. The entrainment effect area of vertically arranged diversion pipes is approximately 1.5~2 m wider than that of lateral diversion pipes. The entrainment area of the vertical diversion pipes is evenly distributed on both sides of the water intake box， while the lateral arrangement causes a deviation of approximately 2.5~4 m in the entrainment effect on both sides of the water intake box. The entrainment effect area is influenced by the river flow， with under low-flow conditions， the entrainment area for different schemes being between 13.5~18.5 m. Compared with the high flow condition， the entrainment area of each scheme is slightly increased， with an average increase of 1.1 times. Based on the entrainment effect area， the lateral diversion pipes scheme with high-side plates in this study is considered optimal. Its higher side plates and lateral diversion pipes arrangement contributed to reducing the entrainment effect. The elevated steel plates on both sides of the intake obstructed the water flow to some extent， alleviating the direct entrainment of water by the inlet pipes. This study provides a scientific basis for optimizing the design of water intake projects.

The operation of large cascade reservoirs in the upper Yangtze River has significantly improved the capacities of flood controlling， power generation and shipping of the Yangtze River， which in turn， promoted the regional socio-economic development. This is specially the case for the Three Gorges Reservoir （TGR）. The TGR is one of the strategic reserves of freshwater resources in China. Protection and utilization of its waterfront resources in a scientific and effective way are of great significance for ecological environment protection and social economic development around reservoir areas. However， too little attention has been paid to coupling coordination of protection and utilization of waterfront resources along large reservoirs in the upper Yangtze River. Therefore， taking the TGR as an example， firstly， an array of assessment indexes has been carefully established for assessing the protection and utilization of the waterfront resources in the TGR. It consists of eight indicators which can be quantitatively evaluated. Secondly， with the help of remote sensing images and field sampling data of 34 sections in the TGR， a coupling coordination degree model is applied to the assessment indexes for assessing the coupling coordination of protection and utilization in the TGR. The results show that： ① The shoreline utilization level and comprehensive level of the TGR show a decreasing trend from the upstream to the downstream of the reservoir， and the average shoreline protection level is 0.523， which is much higher than the shoreline utilization and comprehensive level.② The coupling coordination degree of the protection and utilization of the waterfront is mainly distributed in the range of 0.161~0.879， and 44% of the shoreline is located in the running-in development area， and the coordination development level is at a primary level. ③ The coupling coordination degree shows a “high in west and low in the east” distribution pattern， indicating that there is a certain linkage with the level of social and economic development. Therefore， we suggest that waterfront protection should be focused on in the future， as well as the waterfront utilization efficiency. The results are expected to provide a reference for the coordinated development of protection and utilization of waterfront resources in the TGR and to help the sustainable operation of the upper Yangtze River cascading reservoirs.

In order to improve the sediment removal efficiency of sediment removal tunnels in reservoir， we have developed a new type of swirl sediment removal device. In this paper， the different combinations of impellers in swirl sediment removal device， the velocity distribution of swirl flow field， and the influence of swirl flow device on the scouring and silting characteristics and the efficiency of sediment removal at the mouth of a sand drainage tunnel are studied by numerical simulation and hydraulic model test.The numerical simulation results show that the flow field range of the single impeller in the swirl sand removal device expands with the increase of the rotational speed， but the flow field range does not increase when the rotational speed of the impeller increases to 20 r/s.The range of swirl flow field after the combination of multiple impels in the swirl sand removal device depends on the rotational speed of the impels and their arrangement. When the swirl sand removal device is arranged in a triangular manner， the range of the combined swirl flow field also expands with the increase of the rotational speed of each impeller. However， too small arrangement distance between impeller groups will lead to too high energy dissipation， and too large arrangement distance between impeller groups can not form an effective combined swirl field. The optimal operating state of swirl sand removal device is that the distance between impeller groups is 70 mm and the rotating speed of impeller is 20 r/s.The results of numerical simulation and hydraulic model test show that the swirl sand removal device can effectively increase the sand removal efficiency of the tunnel and the range of strong scouring and silting. When the reservoir water level is deep and the silting form is a scouring funnel， the swirl sand removal device can increase the efficiency of the tunnel by 71.5%；When the reservoir water level is shallow and the form of sediment deposition is a sand flushing corridor， the swirl sediment removal device can increase the sediment discharge capacity of the tunnel by 4.02 kg， indicating that the device has a better removal effect on the sediment deposition in the reservoir with shallow water depth.It is of great significance to solve the problem of sediment deposition in Hexi reservoir with less water and more sediment in Gansu province.

The regime of flow and sediment changed significantly after the operation of the Three Gorges Project （TGP） and its upstream reservoirs， which led to intensive channel degradation in the Middle Yangtze River （MYR）. Therefore， it is necessary to investigate the temporal and spatial variation characteristics of the flow and sediment fluxes from the main stream and tributaries and channel evolution processes of the MYR. Based on the flow and sediment measurements at the hydrometric stations and the measured channel evolution volume corresponding to bankfull level， this study analyzed the temporal and spatial variations of the flow and sediment fluxes and channel evolution processes in the MYR. The results indicate that： ① In terms of temporal variation， the annual runoff of the MYR has not changed much， while the sediment load decreased by 68%~92% after the TGP operation. The water runoff decreased during the flood seasons and increased during the dry seasons. Except for the increase of annual runoff at Xiantao station and sediment load at Hukou station， the annul fluxes of flow and sediment of other tributaries and lakes decreased； ② In terms of spatial variation， the longitudinal change of runoff along the MYR did not show any significant adjustments. However， the longitudinal change of sediment load adjusted from a decrease to an increase along the MYR following the TGP operation， and the primary source of sediment changed from the upstream input prior to the TGP operation （accounting for about 120%） to the channel evolution after the TGP operation （accounting for 53%）； ③ The cummulative erosion volume corresponding to bankfull level in the MYR was 2.63 billion m³ during the period 2002-2020， accounting for about 54% of the cummulative erosion volume in the middle and lower Yangtze River. Especiall，y the Jingjiang Reach suffered the most dramatic channel erosion （accounting for 47%）， and the channel erosion center moved from the Yizhi Reach to the Hanhu Reach along the MYR. ④ Empirical functions were developed between the sub-reach’s cumulative channel evolution volume and the previous five-year average fluvial erosion intensity during flood seasons at the corresponding hydrometric station， with the determination coefficients （R ²） higher than 0.8. These relations quantitatively reflect the response relationship between the longitudinal channel evolution downstream of the TGP to the changes in incoming flow and sediment conditions and can be used to quantitatively predict the channel evolution volume of each sub-reach in the MYR under various flow and sediment conditions.

Dramatical channel erosion has occurred in the braided reach of the Lower Yellow River （LYR） since the Xiaolangdi Reservoir operation. Study on characteristics and influencing factors of river bed incision has great significance for the river embankment and flood control in the braided reach of the LYR. The accumulated downcutting depths of river bed and channel bankfull depths were calculated based on the observed post-flood profiles at 28 cross-sections in the braided reach from 1999 to 2020. The annual water level-discharge curves of each hydrological station were obtained based on the hydrological data， and the annual change of water level at certain discharges was calculated. The results show that： ① The cumulative scour volume of the LYR was 2.05 billion m³， and the braided reach experiencing the most channel erosion with a cumulative scour volume of approximately 1.47 billion m³ from 1999 to 2020. ② The braided reach of the LYR experienced the most severe river bed downcutting between 2000 and 2007， with an average annual downcutting depth of 0.24 m/a. From 2008 to 2020， the degree of river bed downcutting in the braided reach decreased， with the average annual downcutting depth reducing to 0.05 m/a. ③ There have been significant changes in the water level-discharge relationships at three hydrological stations， with a noticeable decrease in water levels at given discharges at the three hydrological stations. There is a certain time lag in the decline of water levels at hydrological stations along the braided reach， with a lag time of approximately three to four years. The magnitude of water level decline at each hydrological station under a discharge of 500 m³/s is greater than that under a discharge of 3 000 m³/s， with the largest decline observed at Gaocun station. ④ The bankfull depth in the braided reach increased from 1.6 m to 4.0 m from 1999 to 2018， and then decreased to 3.8 m in 2020. ⑤ Influencing factors of river bed cumulative incision were investigated quantitively， including incoming flow and sediment regime and channel boundary conditions. It is found that the previous 6-year average incoming sediment coefficient is the primary factor influencing the accumulated downcutting depth of river bed in the braided reach of the LYR. In addition， the inhibition of continuous river bed coarsening on river bed incision were quantitively analyzed in the braided reach.

Perforated siltation-promoting plates are effective structures for shoreline protection and have been widely used in projects such as beach preservation， riverbank protection， and coastal ecological restoration. The presence of these plates complicates the surrounding flow patterns and increases flow resistance. The flow pattern around the perforated siltation-promoting plates directly influences the movement and transport of suspended sediment. Using a Mixture two-phase flow model， a numerical simulation study was conducted to investigate the flow field characteristics and suspended sediment concentration distribution around siltation-promoting plates with different perforation rates. The results indicate that a recirculation zone appears in the near-wall region at the bottom of the slot behind the perforated siltation-promoting plate （height from the bottom d < H/15）. This recirculation zone is primarily located within the range of 0 to 20/3H behind the plate. As the perforation rate increases， the recirculation zone in the near-wall region at the bottom of the slot in front of the plate essentially disappears， and the area of the recirculation zone behind the plate gradually decreases. Both the length and width of the recirculation zone diminish with increasing perforation rate. In the near-wall region at the bottom of the slot behind the plate， the relative suspended sediment concentration at the cross-section behind the perforated areas is lower than in front of the plate. In the region where d > H/15， the relative suspended sediment concentration behind the perforated sections is higher than in front， while the concentration behind the grille sections is relatively higher than behind the perforated sections. When the inflow velocity is constant， a higher perforation rate of the siltation-promoting plate results in a lower relative suspended sediment concentration around the plate， and the siltation-promoting effectiveness of the plate becomes less ideal. When the perforation rate is 20%， the siltation-promoting effect of the perforated plate is significant.

The combination of hydrological and meteorological forecasts can effectively improve the accuracy and forecast period of flood forecasting. The land-surface hydrological modeling module has become the focus of research by hydrometeorologists. As a new generation of distributed land-surface hydrological model， the WRF-Hydro model has broad application prospects in multi-scale flood forecasting. However， due to the complex parameterization scheme of each physical process and the large amount of calculation of the model， the current parameter sensitivity research of the WRF-Hydro model is insufficient， which also affects the simulation accuracy of the model. This study takes the Tunxi basin in the upper reaches of the Xin'anjiang River in the humid area as the research basin， constructs a set of single-objective and multi-objective functions， and combines Morris method for global sensitivity analysis to explore the parameter sensitivity of the WRF-Hydro model under different objective functions. The result shows that： soil parameters （DKSAT， SMCMAX， BEXP） mainly affect subsurface and surface runoff， and have a significant impact on runoff volume.In particular， DKSAT is the most sensitive and directly affects the movement speed of water in the soil. When increasing， the base flow rate increases significantly while the peak flow rate decreases significantly.； runoff parameters （SLOPE， REFKDT） mainly affect the distribution of surface runoff and baseflow， and have an important effect on the overall shape of the flood hydrograph； the channel routing parameter ManN affects the speed of runoff convergence to channel network and mainly controls the peak time； vegetation parameter MP has a certain influence on annual water volum； overland flow parameter OVROUGHRTFAC and groundwater parameter Zmax are the least sensitive.. There are certain differences in the parameter sensitivity order and optimal parameter values under different objective functions. The single objective function based on relative bias focuses on the simulation of the total annual runoff and the low flow part， while Nash-Sutcliffe and Kling-Gupta coefficients focus more on the simulation of floods and high flow parts. The multi-objective function comprehensively considers the influence of different objective functions， and the results are better than the single-objective function to a certain extent. This work can provide a reference for reasonably determining the WRF-Hydro model parameter optimization strategy.

In order to quantitatively evaluate the effectiveness of sponge city construction in the Lihu area of Guangzhou， this study constructed a SWMM model at the scale of drainage zoning through background analysis and data collection. The simulation analysis of the sponge city construction effect in the Lihu area of Guangzhou was carried out from the aspects of annual runoff total control rate， pipe network overflow capacity， and waterlogging risk， in order to verify the disaster prevention and mitigation ability of the area after development and construction according to the sponge city construction implementation plan. At the same time， the results of this study can provide theoretical reference for sponge city construction in high-density areas in the south to alleviate urban waterlogging. The main conclusions drawn from simulation calculations of the Lihu area in Guangzhou are as follows： ① After low impact development and construction， the annual runoff total control rate in the Lihu area of Guangzhou has significantly increased. In 2022， the annual runoff total control rate in the area was 81.46%，which was 15.37% higher than that before the low impact development and construction in 2019； ② The simulation analysis of the drainage network overflow capacity before and after the low impact development and construction in Lihu area of Guangzhou city shows that the area experienced overflow under different return periods of rainfall conditions before the low impact development and construction， and the overflow ratio of the network increased with the increase of the design return period. After the low impact development and construction of the area， the overflow situation of the pipeline network was significantly reduced under different return periods of rainfall conditions； ③ The simulation analysis of waterlogging risk after the low impact development and construction in Lihu District of Guangzhou City shows that the district is basically a risk-free area when the 24-hour rainfall with a 100 year return period （the accumulated rainfall is 322mm） occurs， and very few places are low-risk areas. The sponge city construction in Lihu District can effectively cope with the 100 year return period rainstorm. The construction of sponge cities in the Lihu area of Guangzhou can effectively reduce rainwater discharge and enhance the disaster prevention and mitigation capabilities of the area.

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

Understanding the maximum wave height of a dam-break flow and its attenuation process during dam failure in reservoirs is crucial for downstream flood risk management. In this study， we conducted experiments using a large-scale flume （length 32m， width 1m， height 1.2m） to measure wave height variations over time and space during dam-break flow evolution. We investigated the effects of different water depth ratio of upstream and downstream （α） and slopes （S） on the evolution pattern of maximum wave height， wave velocity， and attenuation rate. The study results demonstrate a high correlation between the evolution of dam-break flow and the water depth ratio of upstream and downstream， α. This correlation is primarily manifested in two typical patterns： bore wave and undular wave. When α < 0.4， the dam-break flow evolves in the form of a bore wave， rapidly ascending to the stable water level. During this phase， the wave amplitude remains small， and the water surface exhibits minimal fluctuations. When α ≥ 0.4， the dam-break flow evolves in the form of an undular wave. During this phase， the wave rapidly ascends to its maximum value and subsequently decays. At this time， the amplitude of the dam-break flow is large， and the water surface exhibits regular fluctuations. The variations in slope （S） and the water depth ratio of upstream and downstream （α） significantly impact wave speed and growth rate. In scenarios with the same water depth ratio of upstream and downstream （α）， an increase in slope （S） leads to higher wave velocity and growth rate. Conversely， when considering the same （S）， an increase in the water depth ratio of upstream and downstream （α） results in larger wave velocity but reduced growth rate. The Levenberg-Marquardt algorithm is employed to analyze the maximum wave height evolution curve for （α = 0.4~0.8）. Nonlinear regression analysis is conducted to derive the maximum wave height attenuation formula. This formula is subsequently validated through numerical simulations at （x = 21 m）， demonstrating good agreement between the formula and the numerical results. When the upstream and downstream water depth ratio （α > 0.4）， the maximum wave height attenuation rate of the dam-break flow exhibits an initial rapid attenuation for the first wave， followed by a gradual decrease to 0. The research results contribute to a deeper understanding of the dam-break flow evolution process and establish a theoretical foundation for the field of dam-break flow catastrophic disaster science.

As one of the crucial strategies to achieve the “dual-carbon” goal in China， green small hydropower can provide economic benefits in small to medium-sized river basins. However， it will also impacts the ecohydrological processes of the basin， thus limiting the sustainable development of small hydropower river ecosystems. Taking Bin River Basin as an example， the SWAT model was applied to reconstruct the runoff process in different periods. The ecological flow was quantified temporal and spatial terms based on the ecological flow process line group. The change laws of ecological runoff indicators in different scenarios were compared， and the contribution of human activities and climate change to ecological profit and loss was quantitatively revealed. The comprehensive analysis revealed several critical findings： ①There were significant spatiotemporal differences in ecological flow distribution within the Bin River Basin. Compared to the baseline period， climate change and human activities are not conducive to ensuring the ecological flow in the basin. The median value of ecological flow assurance rate has decreased by nearly 7% under the influence of climate change. When compounded with the impact of human activities， there was a cumulative decrease of 17.74% in the median value of ecological flow assurance rate. Especially， the ecological water demand was severe during the flood season and its culmination. Hence， the implementation of seasonally restricted operational protocols for small-scale hydropower facilities arises as a prospective strategy for ameliorating this ecological challenge in future periods. ②On an annual scale， climate change predominantly led to a reduction in eco-surplus， with the most significant decrease occurring in the summer （p < 0.05）. In contrast， human activities primarily caused an increase in eco-deficit， especially during the autumn and winter seasons （p < 0.10）. ③There was a notable consistency between eco-surplus and precipitation anomalies， with correlation coefficients consistently exceeding 0.50. However， the correlation between eco-deficit and precipitation anomalies was weaker， particularly during the autumn and winter seasons， where their correlation coefficients often fall below 0.30. ④Regarding annual variability， human activities have consistently accounted for relative contributions exceeding 80% to the changes in eco-flow over the all periods. Excessive human interference was identified as the primary cause of eco-water scarcity in the Bin River basin. The research results provide reference for the health management of small hydropower rivers under the changing environment.

Due to unscientific groundwater development activities， the groundwater level in some areas of China has declined seriously， triggering a series of geo-environmental problems， and there is an urgent need to formulate the dual control management measures of groundwater level-water quantity to realize the sustainable development and utilization of groundwater. However， a single water quantity control index cannot meet the scientific management demand of water withdrawal control， so this paper takes Xiangyang city plain area as an example， uses groundwater numerical simulation method and combines the simulation prediction of different scenarios to study the response relationship of groundwater level-water quantity， so as to determine the dual-control water withdrawal index. The results show that， the groundwater level in the study area shows a good correlation with the exploitation amount and rainfall. With the increase of exploitation intensity， the groundwater level shows a significant downward trend. The response relationship between groundwater level and exploitation amount can be used as an important basis for determining the control water withdrawal index. By controlling the precipitation conditions and the water level threshold of the over-exploitation area， the water level and water volume thresholds are calculated according to the water level-water volume response relationship. The permissible extraction volume threshold of shallow groundwater under the current exploitation conditions is 1.16×10⁸ m3， and the average water level threshold is 93.11 m. Considering the spatial heterogeneity of the hydrogeological conditions， the spatially differentiated partitioning of the dual-control indexes is carried out， which provides a reference basis for the scientific management of groundwater.

In the context of the national strategy of carbon emission peak and carbon neutrality， implementing dynamic water level control during the flood season can enhance the utilization of flood resources and fully leverage the comprehensive benefits of water conservancy hubs while ensuring flood safety in the basin. The Goupitan， Silin， and Shatuo hydropower stations serve as the primary cascade power stations in the middle and lower reaches of the Wujiang River. Since the current flood control capacity relies on single-reservoir calculations of flood regulation， neglecting joint scheduling and operation， the operating water level during the flood season is statically controlled， thereby limiting power station output and failing to fully realize comprehensive flood season benefits. Based on forecasted pre-discharge and reservoir capacity compensation， this study coordinates flood control risks across multiple regions in the middle and lower reaches of the Wujiang River， constructed a dynamic control and dispatch model for the operating water levels of cascade reservoirs during the flood season and studied the dynamic strategies and risks of raising the operating water levels of the Silin and Shatuo reservoirs based on the impoundment of the Goupitan reservoir. The study findings indicate that implementing joint flood forecasting and dispatching for cascade reservoirs can increase the operating water levels of Silin and Shatuo reservoirs by 2.10~3.86 meters and 6.09~6.42 meters respectively in the pre-flood season （June-July）， and by 4.17~4.86 meters and 6.21~6.42 meters in the post-flood season （August）， respectively. This approach can also mitigate flood control risks for the cascade hubs， the middle and lower reaches of the Wujiang River （Sinan and Yanhe counties）， and the middle and lower reaches of the Yangtze River. The results of this study can provide technical guidance for the safe management of flood control and the utilization of flood resources during the flood season in the Goupitan， Silin， and Shatuo cascade reservoirs.

Snowfall， as an integral part of the water cycle in the Tibetan Plateau， plays an irreplaceable role in maintaining the balance of regional water resources and ecological balance. However， with the intensification of global warming， the characteristics of snowfall change in the Tibetan Plateau region not only pose challenges to the stability of the regional climate but also raise new issues for water resource management and ecological environment protection. To deeply understand the spatiotemporal characteristics of snowfall changes in the Tibetan Plateau and their response to climate change， this study selected six representative basins， namely the Lhasa River， Nianchu River， Naqu River， the source of the Yangtze River， the source of the Yellow River， and the source of the Lancang River， as research objects. The aim is to reveal the spatiotemporal variation patterns of snowfall in the Tibetan Plateau during this period through multi-source remote sensing precipitation data fusion technology. This study selected three types of gridded precipitation data： CMFD， CPC， and TRMM， and constructed an evaluation index for precipitation data based on overall deviation and deviation components to assess the accuracy and optimize the integration of these data. The results show that from 2002 to 2018， the snowfall rate in the typical basins of the Tibetan Plateau generally showed a downward trend， especially in areas above an altitude of 5 000 meters， where the reduction in snowfall rate was more significant. The ranking of the decrease in snowfall rate from large to small is： Lhasa River （28.2%）， the source of the Yellow River （18.2%）， the source of the Yangtze River （17.8%）， Nianchu River （15.4%）， the source of the Lancang River （12.1%）， and Naqu River （10.5%）. This downward trend shows a spatial distribution feature that intensifies gradually from south to north. This finding is closely related to global warming and provides important scientific evidence for understanding the response of the Tibetan Plateau to climate change. In addition， this study has important reference value for the formulation of water resource management and climate change adaptation strategies in the Tibetan Plateau region， and also provides data support and research methods for related fields， which helps to promote the in-depth development of climate change research in the Tibetan Plateau.

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

Water use efficiency of rice and field productivity were affected by irrigation quota. In order to explore the variation law of rice irrigation quota and its correlation with yield， the experiment of water layer location monitoring and supplementary irrigation of paddy field was conducted for eight consecutive years from 2014 to 2021 in Nanning Irrigation Experimental Station， providing fundamental data for quantifying the irrigation quota of rice in the double cropping rice region of southern Guangxi. The upper and lower limits of the water layer in paddy fields were established in regreening stage， tillering stage， jointing and booting stage， heading and flowering stage， milk ripening stage， and yellow ripening stage. The water layer depth was monitored daily by measuring needles. Supplementary irrigation was performed when the depth was below the lower limit， and the cumulative irrigation amount was calculated. At the same time， the rainfall was measured by meteorological facility in Nanning Irrigation Experimental Station. In mature stage of rice， indicators such as panicle length， 1 000-grain weight and yield were measured. The test results show that： ① The amount and time distribution of rainfall were important factors influencing the irrigation quota of paddy fields， and the uneven distribution of rainfall during the growth periods of rice was the main factor causing significant differences of irrigation quota. The irrigation quota of early rice was 210.1~438.4 mm， while that of late rice was 243.9~477.5 mm. ② When the irrigation quota was within the range of 200~320 mm， panicle length， 1 000-grain weight and yield of rice increased with the increase of irrigation amount. While the irrigation quota was more than 320 mm， continued irrigation was not conducive to the increase of rice yield. It could be seen that the appropriate irrigation quota for rice was 320 mm during the experiment. Insufficient or excessive irrigation would affect rice yield and reduce the effective utilization rate of water resources.

The management efficiency of farmland water conservancy facilities is closely related to the high-quality development of rural economy， and plays an important role in protecting the vital interests of the people and the sustainable development of agriculture. In this paper， the panel data of 14 cities （prefectures） in Hunan Province from 2012 to 2021 are selected， and the three-stage SBM and Malmquist index are combined to analyze the governance efficiency of farmland water conservancy facilities from both static and dynamic perspectives. On this basis， the fixed-effect model is used to further explore the influencing factors of governance efficiency. The results show that： after eliminating environmental factors and random errors， farmers' professional cooperatives， farmers' per capita income， regional GDP and urbanization level have positive effects on the management efficiency of farmland water conservancy facilities， and excessive dike construction will weaken the management efficiency of farmland water conservancy facilities. After adjustment， the efficiency of farmland water conservancy management in Hunan Province tends to be stable， while pure technical efficiency and scale efficiency have increased in different degrees. From 2012 to 2021， the total factor productivity of farmland water conservancy facilities in Hunan Province showed a “U-shaped” fluctuation growth， and the growth rate of total factor productivity in Chang-Zhu-Tan region was the fastest， while that in southern Hunan was the slowest. The extreme value was mainly due to the change of technological progress change index. The structure of agricultural planting， the illiteracy rate of rural residents， the level of economic development and the degree of fiscal decentralization have negative effects on the efficiency of farmland water conservancy management.

The average annual rainfall in northwest China is less than 400 mm， which belongs to the perennial irrigation area. Without irrigation， there will be no stable yield. Among them， the mud and sand content of the Yellow River introduced from the Yellow River diversion irrigation area is relatively high， and sediment accumulation will be formed in the channels with low flow velocity in branch and lateral canals. When the sediment accumulates to a certain extent in the flow measuring equipment and gate measurement and control system of the channel， it will seriously affect the accuracy of flow measurement and the perception of gate opening. In order to solve the problem of effective application of water flow measuring equipment with high sediment content in smart irrigation areas and improve the accurate measurement of small canal flow， an ultrasonic vibration unit was designed， which can be placed in the flow measuring equipment and integrated gate of measurement and control. The vibration unit comprises a sealing box， a metal cover plate and a circuit board. The sealing box is provided with a top opening， and the metal cover plate is on the top opening of the sealing box. The circuit board is provided with a signal interface circuit， a power module， a delay circuit， a PWM （Pulse Width Modulation） control chip， a MOS transistor circuit， a leakage protection chip， a transformer circuit， a matching circuit and an ultrasonic transducer. The working time and working interval of the vibration unit are controlled by the delay chip， which can be configured by the signal of the control interface. The opening and closing of the MOSFET transistor is controlled by the PWM control chip， and the ultrasonic frequency is controlled by the PWM frequency. The control of the vibration unit is integrated in the flow measurement system， and the system gives control instructions according to the field situation， which can be divided into fixed and dynamic modes.The device can automatically turn on the vibration to remove the accumulated sediment according to the situation of sediment accumulation. Our prototype was tested in the laboratory and got a set of results of vibration sand removal under different degrees of accumulation， which verified the effective vibration time for removing the accumulated sediment， and was examined on site in Ningxia. The experimental results show that the duration of ultrasonic vibration will increase with the increase of the amount of sediment accumulation. When the thickness of sediment is less than 30 mm， the ultrasonic vibration device can effectively remove the sediment after starting the vibration device once （3 min）

The safety of drinking water in rural areas has always garnered widespread attention from society. In recent years， significant improvements have been made in the safety and security of water supply in rural areas， as well as in water quality. However， due to economic constraints， many rural areas still lack advanced water treatment facilities， resulting in inefficiencies and various other challenges in water treatment. To comprehensively enhance the overall protection level of rural water supply and water quality， this paper initiates discussion from the perspective of water intake sources， delving into innovative solutions to enhance water quality， specifically proposing the utilization of riverbank filtration technology. Riverbank filtration technology， as a pre-treatment method， can be concurrently implemented at water intake sources， effectively alleviating subsequent pressure on the water treatment process. This natural method involves extracting water from the periphery of rivers or lakes， where surface water blends with groundwater as it traverses the aquifer medium. Through physical， chemical， and biological processes， this riverbank filtration method purifies the water source， while also replenishing and elevating groundwater levels. This paper discusses the prospects and challenges to be faced by the application of riverbank filtration technology in the field of rural water supply in China through in-depth analyses of the principles of riverbank filtration technology and the mechanism of pollutant removal. Riverbank filtration technology can not only significantly reduce the turbidity of the source water and reduce the content of harmful microorganisms， but also effectively remove dissolved organic matter in the water， and it also has a certain degree of control of NH₄ ⁺-N and new pollutants. These advantages in improving the quality of rural water supply water has shown great potential for application. However， riverbank filtration technology currently faces a number of challenges in practical application. For example， riverbank filtration filter layers may become clogged due to long-term operation， and may be affected by extreme hydrological conditions， which may reduce their filtration effectiveness. Nevertheless， riverbank filtration technology， as an economical and feasible pre-treatment process for water supply， it has broad prospects for development and application in terms of enhancing the efficiency of water treatment， expanding the scope of application of conventional water treatment processes， and reducing disinfection by-products. With the continuous improvement and promotion of the technology， riverbank filtration technology is expected to open up a new path for solving the problem of drinking water safety in rural areas and provide better living conditions and health protection for rural residents.

Aiming at the problem of insufficient fault samples and unsatisfied diagnosis accuracy， a fault diagnosis method for rolling bearing of hydroelectric unit was proposed in this paper based on improved weighting domain adversarial network （IWDAN） and hybrid attention mechanism （HAM）. First， the one-dimensional vibration signal of bearing was transformed into a two-dimensional time-frequency spectrum by the wavelet transform （WT） method， which contributes to characterize the signal in the higher dimensions. Subsequently， in order to extract more efficient shared features between different domains， the time-frequency spectrum in source domain was weighted adaptively using the developed IWDAN model. Finally， the extracted features were served as the inputs of HAM method to effectively suppress the interference of redundant information and further improve the diagnosis efficiency and accuracy. Based on the case analysis of unit bearing diagnosis， the superior diagnosis performance of the developed IWDAN-HAM method was validated convincingly， and the corresponding results were helpful to provide reliable data foundation for the formulation of unit maintenance strategies.

In order to address the power supply planning optimization issues during power shortages in power systems， considering the economic operation characteristics of the optimal combination of units， the complementary characteristics between multiple power sources， and the fluctuating nature of electricity prices， a multi-factor and multi-objective optimization model for supplementary power sources， which takes into account the characteristics of power systems， is established with the objectives of minimizing the total cost and maximizing the operational efficiency. By treating the costs and benefits of the construction and operation phases as a whole， and using constraint methods to transform the multi-objective problem into a single-objective problem， a solution method based on dynamic programming is provided. The results of the case analysis applied to a regional power system demonstrate that， without considering the constraints of various power resource conditions， the model can more economically and rationally provide an optimized recommendation scheme among a finite set of supplementary power supply options， offering a certain reference for the strategic optimization selection of supplementary power sources in power systems.

Digital twin technology has been developing rapidly in the water industry for several years. Among it， the digital twin data base plate stores large amounts of information in the whole life cycle of water conservancy projects， and there are problems such as large data volume， complicated management and increased updating cost. Meanwhile， the application layer digital twin platform with WebGL as the core engine rendering load is limited by network bandwidth and computer performance， facing the challenge of light-weight processing. Aiming at the geometric model data in the virtual entity of the digital twin， this paper uses the improved Quadric Error Metrics（QEM） and Low-Poly algorithm to carry out light-weight processing. The hydraulic turbine guide mechanism is selected as a case to study the optimal simplification degree to meet the needs of the digital twin business. Results show that light-weight processing is necessary and the file size is greatly reduced after lightweight processing. The upper limits of the simplification degree of the four precision levels in meeting the digital twin fineness level is the original data， about 40%， about 70%， about 98%.

A 23 m wide fault fragmentation zone is developed at the foundation of a medium-sized reservoir gravity dam in Southwest China， and the mechanical properties of the rock body in the fragmentation zone are weak， which will have an important impact on the stability of the dam foundation during the construction， impoundment and operation of the dam. Based on the engineering geological conditions and rock mechanical parameters， a micro-arch concrete plug replacement foundation scheme for dam foundation treatment is proposed， and three-dimensional finite element calculations and sensitivity analyses of rock mechanical parameters of the F1 fault at the dam foundation are carried out. It is concluded that in the case of soft bedrock body with wide fracture zone， the difference of deformation modulus and the weak bearing capacity of the fault zone lead to the uneven deformation phenomenon of the dam foundation. After the replacement of the concrete plugs by micro-arch， the load carrying capacity of the dam foundation and the stress deformation of the gravity dam during the impoundment process meet the requirements. As the concrete plugs can work well， the influence of the variation of fault fracture zone parameters on the stress and deformation of the dam and dam foundation is weakened. The study provides an important reference value for the foundation treatment of gravity dams across wide faults.

With the development of infrastructure construction in China， the problems of water seepage and structural safety caused by the cracking of mass concrete located in subway bottom and side walls have aroused great attention of the builders.Due to the characteristics of high design strength， large consumption of cement and dense layout of steel bars， the special problem of temperature control and crack prevention of mass concrete is formed， so it is of great significance to research on improving the crack resistance of mass concrete. In this paper， the crack resistance test of mass concrete is carried out by using shrinkage compensation materials. The test results show that the tensile strength and ultimate tensile value of mass concrete can be improved and the autogenous volume shrinkage deformation can be converted into expansion deformation under the condition that the compressive strength， adiabatic temperature rise and elastic modulus are less affected by using shrinkage compensation materials.According to the evaluation of the crack resistance value Φ proposed in this paper， the shrinkage deformation can be compensated for the whole time， the crack resistance of concrete can be improved， and the analysis of the crack resistance of concrete is time-effective.At the same time， the mechanism of crack resistance is analyzed through the pore structure， hydration products and compensation shrinkage characteristics. The research results have guiding significance for the crack resistance control of mass concrete.

In earth-rock dam projects， due to the uncertainty of on-site construction compaction and the non-uniformity of material collection in the material field， the mechanical parameters of dam materials have variability in dam body， which leads to the differences between the conventional prediction analysis results of earth-rock dam using deterministic parameters and the actual stress and deformation behaviors of dam body. In this paper， based on the geotechnical test results of dam materials in the built engineering， the spatial random field theory is introduced， and the 3D static analysis of the dam body is carried out by constructing stationary random fields. The influence of the mechanical parameters of Duncan-Chang E-B model on the settlements and horizontal displacements of dam body is obtained. The sensitivity of the mechanical parameters of Duncan-Chang E-B model is studied， and the sensitivity ranking conclusion is given. The results show that the parameters K_b， K and {\phi }_{\mathrm{0}} in Duncan-Chang E-B model have great influence on the deformation of dam body， among which the influence of parameter K_b is the most obvious， followed by the influence of parameters n and R_f， while the parameters Δφ and m are less sensitive. This research conclusion can provide reference for the rational deformation prediction of earth-rock dam and the study of dam material characteristics.

Correlation and distribution model between compressive strength and permeability coefficient of cutoff wall are the key factors affecting the reliability analysis of cutoff wall strength and permeability failure of earth-rock dam. The testing data of high pressure jet grouting wall of 9 earth-rock dams are collected. AIC criterion is used to identify the best marginal distribution type of compressive strength， permeability coefficient and the best Copula function of correlation joint distribution model. The Bootstrap method was used to simulate the statistical uncertainty of the identification results. The results show that there is a significant negative correlation between compressive strength and permeability coefficient， which mainly obeys Weibull distribution. Frank Copula is identified as the best function used to construct the non-normal joint distribution between the two parameters. The identification difference of the best distribution type and best Copula function is mainly due to the different frequency distribution caused by the construction quality of cutoff wall. The research results can provide a simple and effective distribution mode for the reliability analysis of strength reliability of high-pressure Jet cutoff wall and permeability stability of earth-rock dam.

To explore the changing patterns of landslide disasters in Hebei Province under future climate change， and provide scientific basis for the overall planning of disaster prevention and reduction， so that people can better avoid the hazards and risks brought by landslide disasters. This article uses the Ecological Niche Modeling Evaluation Algorithm （ENMeval） to optimize the Maximum Entropy Model （MaxEnt）. Based on 860 landslide disaster points collected from surveys and 11 factors affecting disasters， the article carries out hazard risk assessment on the basis of the main influencing factors， and combines three radiative forcing scenario models of future （recent： 2041-2060， mid-term： 2061-2080， long-term： 2081-2100） climate data （low level forcing scenario： SSP126， medium and high level forcing scenario： SSP370， high level forcing scenario： SSP585）， predict the spatial distribution pattern and change pattern of potential risk areas for landslide disasters. The results show that：①The Area Under the Curve （AUC） of the optimized MaxEnt model is above 0.9， indicating that the model performs well in predicting potential risk areas of landslide disasters.②By optimizing the comprehensive contribution rate analysis calculated by the Maxent model， the main factors affecting landslide disasters are determined to be： precipitation in the wettest quarter， precipitation in the wettest month， and seasonal variation coefficients of elevation and rainfall. This indicates that precipitation related factors are the most important factors affecting landslide occurrence.③A comprehensive evaluation of 14 Coupled Model Intercomparison Project Phase 6（CMIP6） data revealed that BCC-CSM2-MR has the best simulation ability in precipitation compared to other climate models， followed by CMCC-ESM2 and ACCESS-CM2.④In the future climate forcing scenario， the area of low-risk areas for landslide disasters has decreased， while the proportion of areas with medium， medium high， and high risk has increased， which is consistent with the predicted trend of future precipitation changes.

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

This study utilizes the secondary development platform in the VC++ environment of FLAC3D software to enhance the Duncan-Zhang model and validate its accuracy through numerical simulations of triaxial compression tests. Building upon this， a three-dimensional numerical model of a geomembrane-core rockfill dam （with a maximum height of 78 m） is established to analyze stress-strain behaviors during construction and reservoir stages. Results indicate that there exists stress concentration at the joint between the core wall base and the concrete foundation， and the stress distribution in the core wall shows an obvious arch effect. Applying the effective stress method confirms that the core wall is below hydraulic fracturing conditions， affirming the stability of the dam under current operational conditions.

In order to address the issue of traditional creep models failing to accurately reflect the characteristics of rock accelerated creep stage， this paper proposes an enhanced unsteady Maxwell creep model based on the conventional Maxwell model. It takes into consideration the unsteady creep parameters of original clay pot elements in series with a nonlinear viscoplastic body （NVPB）， and deduces the corresponding creep constitutive equation. The improved model comprehensively simulates the nonlinear creep behavior throughout all stages of rock creep， thereby enhancing accurate description. Additionally， origin software is utilized for fitting different rock samples. The research findings demonstrate that this new creep constitutive model better fits the experimental data and identifies parameters， effectively simulating rock's deformation under various stress levels while accurately describing the nonlinear creep characteristics of its three stages of creep. This indicates high accuracy and strong applicability of the newly established model. It provides a new creep constitutive model for future geotechnical engineering.