Based on fractal geometry， the description of soil pore size distribution is established， and a suction model of unsaturated soil matrix considering the fractal characteristic of pores is proposed in combination with Young-Laplace theory. For the loess in Shaanxi region， the soil-water characteristic curves of different dry densities were collected， and the effects of dry density on pore distribution characteristics and matrix suction were analyzed. The results show that the loess pores have obvious fractal properties， which can be well described by the Menger Sponge fractal model. The pore fractal model parameter analysis shows that with the increase of dry density， the fractal dimension D increases approximately linearly， while the maximum aperture L decreases as a power function. Through function fitting， the characteristic relationship between loess pore size distribution and dry density is further established， and the suction capacity of loess matrix suction under different dry densities is quickly predicted.

Utilizing satellite remote sensing technology for the retrieval of water depth is a crucial method for quickly acquiring water depth information over large areas. However， traditional optical satellite images often suffer from low inversion accuracy due to various factors， including the presence of sediments， suspended particles， and chlorophyll in the water. These constituents alter the color and turbidity of the water， making it challenging to accurately estimate water depth through remote sensing techniques. To mitigate the influence of these water color materials on the accuracy of water depth inversion， a novel approach was proposed， centered around a mathematical model and the use of Sentinel-2 remote sensing imagery. This approach involves analyzing the mathematical relationships between water depth and the surface area of different types of water channels. This method deduces the river surface depth model by generalizing and classifying the river section. It combines the Sentinel-2 remote sensing images to determine the relevant parameters in the mathematical model， and derives an expression that can directly calculate the water depth from the water surface area， which can minimize the influence of water color on water depth retrieval from remote sensing images. To validate the effectiveness of this approach， it was applied to the Xiaoqing River， and the results were compared with ground-truth data. The average absolute error in water depth inversion at two hydrographic stations， Huangtaiqiao and Shicun， was found to be 0.03 meters and 0.23 meters， respectively. These results demonstrate a significant improvement in the accuracy of water depth estimation. The method proves to be more reliable in areas with varying water color and turbidity. It can quickly obtain water body depth information based on satellite remote sensing technology and has promotion and application value.

Under the weak mixing condition， the main inflow has a significant effect on the flow structure of the branch inflow convergent area， and the flow characteristics of the branch inflow convergent area are complex. It is of great significance to understand the hydrodynamic characteristics of the branch inflow convergent area for ecological restoration and water environment management. In this study， the RNG k-ε turbulent flow model for the intersection of trunk and tributaries of open channel was constructed and verified by the combination of physical model and numerical simulation. Based on the calculation results of weakly mixed multiple confluence ratios at different intersection angles， the influence of changes in intersection angles and confluence ratios on the velocity distribution characteristics and circulation structure in the branch convergent area was analyzed in detail. The critical value of the ratio of return flow in the different junction angles is calculated and analyzed. The results show that the main flow has a significant influence on the flow structure of the branch inflow area under the condition of weak mixing. In the convergent area， the flow of the tributary flows back to form a return zone on the right bank， and the maximum return velocity zone is formed on the right bank wall. A large-scale transverse vortex structure is formed in the middle surface of the branch inflow convergent area， and there are obvious backflow area and circulation structure. The circulation structure scale decreases with the increase of the convergence ratio， and the correlation between the intersection angle is 150° >30° >90°. The longitudinal vorticity peak value is negatively correlated with the confluence ratio. The larger the confluence ratio is， the smaller the vorticity peak value is. Backflow occurs in the tributaries at intersection angles of 30°， 90° and 150°. The critical values of the confluence ratio γ of the circulation structure are 0.013， 0.011 and 0.031， respectively.

In order to improve the spatio-temporal accuracy of rainfall and evaporation distribution in the Grid-XAJ model， strengthen the hydrological cycle， and provide a foundation for further coupling of the WRF model with the Grid-XAJ model， we constructed the WRF-driven Grid-XAJ model. Firstly， we used the successive correction method to obtain the WRF-merged rainfall by merging WRF forecast rainfall with gauged rainfall. Then， the WRF forecast meteorological data were input into the Grid-XAJ model， and the hourly evaporation capacity of each grid was calculated by Penman-Monteith method （PE_PM ）. Finally， the Grid-XAJ model was driven by WRF-merged rainfall and PE_PM to simulate floods in the humid Tunxi catchment. The results showed that： ① The WRF-merged rainfall exhibited high accuracy and a fine spatial distribution. Compared with WRF forecast rainfall， the WRF-merged rainfall had a higher correlation （RR≥0.99） and a better fitting degree（NSE≥0.98） to actual rainfall， and errors of rainfall peaks （-8.1%~3.5%） and cumulative rainfall （-2.0%~6.7%） were significantly reduced. In terms of spatial distribution， the WRF-merged rainfall displayed more complex spatial information compared to rainfall interpolated from gauged rainfall， as indicated by Shannon Entropy （SE） significantly increased （30.4%~48.2%）. Additionally， the WRF-merged rainfall can incorporate rainfall centers from both the WRF forecast rainfall and the rainfall interpolated by gauged rainfall. ② The PE_PM exhibited hourly variations and showed a close correlation with rainfall. In terms of spatial distribution， PE_PM was closely related to elevation. Regions with higher elevations displayed a relatively lower mean PE_PM values， while areas with moderate elevations exhibited the highest mean PE_PM values， and slightly lower values were observed in lower elevation areas. ③ The WRF-driven Grid-XAJ model held significant potential in flood forecasting. The flood forecasting accuracy of the Grid-XAJ model， when driven by WRF-merged rainfall and PE_PM， was significantly enhanced compared to the model driven by WRF forecast rainfall and PE_PM . The NSE values of flood forecasts were all above 0.90， and the qualified rates of flood volumes， flood peaks and peak occurrence times were 100%.

The evaluation of the flood control risk of the joint operation of the four-level cascade reservoirs in the lower reaches of the Jinsha River can scientifically measure the risk of flood control and provide guarantee for the flood control security in the Sichuan -Chongqing section of the middle and lower reaches of the Yangtze River. In view of the risk problems in flood control operation， based on the joint flood control operation scheme， a risk assessment model of flood control operation based on disaster science is constructed， by establishing a risk assessment system with peak cutting amplitude， flood control risk rate， water level variation amplitude and the risk rate of discharge exceeding the standard， and using Monte Carlo method for risk simulation. The flood control risk results of the reservoir under different inflow frequencies and reservoir levels are evaluated. The results show that under the feasible starting scheme set， the peak cutting amplitude of the Wudongde and Baihetan reservoirs decreases with the increase of the lifting water level of the two reservoirs， and the peak cutting amplitude of the Xiluodu and Xiangjiaba reservoirs is less than 7%， and the flood risk of the cascade reservoir in the lower reaches of Jinsha River is small. The maximum reservoir water level did not exceed the corresponding frequency of flood control high water level （975 m in Wudongde， 825 m in Baihetan， 600 m in Xiluodu， 380 m in Xiangjiaba） in all reservoirs， and the variation of reservoir water level did not exceed the safe variation range. The overall flood control risk of the reservoir area is low， and the flood control risk of the Sichuan-Chongqing reach is within the controllable range. When there is a small flood， the disaster bearing capacity of the downstream protection objects is better， The discharge flow of the control station in the protected area is lower than the standard value of flood control safety， and the flood control risk of downstream protection objects is low. But when there is a bad flood in main and tributary streams（such as the 1% flood in 2012）， the possibility of damage is high， and the risk exceeds the flood control standard. To ensure flood control safety， the joint flood control of tributary reservoirs and main stream reservoirs is required. The model can be applied to the flood control operation risk assessment of cascade reservoir effectively， and provide reference and basis for regional flood control operation risk research and decision-making.

To study the rainfall runoff characteristics of green roofs in the northern semi humid area， this papar explores the impact of structural parameter changes on their rainwater storage effect， and provide data support and guidance for the green New Infrastructure of Sponge city. Based on measured rainfall runoff， we established comparative experiments on three types of roofs： green roofs （gradient of 0°）， ordinary roofs （gradient of 0°）， and sloping roofs （gradient of 5°）， as well as five sets of green roof experiments based on adjustment of matrix layer thickness， matrix layer， drainage layer， and drainage method structural parameters. Research shows that during the monitoring period， the average runoff coefficients of comprehensive rainfall on green roofs， ordinary roofs， and sloping roofs were 0.27， 0.50， and 0.77， respectively. The reduction effect of rainfall runoff on green roofs was significant. As the intensity of rainfall increases， the probability of green roof runoff generation gradually increases， and the total runoff control rate gradually decreases. Green roofs have a significant effect on the storage of rainfall at light to heavy rain levels. During the monitoring period， the runoff coefficient of green roof rainfall is significantly positively correlated with the total rainfall， but weakly negatively correlated with the number of days between previous rainfall intervals and previous rainfall； The green roof significantly reduces the efficiency of rainfall runoff control， corresponding to a critical value of 30 mm of rainfall intensity. The significant factors affecting the rainwater storage effect of green roofs in descending order are： substrate layer （ultra light substrate layer）， drainage method （5 cm drainage from the bottom）， substrate layer thickness （20 cm）， and drainage layer （ceramic layer）. The rainfall runoff characteristics and rainwater storage effect of green roofs are influenced by multiple internal and external factors. Based on long-term rainfall monitoring periods， further research should be conducted on the ecological effects of sponge cities with different structures and scales of green roofs.

Accurate groundwater modeling is essential for the scientific management and decision-making of groundwater resources， as it involves hydraulic conductivity， a key hydrogeological parameter. To fully understand and effectively utilize groundwater， we not only need to accurately estimate the spatial distribution of hydraulic conductivity but also need to quantify the uncertainty of the parameter to evaluate its credibility. In this study， parameter inversion and uncertainty analysis of hydraulic conductivity were investigated using the Bayesian Convolutional Neural Network （BCNN）. To test the validity of the method， a synthetic numerical experiment of a two-dimensional steady-state hydraulic tomography pumping test was conducted. The baseline model is a convolutional neural network with an encoder-decoder structure， which builds an inverse mapping that estimates the parameter field directly from the head fields obtained by spatial interpolation. Based on this deterministic model， we trained the Bayesian Convolutional Neural Network. The results show that the BCNN outperforms the deterministic model in accuracy under various training data sizes， with a more significant advantage when the data is scarce. By analyzing the test set samples， we observe that the models exhibit different levels of confidence for their estimates across different regions. A well-trained BCNN can faithfully capture the approximate pattern of the hydraulic conductivity distribution. Moreover， the BCNN also excels in estimating the more challenging multimodal non-Gaussian logarithmic hydraulic conductivity field compared to the generative model， which indicates the wide applicability of the BCNN under diverse geological media conditions. The use of Bayesian Convolutional Neural Networks enables accurate inversion of hydraulic conductivity and evaluating uncertainty， providing a solid basis for subsequent physical processes such as groundwater flow simulation.

Evapotranspiration change research is important for irrigation water management and water resources utilization. The Sanjiang Plain， as a vital agricultural region in China， faces substantial demands for irrigation water.The primary objective of this study is to investigate the trends in evapotranspiration （ET_A ） in the Sanjiang Plain， and to provide a scientific basis for the sustainable development of water resources in this area. In this study， we selected three evapotranspiration models based on the complementary relationship principle and compared their accuracy in estimating ET_A in the Sanjiang Plain， then adjusted and validated the parameters of the models based on the water balance equations. Ultimately， the model with the highest accuracy was selected for estimating the ET_A in the Sanjiang Plain from 1960 to 2020. Various analytical methods were employed， including the Mann-Kendall test and the inverse distance weighting method， to explore the spatiotemporal patterns of ET_A . Furthermore， correlation coefficients and single-factor sensitivity analysis were used to assess the influence of meteorological factors on ET_A . The results showed that when using the original parameter values， the three evapotranspiration models introduced substantial errors in estimating ET_A . However， after parameter adjustments， the complementary relationship areal evapotranspiration model exhibited superior accuracy and was selected as the optimal model for estimating ET_A in the Sanjiang Plain. Over the 61-year period， the annual ET_A in the Sanjiang Plain is in a significant upward trend with a linear growth rate of 0.4 mm per year. The change trend of summer ET_A is consistent with the annual ET_A， and the change trend of ET_A in other seasons is different. The rising trend in summer ET_A was the dominant factor contributing to the increase in annual ET_A . The spatial distribution of ET_A exhibited variations， with multi-year and seasonal averages predominantly concentrated in the central region of the Sanjiang Plain. The ET_A increase rate of the eastern part is faster than the central and western parts in the Sanjiang Plain. The minimum temperature exhibited the strongest correlation with ET_A， while wind speed had the weakest correlation. ET_A demonstrated sensitivity to temperature changes， with variations in maximum temperature having the most significant impact.

The processes of rising water temperature， photosynthesis， and high dam discharge may all cause the problem of supersaturated dissolved gas， which can affect the biodiversity of fish in rivers and other water bodies. Aeration technology has been proven to significantly promote the release of supersaturated TDG， DO， and DN， and is an important method for mitigating the impact of supersaturated water bodies. This article conducted experiments on the release of supersaturated dissolved gas under different aeration rates and water depths using pinhole aeration discs and microporous aeration pipes， exploring the release laws of supersaturated dissolved gas. The experimental results show that the release processes of supersaturated TDG， DO， and DN under the action of microporous aeration conforms to the first-order dynamic equation. All supersaturated DO under experimental conditions can be released to an equilibrium state， while the release rate of supersaturated DN is slow and cannot reach an equilibrium state for a long time， showing k _DO>k _TDG>k _DN； The release coefficients of supersaturated TDG， DO， and DN increase with the increase of aeration volume， but decrease with the increase of aeration depth. The release effect of supersaturated TDG， DO， and DN using microporous aeration pipes is significantly better than that of pinhole aeration discs under the same aeration volume and aeration depth. A binary linear regression model was used to establish the release coefficient relationships of supersaturated TDG， DO， and DN under microporous aeration， which can effectively predict k _TDG with the correlation coefficient of 0.958. This study reveals the release characteristics of supersaturated dissolved gases under microporous aeration， providing certain reference value for aeration technology to mitigate the impact of supersaturated dissolved gases.

To address the increasingly serious problem of urban waterlogging， we chose the surrounding area of the Panyu District government in Guangzhou as our research subject. Using the SWMM and LISFLOOD-FP coupled model， we simulated the urban rainstorm waterlogging in the study area. We also simulated the effects of LID facilities on runoff reduction under different rainfall recurrence periods. We considered the weight of influencing factors to determine the optimal layout plan for LID facilities in the study area using the AHP-TOPSIS research method. The goal is to guide urban transformation. The results indicate that： ①he model accurately reflects the extent of inundation and water depth in the study area during the heavy rainfall event on “20220804”. ②Based on simulation results of rainfall events with return periods of 2 years， 5 years， 10 years， 20 years， and 30 years， certain areas such as the intersections of Shengtai Road and Dongxing Road， Zhuanhui Square， Qinghe Middle Road， Dabei Road， Fuhua Middle Road， Qiaoxing Avenue， Guangming North Road， as well as blocks where Fanhua Road， Yushan Avenue， Guangming South Road， Jiefang Road， Jiefang Street， and Huancheng West Road are located， are prone to waterlogging. ③We designed a total of 10 different schemes consisting of bioretention zones， rain gardens， and green roofs， taking into account the storage capacity. By considering the weight of different factors influencing waterlogging in each area， we conducted a comprehensive analysis of the benefits of the 10 LID facility layouts using the AHP-TOPSIS method. Consequently， we obtained the optimal LID facility retrofitting schemes for different inundation characteristics.

With the increasing demand for a better life， urban river water environment has become an important component of enhancing urban taste and improving residents' quality of life. Although a large amount of work has been carried out in various regions to improve the overall water environment quality， some river water quality still exceeds the standard. On the basis of implementing engineering measures such as pollution interception and control， river dredging， and ecological water replenishment in the basin， it is still necessary to carry out comprehensive water ecological management for rivers with water quality exceeding the standard in the basin to further improve the water quality of the river. This study aims to understand the background and water quality improvement needs through current situation investigation. Firstly， this study analyzes the pollution loads of endogenous pollution， point source pollution， non-point source pollution， and atmospheric dry wet deposition pollution within the watershed， and obtained the daily average pollution load. Secondly， the maximum amount of pollutants that a water body can accommodate is calculated based on established water quality goals， design water volume， and hydrological conditions. Finally， by comparing the daily average pollution load and the water environment capacity of the water body， the demand for improving the self-purification capacity of the water environment is identified. The pollution load of the river in this research mainly comes from the tail water of sewage treatment plants and the water from upstream rivers. The main pollutant control factors in the river section are COD， NH₃-N， TP， combined with the purification principle and efficiency of ecological wetlands， the purification effect of submerged plants in ecological ponds and reservoirs， and the purification ability of ecological rivers to nitrogen and phosphorus in water bodies， taking composite ecological wetlands as the core functional area for water quality purification， ecological ponds， reservoirs， and ecological rivers as auxiliary measures for pollutant degradation and transformation. Based on the location and actual situation， a multi-level purification composite ecological treatment measure for ecological wetlands， ecological ponds， reservoirs， and ecological rivers is proposed. Through multi-level purification， the self-purification capacity of the river water environment can be enhanced and the water quality of urban rivers can be improved.. This technology route has obvious advantages and strong applicability. Through a combination of multiple ecological measures the self-purification capacity of the water environment can be improved at a low cost， achieving the goal of water quality assessment. At the same time， this provides governance ideas that can be referenced for other regions. Each region can further analyze and study based on actual background， spatial conditions， and water quality objectives. Through the multi-level purification governance concept of river water quality， the positive role of water ecological construction can be played.

Current study of nitrogen loss in the slope with red soil mainly focuses on its transport processes in the runoff and soil interflow with the equipment of artificial soil tank. Few experiments were carried out to monitor the nitrogen transport processes both in the surface and subsurface system on the natural slope. To investigate the nitrogen loss processes in the surface-subsurface system on the slope with red soil， three experiments with different soil surface coverage and soil moisture conditions were carried out in Ecological Science and Technology Park of Water Conservation in Jiangxi Province， China. The runoff， interflow， soil moisture and temperature and the nitrogen concentration （nitrate-N and ammonia-N） were measured in each experiment. The results show that the rough soil surface intercepts rainfall water and decreases the runoff flow， but it causes more nitrate-N infiltrate to soil and move downward with soil water. In natural slope， the existence of macro pores and the strong soil spatial variability are the main reasons for the interflow in soil. The nitrogen concentration in the interflow was obviously more than that in the runoff， which caused the large portion of nitrogen loss by interflow. During the first experiment， the nitrogen loss by interflow accounted for more than 50% of total nitrogen loss. In comparison， the ammonia-N concentration in the interflow and runoff were smaller than those of nitrate-N due to its high adsorption effect by soil. The soil nitrate-N and ammonia-N exhibited high spatial variation along the slope. There was no consistent rule of the variation over time， which was impacted by various factors， such as soil temperature and surface soil hydraulic.

Faced with the phenomenon of nitrate infiltration in irrigated agricultural areas polluting groundwater and damaging human health and the ecological environment， we propose new electrochemical technology that can be added to the traditional permeable reaction barrier （PRB） technology to improve the treatment of nitrates. The results show that the removal rate of nitrate under the action of three-dimensional electric field is increased significantly from 63.25% of the traditional technology to 95.77%， and the reaction time is shortened from 7 days to 3 days， which improves the treatment efficiency and reduces the cost. Furthermore， the study investigated the effects of single factor of hydraulic retention time（HRT）， pH， voltage， and plate spacing on nitrate removal by electrokinetic permeable reaction barrier（EK-PRB）. On this basis， the response surface modeling is used to predicte that the optimal removal rate of EK-PRB was 96.75% under the conditions of HRT=15 h， voltage=31 V， and battery lead plate spacing=8.5 cm， and the actual removal rate was 95.74%. Accordingly， compared with the traditional PRB technology， EK-PRB is filled with biochar particle electrodes to increase the mass transfer rate of pollutants， enhance the adsorption capacity and provide more reaction sites. All our preliminary results show the combined effect of three-dimensional electrolysis and PRB not only greatly improves the removal efficiency of pollutants， but also makes the adsorbed filler medium regenerated under the effect of electro-chemistry， realizing the sustainability of the reaction process，with a view to providing theoretical support for the practical application of nitrate treatment.

Aquatic vegetation extensively thrives in shallow areas of rivers and lakes， playing a crucial role in their ecological functions and significantly impacting riverine flooding and sediment transport. This study is based on a field survey of natural river channel vegetation. A two-dimensional shallow water hydrodynamic model is established to quantitatively evaluate the impact of the large-scale expansion of floodplain vegetation（Phragmites australis and Typha orientalis communities） on water and sediment transport in the Han Kou Beach in the Wuhan segment of the Yangtze River's main stream. Under the hydraulic resistance effect of vegetation， the maximum upstream water level within the vegetated area increases by about 0.04 m. The flow velocity within the vegetated area generally decreases by 0.3~1.2 m/s， while the the flow velocity in the main channel increases by 0.04~0.3 m/s. These hydraulic changes alter the sediment initiation conditions， resulting in the formation of a narrow and elongated sediment initiation weakening zone near the bankside vegetation area， where the maximum sediment initiation particle size decreases by 5 mm. Conversely， the sediment initiation particle size in the main channel increases by 3~10 mm. This study provides valuable insights into the dynamic interplay between vegetation， hydrodynamics， and sediment transport in natural river environment， it offers theoretical guidance for ecological river flood control design.

This study is dedicated to a comprehensive exploration of the intricate relationship between environmental factors and greenhouse gases （GHGs） emissions within the lakeshore zone of urban landscape water bodies， particularly under extreme weather conditions. The chosen research site， Nanjing Xingdian Wetland Park， stands out for its significant GHGs emissions. The investigation involved the meticulous collection of surface sediments from the lakeshore zone and an in-depth analysis of variations in cumulative GHGs emissions and physicochemical properties of sediments. This comprehensive examination took place under diverse water and temperature conditions in controlled indoor cultures. The findings of this study have unearthed compelling insights. ①To begin with， prolonged elevated temperatures were observed to have an inhibitory effect on soil respiration. Specifically， during the pre-cultivation period， the 30°C flooding treatment group exhibited GHGs emission rates 1.6 to 4.1 times higher than those observed in the post-cultivation period. This substantial difference can be attributed to the gradual decrease in dissolved organic carbon （DOC） content and the carbon-to-nitrogen （C/N） ratio within the environment over the course of incubation. The diminishing carbon content proved inadequate to sustain the survival requirements of microbial populations， resulting in a significant decline， which in turn， hindered the emission of GHGs. ②Furthermore， under appropriate temperature conditions， both increased moisture and temperature will promote GHGs emissions from sediments in the lakeshore zone of urban landscape water bodies. The favorable conditions for the reproduction and metabolism of anaerobic microorganisms in sediments， such as flooding and temperature elevation， accelerated the decomposition of dissolved organic matter（DOM）， resembling fulvic acid. Consequently， this process led to heightened emissions of carbon dioxide （CO₂） and methane （CH₄） as by-products of the microorganisms' decomposition of DOM. Moreover， the temperature increase facilitated the activity of biological enzymes， influencing the nitrification-denitrification process and resulting in an overall escalation in nitrous oxide （N₂O） emissions. These insights highlight the significance of future research focusing on the impact of external dissolved carbon inputs on GHGs emissions from landscape water bodies under varying environmental conditions. Such investigations are not only crucial for accurately assessing the contribution of urban landscape water bodies to global carbon emissions but also provide essential theoretical foundations for the development of effective emission reduction policies.

Ecological water replenishment is an important initiative for the ecological environment management of Baiyangdian， and this paper divides the ecological water replenishment process of Baiyangdian into a temporary water replenishment stage， an emergency water replenishment stage， and a stable water replenishment stage according to the change process of ecological water replenishment mechanism. In order to analyze the spatial and temporal pattern changes of water bodies in Baiyangdian under each ecological recharge stage， this paper extracts water bodies and ice bodies from 701 remote sensing images of Baiyangdian from 1990 to 2022 through the GEE platform， analyzes the spatial and temporal pattern of the water bodies under different stages， as well as specifically analyzes the change of the ice bodies' area in the winter freezing period. The main conclusions are as follows： ① In each ecological recharge stage， the water body area of Baiyangdian is the smallest in summer and the largest in winter and spring， and with the continuous improvement of ecological water replenishment mechanism， Baiyangdian water body area change amplitude is gradually reduced， showing the change rule of “cutting peaks to make up for the low”. The range of monthly average water area in the temporary water replenishment stage is between 0.63~186.03 km²， and that in the stable water replenishment stage is between 17.88~109.15 km²， the magnitude of change reduced by 50.77%； ②The perfection of ecological water replenishment mechanism makes Baiyangdian present the change rule of permanent water body increasing greatly and intermittent water body decreasing greatly， among which the permanent water body area in the temporary water replenishment stage is 7.66 km²， while the permanent water body area in the stable water replenishment stage is 23.62 km²， which is an increase of 208.16%， and the area of the intermittent water body is reduced from 263.50 km² to 143.58 km²， a decrease of 45.51%； ③ From the perspective of the change of the ice body area， with the continuous improvement of ecological water replenishment mechanism， the area of Baiyangdian's ice body decreased continuously， in which the average area of the ice body in January decreased from 72.77 km² to 12.60 km²， which was reduced by 82.69%. The results show that the improvement of the ecological water replenishment mechanism did not lead to the continuous increase of the water body area of Baiyangdian， but made the water body environment of Baiyangdian more fragmented； under the influence of global warming and other factors， the ice area of Baiyangdian was greatly reduced； this tendency to fragmentation of the characteristics of the watershed may not be conducive to the preservation of biodiversity， but given that ecosystems have a lag in their hydrological response， it is necessary to further strengthen the monitoring and research on the process of ecological and hydrological response.

The installation of porous orifice plates in pipeline systems can play a role in throttling and reducing pressure， but if the pressure difference between the upstream and downstream of the orifice plate is too large， it is easy to cause cavitation in the downstream of the orifice plate. The occurrence of cavitation can cause pipeline vibration， and have adverse effects on pipeline systems. This article experimentally measures the vibration acceleration， corresponding pressure difference， and flow rate generated by porous plates with different porosity in different cavitation stages. The experimental results indicate that as the degree of cavitation continues to intensify， vibration acceleration in the full frequency range significantly increases， and the peak value of vibration acceleration gradually increases. The vibration acceleration exhibits a broadband characteristic. Based on the experimental results， we plotted the vibration intensity curves of orifice plates with different porosity as a function of cavitation number. By varying the slopes of the fitted curves in the cavitation vibration curve， different cavitation stages and three critical cavitation numbers （including incipient cavitation number， constant cavitation number， and choked cavitation number） can be distinguished. The critical cavitation number of orifice plates with a porosity less than 1.8 rapidly decreases with the increase of porosity. When the porosity is greater than 1.8， the incipient cavitation number and constant cavitation number slow down with the increase of porosity， while the choked cavitation number remains basically unchanged. This means that increasing the porosity appropriately is beneficial for delaying the occurrence of cavitation. Based on the experimental results， we plotted the variation curve of flow resistance coefficient with cavitation number for orifice plates with different porosity. From the cavitation flow resistance curve， it can be seen that： ① When cavitation phenomenon has not yet occurred， the flow resistance coefficients of orifice plates remain basically unchanged. ② When cavitation phenomenon just occurred， the flow resistance coefficient of the orifice plate decreases slightly， but thereafter， as the degree of cavitation intensifies， the flow resistance coefficient begins to rapidly increase. ③ The larger the porosity of the orifice plate， the greater the flow resistance， and the greater the influence of cavitation on the flow resistance. Taking into account the vibration and flow resistance characteristics of the orifice plate， it is recommended that the porosity of the porous orifice should be maintained between 1.8 and 2.0.

Based on the knowledge and understanding of modernization of the physical irrigation district and digitalization of the analog irrigation district， this paper analyzes and summarizes the “five major functions” of the construction of modernized digital irrigation district including “Identification system of irrigation district”， “Stereoscopic Perception System”， “Precise Control System”， “Information Exchange System” and “Water Allocation System”. In order to meet the requirements of intelligent water projects and efficient operation and management of irrigation district， to efficiently simulate water flow in canal system， the generalized map of irrigation district with “joint flow process” as input and output is systematically sorted out， and the key application structure system of modernized digital irrigation district is studied and proposed. That is to build an interactive overall structure with “database” as the carrier， “mathematical model” as the support layer， “nine professional applications” as the interaction layer including “organization management”， “project management”， “security management”， “pumping station management”， “water saving and water supply management”， “economic management”， “information management” and “public services” on the basis of “one digital map of the irrigation district”. It is expected to effectively improve the safety， equity， reliability and flexibility of irrigation water supply services.

The reflux hole is an important auxiliary device in the outer recirculation self-priming pump， and is one of the main factors that affect the self-priming performance and external characteristics. In order to solve the problem of low self-priming efficiency and long time consuming in the operation of the pump， the reflux holes with different area schemes are designed according to the empirical formula， and the internal flow of each scheme is simulated and calculated by numerical simulation. The calculation results are compared with the test results， the differences and laws of the internal flow and external characteristics of the self-priming pump under different schemes are analyzed， and the energy characteristics of the self-priming pump after reconstruction are estimated. The optimal reflux hole area of the model pump was determined. The results show that the size of the reflux hole affects the flow of fluid in the flow channel and the distribution of the flow field， and is positively correlated with the self-priming performance and negatively correlated with the hydraulic performance. After the reconstruction， the return flow of the reflux hole increases， the pump efficiency decreases by 2.2%， the head decreases by 7.6%， and the operating efficiency point tends to the high flow condition area. The research results can provide reference for the design of similar self-priming pump structure.

Through direct shear tests on the modified soil， backfill expansive soil and canal soil of the high-fill canal embankment of the Central Line Project of South-to-North Water Diversion under different moisture contents， the influence of moisture content on the shear stress-shear displacement and shear strength of the three types of soils was studied. The results show that the matric suction of the three types of soils decreases significantly with the increase of moisture content； when the moisture content is low， the shear stress-shear displacement curve shows a shear softening type； as the moisture content increases， the shear stress - shear displacement curve is converted to the shear hardening type. The shear strength of different soils shows a trend of first increasing and then decreasing with the increase of moisture content， and the decrease in shear strength is relatively small when the moisture content reaches the plastic limit of the soil. The moisture content has a significant impact on the cohesion and internal friction angle of modified soil， backfill expansive soil and canal soil， and the cohesion and moisture content satisfy a quadratic polynomial relationship； the internal friction angle of soil shows a nonlinear decreasing trend with the increase of soil moisture content， and the decrease in internal friction angle of canal embankment modified soil with water content is greater than that of canal embankment expansive soil and canal soil.

Reuse of irrigation return flow is a common phenomenon in multi-source irrigation systems. This paper analyzes the mechanism of reuse of irrigation return flow， and generalizes the calculation method of irrigation return flow combined with the characteristics of improved SWAT model， and explains the calculation method of actual irrigation water consumption. Taking Tongjiqiao reservoir irrigation system in Pujiang County， Zhejiang Province as an example， the improved SWAT model was used to construct its hydrological model， and the parameters of the model were calibrated and verified by using the long series of measured monthly runoff and measured irrigation water withdrawal rate at the canal head. The Nash efficiency coefficients of the calibration and the verification period were all greater than or equal to 0.85， and the average relative error between the simulated and measured irrigation water withdrawal rate of the four main canals was less than 5%， indicating that the improved SWAT model has good simulation effect and can be used to simulate the irrigation water withdrawal rate of different water sources in the irrigation system. Further， according to the model simulation results， the irrigation regression water and its repeated utilization as well as the actual irrigation water consumption in Tongjiqiao reservoir irrigation system were calculated. The results showed that the reuse rate of irrigation return flow in the irrigation system reached 40%， and the irrigation water consumption in the irrigation system would be reduced by about 5.4% after deducting the reused irrigation return flow. The irrigation water consumption of the backbone water source accounts for 63% of the total water consumption， which can not replace the irrigation water consumption of the whole irrigation system. It is further indicated that the actual irrigation water consumption statistics should consider deducting the reused irrigation return flow， especially for large irrigation areas or large areas， and the absolute reduction of irrigation water consumption in irrigation systems will be very considerable， which can improve the statistical accuracy of irrigation water consumption in irrigation systems. For the irrigation system with monitoring facilities， the monitored water quantity should not be used as the irrigation water consumption， but the actual irrigation water consumption of different water source types in the irrigation area should be simulated.

Through the analysis of the current water conservancy information technology construction problems and needs， this paper puts forward a multi-network aggregation communication networking scheme. According to the water conservancy information technology of different business scenarios and bearer requirements， the main link mainly selects the aggregation of WIFI transmission， and the backup link selects the aggregation of 4G/5G communication or wired application combinations to help solving the problem of wireless communication difficulties in remote areas in smart water conservancy construction and achieve the high-capacity， high-bandwidth， high-security， easy to build and low-cost characteristics of the data transfer requirements.

By establishing a multi-objective canal system optimal water distribution model， the canal system water distribution process was optimised to provide a scientific basis for water-saving irrigation in Xinjiang agriculture. Taking the Xindong main canal in the Wujiaqu irrigation district of Xinjiang Province as the research object， the multi-objective particle swarm optimisation algorithm was used to establish a multi-objective canal system optimization water distribution model with the optimisation objectives of minimum leakage loss and stable water flow in the distribution channel， and compared with the backtracking search algorithm with regard to the water distribution time and the amount of leakage loss. It was shown that the multi-objective canal optimisation distribution model was able to reduce the distribution time from 15 days to about 11 days with a canal distribution of 0.715 8 million m³， which was a reduction in the distribution time from 14 days to 11 days and a reduction in seepage of 0.083 9 million m³ when compared to the backtracking search algorithm. The multi-objective particle swarm optimisation algorithm was used to optimise the water distribution process of the Xindong main canal in Wujiaqu irrigation district of Xinjiang， which not only satisfied the optimisation objective， reduced canal leakage and shortened the distribution time， but also was more practical than the backtracking algorithm.

In the realm of deeply buried tunnels， traversing intricate geological structures， the tunneling process encounters the formidable challenges of abrupt water influx and mud-rushing， particularly when intersecting highly water-bearing faults. Taking the Wudu River segment as the resesarch subject， this study employs numerical simulation techniques to dissect the percolation phenomena during tunnel excavation within water-rich fault zones and to elucidate the stability of tunnel's rock mass. The findings underscore that tunnel excavation engenders altered infiltration processes within the surrounding rock， consequently subjecting the tunnel lining to substantial external hydraulic pressures. The grouting ring effectively isolates subsurface water， while water is discharged through drainage apertures. This dual strategy cumulatively diminishes the external hydraulic pressure on the lining by around 70%. The faulted rock mass exhibits inferior physical-mechanical properties， displaying significant post-excavation deformations， with horizontal displacements exceeding the vertical displacements. Upon implementation of advanced grouting and pre-support measures， the rock mass displacement is mitigated by 50% to 60%， concurrently leading to a pronounced reduction in lining stress. Following a comprehensive evaluation， it is recommended to adopt a preemptive support strategy involving small conduits with a length of 4.5 m， an overlap length of 1 m， and an external convergence angle of 15°， alongside larger canopies with a length of 30 m， an overlap length of 3 m， and an external convergence angle of 3° for optimal efficacy.

Taking the first stage floating pump station of Jinsha River photovoltaic water-lifting project in Yuanmo County， Yunnan Province as an example， the water hammer prevention of floating pump station is studied. On the basis of reference to the rules of relevant design codes， the pump-stopping water hammer protection standard is determined. By comparing the influence of different inlet water level and the number of stopping-pump on the transient， it is determined that the working condition of the lowest inlet water level with all the operating units stopping is the most unfavorable conditions for the water hammer protection. According to the pipeline topography and the characteristics of the floating pump station， and based on the analysis of transient of various working conditions， the water hammer protection scheme of “axial flow check valve at pump outlet + axial flow check valve in front of air chamber + onshore air chamber” is recommended. The scheme completely prevents the unit from reversing through the axial flow check valve at the pump outlet， eliminates the vaporization phenomenon and reduces the positive water hammer pressure in the pipeline through the onshore air chamber， and prevents the impact of the backflow water on the float and rocker pipe through the check valve in front of the air chamber. The protective measures have good reference significance for similar projects.

The robotic total station is widely used in automatic monitoring of reservoir dams. In order to ensure the reliability of the monitoring results， the refraction correction of the original observations is required. Based on the characteristics that automatic monitoring of robotic total station can improve the monitoring frequency and provide a large amount of observation data， this paper builds a neural network refraction correction model to correct the original observations including vertical angle， slope distance and horizontal angle. And an automatic monitoring system for a hydropower dam is used to carry out experiments， and the accuracy of the observations after correction is analyzed. The results show that for the correction of vertical displacement based on vertical angle， the method based on neural network is more effective than the traditional K-value correction formula， and the maximum accuracy of vertical displacement can be improved by about 2 mm. For slope distance correction， the method based on neural network has a certain effect， showing a trend that the greater the distance， the more obvious the effect. As for the correction of horizontal angle， the results show that the horizontal angle is less affected by refraction， and the correction using neural network cannot further improve its accuracy.

Aiming at the problem that it is difficult for hydropower units to effectively evaluate the deterioration state of units by using real-time monitoring data， and the different operating conditions of hydropower units have a significant impact on the parameters of the trend prediction model of operating state index， a method for predicting the deterioration trend of hydropower units based on parameter adaptive support vector regression （SVR）， variational mode decomposition （VMD） and time convolution network （TCN） is proposed. Firstly， according to the power and water head， the operating conditions of the unit are divided into several typical operating conditions. On this basis， the SVR model is established by using the improved Aquila Optimizer， and the prediction parameters under each operating condition are optimized to establish the data of operating conditions and optimal parameters. Then， the neural network is used to fit the working condition and the optimal prediction parameters， and the nonlinear function mapping the complex relationship between the two is constructed. Then， the constructed mapping relationship is added to the traditional SVR to realize the adaptive SVR health model adapted to the change of the working condition of the hydropower unit. Secondly， according to the standard value and monitoring data output by the health model， the deterioration trend sequence is calculated. Finally， considering the nonlinear factors of the deterioration trend sequence， a time series prediction model based on VMD-TCN is established to realize the accurate prediction of the deterioration trend. Multiple sets of comparative experiments are designed to verify that the proposed model is more accurate and faster.

With the large-scale integration of wind power， photovoltaic， and other random energy sources， the power grid structure has become complex. In this context， hydropower units will often operate under variable operating conditions as needed， and the operating environment is becoming increasingly harsh. It is obviously difficult for the traditional PID control strategy to achieve optimal control under various complex operating conditions. Therefore， the H _∞ theory is applied to the hydropower unit， and its parameters are optimized based on the improved salp swarm algorithm （ISSA） and the comprehensive ITAE indicator， and the adaptive robust control of the hydropower unit based on ISSA-H _∞ is realized. The simulation results show that， compared with the traditional PID controller， the adaptive robust controller designed based on ISSA-H _∞ has excellent regulation performance under different conditions， and realizes the optimal control of hydropower units under multiple conditions.

In order to solve the problems of water seal in hydropower station gates such as cracking sealing performance during operation， difficulty in predicting sealing performance and lack of theoretical basis for determining bolt preload when replacing water seal， a compensation model of bolt preload based on multiple linear regression is proposed. Combined with engineering examples， a hyperelastic constitutive model of square P-type water seal was established by Ogden formula， and the nonlinear finite element model of water seal under complex working conditions was established. Based on Ansys， the water seal contact stress under four influencing factors was calculated， and the independent and comprehensive influence rules of various factors on the sealing performance of water seal were analyzed. On the basis of finite element analysis， the contact stress calculation formula was established based on multiple linear regression， and the bolt preload compensation model was constructed. The prediction of water seal performance and the calculation of bolt preload compensation are realized. The results show that the average relative error between the contact stress based on the bolt preload compensation model and the expected value is 7.6%， and the maximum relative error is 16.9%. The model can correct the bolt preload when the installation condition changes， so as to obtain the expected sealing performance of the water seal， which provides a reliable basis for the design and installation of the water seal structure in practical engineering.

Researches on hydro-wind-solar hybrid energy systems have mostly focused on coordinated operation and enhancing the new energy consumption but often overlooked the potential impact on the water levels of reservoirs. In this paper， a long-term optimal operation model for hydro-wind-solar hybrid energy systems， nested with short-term energy curtailment， is established. Firstly， the curtailment loss function was fitted based on actual hydro-wind-solar output data simulating potential curtailment scenarios， which was incorporated into a long-term optimal operation simulation； Secondly， simulations of the reservoir dispatching operation process before and after the integration of wind and solar energy were conducted； Finally， the impacts of wind and solar energy consumption on the annual， sub-annual， and monthly operating water levels of the cascade reservoir group were analyzed. A case study was carried out using the hydro-wind-solar hybrid energy system from Longyangxia to Liujiaxia cascade reservoirs in the upper reaches of the Yellow River. The results show that： ① After wind and solar energy integration， the annual average output of the cascade reservoirs decreases by approximately 0.5% to enhance the consumption of wind and solar energy， increasing the wind-solar power in grid and total system output by approximately 2.2%. ② The wind and solar energy consumption leads to increased annual and monthly water level fluctuations in the cascade reservoir group. The end-of-year drawdown and annual average water level fluctuations ranges of Longyangxia and Liujiaxia reservoirs increase by 2.5%， 101.6%， 0.8% and 78.9%， respectively. Longyangxia experiences no change in monthly water level fluctuation， while Liujiaxia sees a reduction of 14.7% in the lower limit of monthly water levels. ③ In wet years， the wind and solar energy integration leads to a significant decrease in water levels of the cascade reservoirs. In normal years， Longyangxia reservoir experiences a slight decrease in water levels， while water level of Liujiaxia reservoir decreases in pre-flood spring and increases in post-flood autumn. In dry years， wind and solar energy consumption has almost no impact on reservoir water levels. These research findings hold significant practical implications for better understanding the complex relationship between wind and solar energy integration and reservoir operations and for optimizing the operational strategies of hydropower-wind-solar complementary systems.

Effective load dispatch of cascade hydropower stations plays an important role in improving the power supply capacity of hydropower stations. In order to maximize the advantages of cascade hydropower stations， optimize their scheduling， and ensure stable operation， the research aims to improve the efficiency of joint scheduling and peak valley regulation capacity. By coordinating multiple parameters such as power generation， output adjustment， and water storage among different hydropower stations， and combining factors such as mutual influence and dependency between each hydropower station， the overall performance optimization is the goal. Coordinate the operation plan and scheduling strategy of cascade hydropower stations to achieve more efficient， economical， and stable power supply. On the basis of introducing a fuzzy semi trapezoidal membership function， a fuzzy recognition model is used to divide peak and valley periods， with the highest generation efficiency and the minimum residual load mean square error as the objective functions. The differential evolution algorithm is used to solve the optimal solution that satisfies the objective function under constraint conditions， and finally， a load joint scheduling scheme for cascade hydropower stations is obtained. The experimental results show that after applying this method， the residual load mean square error of the power grid can be reduced， and the total power generation efficiency can be significantly improved， indicating that the joint scheduling effect of this method is better.

In order to study the influence of the characteristic curve on the hydraulic transient process， this paper uses the characteristic curves of three pumped storage turbines with similar specific speeds to calculate and analyze the hydraulic transient process of a power station.According to the calculation result， reducing the unit speed of the intersection of the runaway curve and the unit running trajectory line helps to reduce the maximum speed.The initial operation point should be selected in a relatively smooth area of the characteristic curve，which helps to decrease the flow change of the unit during the transient process，then the maximum pressure at the volute inlet can be reduced.The smaller and smoother the slope change rate of the “S” characteristic， the higher the minimum pressure at the inlet of the draft tube.These research results can provide a theoretical basis for selecting appropriate runner in the early stage of the project.

The daily peaking capacity is one of the main performance indicators of hydropower station which is of great significance in the grid scheduling of combined water， wind and photovoltaic power. This paper defines the concept of daily peaking capacity of hydropower station from the aspects of peaking magnitude and peaking power， and calculates the daily peaking capacity of hydropower stations based on four typical daily load diagrams of fixed shapes and a generalized typical daily load diagram. For the typical daily load diagrams of fixed shapes， the calculation method of the hydropower stations’ maximum peaking magnitude under the known peaking time is given. For the generalized typical daily load diagram， the calculation method of the maximum peaking power is given. Four reservoirs of hydropower plants with different regulation performance in the midstream and downstream of the Hongshui River were used as research objects. The peaking capacity of each reservoir was calculated at different initial water levels and different average daily inflow under five different typical daily load diagrams. The results show that For hydropower stations with strong regulating capacity such as seasonal and annual regulation， their daily peaking capacity is mainly affected by the reservoir water level， while the average daily inflow has little effect on it. For daily regulated hydropower stations， when the inflow is small， the daily peaking capacity is greatly affected by the daily initial water level and the daily average inflow. When the inflow reaches a certain value， the daily initial water level has less influence on the daily peaking capacity. When the average inflow and initial water level are determined， the maximum peaking amplitude and maximum peaking power of the hydropower station as well as related operation data can be quantitatively derived， which facilitates the optimal effect of the hydropower station to participate in the grid peaking. The concept of daily peaking capacity of hydropower station proposed in this paper is objective and comprehensive. The established method of calculating daily peaking capacity has strong practicality and operability which can provides scientific basis to determine the daily peaking capacity of hydropower station.

Seepage analysis and calculation is an important work in the design and safety evaluation of earth-rock dam. At present， mature commercial software for seepage calculation includes the seepage module of Lizheng-rock software， AutoBank， GeoStudio\SEEP/W module， Ansys software， etc. These software focus on seepage analysis. For multiple schemes， results extraction， report preparation and post-processing， designers need to operate manually， and the overall work efficiency of the guidelines is low. To solve this problem， VBA language is combined with API function. Excel， Word， AutoCAD and Lizheng software are integrated to realize automatic analysis and calculation of seepage flow schemes of earth-rock dam， extraction of results and compilation of reports， and the slope stability analysis of earth-rock dam with multi-section and multi-working conditions can be generated with one click. It lowers the threshold of calculation， drawing and report writing， realizes the standardized production of calculation， and greatly improves the work efficiency and quality.

Earth-rock dam is one of the most widely used dam types in hydropower industry， among which rockfill dam is the best choice and its dam material particle size distribution has an important impact on construction quality and operation safety. Because of the disadvantages of manual screening， image recognition technology is becoming a hot spot. Based on image recognition， this paper carries out in-situ gradation detection of rockfill materials. According to the shape and distribution characteristics of stone particles， the rockfill materials are divided into four layers： upper， middle upper， middle lower and lower， and the four gradation curves are weighted and merged according to their respective proportions. The error between the merged curve and the screening curve is about 10%， which is reduced by 10% compared with the previous ones， and the detection results are more accurate； At the same time， an evaluation model for the particle size gradation of the dam material has been established. By comparing the fractal index and screening index of the model， the feasibility of using fractal dimension D to evaluate the gradation distribution of dam materials is verified. This method can provide reference for rapid and accurate detection of particle size distribution in similar projects.

Dam deformation is the visual representation of the state of a dam under the influence of internal and external loads during its operation. Building a high-precision deformation prediction model is of significant importance for dam safety monitoring and operational assessment. Existing dam displacement models have long training times， and their prediction accuracy and generalization capabilities are often suboptimal， making them unsuitable for accurate short- to medium-term displacement predictions. This paper coupled Long Short-Term Memory （LSTM） with the Transformer framework and introduced an improved Invasive Particle Swarm Optimization （IPSO） algorithm for optimization to create the IPSO-LSTM-Transformer （ILT） dam deformation prediction model. Using data from measurement point 11-1 on the vertical axis of the Jinshuitan arch dam as an example， this paper analyzed and predicted deformation time series data from 6，150 data sets. The research results demonstrate that the model's prediction accuracy decreases to a certain extent as the prediction horizon increases， but it maintains good predictive capabilities within a prediction step of 10. Compared to traditional Particle Swarm Optimization algorithms， the ILT model significantly improves the model's optimization precision and convergence speed. When compared to the single-step and multi-step prediction results of RNN， LSTM， and IPSO-Transformer neural network models， the ILT model exhibits higher accuracy and better stability， even when trained with limited data. The research findings provide new technical means for the precise short-to-medium-term prediction of dam displacement during operation.