Uneven spatial and temporal distribution of water resources is widely existed. Building reservoirs is one of the most effective means to regulate water resources. In China， more than 90 000 reservoirs of various kinds have been built. In order to maximizing the engineering benefits and water security capability of reservoirs， comprehensive， accurate and georeferenced attribute datasets of reservoirs and dams at national and global scales are urgently needed including location， boundary， height， storage capacity and function. During the past decade， several reservoir and dam data sets have been published and significantly advanced the large-scale researches on the environmental impacts of reservoirs and dams. However， there are significant discrepancies in the numbers and values of attributes amongst data sets. Therefore， it is urgent to carry out comparative assessment and to identify the future direction of these data sets. In this study， main contents of the present publicly available reservoir and dam data sets were introduced， data sources of reservoir and dam information and the production procedures were summarized， and basic georeferenced attributes were compared amongst different data sets including location， classification， boundary， etc. More importantly， the spatial distribution characteristics and statistical differences of each data set in China are compared comprehensively. Problems such as timeliness of data set， repeated definition of reservoir and lake， and difference of reservoir area are also explored. Moreover， urgent and important research issues related to such data are reviewed， such as flood control， power generation and irrigation benefit of reservoirs， hydrological， carbon and interception effects of reservoirs and dams， and river habitat fragmentation， etc. Finally， the future production and application of dam and reservoir data sets are discussed. It is found that present data sets contain more large reservoirs and less mall reservoirs， and large reservoirs have comprehensive attributes， while small reservoirs have insufficient attributes. There are also many other differences between different data sets. In the future， it is necessary to further improve the data records of reservoirs and dams and coordinate the differences of data sets to achieve complete simulation of reservoirs and dams.

Under the background of climate change， the trend-caused nonstationarity of the hydrometeorological series in Huaihe River Basin are bound to impose a potential impact on the multivariable flood risk. Based on the LR-AIC criteria， this paper constructs a joint distribution model with dynamic Copula function as the core， takes the flood peak and flood volume series of Bengbu Hydrological Station in the Huaihe River Basin as the research object， and incorporates the urbanization factors and climate change factors related to the flood peak and flood volume series as covariates into the parameter structure of time-varying marginal distribution model and Copula model. The analytic results show that the proposed LR-AIC criteria for nonstationary detection can better capture the nonmonotonicity of extreme value series and the reverse trend of parameters than the nonparametric trend detection method. Due to the time-varying characteristics of maginal distribution parameters， the quantile pairs of peak flood volume at the level of 50-year joint return period show certain time-varying characteristics： ① From 1960 to 1970， the design values of the peak flood volume showed an increasing trend； ② From 1970 to 1990， it showed a downward trend； ③ From 1990 to 2010， it showed a gradually increasing trend. Only considering climate change or urbanization factors will lead to overestimation or underestimation of the design quantile of flood peak flood volume to a certain extent. Compared with urbanization factors， climate change factors are the dominant factors affecting flood univariate and multivariable risks in the sub-watershed controlled by Bengbu Hydrological Station. The nonstationary frequency analysis idea based on the dynamic Copula model is conducive to quantitatively isolating the impact of climate change factors and human activity factors （urbanization） on flood multivariate risk.

Water is the vital factor constraining the sustainable development in arid area. To alleviate water shortage due to increasing socioeconomic water demand in arid area， Yizhou District in Hami is taken as a case study to evaluate the balance between water demand and supply in the future. Water demand in 2021， 2030， and 2040 are selected as baseline， short-term planning， and long-term planning years， respectively， based on which rational water resources allocation is conducted. Results indicate that water demand in Yizhou District will increase remarkably due to rapid socioeconomic expansion， from 375.02 million m³ in 2021， to 397.17 and 487.56 million m³ in 2030 and 2040， respectively. Water resources allocation can effectively alleviate the water shortage led by the uneven temporal-spatial distribution of water availability. Water supply for socioeconomic users is thus ensured （the total water shortage rate in 2021 and 2030 are 2.78% and 4.2%， respectively）， which is of significance for the local sustainability. However， as the over-increased water demand will exceed the regulating capacity of local water system in 2040， the total water shortage rate will considerably increase to 15.56%， among which the shortage rates of ecological， industrial， and agricultural users will be 8.37%， 9.98%， and 22.15%， respectively. The stability of the local ecosystem， and economy will be altered， which will further challenge the sustainable development goals of Yizhou District. This paper cannot only help the rational water resources allocation and water use structure improving in Yizhou District， but also contribute to the water resources management in arid areas.

The evaluation and decision of multi-objective operation scheme have always been one of the research focuses in the field of reservoir operation. There are some problems in the evaluation of existing eco-friendly reservoir operation schemes， such as few ecological indicators， and the subjectivity of the evaluator’s cognition is difficult to express accurately， which affects the reasonable evaluation and decision-making of eco-friendly reservoir operation schemes. Taking Jiayan Water Control Project in Guizhou Province as an example， this paper constructs an evaluation index system of eco-friendly dispatching scheme from the four dimensions （i.e. criteria） of urban water supply， irrigation， power generation and ecology conservation， and adopts the hydrological alteration indicators based on monthly （or ten-day） flow data to quantify the ecological impact of reservoir dispatching. These indicators involve the magnitude of monthly（or ten day）water conditions， the uneven coefficient of annual runoff， the magnitude and the timing of annual extreme （i.e. maximum and minimum ）water conditions. For the imprecision of criteria attribute values and the difficulty in determining the weights of criteria attribute， a multi-attribute evaluation method （HPR-MAEM） coupling hesitant fuzzy set， prospect theory and rough set theory is proposed. The indicators under each criterion are weighted by using the following four methods， namely， dualistic factor contrast， variation coefficient， entropy and CRITIC methods. The obtained attribute values of each criterion form a hesitant fuzzy number. Then， the prospect value function is used to calculate the loss and the gain of the attribute values of each scheme’s criterion deviating from the positive and the negative ideal attribute values， as well as the comprehensive prospect value. The weight of the criterion attribute is calculated through the attribute reduction of rough set. Finally， the weighted comprehensive prospect value of each scheme is calculated to rank the schemes. To further verify the rationality and effectiveness of the proposed method， the ranking result of HPR-MAEM is compared with those of traditional TOPSIS method， variation coefficient method， entropy weight method and CRITIC method. The evaluation results of 10 long-term operation schemes of Jiayan Water Control Project show that the hydrological alteration index based on monthly （or ten-day） flow data can comprehensively reflect the ecological effect of reservoir operation， HPR-MAEM method can reasonably consider the impact of different weighting methods and the limited rationality of decision-makers on the evaluation results， and the four dimensions of urban water supply， irrigation， power generation and ecology conservation of the recommended operation scheme are more balanced.

Precipitation is the basic component of the earth water cycle. As a water flux， it connects the atmospheric process with the surface process， and has important significance in meteorology， climatology and hydrology. Due to the strong temporal and spatial variability of precipitation， it is one of the most difficult hydrological variables to measure accurately at present. Accurate precipitation data with high temporal and spatial resolution is very important for many applications such as hydrological and meteorological analysis. This paper takes Hanjiang River Basin as the research area and puts forward a two-step downscaling-merging method. By using the complementary characteristics of data availability and accuracy of precipitation observed by rainfall gauges and retrieved by satellites， a high-quality daily precipitation product with a spatial resolution of 0.01 can be generated by fusing gauge observations and GPM satellite precipitation products. The obtained fused precipitation product is driven by semi-distributed hydrological model WASMOD-D to simulate the rainfall-runoff process， and its runoff simulation effect is verified. The results show that： ① The downscaling algorithm based on random forest model not only significantly improves the spatial resolution of GPM precipitation， but also maintains good accuracy. ②The linear fusion model of precipitation data based on the co-Kriging method， the fusion scheme greatly improves the estimation accuracy of GPM precipitation， with the average absolute error and root mean square error reduced by 32.38% and 21.38% respectively， and the bias dropped below 1%； ③ Considering the simulation results of daily runoff under two different scenarios， the overall simulation effect of integrating precipitation data is the best because of combining the advantages of satellite precipitation data and gauge observations， and the overall improvement effect is obvious. This paper provides a new idea for the data fusion method based on Satellite-Gauge（S-G），and the research results can be used as a reference for obtaining high-resolution and high-precision precipitation data.

Monthly precipitation prediction is crucial for water resources allocation， planning and management. However， the prediction is influenced by various factors， thus it is extreamly difficult and uncertain. To investigate the performance of monthly precipitation predictions based on climate models in China and the influence of bias correction methods， this paper selects China’s mainland as the research area， adopts 1981 to 2014 as the research period， and evaluates the predictive capability of nine climate models （CFSv2， SEAS5， CanSips， GEMNEMO， CCSM4， GFDL， CanCM3， CanCM4， GEOSS2S） for monthly precipitation prediction in different forecasting periods. Clustering analysis is adopted to analyze the patterns of prediction ability of climate models with forecasting period. The linear scaling （LS） and quantile mapping （QM） bias correction methods are used for the post-processing of the predicted precipitation， and the effects of the two methods are compared in validation （2008 to 2014）. The results show that the accuracy of precipitation prediction varies among climate models， and the capability to summer precipitation prediction depends on the forecasting periods and forecast regions. The SEAS5 climate model performs optimal in different regions and forecasting periods， and its forecasting capability stabilized with the extension of forecasting period. In terms of bias correction， the bias correction methods can significantly improve the prediction ability of precipitation for all of the climate models and the two methods exhibited similar performs， however， the mean absolute relative error of LS method is less than 50%， which indicates that the LS method is generally slightly outperforms QM method. In addition， the SEAS5 climate model still performs best after bias corrections. This paper reveals the superiority of the SEAS5 climate model for monthly precipitation prediction in China’s mainland and the enhancement of the prediction capability of climate models by the bias correction methods. This study provides a reference for the application of precipitation predictions based on climate models.

Taking the Ningxia Yinchuan metropolitan area urban-rural east water supply project and its water supply range as the research object， this paper establishes a multi-objective mathematical optimal allocation model of water resources， economy and environment and solves the multi-objective problem by the non-dominated sorting genetic algorithm-II（NSGA-II）. The hypervolume （HV） index is used to evaluate the convergence and distribution of the Pareto solution set obtained at different iterations. Considering the computing time， convergence and distribution， the Pareto solution set obtained at 700 iterations is determined as the basis for subsequent data analysis and calculation. By calculating the fuzzy membership degree of each target value in the scheme set and analyzing the pairwise relationship between each target， it is found that there is a negative correlation between water resources objectives and economic objectives， as well as economic objectives and environmental objectives， and a positive correlation between water resources objectives and environmental objectives. Then， the weight of each objective is determined as （0.48， 0.32， 0.2） by using the method of two elements contrasting. The multi-objective fuzzy optimization model is used to screen the Pareto solution set， and the scheme with the largest superior genus degree （u_i =0.757） is determined as the optimal scheme. Under the optimal scheme， the groundwater consumption is 9 932.9 thousand m³， the surface water consumption is 64 569.0 thousand m³， the economic target is 40.745 billion yuan， and the environmental target is 1 040.9 thousand kg. This scheme can realize the optimal allocation of water resources and provide a reference for regional decision makers in water resources allocation.

The Yalong River Basin is the third largest hydropower base in China. Accurately simulating the future climate change in the Yalong River Basin can provide a scientific basis for the rational and efficient development of water resources in the basin. In order to evaluate and simulate the future climate change in the basin under different scenarios， this paper uses the data of 13 meteorological stations in the Yalong River Basin from 1970 to 2005， it adopts the MIROC climate model data in the Coupled Model Intercomparison Project phase 5 （CMIP5） and it passes through the Statistical DownScaling Model （SDSM） downscales low-resolution raster data to measured site data. In this paper， the coefficient correction method and the frequency matching method are used to couple and correct the deviation and frequency distribution of daily precipitation. In this paper， the coefficient correction method and the frequency matching method are used to couple the correction of the deviation and frequency distribution of daily precipitation. Finally， the corrected data is used to analyze the future climate change in the Yalong River Basin. The results show that ① After the correction， the certainty coefficient of daily-scale precipitation is improved from 0.12 to 0.2； ② the future temperature and precipitation in the Yalong River basin show an overall increasing trend； ③ Under the three emission scenarios of three different representative concentration pathways （RCP2.6， RCP4.5， RCP8.5）， the future maximum air temperature in the Yalong River Basin will increase by 0.71， 1.16， and 1.35 ℃， respectively. The increase in December is more obvious； the future minimum temperature will increase by 0.72， 0.83 and 1.08 ℃ respectively， and the increase will be more obvious in August， September and December. ④Under the three emission scenarios for the future period 2022-2100， the future precipitation in the Yalong River Basin will show an increasing trend， and the average daily precipitation will increase by 117.6%， 131.7%， 124.2%； the largest increase in RCP4.5 precipitation in spring， and the stronger the radiation forcing in summer， the more obvious the increase in precipitation in Yalong River Basin. The increase in temperature and precipitation in the Yalong River basin in the future will increase the frequency of extreme weather events. In the future， the uneven distribution of water resources will be further aggravated， and natural disasters such as drought and flood caused by climate warming will have adverse effects on the construction and operation of hydropower stations. The analytic results can provide a scientific basis for the water resources development of Yalong River hydropower base.

This paper takes Hongze Lake in the lower reaches of Huaihe River system as the research object and divides the flood season into different stages，the method of rainfall time-area-depth analysis and calculation is adopted and it is based on the daily rainfall data of more than 1 000 rainfall stations with continuous records and uniform distribution since 1990， according to the flood season division standard of the Ministry of Water Resources， the calculation period is selected as 3 d， and the cumulative rainfall standard is 30/50 mm， this paper adopts the index of the dynamic change of 3 d cumulative rainfall coverage area of the Huai River and analyzes the date of the flood season and the main flood season. As a large plain lake located in the lower reaches of the Huai River system， Hongze Lake receives water from the upper and middle reaches of the Huai River. In this paper， the runoff data of seven stations entering Hongze Lake from 1990 to 2019 （a total of 30 years） are synthesized， and the daily synthetic flow is calculated by fractal analysis and change-point analysis， flood season and main flood season of Hongze Lake are obtained by comprehensive analysis. The flood season of Huaihe River system is from May 23 to September 17 according to time-area-depth analysis of rainfall， among which the main flood season is from June 26 to August 28. The flood season of Hongze Lake is from May 25 to September 30 according to Fractal analysis method， among which the main flood season is from June 20 to August 20； the flood season of Hongze Lake is from May 1 to September 28 according to change point analysis， among which the main flood season is from June 19 to August 28. The results are comprehensively analyzed and can be used to provide a basis for the classification of Hongze Lake in flood seasons and the setting and dispatching of control water level in flood seasons.

The source area of Yangtze River （SAYAR） and the source area of the Yellow River （SAYER） are located in the hinterland of the Qinghai-Tibet Plateau， which are sensitive areas for global climate change. Different runoff components in these regions are strongly affected by climate change， and changes in runoff components， especially high flow， may cause a series of impacts on the ecology and human production activities. To investigate the characteristics and the reasons of different runoff components for their changes， relevant studies are conducted based on multi-year runoff and meteorological data of SAYAR and SAYER with the methods such as flow duration curve （FDC）， Mann-Kendall （M-K） method and multiple linear regression. The results show that： ①The high flow （Q ₁₀ ~Q ₃₀）， medium flow （Q ₄₀ ~Q ₆₀） and low flow （Q ₇₀ ~Q ₉₀） in SAYAR increases at the rates of 4.68， 2.18 and 0.38 m³/（s·a）， respectively， during 1964-2021； the high flow and total discharge in SAYER had the same trend during 1962-2021， decreasing at the rate of 1.99 and 0.16 m³/（s·a） respectively， but the medium flow and low flow increased at rates of 0.12 and 0.68 m³/（s·a）， respectively. ② During the period from 1979 to 2018， the increase in precipitation was the main reason for the increase in high flow and medium flow in SAYAR， and its contribution rate to the change of high flow and medium flow was 92.93% and 71.17%， respectively. The temperature rise was the main reason for the increase in low flow in SAYAR， and its contribution rate to the change of low flow was 77.72%. ③ During the period from 1979 to 2018， the increase in temperature was the main reason for the reduction of high flow and medium flow in SAYER， and its contribution to the change of high flow and medium flow was -58.79% and -53.98%， respectively. The increase in precipitation was the main reason for the increase of low flow in SAYER， and its contribution rate to the low flow was 67.11%.This paper may provide some reference for water resources management and ecological environment protection in the source regions of the Yangtze River and the Yellow River under the background of climate change.

The existing reservoir flood control safety design is largely governed by a single variable， disregarding the correlation between factors and failing to accurately reflect the true nature of flood events. In this study， the combined distribution of the annual maximum flood peak and volume is constructed by using the two-dimensional Copula function. To magnify the typical flood hydrograph， various groups of peak and volume combinations were chosen using the two variable return period as the flood control standard. The reservoir flood routing was used to obtain a series of design water levels， and it is this series’ variation range that is then determined. In order to research how various design return times affect the reservoir’s design value， this paper studies the reservoir safety design based on flood control return periods. Four traditional return periods （Joint return period， concurrent return period， Kendall return period and survival Kendall return period） commonly used at present are compared and analyzed. Taking Yangxi Reservoir located in Duliujiang reach of Liujiang River basin as an example， this paper calculates design water level of the five return period standards， and discusses the rationality， reliability， and advantages of flood control return period in reservoir flood control safety design. The results show that the risk region of flood control return period at any return period level is definite and unique. There is a coupling relationship between the contour shape of flood control return period and flood discharge interface. The design water levels under different return period standards vary greatly， and basically meet the rule of {\mathit{T}}_{\mathit{O}\mathit{R}} > {\mathit{T}}_{\mathit{F}} > {\mathit{T}}_{\mathit{K}\mathit{D}} > {\mathit{T}}_{\mathit{S}\mathit{K}} > {\mathit{T}}_{\mathit{A}\mathit{N}\mathit{D}}. The flood control capacity corresponding to the flood control design parameters under the flood control return period corresponds to the project flood control standard， which can reduce the project cost， effectively resist the flood risk， and ensure the safety of the project.

In order to explore the effect of vegetation on the hydraulic characteristics of naturally curved rivers， this paper designs two layout forms of uniform and cluster to simulate artificial regular planting and natural cluster vegetation groups respectively. Through continuous bending flume experiment， the paper comparatively analyzes the influence of different layouts on flow field， hydrodynamic axis and turbulent kinetic energy distribution. The results show that： ①There are obvious velocity zones in the flow field of the continuous curved channel ： the high velocity zone is close to the convex bank， and the low velocity zone is distributed near the concave bank. Compared with the surface flow， the distribution range of the high velocity zone of the bottom flow is expanded， and the low velocity zone is reduced. The distribution range of high velocity area increases and that of low velocity area decreases greatly after vegetation distribution， and the influence of cluster layout is obviously greater than that of uniform layout. ②The hydrodynamic axis of the continuous curved channel flow deviates from the normal position， which shows the dynamic change process of closing to the convex bank firstly and then leaving the convex bank. Vegetation layout greatly delays the process， and the delay degree of cluster layout is greater than that of uniform layout. ③The turbulent kinetic energy distribution along the continuous curved channel flow is uneven， and the maximum value appears near the top of the bend. From the numerical changes of turbulent kinetic energy， it can be seen that the vegetation layout makes the turbulent kinetic energy of the water flow generally increase， and the influence of cluster layout is greater than that of uniform layout.

Urban waterlogging threatens people’s life and property safety seriously. A scientific assessment of urban waterlogging risk and corresponding measures are effective ways to reduce waterlogging losses. In this paper， taking a certain area of Changzhou City as a research case， MIKE FLOOD model is used to carry out drainage capacity analysis of rainwater pipes and urban flood simulation， and quantitatively analyze the drainage capacity of rainwater system facilities through waterlogging scenario simulation. Combining scenario simulation method with index evaluation method， the index system of waterlogging risk assessment based on “Risk， vulnerability and exposure” is used to assess urban waterlogging risks. The waterlogging risk assessment system is mainly divided into the target layer， the criterion layer and the index layer. The main indicators include the depth of standing water， the length of standing water， the drainage capacity of the pipe network， the ground elevation of the site， the regional importance and the intensity of development and construction. According to the evaluation results， this paper focuses on the implementation of risk management for key issues in the flood control system. It is suggested that the systematic problems should be solved by optimizing the drainage scheme. Flexible adjustment shall be carried out for waterfront waterlogging prone depressions to avoid risks. Aiming at the problem of urban construction mode， the mode of combining green and gray facilities is implemented. This paper puts forward management measures such as adjustment of drainage scheme， risk avoidance and risk response， so as to provide scientific support for improving the urban waterlogging risk system. The results show that： ① Multi-factor analysis is used to evaluate the impact of waterlogging disaster， which makes the evaluation results more comprehensive and can provide a reliable basis for waterlogging management. ② The adjustment of waterlogging prevention in the southern part of the city from “completely self-draining” to “low water level based on self-draining， high water level flexible pumping” can reduce the water level of inland rivers， reduce the jacking effect on pipelines， and effectively reduce the risk of water logging in the area. ③ The riverside depression risk area should give priority to the layout of hydrophilic land or facilities. For other types of land that really need to be built， the vertical elevation should not be less than 3.9 m. ④In the process of urban development and construction， we need to pay more attention to the risk response of the combination of green and gray facilities. Headwaters sponge facilities need to be built to cut stormwater runoff. Public sponge facilities need to be built to play a role in storage and reduce the risk of waterlogging.

Lakes are important territorial resources and have many functions such as regulating runoff， multiplying aquatic organisms and maintaining the regional ecological environment. They are also an important source of water for agricultural irrigation， industry and domestic use. With the rapid socio-economic development of the Taihu Lake Basin， and the acceleration of urbanization and industrialization， the lake morphology in the region has undergone significant changes. Based on multi-source remote sensing images， the research uses the regional growth method combined with the artificial visual interpretation method to interactively extract lake water information. Through the three main indicators of area change rate， lake landscape shape index （LSI） and lake centroid offset， this paper analyzes the temporal and spatial evolution laws and the causes of Taihu Lake， Gehu Lake and Changdang Lake from 1960s to 2020s. The results show that through a comparative analysis of SuperView-1 and Landsat8 image data during the same period， the errors of the extraction area of three typical lakes are 0.1%， 0.3% and 0.3% respectively. When remote sensing data of different spatial resolutions is used to extract water area， they have little effect on the extraction area of large water bodies such as lakes. The area of the three typical lakes shows the characteristics of decreasing- increasing-decreasing-increasing wave-like undulations. Among them， the lakes shrank the most seriously during the period from 1960s to 1980s， The shrinkage rates of Taihu Lake， Gehu Lake and Changdang Lake are 5.44%， 26.11% and 25.84% respectively. The three typical lake landscape indexes （LSI） show an overall trend of decreasing and then increasing. The evolution characteristics of different lakes have obvious spatial differences. The decrease in lake area is mainly affected by human activities such as polder farming， reclaiming farmland and building construction. An analysis of the reasons for the evolution of three typical lakes can provide a basis for the study of lake protection and the driving force mechanism of evolution in the Taihu Lake Basin.

By taking cascade reservoirs on the middle Jinsha River as the research object and taking advantage of the fact that many aquatic organisms have high demands on flow and water level， this paper puts forward a method to meet the target ecological demands. A ecological connected water level is set at the ecological control section below the dam. A linkage response mechanism between ecological connected water level and ecological flow is formed by using the partially connected relationship between two adjacent reservoirs. The objective of this method is that the water level of the ecological control section meets the ecological connected water level. Through the joint regulation of adjacent cascades reservoirs， the control of ecological flow can be changed from a fixed value to a dynamic adjustment. Based on the Jinsha River fish spawning characteristics and demand for aquatic habitat， In this paper， main fish distributed in the tail of each reservoir are selected as target fish. The water depth， velocity and water temperature required for their survival and reproduction are the target ecological requirements. According to the water depth conditions required by the target fish during spawning period， a suitable inundation depth index and a ecological connected water level index are constructed at the tail stream reaches. Taking the two typical cases of the maximum length of the fish spawning reach and the nearest distance between suitable areas under the dam， the river length， starting and the ending points satisfying the suitable inundation depth are calculated. In addition， combined with the spawning velocity and water temperature requirements， ecological scheduling simulation is carried out， and the most suitable time for ecological scheduling is determined as late June， which can better play the ecological benefits of the cascade reservoirs. At last， the feasibility of flexible application of the method in different positions between adjacent cascades is demonstrated.

The Henan section of the Yellow River is predominantly a wandering river section， which has a severe impact on the river habitat due to its violent water-sediment changes， frequent main channel oscillations and severe riverbed deformation. This paper uses Landsat satellite images and the MNDVI water body index to extract the river boundary information of 30 a water bodies in the wandering section of the Yellow River. By dividing different river sections and regions and calculating the main channel morphological parameters， river oscillation area， oscillation direction， migration distance and other indicators in different periods， the changing characteristics of river oscillation in the wandering section are analyzed. The results show that： the main channel water area of the wandering section is obviously reduced and transformed to a curved river； the R2 area is the area with the largest oscillation area and the largest average oscillation area； the total area of oscillation to the left bank of the wandering section from 1986 to 2019 is 59.9 km²， and the total area of oscillation to the right bank is 53.3 km²， the area of oscillation to the left bank and right bank of the R1 and R4 sections is approximately equal， the R2 section mainly oscillates to the left bank R1 and R4 sections oscillate to the left bank and right bank in roughly equal areas， R2 section oscillates mainly to the left bank， R3 section oscillates mainly to the right bank and the wandering section as a whole has a slight tendency to oscillate to the left bank； R1 area as a whole migrates slightly to the south， R2 area as a whole migrates significantly to the north， R3 area as a whole migrates to the south and R4 area as a whole migrates slightly to the west. After the operation of Xiaolangdi Reservoir， the amount of water entering the wandering section is basically the same as before the reservoir operation， while the sediment is mainly transported during the flood season； the change of the main channel of the wandering section is related to the scouring of the beach bank soil by the water and the collapse after the flood； the control and guide project has an obvious restraining effect on the river， and some sections S11 and S12 in the R3 area lack the control and guide project， and the main channel of the river wavers sharply.

Vegetation is an important part of the river ecosystem， which plays an important role in river ecological restoration， river morphology evolution and sustainable utilization of water resources. However， the existence of aquatic vegetation will also change the flow pattern and reduce the flow velocity. Flexible vegetation present certain oscillation and deformation under the action of water flow， which makes the water movement more complicated. In this paper， the deformation of the flexible vegetation is considered in the classical Darcy-Weisbach equation， and the vegetation properties that affect the resistance coefficient are analyzed. The maximum difference algorithm is used to screen and classify the experimental data， and then the genetic algorithm is used to determine the expression of the resistance coefficient of the submerged flexible vegetation. At the same time， the formula of Manning coefficient is derived by the relationship between the Darcy-Weisbach coefficient and the Manning coefficient.The results show that the friction formulae of Darcy-Weisbach and Manning have relatively concise expressions and can be applied to the calculation of the resistance coefficient of submerged flexible vegetation under different water depths， different vegetation densities and different vegetation heights. The research results can provide a theoretical basis for the design of vegetated ecological channel.

The study on the mechanism of the channel avulsion in the tail reach of the Yellow River Estuary （YRE） involves issues such as characteristics of flow and outflow， water and sediment volume， and river bed boundary conditions. On the basis of proving the recent swing characteristics of the river channel in the tail reach of the YRE， this paper reveals the mechanism of the channel avulsion in the tail reach of the YRE and the temporal and spatial changes of the river bed boundary conditions， and analyzes their impact on the outflow of the river based on the measured topographic data. The results show that， the coefficient of fluvial facies is the critical influencing factor to determine the avulsion position of the river channel in the tail reach of the YRE. The variation characteristics of the horizontal gradient of the floodplain and the change of the position of the deep river line determine the swing direction of the river channel.

Lakes are important water resources for many aspects of people’s life and production and socio-economic development in northwest China， and the dynamic changes of lake systems will lead to a series of ecological and environmental problems， but less attention has been paid to the problem of lake changes in arid areas. In this paper， remote sensing and GIS techniques， spatial analysis， continuous wavelet analysis and principal component analysis are used to explore the dynamic changes of typical lakes in Yinchuan Plain over the past 30 years and to reveal the influence of key factors such as meteorological factors， human activities and Yellow River irrigation on the evolution of lakes， taking Yinchuan Plains， a water scarce area， as the study area in northwestern China. The results show that the lake area of Yinchuan Plains showed an obvious decreasing trend from 1990 to 2020， and the lake area decreased from 92 to 81 km². The number of lakes in Yinchuan Plain was drastically reduced due to the water system connection project and the large-scale merging of small lakes， but the number of lakes only helped to indicate the dynamic changes of lakes in Yinchuan Plains， and the decreasing trend of lake area and number indicate that the Yinchuan Plain of lake hydrology and ecological functions are facing threats. The statistical analysis shows that the average temperature and annual rainfall from 1990 to 2020 showed a slight increasing trend， while the water extraction and consumption by urban residents， the total amount of Yellow River diversion and the total amount of Yellow River discharge show a gradually decreasing trend， which has some influence on the dynamic change of lake areas in Yinchuan Plains. The attribution analysis shows that the meteorological factors， i.e.， temperature and precipitation， have less influence on the dynamic change of lake areas in Yinchuan Plains， and the amount of Yellow River irrigation is the main factor leading to the decrease in lake area in Yinchuan Plains. This paper can provide a scientific basis for the utilization of water resources in the lakes of Yinchuan Plains， ecological protection of the arid areas and effective development of urban economy.

Revealing the transverse distribution characteristics of sediment-laden flow and sediment factors can provide a theoretical basis for utilization of lower Yellow River beach area and river management. By means of experimental simulation and theoretical research， the generalized model test of floodplain flood evolution is carried out， and the transverse distribution characteristics of sediment factors of sediment-laden flow in curved compound channel under the condition of beach vegetation are analyzed. Meanwhile， the theoretical model of transverse distribution of velocity and sediment concentration based on the momentum equation considering the inertial force of the lateral secondary flow and river curvature is verified. The results show that： ①The slowing effect of beach vegetation on the flow velocity is significant； ② The arrangement of full vegetation on the beach has a uniform effect on the velocity distribution of the beach， which can reduce the phenomenon of excessive velocity at the foot of the beach and increase the velocity effect in the main channel； ③ Through five numerical examples， the lateral velocity distribution model of a curved compound channel with beach vegetation is tested and， in general， the analysis model is consistent with the experimental results.

A branched river exists widely as an important river form. When the river channel is wide， the cross section of the river channel is likely to form a compound section. In the evolution of the whole river morphology with the central bar， the flow movement often plays an extremely important role in the diversion section of the head of central bar. The distributary action of central bar superimposed on the interaction of compound cross-section floodplains and main channel will jointly affect the distributary and sediment separation， and ultimately affect the evolution of the whole channel morphology. In order to explore the characteristics of the flow motion of the head of central bar on the evolution of the compound braided channel， an experiment of a straight compound braided channel eroded by clear water is designed in this paper. The test results show that， ① the vertical velocity distribution basically meets the logarithmic distribution in the compound section in front of the central bar in the straight compound braided channel； ② the flow velocity of the compound braided river is mainly affected by the braided morphology； ③ the shape of compound cross section is the main influencing factor of the flow velocity change in the main channel and floodland at the bifurcation； ④ in the realignment and protection of compound braided channel， we should pay more attention to the scouring at the head of the central bar and both sides and the siltation and scouring caused by the difference of flow velocity between the two branches； ⑤ When the discharge increases to a certain value， the section shape of compound braided channel can be simplified to a simple rectangular channel for research.

Dean vortex and spiral flow are a common turbulent vortex structure in the pipeline. Although the two types of vortex have similar functions such as heat and mass transfer， the Dean vortex is prone to cause pipeline system oscillation， which is a great threat to the safety of pressurized water pipeline system. In this paper， the bend pipe system with pipe diameter D=50 mm and radius of curvature 2.8 D is established by the previous physical model test， and the mathematical model is verified based on the test data. The model pipe section is designed with 27 combinations of guide sheets to form spiral flow， and the multi-scale vortex structure in the pipe is simulated， the flow velocity， pressure and turbulent energy distribution of the vortex in the bend and outlet straight pipe are mainly analyzed. The simulation results show that the pipeline system is affected by the turbulent energy of the vortex and the intensity of the turbulence to varying degrees， the bent pipe system has a higher water transfer capacity under conditions of higher turbulent kinetic energy and lower turbulent intensity. Spiral flow strength has a significant impact on the water transfer efficiency of the bend and the safety of the pipeline system. When the pipe inlet flow velocity V=1.5 m/s， the water transmission efficiency of curved pipe system is increased by 10.62% and the probability of pipeline accident is reduced by 24.41% under the action of guide sheet （number N=8， height H=15 mm， deflection angle {\theta }^{\mathrm{*}}=60°）. The research results can provide a technical guidance for the long-distance spiral flow conveying theory and pressurized pipeline system optimization.

Stomatal conductance is an important indicator of plant transpiration， and accurate quantification of stomatal conductance is significant for the study of the surface hydrological cycle. To improve the accuracy of stomatal conductance simulations， this paper uses two machine learning models， CatBoost （CAT） and Artificial Neural Network （ANN）， and a dataset consisting of Pinus edulis and Juniperus monosperma， to simulate stomatal conductance， and the simulation results are compared with the Ball-Berry model and Medlyn model. The input variables of net photosynthetic rate （A_n ）， leaf surface carbon dioxide concentration （C_s ）， relative humidity （RH）， saturated vapor pressure difference （VPD）， leaf temperature （TL）， and predawn leaf water potential （LWP） are designed as three modeling strategies in machine learning models. The input variables in strategy ①are An， C_{s ，} and RH； in Strategy ②are A_n， C_s， and VPD； in Strategy ③are A_n， C_s， RH， VPD， TL， and LWP. The results show that ① Ball-Berry model and Medlyn model have similar simulation effects， with RMSE of 0.013 8 and 0.013 9 mol/（m²·s）， respectively. ② Compared with the Ball-Berry model and Medlyn model， the RMSE of the CAT model and ANN model under different input strategies decrease by 19.35%~45.65% and 26.90%~55.07%， respectively. ③ In the machine learning models， the simulation effect of strategy ③ is better than strategy ① and ②， and ANN is better than CAT. In strategy ③， the RMSE of the ANN model is 36.70% and 38.54% higher than that of strategy ① and ②， respectively.④ Stomatal conductance simulations for the entire dataset consisting of both plants under each model and strategy are consistent with the simulated patterns of stomatal conductance for Pinus edulis and Juniperus monosperma， respectively， with better results for Pinus edulis and then for Juniperus monosperma. These results indicate that the machine learning model （ANN model in particular） is more suitable for accurate simulation of the stomatal conductance of plants， and can provide a practical tool for estimating plant transpiration capacity and simulating agricultural hydrology.

Water loss has an important impact on the efficiency of water transfer projects and is a key parameter in the formulation of scheduling plans， accurate prediction of water loss is of great significance for formulating refined water transfer plans and optimizing scheduling operations. Aiming at the existing problems of water loss prediction methods， this paper proposes a water transmission loss prediction method with high calculation accuracy， high construction efficiency and wide application scope： the correlation analysis method and principal component analysis method are used to screen the influencing factors of water loss， and the indicators reflecting the duplication of information are deleted through the correlation analysis， and the indicators with high importance are screened out by the principal component analysis； based on the filtered index system， a water transmission loss prediction model based on the improved particle swarm optimization extreme learning machine is constructed. The Liangji Canal section of the eastern line of the South-to-North Water Diversion Project is taken as an example. After screening， water depth， flow rate， air temperature and wind speed are the main influencing factors， and an IPSO-ELM water loss prediction model is established by using the predictive model trained and validated by the measured data， the daily water loss prediction is made on the data in different scenarios， and the prediction results of extreme learning machine model and the multivariate nonlinear regression model are compared and analyzed， respectively. The results show that the water loss and actual water loss calculated by the IPSO-ELM water transmission loss prediction model are very close， and the determination coefficient is 0.962 5， and the average absolute percentage error is 1.322%， which is 52.89% and 51.06% lower than the MNR model and the ELM model， respectively. The prediction error is mainly distributed within ［-25， 30］ thousand m3， and the error distribution range is smaller than the other two models. That is， the prediction accuracy and generalization ability of the IPSO-ELM model are better than the other two models， which proves that the method is reasonable and feasible， which can be used to calculate the water transmission loss in different water transfer scenarios and provide more accurate water quantity information for water resource dispatch.

By exploring the effect of altitude change on soil organic matter and nutrients after the conversion of paddy field to dry land in Hani terrace， the objective of grading evaluation of soil fertility in this region is achieved， so as to provide a scientific basis for the nutrient management， and balanced fertilization in Hani terrace. Based on five maize plots converted from paddy fields， the paddy field and ridge soil with the same soil type near each dry land， the study explores the soil organic matter and nutrients by using correlation analysis and TOPSIS integrated fertility index method to quantify the soil fertility in different altitudes areas. Results show： ① the soil organic matter， total nitrogen and available phosphorus in the study area are at a medium level， the alkali hydrolysable nitrogen is at a very rich level， and the available potassium is deficient； ② there are significant differences between paddy field and dry land， ridge， and no significant differences between dry land and ridge. After the paddy field is changed into dry land， the contents of soil organic matter， total nitrogen and soil alkali hydrolysable nitrogen decrease， while the contents of available phosphorus and available potassium increase significantly， with an average increase of 38.55 and 66.61mg/kg. There is a significant correlation between altitude and soil nutrient content； ③ with the increase in altitude， the contents of soil organic matter， total nitrogen and alkali hydrolysable nitrogen are generally increased， with an increase range of 26.85~34.81%. The contents of available phosphorus and available potassium first increase and then decrease， the highest value is at altitude of 1 729 and 1 783 m， respectively， and the lowest value is at 1 829 m altitude. Collectively， the soil fertility of Hani terraces increases with altitude， and soil fertility of paddy fields is higher than that of dry land and ridges. This study can provide a reference for the sustainable development and protection of terraced fields in Southwest China.

The horizontal displacement of the pump station buildings is an important monitoring item in the long-term operation of the pump station， and it is also an important index reflecting the operation status of pump stations. The fixed regression parameters of the traditional statistical model cannot describe the dynamic characteristics of the deformation behavior for the pump station structures. In view of that， this paper constructs a dynamic monitoring model of horizontal displacement for pump station based on forgetting factor recursive least square （FFRLS） method. By introducing forgetting factor， the correction ability of the new monitoring data to the model is enhanced and the parameters of statistical model are got dynamically to improve prediction accuracy. Then the validity of the proposed model is verified through a case study of a pump station project of South-to-North Water Diversion Project. The results show that the model can update the parameters of the statistical model adaptively with the addition of new data， and the regression and prediction accuracies of the statistical model are effectively promoted， which provides a new method to master the operation status of pump station buildings.

Improving the green efficiency of agricultural water use under environmental constraints is important for alleviating the contradiction between water supply and demand and achieving high-quality agricultural development. Based on the global reference non-expected output SBM model to measure the green efficiency of agricultural water use （ G E A W） in China， the Dagum Gini coefficient was used to explore the source of regional differences， the Markov matrix was used to analyze the spatial and temporal evolution of G E A W， and its convergence was tested by regression models. The research results show that the G E A W in China and each region shows a fluctuating upward trend， with the highest efficiency level in the eastern region and the lowest in the western region； the contribution of inter-regional differences gradually rises to the main contribution； there is a “club convergence” and “Matthew effect” in the green efficiency of agricultural water use. There is a “club convergence” and “Matthew effect” in agricultural water use green efficiency， which is influenced by the efficiency of “neighbors” and their own efficiency levels. Except for the central region， there is convergence in G E A W in the whole country and other three regions， and except for the northeast region， there is absolute convergence and conditional convergence in G E A W in the whole country and other three regions. Accordingly， it is proposed to promote agricultural water conservation technology， increase inter-regional collaboration， and give play to the role of the market to improve the overall green efficiency of agricultural water use.

With global resources and environmental problems becoming more and more prominent， soil salinization has received widespread attention， and about 8% of the world’s land is threatened by salinization. China is a country where soil salinization is relatively serious， and the saline soil area accounts for 1/10 of the global saline soil area， and in recent years， under the influence of natural and human factors and other conditions， the soil under salinization stress is still developing， which seriously affects other aspects such as arable land resources， crop yield， and agricultural development. Therefore， it is of practical importance to improve the quality of saline soils and crop yields using economically rational and efficient management measures. This paper summarizes the causes and sources of soil salinization， and reviews the management pathways of saline soils from four aspects： irrigation and drainage measures， physical regulation， chemical improvement， and biological measures， to provide references for further research on saline soils management.

In order to understand the changing law of soil enzyme activities of different root dry crops under waterlogging， the experiment takes summer maize and summer soybean as the test objects， and carries out the test tube simulation test. The experiment analyzes the effects of waterlogging stress on crop roots and soil enzyme activities， and the relationship between root dry weight and soil enzyme activities. The results show that different root crops are differently affected by waterlogging stress. The overall growth of fibrous root crops was hindered， the root dry weight decreased by 3.98%～29.41%， the invertase activity decreased by 1.06%～44.08%， the urease activity decreased by 6.21%～24.45%， the soil enzyme activity rebounded for a period of time after the end of waterlogging. Taproot crops had excessive root growth， the root dry weight increased by 1.77%～76.98%， the invertase activity decreased by 5.47%～15.65%， the urease activity decreased by 0.13%～2.95%， and the soil enzyme activity could not be recovered for a period of time after the end of waterlogging. There is a strong correlation between root dry weight， soil enzyme activity and accumulated waterlogging depth of the two root crops.

With the acceleration of the urbanization process， residential water has become a new growth point of water demand. At present， most studies based on factor decomposition model are devoted to the influencing factors of total water use， and there is no report on the decomposition of residential water use factors at the rigid， elastic and luxury levels. Based on the research on the hierarchical water demand of urban residents in Hebei Province and the theory of rigid， elastic and luxury water levels， this paper constructs the hierarchical water demand evaluation model of residents， and carries out parameter calibration through questionnaires to calculate the hierarchical water consumption of each water use behavior. In order to quantitatively identify the influencing factors of water use change at different levels in Hebei Province， Kayal identity and LMDI decomposition method are used to calculate the influence degree of population size， economic development level and water-saving technology level on the rigid， elastic and luxury levels of urban residents in 11 cities in Hebei Province， and then analyzed. The results show that： ① the population size effect and the level of economic development effect are positive promoting effect， while the level of water-saving technology is negative inhibiting effect； In the whole province， the effect of water-saving technology level in rigid water plays a leading role， and the effect of economic development level in flexible water and luxury water plays a leading role. ② The rigid water consumption in most cities shows an increasing trend， in which the economic development level plays a major role in promoting， and the development of water-saving technology has a certain inhibitory effect； ③ Except Xingtai City， the elastic water consumption of all cities shows an increasing trend. Population size and economic development has a positive effect on the growth of elastic water consumption， and the effect of water-saving technology level has an inhibitory effect on the growth of elastic water consumption. ④ The growth of luxury water consumption in most cities is mainly driven by population growth and economic development， while the development of water-saving technologies inhibits the growth. The research results can provide a reference for water resources planning and management in Hebei Province， and provide basic support for improving residents' water-saving level and ensuring water supply security.

The lithology， thickness and structure of the vadose zone have large spatial-temporal variation， while the moisture movement rules of the vadose zone are very complex due to the influence of characteristics. The research summarizes characteristics of the lithology， thickness and structure of the vadose zone in the Northern Ningxia Irrigation Area based on the field drilling and sectional survey； and selects three soil columns with a typical stratified structure in the vadose zone to discuss the water content characteristics of the vadose zone with stratified structures in the non-irrigation period. According to the results， ① the lithology of the vadose zone in Ningxia North Irrigation Zone mainly includes silt， fine sand， floury soil， silty clay， clay and cobble and gravel； the lithologic structure includes the single lithology， upper-fine-bottom-coarse or upper-coarse-bottom-fine stratified structure. ② The thickness variation and structural characteristics of the vadose zone are controlled by the irrigation activity， and the thickness of the vadose zone in the irrigation period is smaller than the one in the non-irrigation period as a whole. ③ The soil moisture content of the vadose zone with stratified structure has an abrupt change at the lithologic interface. When the moisture flows from the fine particle layer into the coarse particle layer， the soil moisture content at the lithologic interface decreases dramatically. When the moisture flows from the coarse particle into the fine particle layer， the soil moisture content at the lithologic interface decreases dramatically.

This paper uses GIS and indicator Kriging method to analyze the spatial variability of soil total salinity， burial depth of phreatic water level and phreatic salinity before spring irrigation in Qingtongxia Irrigation Area at depths of 0~20， 20~40 and 40~60 cm， and satisfy the probability distribution map of certain threshold conditions， and the relationship between them is judged. The result shows：① The coefficients of variation of total soil salinity， burial depth of phreatic water level， and phreatic salinity in Qingtongxia Irrigation Area are all more than 1， which belongs to strong variation； the frequency distribution shows an obvious “high-top” phenomenon. ② The indicated semi-variance function of soil total salinity at different depths and thresholds in Qingtongxia Irrigation Area conforms to different types such as spherical model， exponential model and Gaussian model. The indicated semi-variance function of the burial depth of the phreatic water level conforms to the exponential model. When the salinity thresholds are 1.0 and 2.0 g/L， the semi-variance function conforms to the exponential model， and when the thresholds are 2.5 and 3.0 g/L， the semi-variance function conforms to the Gaussian model. The soil total salinity and the burial depth of the phreatic water table under different threshold conditions show moderate-strong spatial autocorrelation， and the phreatic salinity shows a strong spatial autocorrelation. ③ The areas with high probability of mild， moderate and severe salinization and salinization of soil at the depth of 0~20 cm in Qingtongxia irrigation area account for 92.38%， 73.71%， 51.83% and 24.61% of the irrigation area. 20~40 cm depth ratio is 92.15%， 50.21%， 6.87%， 0.53%； 40~60 cm depth ratio is 89.16%， 43.06%， 6.09%， 0.46%. When the depth of phreatic water thresholds are 1.5， 2.0， 2.5 and 3.0 m， the high probability areas account for 13.42%， 30.25%， 41.87% and 65.18% of the irrigation area. The high probability area accounts for 59.13%， 55.22%， 33.76% and 31.96% of the irrigated area when the phreatic salinity thresholds are 1.0， 2.0， 2.5 and 3.0 g/L. With the increase in the threshold， the area of high probability areas is significantly smaller. ④ When the soil in Qingtongxia Irrigation Area is moderately and severely salinized， the depth of phreatic water is 2.0 m， and the phreatic salinity is 2.0 g/L respectively. The comprehensive indicator probability distribution map and probability risk assessment obtained from the research have a guiding significance for the prevention and control of soil salinization in Qingtongxia Irrigation District， and can provide a reference for the high-quality protection and utilization of land resources.

The judgment and comprehensive evaluation of the high-quality development level of irrigation districts are the basis for achieving high-quality development of irrigation districts， and also an important decision-making basis for the rehabilitation and modernization of irrigation districts. In order to build an evaluation index system that reflects the high-quality development level of irrigation areas in the new era，on the basis of the analysis of China's socio-economic and irrigation district development stage characteristics， the objectives of high quality development of irrigation districts in the new period are clarified， This paper analyzes the concept and connotation of high-quality development of irrigation districts， and the evaluation index system is constructed， including the first grade indexes，namely， engineering improvement， operation safety， management science， water-saving and efficiency， ecological soundness， cultural self-confidence and 19 second grade indexes， the meaning of each indicator and its evaluation criteria are clarified. The “single index quantification–multiple indices synthesis–poly-criteria integration” method was used to calculate the index， which is applied to a large irrigation district in Jiangsu Province. The evaluation results of the case irrigation district show that the overall level of high quality of the irrigation district has increased significantly from level IV in 2010 to level II in 2021， and all indicators have increased significantly， which is consistent with the actual situation of the irrigation district. The research results provide guidance for correctly understanding the connotation of the high-quality irrigation districts， scientifically assessing the high-quality level and actively promoting the process of high-quality development of irrigation districts.

In order to investigate the spatial variation of soil nutrient indexes and fertility quality of long-term sub-membrane drip irrigated farmland in Xinjiang， this paper samples the soil in the 0~20 cm soil layer of typical sub-membrane drip irrigated plots， measures and analyzes six indexes of soil pH， conductivity， organic matter， alkaline soluble nitrogen， fast-acting phosphorus and fast-acting potassium， and calculates and analyzes them by using geostatistical methods and the affiliation function method. The results show that the block gold coefficients of pH， conductivity， alkaline decomposition nitrogen， fast-acting phosphorus and fast-acting potassium are 0.97， 0.98， 0.97 and 0.99， respectively， all of which are more than 0.75， indicating that their spatial autocorrelation is weak and the spatial variation is mainly affected by human factors. The spatial distribution shows that the soils in the study area are occupied by class II and III lands， accounting for 71.11% and 28.89%， respectively， which are of medium and medium-upper fertility status. The overall level of soil fertility of under-membrane drip irrigation is high， among which fast-acting phosphorus is the main limiting factor limiting soil fertility， and the soil should be cultivated and improved by increasing phosphorus fertilizer and other means.

In view of the problems existing in the consolidation grouting of the ultra-high arch dam of Wudongde Hydropower Station， the relaxation characteristics of dam foundation excavation are analyzed. Through indoor material tests and field process tests， the materials and processes for sealing the cracks in bare rock are developed， which solves the problems of low pressure and poor effect of the consolidation grouting without cover weight， and puts forward the method of "surface sealing， shallow densification， deep pressure rise， less lead pipe" for the whole dam without cover weight consolidation grouting， which not only ensures the quality of the consolidation grouting of the dam foundation， Moreover， it does not occupy the concrete warehouse surface， and solves the problem of the interference between the covered consolidation grouting and the concrete pouring construction. It has been successfully applied in the consolidation grouting of the dam foundation of the ultra-high arch dam of Wudongde Hydropower Station， which can be used as a reference for similar projects.

Through the conventional triaxial compression experiment of ultra-high performance concrete with 4 kinds of steel fiber volume contents（0%，1%，2% and 3%）at 5 grades confining pressures （0，10，20，40 and 60 MPa）， The specific values of internal friction angle φ and adhesion c in different confining pressure of each steel fiber content ultra-high performance concrete are deduced from the test data， the parameter in the Mohr-Coulomb failure criterion is determined by the c and φ values， and the specific expression of Mohr-Coulomb failure criterion under different confining pressures and different steel fiber contents are obtained too. It is found that the Mohr-Coulomb failure criterion can better describe the development law of the triaxial compressive strength of ultra-high performance concrete.

Aiming at the problems of slow speed of guide vane opening and active power regulation， susceptible to water hammer reaction and unit inertia during regulation process of hydro-generator unit under open mode power closed-loop control， this paper puts forward a new open-loop and sectional open-loop control method of guide vane opening based on opening mode of turbine monitoring system step by step. The structure model and control principle of open-loop and sectional open-loop control of guide vane in opening mode are elaborated， and three control methods of guide vane opening in opening mode are modeled and simulated by using matlab. By comparing and analyzing the simulation results， it is found that the sectional open-loop control method of guide vane opening analogue of turbine monitoring system has the best performance. It not only has the characteristics of fast open-loop control， but also has the advantage of small overshoot of sectional open-loop control. It can effectively solve the problems of water hammer reaction and unit inertia action during guide vane opening and active power regulation of turbine-generator unit.

In order to explore the influence of the length of the toothed piers on the hydraulic characteristics of the tooth-block inner energy dissipaters， the \mathit{k}- \mathit{\epsilon } mathematical model in the Fluent simulation software is used to numerically simulate it， and the results obtained from the numerical simulation calculation are compared with the results of the previous physical model test， and the accuracy of the numerical model of the internal energy dissipaters with different lengths of toothed piers is verified and proved. After that， the model is used to analyze and study the hydraulic parameters such as central axis flow velocity， time-average pressure， flow coefficient， energy dissipation rate， turbulent kinetic energy and flow field of 7 kinds of pier-type internal energy dissipaters with different pier relative lengths（The relative length η is the ratio of the length \mathit{l} of the toothed piers to the inner diameter D of the simulated pipe）. The numerical simulation results show that the distribution law of the central axis flow velocity of the toothed piers type internal energy dissipaters for the schemes with different relative lengths is basically the same. The maximum flow velocity value appears at the same position. The position of the maximum flow velocity value is fixed and does not change with the change of the relative length of the toothed piers. Under different relative lengths， the position appears 0.38D behind the inlet of the toothed piers. The time-averaged pressure of the front wall and the rear wall of the toothed piers changes obviously， and there is a lower pressure area in these two areas. There is a vortex area in the rear area of ??the toothed piers， and the turbulent kinetic energy value inside the vortex area is relatively high， and the length of the reflow zone on the rear side of the piers gradually decreases with the increase in the relative length of the piers. Within the simulation range of the numerical simulation， the magnitude of the flow coefficient increases first and then decreases with the increase in the relative length of the toothed piers， and η is within the range of 0.2 to 0.9， the value of the flow coefficient of these relative length schemes is relatively large， and the change law of the value of the energy dissipation rate is opposite to that of the flow coefficient. When η is more than 0.9， the vortex area of the part of constriction expansion on both sides of the toothed piers section separation occurs. After that， as the relative length of the toothed piers increases， the effect of the excess length on energy dissipation is only caused by the head loss along the route， and the excess length does not contribute much to the energy dissipation rate of the energy dissipaters， therefore， the influence of excess length on energy dissipaters can be ignored. Comprehensive analysis shows that the length of the toothed piers with relative lengths in the range of 0.2~0.9 is superior， which provides a basis for the optimization of the body shape of the tooth-block inner energy dissipaters.

The culvert valve of the ship lock operates frequently every day， and the working conditions are complicated. Under the action of unsteady high-speed water flow， cavitation is easily formed in the valve section， diversion port， and other parts， threatening the safety of buildings and ship navigation. Therefore， the hydraulic conditions and hydraulic safety of the ship lock valve section have attracted the attention of scholars. In the present study， a three-dimensional numerical simulation of the ship lock with an overall filling and emptying system is carried out. At the same time， in order to verify the accuracy of the numerical results， a physical model test is carried out to measure the relevant data. The maximum water head of the ship lock is 8.0 m， the length of the lock chamber is 220 m， the width is 23 m， and the threshold water depth is 4.5 m. The culvert behind the valve adopts the top expansion type. The dynamic mesh method and user-defined function （UDF） are adopted to realize the uniform opening process of the vertical-lift valve. The hydraulic parameters， such as the flow pattern， velocity， and pressure are analyzed. The numerical water level， discharge， and pressure of a typical measurement point are compared with the physical model results， and they are in good agreement， indicating the feasibility of the numerical simulation method. The numerical results show that a counter-clockwise circumfluence appeared behind the valve during the opening of the valve. With the increase in the valve opening ratio， the range of circumfluence gradually decreases， and the center of circumfluence gradually moves to the upstream and the top of the culvert. When the valve is fully opened， the water flows smoothly to the downstream. The area between the lower bottom edge of the valve and the culvert floor is the high-speed mainstream area. When the valve is opened from closed to fully opened for four minutes， the velocity is the largest when the valve opening ratio is 0.4. Meanwhile， the velocity near the wall is relatively small. The velocity， turbulent kinetic energy， and turbulent dissipation rate increase and then decrease as the valve opens， but the pressure is the opposite. The low-pressure area appears on the top of the culvert behind the valve and gradually moves upstream with the increase in the valve opening ratio. When the valve opening time is four minutes， the minimum pressure appears at top of the culvert when the valve opening ratio is 0.4， but there is no negative pressure. Under this body type and hydraulic conditions of the culvert， when the valve opening time is 5 minutes， the time-averaged pressure behind the culvert is the smallest. Numerical simulation has the advantages of rich information and economical economy in understanding the flow pattern of the ship lock valve section and is a powerful supplementary method for physical model test research.

How to improve the utilization rate of water and increase the efficiency of power generation has always been the main goal and direction of hydropower dispatching research. Based on the traditional optimal dispatching， an optimal dispatching model of cascade hydropower station based on the maximization of unstored power is established in this paper， which takes the utilization of the unstored water of the reservoir as the starting point. Through an analysis of the dispatching model and the application of POA algorithm to solve it， and combined with the verification of an engineering example， the rationality and feasibility of the model and method are illustrated. Compared with the traditional dispatching mode， the dispatching model provided in this paper can improve the power generation utilization rate of unstored water by reasonably adjusting the output distribution of each cascade power station according to the change of power network load demand under various constraint conditions. It indirectly reflects the saving and utilization of water resources and is helpful to the arrangement of joint dispatching mode of cascade hydropower stations， and can promote the development of optimal dispatching of cascade hydropower stations to a certain extent.

Vibration monitoring and analysis are an important means of fault diagnosis of hydropower units. How to filter noise from vibration signals to extract fault features effectively is a key problem. Therefore， a new method for the analysis of throw signals is proposed based on non-local means （NLM） and complementary ensemble empirical mode decomposition with adaptive noise （CEEMDAN） in this paper， which is applied in the swing monitoring and analysis of hydropower units. In this method， the signals are denoised by NLM-CEEMDAN. Several intrinsic mode function （IMF） are obtained and the sample entropy of each component is calculated for component classification. The denoising of the throw signal is completed by discarding the high-frequency noise components and noise component of the mixed information and noise components. Through an analysis of simulated signals and real-world signals， it can be found that this method is superior to the conventional decomposition component reconstruction and wavelet threshold denoising algorithms， which can remove noise more effectively， providing a new idea for the fault feature extraction of hydropower units.

The multistage hydropower station with regulating reservoir is a main layout scheme to deal with the complex terrain problems in the development of southwest hydropower base. How to realize the flow matching of series hydropower station under load regulation conditions is the key to ensuring the safe and stable operation of units. For this purpose， from the perspective of hydropower station transition process and control， this paper establishes a two-stage series hydropower station transition process simulation model with regulating reservoir， and analyzes the dynamic variation of unit parameters such as unit speed， output and draft tube inlet pressure， as well as hydraulic parameters of regulating reservoir such as water level and flow under load changes. The results show that the regulation reservoir has no effect on the regulation quality of hydropower stations at all levels when the series power stations participate in the power grid regulation. However， if there is no follow-up regulation， the series hydropower station can only maintain the operation for a short time. Under the load redistribution condition after load rejection of some units， the inlet pressure of the draft tube of load distribution units decreases obviously. The adjustment time of load distribution unit and load distribution scheme also have no significant impact on the operation of series hydropower stations. The above research provides some technical support for the safe operation of the two-stage hydropower station.

In order to solve the problem of slow repair efficiency of current microbial repair materials， sodium alginate is used to modify existing microbial repair materials， and a new external repair material with fast and high efficiency is developed. The basic properties and repair effects of the repair material are explored. The results show that the repair material with sodium alginate has good Ca²⁺ adsorption and can repair mortar cracks with a width of 1.5 mm and depth of 20 mm only once. The repair products are mainly calcium alginate and calcium carbonate， filling the cracks together. The flexural strength increases by 20% compared to before repair， which is restored from 3.5 MPa to 4.2 MPa.