In order to scientifically and effectively quantify the water supply benefits of the basin and provide a reference for the high-quality development planning of the basin， based on energy analysis theory， this paper puts forward the quantification method system of water supply benefits in different industries， including water resources ecological economic value calculation and water supply benefits calculation so as to obtain multi-object and sub-industry water supply benefits. On this basis， the Moran' I index and LISA index are used for spatial autocorrelation analysis to analyze the distribution law of water supply in space. By taking 56 water supply cities in the Yellow River Basin as the research object， this paper calculates the industrial， agricultural， domestic and total water supply benefits of each city in the Yellow River basin， and analyzes the spatial distribution characteristics and correlation of water supply benefits of each industry in the region. The result shows that ① the value of water resources in various industries in the Yellow River Basin is numerically expressed as life > industry > agriculture， and spatially presents a trend of low in the west and high in the east； ② the benefits of industrial， agricultural and domestic water supply in the Yellow River basin are 58.129 billion yuan， 89.163 billion yuan and 68.266 billion yuan respectively， among them， the industrial water supply benefits of Henan Province and Shandong Province， which is located in the middle and lower reaches of the Yellow River， are relatively high， and the agricultural water supply benefits of Ningxia， Inner Mongolia and Shandong Province are significantly greater than that of the other two industries in this province. ③ The Moran' I indices of industrial， agricultural， domestic and total water supply benefits are 0.286， 0.412， 0.225 and 0.357， respectively， with significant spatial clustering， the “high-high” pattern is mainly concentrated in the Shandong and Henan in the middle and lower reaches of the Yellow River， and the “low-low” pattern is distributed in Qinghai and Ningxia in the upper reaches of the Yellow River， the distribution characteristics of the spatial pattern are related to factors such as the level of regional economic development， climatic and geographical conditions， natural resource conditions， and urban development strategies and policies. The research results can provide a reference for the rational allocation of water resources and the adjustment of water diversion structure in the Yellow River Basin.

The soil layer in the Loess Plateau is extremely thick， and the soil infiltration process includes preferential flow and matrix flow， but the infiltration process in the two-flow zone is different from that in mountainous areas. At present， when the distributed hydrological model is applied in the Loess Plateau without considering the effect of preferential flow on the rainfall infiltration process， resulting in the simulation distortion and low accuracy of the model， which greatly limits the wide applicability of the watershed distributed hydrological model. Based on the traditional rainfall infiltration model （Green-Ampt model）， this paper improves the distributed hydrological model by introducing the total soil saturated water content and the total soil saturated hydraulic conductivity， and constructs the WEP distributed hydrological model in the two-flow region of the Loess Plateau. The Heihe River Basin is selected as the study area， and the rainfall-runoff process in the study area is simulated by using the WEP model before and after the improvement to verify the applicability of the improved WEP model. The results show that compared with the traditional WEP model， by considering the influence of the two-flow zone， for the monthly runoff， the absolute values of the relative error of monthly runoff of the basin section are less than 0.05%， and the Nash-Sutcliffe efficiency coefficient is more than 0.69. The relative error of the unimproved model is 0.06%~0.24%， and the Nash-Sutcliffe efficiency coefficient is 0.66~0.70. The Nash-Sutcliffe efficiency coefficient of the improved model increases from 0.66 to 0.69 and the absolute value of relative error decreases from 0.24% to 0.05% within the rate period. During the verification period， the Nash-Sutcliffe efficiency coefficient increases from 0.70 to 0.73， and the relative error decreases from 0.06% to 0.01%. In terms of the daily runoff process， the Nash-Sutcliffe efficiency coefficient of the model increases from -4.22 to 0.64， and the relative error decreases from 57.17% to 19.80% after the improvement of WEP model. By considering the influence of two-flow zone on rainfall infiltration， the simulation effect of WEP model on monthly runoff and daily runoff process in the Heihe River Basin has obviously improved， which shows that the improved WEP model has better applicability in Loess Plateau region and helps to enhance the understanding of water infiltration process.

Regional water use differences and influencing factors are studied in this paper. According to the data of 31 provincial administrative regions in China in 2019， the WUE （water use efficiency） of each region is calculated. Regional differences in WUE in China are analyzed by one-way ANOVA and nonparametric tests. Further， the influencing factors of regional water use are studied by the canonical correlation method. The study indicates that： ①The Northeast China， North China， Northwest China， Southwest China， Central and the coastal areas of Southeast China have significant differences in the mean values ??of the following four WUE indicators： effective utilization coefficient of farmland irrigation water， per capita domestic water consumption of urban residents， per capita domestic water consumption of rural residents and total score of WUE. In terms of the total score of WUE， North China is significantly higher than other regions， and only significant differences exist between North China and the coastal areas of Southeast China， Central China， Southwest and Northwest China， while no significant differences exist between other regions.②There are significant differences in eight WUE indicators ranked in six regions， and six regions ranked on eight WUE indicators.③The water consumption per 10 000 Yuan of GDP is mainly affected by economic and social development， capital input and human quality. Industrial water is mainly affected by natural conditions， water resources endowment， factor input of water industry， industrial structure and sustainable utilization level. Domestic water is mainly affected by water demand level， water resource endowment and natural conditions. Regional differences have an impact on the eight WUE indicators.

Drought is one of the most destructive natural disasters because of its wide range of influence， long duration， and great losses. The spatiotemporal dynamic evolution of droughts in Guangdong from 1979 to 2021 is analyzed based on the Palmer Drought Severity Index （PDSI） in this paper. By giving the drought event in the area， duration， and intensity index definitions， the large-scale persistent drought processes that have occurred in Guangdong are identified. And the causes of drought are investigated based on the ERA5 reanalysis data. The results show that five large-scale persistent droughts occurred in Guangdong from 1979 to 2021， including November 1980-February 1981， December 1998-June 1999， February-May 2002， March 2004-January 2005 and November 2020-September 2021. The average drought area index， average drought duration index， and average drought severity index were 78.87 percent， 7.4 months， and -6.00， respectively. The drought process from November 2020 to September 2021 was the most widely affected， longest duration， and most severe drought process since 1979. The atmospheric circulation background field and its seasonal evolution were different in different drought processes. However， all circulation anomalies ultimately affected the interaction between cold and warm air masses， or weakened the dynamic conditions or water vapor conditions essential for precipitation， which led to the long-term maintenance of large-scale drought. The findings can provide an important reference for understanding the drought evolution mechanism and drought prevention in Guangdong.

To explore the characteristics of precipitation in the Yellow River Basin， based on 92 meteorological stations， this paper analyzes the trend of annual and seasonal precipitation in the Yellow River Basin from 1960 to 2015 by using an innovative trend analysis （ITA） method， Mann-Kendall test and Sen’s Slope. The results show that precipitation increases from the northwest area to the southeast area. The Yellow River Basin exhibits an overall decreasing trend in annual precipitation with inter-annual precipitation becoming more even. In terms of seasonal precipitation， spring and winter precipitation show increasing trends， while summer and autumn precipitation exhibit decreasing trends in the Yellow River Basin. Furthermore， in spring， the light precipitation has a non-monotonic trend in the Yellow River Basin.The summer light precipitation in the middle and lower reaches of the Yellow River Basin shows a downward trend. The light precipitation in the Yellow River Basin shows a downward trend in autumn， while it exhibits an upward trend in winter. In summer， the heavy precipitation in the upper reaches of the Yellow River shows a downward trend of about 10%， while it shows an upward trend of about 5% in the middle reaches of the Yellow River. By exploring the changing trend of annual and seasonal precipitation of different magnitudes in the Yellow River Basin， this paper can provide a reference for the water resources management and flood and drought disaster prevention in the Yellow River Basin， and then support the high-quality development of the Yellow River Basin.

The Luanhe River Basin plays an essential ecological role in the Beijing-Tianjin-Hebei region. In the context of global warming， it is momentous to study the future climate change and runoff pattern of the Luanhe River Basin for the development of the Beijing-Tianjin-Hebei region. In this thesis， the historical runoff of Luanhe River Basin is simulated based on VIC model. The CMIP5 future global climate model evaluation index system is constructed by using correlation coefficient， central root mean square error， standard deviation and mean value， and normalized. The optimal precipitation， maximum temperature， minimum temperature and wind speed data are selected from each model to analyze the future climate change in the Luanhe River Basin. The spatial downscaling of meteorological elements is carried out by using Delta Method， and the VIC model is coupled with THE CMIP5 global climate model to analyze the future runoff changes in the Luanhe River Basin. The results show that VIC model has a satisfactory effect on runoff simulation in the Luanhe River Basin. At the interannual level， annual precipitation， daily maximum and minimum temperature show an increasing trend in the future， while daily mean wind speed shows no obvious increasing trend. In terms of annual distribution， compared with the same month in the historical period， the average precipitation of the next month will increase or decrease， and the increase rate of October is the highest， reaching 138.64%. In the future， the average maximum temperature will increase， with the greatest change in September， with an average increase of 2.45 ℃. In the future， the mean minimum temperature will increase by 3.24 ℃ on average， with the largest increase of 4.45 ℃ in February. The future wind speed increases and decreases in different months， with the largest change in August， with an average increase of 0.23 m/s and an increase rate of 16.35%. The multi-year average flow of the future period is 134.41 m³/s， increasing by 9.96% compared with the historical period. In the future， the average annual flow rate fluctuates at a rate of 10.2 m³/（s·10 a）. In the 2020s and 2080s， the annual flow will fluctuate at an average rate of 12.8 and 28.9 m³/（s·10 a）， with a significant upward trend. The proportion of runoff in summer decreases from 53% to 43%， and that in winter increases from 7% to 12%.

Water right trading in the Yellow River Basin is an effective way to improve the utilization efficiency and utilization benefit of water resources. Besides， it is effective to achieve ecological protection and high-quality development in the Yellow River Basin. In order to analyze the development status of water right trading in the Yellow River Basin， the SWOT model is adopted， and the evaluation index system of the development trend of water right trading in the Yellow River Basin， which contains 14 variable indexes， is constructed. In addition， EFE and IFE matrix analyses are combined to quantitatively evaluate the internal and external influencing factors which includes the strengths（S）， weakness （W）， opportunities （O） and threats （T） of water right trading in the Yellow River Basin. Then the development strategy of water right trading in the Yellow River Basin is determined. The results show that there are more opportunities than threats in water right trading in the Yellow River Basin， and strengths surpass weaknesses， but weaknesses have a greater impact on water right trading in the Yellow River. The current situation of water right trading in the Yellow River Basin is generally in a SO growth strategy， and it is necessary to take advantage of the external opportunities and maximize the internal strengths. Finally， some suggestions are put forward to promote water right trading， including broadening the scope of tradable water rights， innovating the incentive mechanism of water right trading， exploring the price formation mechanism of water right trading， improving the supervision mechanism of water right trading and so on. This paper can provide a reference for the future development direction of water right trading in the Yellow River Basin.

The unit hydrograph method is commonly used for the calculation of flow routing in the small and medium-sized basins. However， the current synthetic unit hydrograph method cannot consider the heterogeneity of temporal and spatial distribution of rainfall and the heterogeneity of underlying surface， resulting in poor prediction accuracy. In addition， the current distributed unit hydrograph calculation process is complicated and requires plenty of data， which limits its application in small and medium-sized basins. To this end， the concept of distributed unit hydrograph is introduced in this study. Based on the flow travel time and the lag time of flow peak， a distributed unit hydrograph model considering the attenuation actions is proposed. After a group of unit hydrographs are calculated， different distributed unit hydrograph accorporates to each watershed. Then， the flood process of the outlet basin can be calculated. The Meizhou River basin is selected as a study case. A distributed unit hydrograph model considering attenuation actions is established based on the observed rainfall data of 21 rainfall stations. The relative flood peak error， flood peak appearance time error and deterministic coefficient are used to evaluate the applicability of the model， and the result of the current synthetic unit hydrograph method is compared with the proposed method. The result shows that the relative peak error and peak appearance time error of the proposed method are smaller than those of the synthetic method and the certainty coefficient is significantly improved. On the whole， the accuracy of the proposed method is better. The proposed method simplifies the calculation steps of the distributed unit hydrograph， improves the accuracy of flood prediction， which is easy to be popularized in small and medium-sized basins.

The determination of the carrying capacity of regional water resources and the bottom line constraints are the prerequisite and basis for ecological security and harmonious regional development， and are the main factors affecting regional economic development. All aspects of human life are dependent on the control of water conditions， and water resources are facing increasingly severe conditions. The traditional assessment of the carrying capacity of water resources is mostly based on static description and classification， and the understanding of the size of the carrying capacity of water resources is still lacking. This paper takes a county in the Qinling Mountains as the study area. Based on literature， data collection and field surveys， this paper uses the ecological footprint theory to evaluate the carrying capacity of water resources with the help of the “four determinations of water” principle， and calculates and analyses the ecological footprint， ecological carrying capacity and ecological surplus and deficit of the county from 2017 to 2020. The spatial distribution of the ecological footprint data is visualized in ArcGIS， and a barrier degree model is used to identify the barriers affecting the water resources carrying capacity， and finally to make scientific optimization of the rational layout of water resources. The study shows that the supply of water resources in the region is slightly greater than the demand. The high value of the spatial distribution of the ecological footprint of water resources is mostly in the central area； the ecological footprint of water resources per capita， the ecological footprint of sewage and the ecological footprint of ecological water use are the main obstacle factors affecting the improvement of the carrying capacity of water resources； the direction of optimization should be adjusted according to the distribution of water resources in order to develop special industries. The scientific use of water resources is essential to ensuring economic development. Only by reasonably scheduling the direction of water resources use， clarifying the water resources carrying capacity and improving the efficiency of water resources use can we promote the synergistic development of society， economy and environment.

Scientific and reasonable initial allocation of water rights is of great significance to giving full play to the key regulatory role of the market in the efficient utilization and optimal allocation of water resources， and to promote the construction of water right trading system. To address the constraints of quantitative weighting determination of multi-index systems， as well as the randomness of multi-variables in regional initial water rights allocation， this paper applies the Principal Component Analysis （PCA） to extract principal component factors of water right allocation and constructs independent key index systems. A hybrid model for the regional initial water rights allocation coupling the PCA and Copula function is constructed， and the comprehensive weight of water rights allocation is quantitatively determined. Taking the new principal component factors as random variables， this paper optimizes the edge distribution functions to calculate cumulative theoretical frequency values. Then， the Copula function is input to determine the comprehensive weight of water right allocation， and the initial water right allocation ratio of each calculation area is obtained after normalization. The calculation process is simple and clear， which can realize the objective index weight， overcome the randomness of multivariate variables， and has good applicability. The proposed method is applied to the regional initial water right allocation in the Zouping City （ZPC）， Shandong Province， China. The results show that the proportion of initial water rights allocation in the urban and irrigation areas of the ZPC in 2020 is 0.432 and 0.568， respectively， and the proportion of water demand in the urban and irrigation areas is 0.402 and 0.598，respectively， indicating that the initial water right allocation in each calculation area is consistent with the actual water consumption of the ZPC， which accords with the principle of fairness and sustainability in regional initial water right allocation. The calculation results are scientific and reasonable. This paper provides a scientific reference for promoting the scientific and efficient utilization of regional water resources， guiding the construction of water-saving society， ensuring the safety of regional water supply， and a sustainable and healthy development of economy and society.

The Grain for Green Program has significantly affected the regional ecosystem， so it is important to understand the spatiotemporal pattern of interactions among ecosystem services to achieve the sustainable management of the regional ecosystem. Unfortunately， few existing studies have been in a position to consider both the temporal characteristics and spatial scales of interactions among ecosystem services. Moreover， due to the diversity and complexity of ecosystems， the resolution of knowledge related to ecosystem services in typical regions， especially in regions with significant ecosystem changes， is still lacking in the field of ecosystem management， which cannot provide an adequate basis for a comprehensive understanding of the state of regional ecosystem services. Therefore， by taking Shaanxi Loess Plateau， one of the main battlefields of Grain for Green Program as an example and taking into account the ecological problems of water scarcity， poor vegetation conditions and severe soil erosion there， the spatiotemporal pattern of three key ecosystem services， namely water yield， NPP and soil retention in the region in 2000 and 2018 are quantified by using the InVEST， CASA and RUSLE models. Then， this study reveals the spatiotemporal changes of the synergy and tradeoff relationships among the three ecosystem services at grid and county scales by the correlation coefficient method， identified the hotspots of ecosystem services by hotspot method. The results show that the average water yield and NPP in the study area increased， and the average soil retention decreased from 2000 to 2018. In terms of spatial distribution， all three ecosystem services were more spatially heterogeneous at grid scale than that at county scale because of the high values of the three ecosystem services were “cut” and the low values were “filled” with increasing scales. All three ecosystem services had synergistic relationships in 2000. However， by 2018， there were tradeoffs between water yield and NPP， water yield and soil retention. Moreover， the synergy between NPP and soil retention was weakened in 2018. From 2000 to 2018， as the changing of scales， the intensity or direction of the interactions between three ecosystem services had all changed， which confirmed the view that interactions among ecosystem services might be different at different spatial scales. The hotspots roughly showed a spatial variation characteristic of hotspots decreasing from south to north of the study area. The number of counties with category 0 and 1 hotspots decreased， while the number of counties with category 2 and 3 hotspots increased. In addition， NPP is the dominant ecosystem service that most counties can provide. The research results can help to enhance the understanding of the interactions among ecosystem services depending on temporal and spatial scales， and provide a scientific basis for making differentiated ecological management strategy.

Based on the analysis of adaptability， the advantages and disadvantages of the intercepting confluence sewage system and completely separate sewage system are studied in order to demonstrate the necessity and feasibility of hydraulic scouring facilities of sewage culvert system. Detailed prototype thickness observations， silting sampling， sediment composition and silting causes investigations are carried out for a certain sewage culvert system in Guangzhou. By simulating the boundary and initial conditions of hydraulic flushing facilities， a moving-bed physical model with hydraulic flushing function for sewage culvert system is established， and the hydrodynamic parameters along sewage culverts are measured under several working conditions. Combined with the practical engineering management experience， the engineering effect and feasibility of the scheme of “sudden sluice opening and relay flushing silting” by using the hydraulic flushing facility to store the sewage in the dry season and early light rain are demonstrated. Considering the water storage gate height of the sewage culvert system is only 1.0 m， the water storage capacity of these gates is limited， and the hydraulic slope of the sewage culvert is only 0.1%， the physical model test results show that the hydrodynamic conditions of the hydraulic scouring scheme are insufficient， and the effect of hydrodynamic scouring is poor. Cancelling the remaining uninstalled hydraulic scouring facilities is suggested. Moreover， a dredging scheme of “manual and mechanical” is recommended with more adaptability for this specific engineering project. According to the engineering characteristics of the intercepting sewage system， adaptive and economical countermeasures for silting prevention， silting reduction and silting removal should be recommended scientifically. The strategies proposed in this research can provide a technical reference for similar intercepting sewage culvert systems.

To explore the water quality response and the change rule of the South-to-North Water Transfer Project and the Project of Yellow River to Qingdao City in the water delivery section of the pilot trench of the Xiaoqing River under the multi-source water transfer scheme of the diversion of the Yellow River water and Yangtze River water， and to find the best water quality and water distribution scheme under the current water transfer capacity， this paper takes dissolved oxygen， permanganate index， COD， BOD₅， ammonia nitrogen， total nitrogen， total phosphorus， and fluoride as research indexes and studies the water quality optimization scheme of multi-source water transfer during water delivery period， hoping to provide a theoretical basis for water transfer management in the research area. First of all， 11 monitoring points were set to monitor the water quality during the water transfer period. The measured water quality data and the design materials of the research area were taken as the basic data， the MIKE11 hydrodynamic-water quality coupling model was constructed and calibrated from the flood diversion gate to the section of the lower check gate. Then， the upstream section of the Dongqing Expressway was taken as the assessment section， the flow rate of the lower check gate of 36m³/s was taken as the control condition to set 99 kinds of water distribution scenarios， and the changes in water quality indexes in the simulation results under different water distribution schemes were summarized and analyzed. In the end， the water pollution index method was adopted to assess the water quality simulation results and the best water distribution scheme was determined. The conclusions are as follows： the total nitrogen content in the research canal section was relatively high， the other indexes met the class III water standards， the dissolved oxygen， permanganate index， COD， and fluoride in the water source of the Yangtze River were relatively high， and the BOD₅， ammonia nitrogen， total nitrogen， total phosphorus content in the water source of the Yellow River were relatively high. The efficiency coefficient E n s of the flow in the hydrodynamic-water quality coupling model was 0.86， the determination coefficient R ² was 0.88， the error of the water quality simulation results was within 30%， and the effect of the model simulation was good. With the constant improvement of the contribution rate of the Yangtze River water to the water transfer， the fluoride， dissolved oxygen， and permanganate indexes in the water after the catchment showed an upward trend， and the COD first decreased and then increased， the other indexes showed a downward trend. The contents of most pollutants had a linear relationship with the contribution rate of the Yangtze River water， the difference in water quality between the two water sources had a relatively great influence on the water quality of the catchment， and the water environment had a relatively small effect on the decomposition and diffusion of pollutants. In various simulation scenarios， the COD and BOD⁵ at the assessment section （the upstream section of the Dongqing Expressway） played a decisive role in the WPI of this section. When the water supply of the Yangtze River accounted for 49% of the total water supply （17.64 m³/s）， the WPI of this section reached the minimum value （51.17）. Therefore， this scheme is the best water distribution scheme obtained by the research.

The effect of cascade reservoirs constructions on the migration process of biogenic materials in the Lancang River has attracted extensive attention of scholars around the world. Stable isotope technology is implemented in the current study： total phosphorus （TP） concentrations and hydrogen and oxygen stable isotope concentrations （D， ¹⁸O） of different sources of water in the XW，MW，NZD，JH reservoirs （discharge of upper reservoir， inflow of tributaries， slope runoff and artificial water cycle） were measured from the dry season （February 2017） to the wet season （June 2017）. According to the multivariate linear mixed model， contribution rates of water volume from different sources are analyzed， and TP retention of cascade reservoirs in the Lancang River is simulated and calculated. Modeling and analysis results indicate that the contribution rates of discharges in the upper reservoir to the retention effect of TP in reservoirs accounts for the main part in both wet seasons and dry seasons， with contribution rates of 54.8%~79.3% and 39.1% ~ 82.8% ，respectively. Contribution rates increase from the upstream to the downstream. The amount of artificial water circulation increases along the way in the dry season. The runoff on the slope increases along the way during the wet season. The retention rates of TP in the dry season and the wet season is -49.34%~66.72% and -88.79%~88.40% respectively. The retention rate of TP in the wet season is greatly affected by increasing water volume， while in the dry season， it is greatly affected by human activities and excessive inputs from the upstream. This study can provide data support for the targeted controlling of TP retention in the Lancang Basin and the evaluation of downstream water ecological environment quality.

In order to explore the ecological flow of the mainstream of the Hulan River and use it as a basis for ecological scheduling in the basin， this paper improves the River2D model by coupling the river hydrodynamic model and the fish habitat model to simulate the river flow range corresponding to the optimal habitat area of the Hulan River mainstream Benthosemapterotum. With the objective of obtaining better habitat simulation results， the preference of river substrate in the original River2D model is instead replaced with the preference of indicator species for water quality， which makes the simulation more effective when ecological flow studies are conducted in rivers with a smaller range of river substrate variation and more pronounced fish preference for water quality. With the improved physical habitat module， the two-dimensional hydrodynamic model in River2D is used to simulate flow velocity， water depth and suitable habitat distribution in the mainstream of the Hulan River under different flow conditions， and the flow-suitable habitat area relationship curves are made to obtain the suitable ecological flow values of 2.75， 8.25 and 27.5 m3/s for the seven-starred fish during the dry， flat and abundant water periods， respectively. The range of suitable ecological flow is 2.75~27.5 m3/s. Because the ecological flow range of Benthosemapterotum in the mainstream of the Hulan River is obtained based on the improved River2D model matches with the evaluation range of Tennant Method， the research results are considered reasonable and can provide a reference for the protection and ecological scheduling of Benthosemapterotum in the mainstream of the Hulan River.

To establish a stable and accurate UAV remote sensing inversion model for urban river water quality parameters， the study takes five reaches of Fuyang River in Handan as the study sample area， and constructs four mathematical statistical models and XGBoost model based on the three phases UAV multispectral images and measured data of ammonia nitrogen concentration in water. And the optimal model is selected to analyze the spatial-temporal distribution of ammonia nitrogen concentration in the study area on the basis of model verification and evaluation. The results indicate that the inversion effect of XGBoost model is better than that of mathematical statistical model， and the XGBoost model accuracy evaluation indicators of R ²， RMSE and MAPE re generally better than mathematical statistical models and the XGBoost model shows strong fitting ability and high prediction accuracy； the UAV remote sensing inversion technology is applicable to the ammonia nitrogen concentration inversion of urban rivers， and the B1 band of multispectral data plays a key role in the model. The overall ammonia nitrogen concentration of each reach of Fuyang River Basin in Handan was from high to low in December 2020， August 2020 and May 2021， and it exhibited certain seasonal differences.

With the acceleration of global warming and urbanization， the frequency of urban impervious surfaces and extreme rainstorms has increased， resulting in frequent urban floods. Recent studies have indicated the effectiveness of low impact development （LID） at urban catchment scale in preventing urban flooding. Most of the past researches have mainly focused on the comprehensive impact of different configurations on urban flood risk reduction， such as the footprint ratio， placement location， and design parameters of LID facilities. However， there are few studies on the effectiveness of runoff control of LID facilities under different spatial placement strategies. A practical Urban Drainage System （UDS） of Xiushan Sponge City Demonstration Area in Chongqing is chosen as a case study and divided into three sections （upstream， center， and downstream） according to the catchment area. A combination of three typical LID practices， rain gardens （RG）， bioretention cell （BRC）， and permeable paving （PP）， is installed on one of these sections or the entire catchment under different rainfall scenarios. The SWMM model is used to evaluate the influence of spatial distribution effects of LID facilities on runoff control and the impact on the formation process of UDS urban flood points under different rainfall return scenarios， and improve the ability of sponge city construction to cope with urban flood risks. The results show that surface runoff and flooding volume were reduced significantly， while poor reduction on peak runoff was observed when laid out with individual LID practices， and the overall performance of LID practices was RG>BRC>PP. Results also confirm the combination distribution of LID facilities under different spatial placement strategies. Uniform placement strategy proves to be the best among the four strategies because of the maximum potential for flood mitigation. Other investigated spatial distribution scenarios have relatively potential for peak runoff mitigation under a low rainfall return periods （P≤5 a）. Furthermore， the mitigation effect of LID spatial distribution on urban flooding is significantly influenced by the distribution of pipe overflowing nodes. The placement of LID facilities nearer to the flooded locations maximizes the benefits in terms of urban flood alleviation and also reduces the probability of transferring hydraulic load to other parts of UDS. Therefore， factors such as the topology and hydraulic characteristics of UDS， the distribution of overflow nodes， and the design standards of LID facilities should be fully considered when the optimal location and proportion of LID facilities in the construction of sponge cities are determined.

The frequent occurrence of drought disasters in irrigation areas seriously restricts the development of local economy. In order to realize the rational allocation and utilization of water resources in irrigation areas， it is necessary for this paper to effectively predict the future drought situation in irrigation areas so as to take targeted preventive measures to reduce the impact of drought events. Based on the idea of decomposing and reconstructing， the VMD-GRU drought prediction model is established by combining the variational modal decomposition VMD （Variational Mode Decomposition） which can preprocess nonlinear and non-stationary time series with GRU （Gated Recurrent Unit）， and the standardized precipitation index SPI time series is established according to the monthly precipitation data of four meteorological stations in large irrigation areas in Zhaokou from 1981 to 2017， and the SPI value is predicted by using the established drought prediction model and three single prediction models. The paper adopts a three-month time scale. The results show that the average relative error of SPI value predicted by VMD-GRU drought prediction model in four meteorological stations is between 18.7% and 20.6%， and the prediction error is relatively stable. The mean absolute error MAE， mean square error MSE and root mean square error RMSE of VMD-GRU drought prediction model are the smallest among the four models， and the values of the three evaluation indexes of different meteorological stations are close to each other， so there is no over-fitting or under-fitting problem in the established model. According to the theory of run to identify drought duration and drought intensity and Kaifeng Meteorological Station， the prediction accuracy of drought duration from 1981 to 2017 reached 81.1%， and the overall fluctuation trend of actual drought intensity is basically consistent with the predicted drought intensity. Pearson correlation coefficient of the two series reaches 0.961， indicating that the established VMD-GRU drought prediction model can accurately predict the drought in irrigation areas and provide a reliable research method for droughts’ early warning in large irrigation areas.

The inflow shaft is an important part of the city deep tunnel drainage system. The water tongues of the traditional baffle inflow shaft alternately hit the shaft wall， which can easily cause unbalanced force and unfavorable vibration. In this paper， a baffle inflow shaft with symmetrically colliding water tongues is proposed， and an empirical formula for estimating basic parameters of baffles is derived. Through example design and CFD simulation， the flow characteristics， energy dissipation mechanism and effect are analyzed.In order to provide reference for future shaft design， the paper summarizes several basic principles of inflow shaft design. The results shows that the baffle inflow shaft with symmetrically colliding water tongues has sufficient overcurrent capacity and that the water doesn’t block the ventilation holes under normal operation.Colliding water tongues have a good effect of dissipating energy， and the structural force of shaft is balanced. The bottom sieve hole and the water cushion are matched to ensure the smooth connection between the shaft and the main tunnel. As the inflow decreases， the energy dissipation rate of the shaft increases.

The reconstruction and expansion of the ship lock is faced with the problems of limited space construction and security. It is necessary to comprehensively consider the balance between the enclosure function and the transformation of the ship lock function， safety and economy. By relying on the second line ship lock project， this paper summarizes the common engineering problems faced by reconstruction and expansion. A new type of double row continuous wall with rigid connection cushion cap and vertical front and rear vertical wall cofferdam structure system is developed and applied to the second line ship lock project of Mengli Water Control Project. The conclusions are as follows： ① A new structural system of double row continuous wall with rigid connection cushion cap and vertical front and rear vertical wall cofferdam is developed， and a computational mechanical model of the structural system is proposed， which effectively solves the problem of combining the triple functions of foundation pit retaining， cofferdam structure and navigation wall under narrow terrain conditions. ② Compared with the traditional retaining structure， the structure system can effectively reduce the depth of the foundation pit， the length of the cantilever section of the continuous wall structure， the embedded depth of the continuous wall at the bottom of the pit and its structural internal force， and optimize the thickness of the continuous wall. The upper part of the rigid connection cushion cap is backfilled with light permeable materials， and drainage holes are set on the front and rear vertical walls of the cofferdam， effectively reducing the thickness and reinforcement ratio of the front and rear vertical walls of the cofferdam. Combined with the construction process of diaphragm wall and cofferdam， large amount of earthwork backfilling and excavation are avoided， and the project cost is reduced. The development of the new cofferdam structure is conducive to solving the limited space construction problems faced by the reconstruction and expansion of the ship lock， and provides reference for similar projects.

The regulation and storage project of Miyun Reservoir is a key project ensuring the safety of water supply in Beijing， which greatly alleviates the tight balance between supply and demand of water resources in Beijing. In order to realize the economic operation of the project， the cascade head optimization distribution model is established based on the hydraulic model with the third stage pump stations （Guojiawu， Yanqi， Xiwengzhuang） of Miyun Reservoir Regulation and Storage Project as the research object， and the IAPSO optimization algorithm is used to solve the model. The results show that the efficiency of the head optimization scheme of the cascade pumping stations can be improved by 5.2% compared with the actual operation scheme under different water delivery flows for the water conveyance system of the cascade pumping stations with the combination of pipes and canals. The hydraulic loss between the steps and the rotating speed of the pump station will have a greater impact on the optimization results. This paper can provide an effective operation scheme for the economic operation of the cascade pump stations， and ensure the safe and economic operation of the water conveyance system of the cascade pump stations.

The solar constant temperature intelligent water supply system is designed for livestock to solve the problems of low water consumption， reduced diet， stunted growth and reduced physical performance of livestock in the cold winter climate of alpine regions. At the same time， the quality and economic efficiency of breeding has been improved.The system uses solar photovoltaic power generation to provide electricity for system operation，and solar heating to heat the water to the appropriate drinking temperature range to meet the needs of livestock drinking warm water in winter， and adopts temperature control module， infrared sensor， liquid level switch and other equipment to achieve solar heating and livestock drinking water automatic control and other functions. The results show that the system runs stably， the heat collection effect is obvious， and the energy required by the system is all from solar energy， energy saving and environmental protection， and the operation cost is low. Automatic drinking water control for livestock greatly reduces herdsmen’s labor and improves breeding conditions.

Irrigation-drainage channels have significant advantages such as saving land resources and water. Meanwhile， its safe operation and scheduling are more complex， especially in the case of emergency situations such as a sudden rainstorm. How to prevent risks and improve the utilization rate of rainwater and flood by optimizing regulation has attracted much attention. Based on the approach of unified representation in multiple processes， a typical irrigation area with dual use of irrigation and drainage is selected in the paper. At the same time， an overall simulation model of farmland-channel hydrodynamic processes is established to analyze the changes law of farmland/channels’ water depths and the water-saving amount with different water depths of farmland and different gate control schemes when a rainstorm occurs. The results show that the variation trend of water depths in farmland and channels is basically consistent with the rainfall process， and the variation range is affected by rainfall intensity to a large extent. The initial water depth of the field has a significant impact on the drainage time of farmland and channels. As the initial state of the field water layer increases by 1 cm， the drainage time of the field increases by about 8.5 h. The closure time of the diversion sluice at channel head has a significant effect on the water depth in the early stage of drainage. The scheme of gate regulation and control and initial water depth of field surface are jointly optimized in this typical region， which can shorten the continuous operation time of high water level by 24 h and save water by 46.8 m³/hm². All in all， the results of the paper indicate the law of farmland/channel drainage in the irrigation-drainage area， thus providing some reference for the formulation of an emergency scheme of irrigation-drainage channel under a sudden rainstorm.

With the increasing demand for bidirectional axial flow pumps in the process of wetland ecological protection and management， the development and design of bidirectional axial flow pumps has become an important topic. In order to investigate the influence of guide vane outlet angle on the bi-directional operation performance of axial flow pump， this paper takes an axial flow pump with specific speed of 903 as the research object， and uses the standard turbulence model of ANSYS CFX software to conduct constant and non-constant numerical simulations of five different guide vane outlet angles of bi-directional axial flow pump， and studies and analyzes the influence of guide vane outlet angle on the external characteristics， hydraulic loss， internal flow field， pressure pulsation. The results show that under the design conditions of forward operation， reducing the angle of the guide vane outlet can reduce the hydraulic loss of the guide vane and the area of the low-pressure area of the suction surface of the guide vane， the energy loss due to decurrent flow is also reduced， and the efficiency of the axial flow pump is obviously increased. In reverse operation， with the decrease in the placement angle of the guide vane outlet， the ability of the guide vane to recover energy also decreases， the hydraulic loss of the guide vane part increases， and the efficiency of the axial flow pump decreases. Changing the placement angle of the guide vane outlet can have a certain impact on the pressure pulsation in the axial flow pump during the forward operation. Properly increasing the guide vane outlet placement angle during the forward operation can reduce the amplitude of pressure pulsation in the axial flow pump to a certain extent and improve the energy loss. The placement angle of the guide vane outlet has no significant effect on the pressure pulsation amplitude when the bidirectional axial flow pump runs in reverse. Because the axial flow pump studied in this paper operates in two directions， combined with the situation that the efficiency changes in the forward and reverse directions are opposite， considering that the axial flow pump has a high efficiency operating range in the two-way operation， so when the guide vane outlet placement angle is 80°， the comprehensive performance of the two-way axial flow pump is optimal.

The ecological seawall is a new requirement in the new era. The interactions between different seawall sections and waves are different. The generalized model research cannot meet the needs of the actual disaster prevention effect research. The existing seawall projects in the Pearl River Estuary have slope type， composite type and other cross-section types. In order to explore the wave protection characteristics of four typical seawall sections， this paper studies the maximum wave pressure and overtopping conditions through physical model tests. The results show that the plants on the ecological seawall have obvious synergistic effect on the seawall wave protection and can effectively reduce the wave pressure on the seawall body compared with the traditional riprap seawall. The parapet wall on the top of the dike plays an important role in reducing overtopping. In most of the areas， the typical slope seawall can achieve ideal wave prevention effect. Regarding the area with sufficient space， the pressure on the cross section of the composite seawall with relatively small slope change of the embankment body is less， which is conducive to the stability of the embankment. The experimental results can provide the foundation for designing ecological seawall， and have important scientific and application value.

An accurate understanding of the hydro-wind-solar multi-energy complementarity law is of great significance to guiding the planning of clean energy and the optimal operation of multi-energy systems. In this paper， by using the method of mathematical statistics， statistics of daily standardized data of hydro-wind-solar power output in the Longyangxia Area of a typical year are calculated， and the complementary characteristics of hydro-wind-solar power output in a long-term time scale are evaluated. Furthermore， based on the daily standardized data in the Longyangxia area of a typical year， a Spearman rank correlation coefficient-based evaluation index of hydro-wind-solar complementarity is established， and the complementary characteristics of hydro-wind-solar power output in a long-term time scale are quantitatively re-evaluated， and compared with the results of mathematical statistics. In addition， this paper proposes a typical daily output feature identification model based on K-means clustering algorithm， and analyzes the influence of different time scale divisions on the evaluation of hydro-wind-solar output complementarity pattern. The results show that： ① the complementary characteristics of hydro-wind-solar power output in the Longyangxia area are stronger in longer time scales， with smaller hydropower output and larger wind-solar power output in spring and winter； while the summer and autumn seasons show the opposite characteristics； ② the evaluation result of the complementarity of hydro-wind-solar power output based on the Spearman rank correlation coefficient is “more complementary”， which is consistent with the results of the method of mathematical statistics；③ different time scales have significant impact on the evaluation of hydro-wind-solar complementary characteristics， with the increase in time scales， the complementary trend of hydro-wind-solar power output is enhanced. Specifically， the seasonal complementary characteristics are stronger than the inter-month complementary characteristics， and the inter-month complementary characteristics are stronger than the inter-day complementary characteristics.

Aiming at the coupling relationship between task， resource and time and optimal sequencing of dam concrete jump pouring， this paper develops a multi-cable crane scheduling model and method based on jump pouring sequencing. It decomposes the dam skip pouring task， analyzes the task change process of the cable crane working state， determines the hoisting， pouring and hoisting time series， establishes the cable crane scheduling model for dam concrete skip pouring， and formulates the optimal dam cable crane scheduling scheme under the skip pouring mode. The case analysis shows that the dam cable crane dispatching model can shorten the construction period and save production resources， increase the average hourly working time of cable crane by 4.88% and advance the overall construction period by 8.86%， which can provide theoretical support for the formulation of cable crane dispatching scheme.

In order to optimize the economic cost of anti-seepage system， this paper studies the influence of anti-seepage curtain size parameters and dam foundation parameters on dam seepage. By taking a deep overburden rockfill dam in Xinjiang as an example， the seepage model is established by self-programmed quasi-three-dimensional seepage analysis program. By using the sensitivity analysis method of progressive discrimination， a sensitivity analysis is carried out on the depth H of impervious curtain， thickness D of impervious curtain， permeability coefficient K _a of impervious curtain， permeability coefficient K _b of foundation and permeability coefficient K _c of transition zone， and the sensitivity order of each parameter is determined. Example analysis shows that H， K _a， K _b are more sensitive to the seepage flow rate of single width， and H， K _c are more sensitive to the seepage gradient of anti-seepage curtain. The significance level of parameter sensitivity is given quantitatively to improve the accuracy and reliability of sensitivity analysis， which can serve as a basis for a seepage analysis of the face rockfill dam on deep overburden.

Based on the criterion of filling relative density， the deforming compatibility and safety of a 300-meter high core rockfill dam are studied. Three-dimensional elastoplastic consolidation finite element analysis is carried out to evaluate the dam’s operational safety from the perspectives of deformation distribution， arching effect， hydraulic splitting and crest cracking. The results show that increasing the filling parameters of all zones blindly cannot improve the dam’s deforming compatibility. However， reducing the filling relative density of the transition zone appropriately and increasing that of the rockfill zone can induce a smooth transition of the dam settlement from the core wall to the rockfill shell. Meanwhile， weakening the arching effect of the transition zone on the core wall is beneficial to the dam safety against hydraulic splitting. The Leonards and finite element method are adopted to judge the cracks’ development on the dam crest， and it is considered that too low filling relative density in the rockfill zone is one of the necessary conditions for transversal cracking. According to the results， the theoretical and economical optimal schemes for dam filling are suggested.

Pumped storage units are characterized by complex structure， complex and variable operating conditions， and complex and diverse faults. It is still a challenge to effectively evaluate the deterioration state of pumped storage units and accurately predict the deterioration trend using real-time monitoring data. To this end， this paper proposes a method to predict the deterioration trend of pumped storage units based on Random Forest Regression （RFR）， Variational Mode Decomposition （VMD） and Temporal Convolutional Networks （TCN）. Firstly， based on the historical monitoring data under the health state， the working condition parameter data with strong correlation with the condition monitoring data are selected as the input of the health state model， and the RFR-based health state model is established. Secondly， the real-time working condition parameter data are input， and the deterioration trend series are calculated based on the standard values output from the health model and the real-time condition monitoring data. Finally， considering the nonlinear factors of the deterioration trend series， a time-series prediction model based on VMD-TCN is designed to achieve an accurate prediction of the deterioration trend. To verify the effectiveness of the proposed method， real monitoring data from a pumped storage plant located in Zhejiang， China， are collected for multiple comparison experiments. The results show that the proposed method achieves a fitting accuracy of 0.98 in building a health model and that the VMD-TCN-based time-series prediction model has higher prediction accuracy compared to other comparative models in the deterioration trend prediction task.

The air content of concrete mixture with different sand ratio， stone powder content， fineness modulus and particle gradation are experimentally studied. And the influence of the manufactured sand on the air content characteristics of concrete mixture is analyzed. The results show that the air content of concrete mixture increases with the sand rate in a certain range， and decreases with the increase in stone powder content and fineness modulus. When the particle content in the range of 0.15~0.3 mm mm particle size decreases， the air content of concrete mixture decreases significantly. While the air content of concrete increases significantly when the 0.3~0.6 mm particle content increases. The particle content in the range of 0.6~1.18 mm has little effect on the gas content. The research conclusion can provide a reference for the mix proportion of machine-made sand concrete.

The stilling pool with drop sill and sudden expansion is an environment-friendly energy dissipater， which can adapt to high water head and large unit width discharge， has a good application prospect. After the high-speed incident water flows into the stilling pool with drop sill and sudden expansion， it is involved in a large amount of air， forming the aerated water flow. The aerated characteristics are closely related to the turbulent structure. The existence of bubbles changes the hydraulic factors such as velocity， pressure and energy dissipation efficiency， and then affects engineering safety： the aerated pulsation affects the velocity pulsation and pressure pulsation， which may lead to the resonance damage of the building. In the process of the aerated jet impacting the bottom plate of the stilling pool， in severe cases， the collapse of bubbles will peel off the concrete floor and adversely affect the stability of buildings. At the same time， relevant studies show that aerated water flow will also reduce the cavitation damage of buildings effectively and enhance the energy dissipation effect of energy dissipaters. Therefore， we should fully understand the role and impact of aerated water flow on energy dissipaters， pursue advantages and avoid disadvantages， and ensure their safe operation. At present， there are many research results on the distribution characteristics and influencing factors of aerated concentration in water cushion energy dissipation， but there is little research on the characteristics of aerated concentration fluctuation. The characteristics of aerated fluctuation of three-dimensional mixed flow in the stilling pool with drop sill and sudden expansion are still unclear， and need to be further studied. Based on the physical model test， the aeration pulsation characteristics of a stilling pool with drop sill and sudden expansion are studied， the aeration pulsation amplitude characteristics， probability density distribution characteristics and frequency spectrum characteristics are analyzed. The results show that the aerated pulsation amplitude of the bottom plate of the stilling pool without sudden expansion decreases along the way， and the peak appears at the head of the stilling pool. The pulsation amplitude of aeration in the middle line of the stilling pool with drop sill and sudden expansion increases first and then decreases， the peak appears at the impact area. Compared with the stilling pool without sudden expansion， the stilling pool with sudden expansion can reduce the aeration pulsation intensity of the bottom plate significantly. The probability density curve of aeration pulsation on the bottom plate of stilling pool does not obey the normal distribution. The aeration pulsation energy belongs to low-frequency pulsation， which increases with the increase in the flow energy ratio. The largest aerated pulsation energy of the bottom plate of the stilling pool with drop sill and sudden expansion appears in the impact area. The existence of sudden expansion can reduce the energy of the aerated pulsation acting on the bottom plate effectively.

A back analysis of concrete dams can provide useful information for assessing the safety behavior of a dam. Traditional parameter inversion methods commonly use the weighted summation method to simplify the multi-objective functions established by combining various types of monitoring data and combining single-objective optimization algorithms to search for the optimal parameters. The subjective factor of determining the weights and the limitations of single-objective optimization algorithms in practical applications can lead to significant deviations in the inversion results. Therefore， this paper considers various types of monitoring data to construct different objective functions， combines NSGA-II algorithm to search for Pareto optimal solutions， and proposes a concrete dam parameter inversion method based on the PSO-BPNN model and multi-objective optimization. The research results are applied to the GD gravity dam and are compared and analyzed with the traditional back analysis method. The application shows that the method is more reasonable and accurate for the parameter inversion of concrete dams.

In order to adopt the scientific and effective support strategy forthe later stage of reservoir resettlement according to local conditions， the optimization system of late support strategy based on SWT-AHP method is established. By taking the actual situation of Nanxiong， Guangdong Province as an example， combined with field investigation， this paper analyzes the strengths， weaknesses， opportunities and threats of project support comprehensively. SWOT-AHP method is used to compare and analyze the strategic characteristics of the three modes of “infrastructure construction project support， industry support and productive project support.” The results show that OS strategy should be adopted to support productive projects on the basis of improving infrastructures. Suggestions are put forward to upgrade industrial structure， strengthen personnel training and promote high-quality modern agriculture. This method provides a reference for the innovative support strategy at the stage of reservoir resettlement.

Pelton turbines are often deployed in high-head areas of sediment laden rivers. The high-speed flow carrying sediment passes through the unit， causing erosion on the injector and buckets. For the purpose of exploring the hydraulic performance and sediment erosion characteristics of the injector for Pelton turbines， this paper numerically simulates the water-air-sediment flow in the injector for 500 MW Pelton turbine based on the VOF model and DPM model. The hydraulic efficiency and flow rate of the injector with different needle/nozzle angles are solved， the flow pattern and erosion characteristics of the injector under different openings are obtained， which are compared with the real hydropower plant. The results show that the control performance of the injector with 45°/62° angle combination is better than that with 54°/80° and 60°/90° angle combination. Under the design condition， the hydraulic efficiency reaches 98.5%， which is slightly higher than that of small capacity units. High efficiency can be maintained in the range of 60%~100% opening， and the efficiency decreases rapidly when the opening is less than 60%. As the opening decreases， the velocity gradient near the outlet rises and the jet diameter shrinks， there is a high-pressure zone at the tip of the needle and a “velocity deficit” zone at the center of the water jet. Meanwhile， three kinds of vortices in the injector and water jet are analyzed. The supporting ribs lead to the formation of attached vortex in the injector. Furthermore， this vortex accelerates the particle and results in asymmetrical erosion on the needle surface. The attached vortex at the outlet induces the uneven distribution of velocity and generates the air vortex which makes sediment particles escape. Besides， the friction between the surface of water jet and air causes the vortex of surrounding air and consumes the energy of water jet. This paper can provide references for the design and operation of large capacity Pelton turbines.