Carrying out water resource vulnerability assessment is an effective way to strengthen water resource management. Aiming at the problem that the linear expression of the connection number in the set pair analysis cannot accurately reflect the ambiguity and randomness existing in the water resources system， the cloud model is introduced to improve the calculation of the connection number in the set pair analysis. The analytic hierarchy process and entropy weight method are combined to calculate the combined weights of the evaluation indexes through the principle of maximizing variance， and the set pair cloud model of fusion weights is established. The model is applied in the water resource vulnerability assessment in the prefecture-level cities of Henan Province from 2010 to 2019. Moreover， the five-element subtraction set pair potential is introduced to analyze the development trend of water resource vulnerability in prefecture-level cities. The results show that there are three levels of water resources in Henan Province： mild vulnerability， moderate vulnerability and severe vulnerability. The distribution shows that the overall water vulnerability of the cities in the south and the west are lower， and the cities in the north and the middle are more vulnerable， mainly due to the lack of natural endowments and the high degree of development and utilization of water resources. The system situation of Xinyang， Sanmenxia and Zhumadian are in the trend of equilibrium potential or partial identical potential in most years， with a better state of water resources vulnerability than the remaining cities and a healthy development situation. In Zhengzhou， Jiaozuo， Kaifeng and other cities， the overall situation of system are in the trend of inverse potential or partial inverse potential in all years， so the development situation is severe， which belongs to the areas where water resources vulnerability need to focus on regulation.The implementation of the strictest water resource management system in Henan Province and the supply of water from the South-to-North Water Diversion Central Project have eased the pressure of water shortage， and the vulnerability of water resources has shown a downward trend since 2014， which is in line with the actual situation of Henan Province. The research findings can provide a decision-making basis for the rational development and utilization of water resources and the coordinated development of water resources， socio-economic and ecological environment in Henan Province.

To improve the accuracy of the medium-term runoff forecasting of the watershed， a multi-model fusion method of medium-term runoff prediction method based on machine learning is proposed， which is applied to the Huanren Reservoir Basin. Firstly， BP neural network model， multiple linear regression model， and support vector machine model are used to forecast the ten-day runoff. The above models are merged based on information entropy， BP neural network， and SVM. Then， a ten-day runoff forecasting model for the spring flooding period that considers the snowmelt effect is constructed.Three error evaluation indicators， MAE， RMSE and QR， are introduced to evaluate the runoff forecasting accuracy of each model in the flood and non-flood periods. The results in Huanren Reservoir show that all models can accurately simulate the runoff change process， but the single forecasting models are poorly fitted in the peak section. The information fusion models based on machine learning algorithms can well combine the advantages of different forecasting models， and outperform each single forecasting model and the fusion model based on information entropy， which can improve the runoff forecast accuracy for 10 periods throughout the year and increase the forecast qualification rate to 100% for 6 periods with a maximum increment of 24%. The ten-day runoff forecasting model considering the effect of snowmelt has a passing rate of over 90% in both March and April， improving the non-flood runoff forecasting capability of the basin.The proposed information fusion prediction method based on machine learning can obtain runoff prediction models with high accuracy and reliability， providing data support and theoretical support for runoff forecasting work and efficient water resources management in the Huanren Reservoir.

The trend-caused nonstationarity of the hydrometeorological time series in the context of climate change will pose a signifiacnt impact on the optimization results of the hydrometeorological gauge network. This paper establishes a C-Vine copula entropy-based multi-objective gauge network optimization model to analyze the daily precipitation time series of the Yellow River and the Huaihe River Basin. Through the constructed optimization model， the rank of each station in two basins under different window width conditions is analyzed， and the influence of the trend degree of rainfall series on the optimization results is analyzed quantitatively. The results show that because Archimedean Copula is only suitable for describing the multivariable dependence structure of positive correlation， C-Vine Copula Model is able to achieve the better estimation of total correlation， which is just the actual network information redundancy， especially in the case of high dimension. The annual variation of rank of the Huaihe River Basin with a larger trend is more significant than that of the Yellow River Basin station network with small trend degree， and the trend-caused nonstationarity of the series increases the uncertainty of the evaluation results of hydrometeorological station network.Different time domain ranges may have different effects on the station network design results， which means that the best network design may only be applicable to specific observation periods. Therefore， this study shows that it should be very cautious in dealing with the optimization of hydrometeorological gauge network， because under the other identical conditions， the elimination or addition of some stations based on the fixed whole series will lead to the loss or redundancy of hydrometeorological information of the whole gauge network. The optimal design of station network should make it more suitable for the changing hydrometeorological conditions.

The physically-based distributed hydrologic model（ GSSHA model ）develops a one-dimensional Richards’ infiltration equation based on saturated or unsaturated zone to describe the soil water infiltration process. Richards’ equation is more accurate in describing soil water movement. However， a large number of parameters lead to certain difficulties in practical applications. In this paper， the sensitivity of the eight parameters， which have clear physical meaning and significant influence on runoff and concentration calculation in GSSHA model， is analyzed. The control variable method is used to simulate and compare with about ten different values of single parameter. The ratio or difference between simulated maximum values and minimum values of peak discharge and peak time is used as a criterion to judge sensitive parameters. Then the sensitive parameters of peak discharge and peak time are selected and sorted. Huangjiahe watershed in the southern part of Ningxia is selected as the research area. 18 flood events from 2000 to 2015 are simulated， of which the first 13 events are calibration period and the rest of 5 events are validation period. The application effect of GSSHA model in semi-arid areas is studied with the parameters calibrated based on the principle of runoff depth first and peak discharge then. The result of parameter sensitivity analysis show that the saturated hydraulic conductivity， bubbling pressure， and initial soil moisture are the highest sensitivity to peak discharge， and these three parameters are also the parameters with the highest sensitivity to peak time. GSSHA model has high simulation accuracy for the flood events in Huangjiahe watershed in both calibration period and validation period. The relative error for runoff depth， the relative error for peak discharge， the relative error for peak time， and Nash efficiency coefficient in the calibration period are 3.51%， 10.84%， -0.77 and 0.80， the values in the validation period are 2.18%， -6.98， 0 and 0.79.

The refined and optimal allocation of water resources is an important means for the sustainable utilization of water resources. Describing the high spatial complexity of water resources system and the time-varying characteristics of water command and supply elements accurately is an important and difficult problem to be solved in establishing the refined and optimal allocation model of water resources， which has not been well solved at present. In view of this difficulty， this paper establishes a refined and optimal allocation model of water resources in the basin on two scales of space and time. At the same time， it also considers the influence of reservoir storage requirements， evaporation and leakage loss， backwater relationship between water command and water supply nodes on the accuracy and applicability of the model. The water supply units and water command units in the basin are classified， and the constraint conditions are established for different types of units. Taking the minimum water shortage as the optimization criterion， the refined and optimal allocation model of water resources in the basin is established and solved by linear programming. The conclusions of the practical application in Nanpanjiang River Basin are as follows： ① the satisfaction rate of rural water and urban water in the basin is 100%， the satisfaction rate of agricultural water is 97.7%， and the satisfaction rate of industrial water is 82.4%. Considering the requirement of reservoir impounding at the end of the year and the restriction of pipeline， some agricultural and industrial water consumption joints are short of water， and fine allocation on two-way scale of time and space has been realized on the whole. ② The total evaporation loss of Heitan Reservoir accounts for 6.6% of the initial reservoir capacity， and the monthly total backwater flow in agricultural water consumption of Bailang Irrigation Film accounts for 25% of the actual water flow， which indicates that factors such as evaporation leakage loss of reservoir and backwater flow have an important influence on the optimal allocation of water resources. ③ The model accurately describes the complex relationships among the nodes in the water resource system， which can provide a guidance for the scheme formulation of optimal allocation of water resources in complex watershed.

Climate change leads to more extreme weather around the world， resulting in significant affects on human societies and natural ecosystems. The encounter probability of catastrophic floods in Upper Yangtze River and in Dongting Lake Basin is increasing， causing higher risks of disastrous floods. This study summarizes the literature of flood occurrence and flood control strategy in Dongting Lake Basin. Besides， the deficiencies existing in flood risk management are elaborated. The main problems in the flood control of Dongting Lake Basin are as follows： there is a gap between the flood control planning of the middle reaches of the Yangtze River and the actual safe discharge of the river channel and the scale of flood storage and detention area. Since the operation of the Three Gorges Reservoir， the long-term operation of exceeding the flood limit water level has reduced the flood discharge capacity of the river channel， and the problem of bank collapse caused by washing with clean water is prominent. The construction of flood storage and detention area has lagged behind seriously for a long time， and the safety facilities are weak. The level of informatization and intelligence of joint dispatching of water projects is not high and cannot meet the needs of comprehensive dispatching. For these reasons， it is concluded that the flood control is still a main task of development and protection of Dongting Lake Basin. In the light of the above problems， it is proposed establishing a perception layer based on point， line and area， which can timely obtain the data resources required for flood prediction， intelligently process data through cloud computing， optimize flood control resources， and a multi-dimensional flood control strategy for the Dongting Lake Basin is proposed by engineering and non-engineering means so as to achieve the purpose of disaster prevention and reduction， then lay the foundation for the realization of “forecast， early warning， rehearsal and plan”. The research serves as an important guidance and reference for the formulation of the overall flood control strategy in the middle and lower reaches of the Yangtze River and the Dongting Lake Basin.

The government departments and institutions are the industry with the largest water consumption and the highest proportion of water in Beijing’s public service industry. In view of the characteristics of difficult control of water consumption and strong uncertainty of influencing factors， it is necessary to formulate provincial water quota covering major water use industries and gradually control water efficiency within the quota range. Based on the sample statistical data and water efficiency comparison， the appropriate water quota indicators of departments and institutions are scientifically screened. On this basis， the sample scores of 483 departments and institutions in Beijing are calculated， and the values of general and advanced grading quota standards are calculated so as to provide a reference for the revision of local water quota standards and the improvement of water-saving policies in Beijing.

In recent years， extreme climate events have occurred frequently in China. Studying the laws of extreme climate change can prevent the harm caused by natural disasters to human life and the imbalance of water resources distribution. The Yalong River has important hydropower energy in China. Based on the daily rainfall and temperature data of Yalong River Basin from 1961 to 2018， 26 extreme climate indexes are calculated， and the trend and mutation of extreme climate indexes are analyzed by linear fitting， Sen’s slope estimation， Mann Kendall Catastrophe Test and Pettitt Test. The inverse distance weighted spatial interpolation method （IDW） is used for spatial interpolation to analyze the spatial distribution characteristics of extreme climate indexes. The results show that the extreme high temperature， low temperature and average temperature difference index in the Yalong River Basin are high in the south and low in the north； The temperature in the north of the basin is cold， and the number of freezing and frost days is long， while the temperature in the south is warm， and the number of summer days and the length of growth period are long. In addition to the continuous dry period， the extreme precipitation index is also high in the south and low in the north in space， and reaches the maximum in the southeast. Under the trend of global warming， the maximum and minimum temperature extremes rise， and the high-temperature growth rate is less than the low-temperature growth rate， so that the temperature difference gradually decreases. The number of freezing and frost days decreases， the number of summer days， the length of growth period and the duration of warm days increase， making winter shorter and summer longer in the basin， and the temperature duration suitable for animal and plant growth increases. Except for the continuous dry period， the extreme precipitation index shows an upward trend. The annual precipitation increases the most， followed by heavy precipitation. It indicates that from 1961 to 2018， the extreme temperature in the Yalong River Basin tended to be warmer， the number of warm days in the year increased， the extreme precipitation increased as a whole， the precipitation and precipitation intensity increased， and the precipitation duration lengthened. It is also necessary to prevent the increase in extreme precipitation in the Yalong River Basin. The study of the space-time change law of extreme climate in Yalong River Basin provides a scientific basis for the development and management of water resources and disaster warning in the basin.

For water supply reservoirs in parallel，through the mutual connection of common users， it is necessary not only to determine the water supply decision according to the state characteristics of each member reservoir， but also to reasonably allocate common tasks of water supply according to the state characteristics of each member reservoir. Considering the allocation of common tasks of water supply for inter-basin reservoir groups， in order to formulate scientific， effective and reasonable， balanced and equitable inter-reservoir allocation rules for common tasks of water supply， and seek optimal operational strategies for common scheduling rules of reservoirs in parallel， the way in which a reasonable balancing curves are formulated， the distribution proportion of common tasks of water supply is determined to show the optimal allocation rule in the different scheduling period of reservoirs， the mutation point and slope are used to described the segmentation of balancing curves， and changes in water storage and supply of reservoirs during flood seasons and non-flood seasons are characterized. The optimization model is established with the minimum water shortage rate and the minimum water abandonment as the objective functions to modify the allocation rules. Finally， the particle swarm optimization algorithm based on immune evolution is used to calibrate the mutation points and slopes of the decision variables of the balance curve， and finally the relatively excellent water supply rules are obtained. The reservoir groups use the downstream of the Luanhe River as an example， the research findings show that the suggested method can achieve operation goal effectively， divide common tasks of water supply reasonably and also improve computational efficiency of common tasks of water supply of reservoir groups. The reasonable balancing curves are formulated to allocate the common tasks of water supply of reservoirs in parallel. The water supply of the reservoir groups system increases by about 5% compared with the compensation control， and the amount of abandoned water decreases by about 10%， which is close to the maximum water supply， annual average abandoned water and guarantee rate obtained by dynamic planning. The distribution ratio of water supply tasks between reservoirs is close to the ratio of its beneficial reservoir capacity， the member reservoirs have larger water supply capacity and higher synchronization of storage rate of member reservoirs， and reflects the rationality and superiority of the balancing curves to a certain extent.

Phenology reflects the responses of ecosystem to climate change， and is considered as a major indicator of terrestrial ecosystem changes. As one of the most important phenological indicators， the trend of green-up dates （GUD） has an important impact on the water and carbon processes of the ecosystem. A number of studies have shown that the change direction and amplitude of green-up dates （GUD） depend on the climatic conditions of the region. The upper Minjiang River （UMR） is a typical mountainous watershed in southwest China， where vegetation has a vertical distribution pattern，and climate has a warming-drying trend. In this study， based on the MCD12Q2 products， the green-up dynamics of the major three vegetation types in UMR from 2001 to 2016 and its driving factors are analyzed by tendency test and or relation analysis. The results show that the average GUD are DOY 124.5±12.5， 105.0±14.5 and 113.2±10.5 for grass land （GL）， mixed forest （MF） and deciduous broadleaved forest （DBF）. The vertical distribution of the average GUD in UMR has obvious altitude differences. The average GUD has increasing trends with altitude for the three vegetation types. The GUD shows significantly decreasing trends （p< 0.05） for both GL and DBF， and insignificant decreasing trend （p> 0.05） for MF. The altitude boundary line of 3 500 m is found for the GUD trend distribution， above which the advancing rates of GUD are significant and higher. The advances of the GUD for the three vegetation types in the UMR during 2001-2016 mainly results from the warmer and drier spring climate， and the minimum temperature and precipitation in March and April are main driving factors. The research findings can serve a further research on the ecological process of ecosystem in UMR.

To identify the water environment problems in small mountainous urban watersheds， this paper seeks appropriate solutions. By taking the DS Creek in a mountain city as an example， its water quality and quantity characteristics and corresponding environmental problems are studied. The results show that the comprehensive pollution index qi of the upper， middle and lower reaches of DS Creek is 0.78， 1.9 and 1.65， respectively. And the main pollutant is the discharge of sewage along the creek. Every year， it’s about 560 000 m³ sewage water and 4.06 million groundwater that finally runs into the wastewater treatment plant， and about 990 000 m³ mixed rainwater and sewage discharges into the Yangtze River. Based on the above analysis， a comprehensive water environment management engineering system in mountain urban watersheds is constructed with the core concept of “mountain water diversion - sewage diversion - ecological restoration - intelligent flow interception.” It is also expected that this case study can provide a reference for the water environment management of other mountain cities， and improve the water ecological environment as a whole.

In order to explore variation law of hydrodynamics in tidal branching channels， this paper investigates the changing features and mechanisms of ebb-tide and flood-tide partition ratios within two branches of waterways of the Chengtong reach of the Yangtze River under varying runoffs and tide forces by using measured hydrologic and topographic data during the wet season in 2004 and the dry season in 2005. Results show that variations of ebb-tide and flood-tide partition ratios in the two branches of the waterways under varying relative tidal level and a certain runoff discharge are determined by the decline-growth rates of tidal current velocities in the two branches， while the variations of the ebb-tide and flood-tide partition ratios in two branches of the waterways under varying runoff discharge and a certain relative tidal level depend on paths of ebb-flow axes， deflecting effects on the flow of alongshore nodes， flood tidal levels and flood tidal velocities under different confrontation strengths between runoffs and tides.

The threshold of water exploitation index is a controlling indicator for water stress assessment， risk control and comprehensive management. Although the threshold which is usually set as 40% of the ratio of annual water withdrawals to annual available water resources has been widely used in water resources arrangement， its justification has not been fully explained. Furthermore， the threshold is always a constant and fails to reflect the uneven spatial and temporal distributions of water resources， so it is a challenge to implement the threshold in the practice of water resources management. According to the complementary relationship between the threshold of water exploitation index and ecological flow， a modified Tennant Method based on multilevel habitat conditions（MTMMHC Method）is adopted to estimate the ecological flows in Hanjiang River Basin on the basis of simulated runoff from SWAT Model. And dynamic thresholds of water exploitation index are determined by the complementary relationship. The results show that the MTMMHC Method can simultaneously consider the intra-annual and inter-annual variabilities of flow and reflect the difference of flow in wet， normal and dry years， and the thresholds of water exploitation index based on the MTMMHC Method in each sub-basin are different in Hanjiang River Basin. In addition， most of the thresholds of water exploitation index corresponding to the optimal ecological flows are less than 20% and are obviously lower than the so-called international standard of 40%. The proposed method is based on the complementary relationship between the water exploitation and the ecological flow， and it has taken the unevenly spatial and temporal distributions of water resources as a dynamic metric for water resources management.

The spatial distribution of vegetation groups in river channels has an important influence on the upstream and downstream flow characteristics and the riverbed evolution of vegetation groups. In order to study the influence of different arrangements of vegetation groups on flow structures， a flume experiment is designed under the condition of the fixed bed. PVC cylinder is used to simulate two identical rigid non-submerged vegetation groups， and four groups of different distances between upstream and downstream vegetation groups are set up. By studying flow velocity and turbulence intensity distribution， the formation and development process of upstream flow adjustment length and wake are analyzed under different spaces between upstream and downstream vegetation groups， and the effect of individual vegetation on flow structures is compared. The results show that upstream vegetation groups shorten the length of downstream vegetation groups’ front adjustment zone， which has nothing to do with vegetation group spacing. With the emergence of upstream vegetation groups， the overflow velocity of downstream vegetation groups， the length of wake stabilization zone and the velocity of stabilization zone all decrease， and their sizes are related to the spacing between vegetation groups， and the smaller the spacing is， the smaller each value is. At the same time， the length of wake formation zone of downstream vegetation groups became shorter， and decreased first and then increased with the increase of spacing. The wake recovery rate of the downstream vegetation groups changed more rapidly with the emergence of the upstream vegetation. The existence of upstream vegetation groups intensified the wake turbulence of downstream vegetation groups， and the change trend was also related to the spacing of vegetation groups. Vegetation groups have both inhibiting and promoting effects on water flow， mainly depending on the intensity of turbulence in front of vegetation groups. The effects of different longitudinal spacing of vegetation groups on river flow structure were investigated， which provided a supplement for the effects of spatial distribution of vegetation groups on river flow characteristics.

In the lower reaches of the Huaihe River Basin， there is a large range of plain water network area， with staggered terrain and dense water system and polder. The Lixiahe Region in Jiangsu Province is its typical representative. Affected by regional rainfall， highland water enters the low-lying area quickly， and polder drainage water mix， jointly raise the rivers water level， cause floods， from the flood and waterlogging， both the surrounding highlands to low-lying polder caused by flood disaster， also have low-lying polder drainage to the polder itself and the upstream highland waterlogging flood disaster. In the face of the complex flood situation， the primary task is to construct a water network pattern that adapts to the location and terrain characteristics and meet the multi-destination drainage area so as to provide possibilities for multi-target utilization. This paper carries out water network planning with the help of resilience theory， seeks the combination of flood control and drainage management scheme with avoidance， recovery， adaptations and utilization， and discusses the realization method from the perspective of optimizing the structure and function of water network. The construction method of resilient water network driven by flood is studied， and the hydrological-hydrodynamic numerical model is established to evaluate the flood control and waterlogging capacity of the existing engineering system and compare the efficiency of planning measures. Regional flood conversion mechanism and existing problems are summarized， flood impact factors are analyzed， resilience object of rivers-lakes-channels-polder and connotation are identified， the scheme is planned， the scale of polder and canal system layout is controlled. The model calculation shows that the single measures can reduce the storage level of the water network and improve the drainage efficiency； the strong to weak effects ranking are river treatment. From the perspective of system governance and influence correlation， at least two combined measures are recommended； the comprehensive scheme significantly reduces the drainage water level of the rivers network. Compared with the current situation， the scheme can reduce DAHWL of the hydrological stations by 0.28~0.36 m， and the water network is good at flood control and drainage， meeting the design standard. On this basis， through the layout of rivers and lakes connectivity scheme， lakes are divided according to functional utilization， mainly by comprehensive utilization， flood detention and ecological restoration， realizing multi-functional coordinated and integrated development， and laying a foundation for multi-objective utilization such as water quality improvement. The study reveals the combination of planning measures such as remodeling of water network spatial pattern， storage capacity， improvement hydrodynamic and hydrological process regulation， which forms the main content of building resilient water network and provides a reference for water network governance. Resilience theory provides a new paradigm for plain water network planning and governance.

The fluctuating characteristics of flow pressure during pipeline transportation reflect the degree and energy of turbulence in pipe flow， fluctuation pressure has a significant impact on the safety and stable operation of pipeline transportation. In this study， the research team self-designed a physical model test device based on the research background of pipeline clean water coarse particle transportation. The hydraulic transport process of coarse sediment under different adverse slope angles of the pipeline is simulated by model experimental device. The fluctuation change of solid-liquid two-phase flow in pipeline transportation is obtained by analyzing the distribution diagram of instantaneous pressure and fluctuating pressure in the pipeline at different angles. The research team analyzes the change rules of the instantaneous pressure， time average pressure， amplitude distribution of fluctuating pressure and frequency spectrum characteristics of the pipe wall under different adverse slope angles. The experimental results of the physical experiment model device show that the fluctuation of solid-liquid two-phase flow in pipeline transportation increases significantly with the increase in the adverse slope angle of the pipeline， and the variance distribution diagram of the fluctuating pressure intuitively shows the trend of the fluctuating pressure volatility. When the inclination angle of the pipeline is increased， the time average pressure and instantaneous peak pressure of fluctuating pressure decrease with the increase in the inclination angle. With the increase in the inclination angle， the general trend of fluctuating peak pressure on the pipe wall increases gradually； the amplitude distribution law of fluctuating pressure conforms to the Gaussian distribution， and it is universally acknowledged that the Gaussian distribution function can be used to fit the amplitude distribution of fluctuating pressure. With the increase in the tilt angle， the amplitude of fluctuating pressure increases gradually relatively， and the shape of the probability density function of fluctuating pressure has gradually developed from “tall and thin” to “short and fat”. The dominant frequency of the power spectrum function of fluctuating pressure is mainly concentrated in the main frequency range of 25 Hz. As the inclination angle of the pipeline increases， the dominant frequency of fluctuating pressure gradually develops to a larger frequency， and the overall change trend of fluctuating pressure is small in general.

Reclaimed water has been widely used to restore rivers and lakes in water scarce areas. The hyporheic layer， which is an important interface between the surface of the water and groundwater， is an active ecotone in a river ecosystem. In order to figure out the distribution of temperature and flow field of hyporheic layer in riparian zones under the influence of temperature water， a real-time monitoring of water temperature and water level was conducted from September 2013 to January 2014. The temporal and spatial variation of temperature in the hyporheic layer is analyzed in this study. The corresponding influencing factors are also discussed. Three different methods are used to calculate groundwater flow rate， including Hatch phase method， Hatch amplitude method and hydrodynamic method， respectively. The results of the calculation via different methods are compared and discussed. The results show that ground temperature of vadose zone increases gradually with the increase in soil depth， and it varies dramatically with time. Air temperature and water contents are the major factors affecting vadose zone temperature in the hyporheic layer. Groundwater temperature decreases with increased depth， and it changes gently with time. The variation trend of groundwater temperature with depth is different from that in the vadose zone temperature. The groundwater flow rate ranges from 6.34 to 8.36×10^-5 m/s， 0.61 to 1.01×10^-5 m/s and 6.74 to 7.74×10^-5 m/s during the observation period， according to the Hatch phase method， Hatch amplitude method and hydrodynamic method， respectively.Compared to hydrodynamic method， groundwater flow rate obtained from the Hatch phase method and Hatch amplitude method shows a lag in time. Among three methods， the Hatch phase method has the highest accuracy. The results also show that the groundwater flow rate decreases with depth. For three different methods， the variations of groundwater flow rate show a similar trend. The study on hyporheic zones and hyporheic exchange mechanism will impose significant effects on assessing the development and utilization of water resources， and on maintaining and restoring the health of a river ecosystem.

This paper comprehensively analyzes the changes of meteorological elements and reference crop evapotranspiration （ET₀ ） under the influence of aerosol in Luoyang during an air pollution process in western Henan from 20∶00 on June 15 to 8∶00 on June 20， 2016. WRF-Chem bidirectional feedback test is used to quantify the changes， and the accuracy of simulation results is verified by meteorological observation data， so as to further analyze the influence of aerosol on ET ₀ and its mechanism. The research findings show that in this process of air pollution， the PM_2.5 concentration in Luoyang is generally high， and that the peaks mostly occur in the morning and evening. The PM_2.5 concentration in the northeast of Luoyang is generally higher than that in the southwest. The presence of aerosol changes various meteorological elements in Luoyang， which leads to the change of ET ₀， and the ΔET ₀ of each site is between -0.23~0.33 mm/d. Affected by aerosol， the variation range of ET _{0 - d} is -0.26~0.04 mm/d， which is more than that of ET _{0 - n} （-0.08~0.02 mm/d）. The variation of the aerodynamic term （ET _{0 - A}） at each site is more than the radiation term （ET _{0 - R}）， which also dominates the variation of ET ₀ in various parts of Luoyang.

Pump stations are widely used and consume huge amounts of energy. Parallel pump stations are a common arrangement of pump stations. Research on optimal flow distribution schemes for parallel pump stations is of great significance to energy saving and consumption reduction in pumping stations. However， in current researches， electricity costs are considered too much， and the consideration of non-electricity costs is insufficient. In this paper， considering the electricity costs and other non-electricity costs， the dynamic programming method is used to construct the optimal flow distribution model between parallel pump stations considering the cost of non-electricity water transfer. Two stations in Suining are operated in parallel. The application results show that： ① when the proportion of non-electricity cost is low， it has no effect on the traffic optimization scheme， and when the proportion of non-electricity cost reaches the threshold of 65%， it has a strong guiding effect on the distribution scheme. ② When the proportion is low， the hardware constraints of the units determine the flow distribution method between the parallel pump stations. However， as the proportion of non-electricity cost increases， the influence of unit hardware constraints is weakened， so that non-electricity cost begins to dominate the inter-station flow distribution method of parallel pump stations， and this change first occurs in the case of high lift. The findings show that after reaching a certain threshold， the non-electricity cost has an important impact on the optimal operation plan of the pumping station group， and it needs to be included in the optimization objective in the optimization scheduling process.

The technique of ridge planting and furrow sowing and sprinkling irrigation has obvious effect on the superposition utilization of precipitation and irrigation water， and is suitable for the well irrigation agricultural area in the north. By measuring soil moisture change， soil temperature change， dry matter accumulation and distribution， yield， water use efficiency and benefit under different irrigation treatments， the mechanism and effect of different irrigation treatments on soil moisture and soil temperature and water and heat efficient utilization of oil sunflower are analyzed. The results show that ridge and furrow seeding can reduce evaporation between trees， make full use of winter irrigation water storage and limited irrigation water resources， and improve water use efficiency. Compared with CK（effect of the culture sprinkler irrigation）， the variation range of soil temperature is smaller and more gentle， and the regulation effect of soil moisture and heat is obvious， which improves the utilization efficiency of water and heat， and promotes the formation of oil sunflower yield. The dry matter accumulation of T3（furrow seeding sprinkler irrigation， irrigation quota of 36mm） and T4 （furrow seeding sprinkler irrigation， irrigation quota of 42 mm）in ridge and furrow treatment is higher than that in other ridge and furrow treatments and CK treatments， which increases the total photosynthetic products and the accumulation of economic products. Under the condition of suitable irrigation quota （T3）， the oil sunflower yield is 6.1% and 8.3% higher than CK， the water use efficiency is 0.34 and 0.54 kg/m³ higher than CK， and the net output value is 6.7% and 10.2% higher than CK. In the practice of oil sunflower planting and production， it is suggested that the irrigation quota should be 28 mm， and the irrigation frequency should be kept at 3~5 times according to the climatic conditions.

In recent years， the construction of long-distance water transmission pipeline projects in Xinjiang has been developing rapidly， steel pipes （SP pipes） and prestressed concrete cylinder pipes （PCCP pipes） are widely used. Due to the large number of landform units and complex geological conditions in Xinjiang， engineering construction is generally faced with the test of high earthquake， severe cold， and corrosive soil environment. In addition to considering the factors of large flow and high pressure in pipeline design， pipeline design also needs to focus on the damage caused by water， soil and other erosive media. This paper introduces the mechanism of soil corrosion and cathodic protection methods， emphatically introduces the relevant progress in the field of cathodic protection engineering， and summarizes the necessity and technical application of cathodic protection. The development of cathodic protection technology is summarized in combination with several engineering water pipeline examples， and the key technologies of cathodic protection technology development and the key points that need further attention in the future are put forward.

To promote the development of technology modernization and irrigation water management modernization in Jiangxi Province and provide more accurate and timely crop water demand forecast data support for real-time irrigation decision-making， this paper develops a daily rice water demand forecast and web-based release system in Jiangxi Province. The system uses the relational data management system MySQL to obtain the parameters and basic information required for the calculation of the rice water demand forecast model by using calibrated Hargreaves-Samani （HS）， Blaney-Criddle （BC） and McCloud （MC） models， and crop coefficient to predict the ET _c value of crop evapotranspiration at 26 meteorological stations in Jiangxi Province in the next 7 days. Users can login to the website to check ET _c forecasts for any site， any stage of rice growth， and any model. The website page is simple and easy to use. In general， the four calibrated models have good forecast accuracy and can be used to forecast the water requirements of rice in the whole province， laying a scientific foundation for irrigation decision-making toward water saving.

The river-reservoir connection project in “Mengkaige Area” is a key project for the optimal allocation and unified dispatching of water resources in central cities in southern Yunnan including Nandong Primary Pumping Station， Nandong Secondary Pumping Station and Changqiaohai Pumping Station. Studying the unit commitment of pumping stations will help to reduce the operation cost of the project. Taking the minimum energy consumption of pumping stations as the goal， this paper constructs the optimal unit commitment model of three pump stations， and solves the model by genetic algorithm （GA） and differential evolution algorithm （DE/rand， DE/best）. The results show that the DE/rand algorithm has better solution effect， larger search space and strong stability and is suitable for solving the optimal unit commitment models of river-reservoir connection project in “Mengkaige Area”. The optimal operation process will maintain the minimum number of start-up units. When the total flow is at the start-up critical point， the total power will increase sharply. The optimized unit commitment modes improve the operation efficiency of the pump stations and reduce the operation cost， which can provide a reference for the pumping station economic operation of the river-reservoir connection project in “Mengkaige Area”.

In order to study the influence of shunt blade wrapping angle on solid-liquid two-phase flow in low specific speed centrifugal pump. This paper uses the mixture multiphase flow model and ANSYS CFX software to simulate the solid-liquid two-phase flow of five low-specific speed centrifugal pumps with different blade angles. The influencing factors of low specific speed centrifugal pump efficiency， head， static pressure distribution， solid phase volume fraction and radial force with different blade angles are discussed. The results show that the efficiency reaches the highest when the shunt blade envelope angle φ=70° under clean water conditions， and decreases with the increase in the shunt blade envelope angle under the solid-liquid two phase condition. The solid particles are mainly distributed on the back of the blade. With the increase in the shunt blade envelope angle， the solid particles on the shunt blade gradually spread to the inlet of the impeller， and the distribution of solid particles on the main blade is basically unchanged. Too large or too small cladding angle of the shunt blade is not conducive to reducing the pressure pulsation and radial force of the centrifugal pump， and there exists the optimal cladding angle of the shunt blade φ=70°.

Rotor is one of the important components of centrifugal pump， which is of great significance to the detection and diagnosis of rotor running state. The characteristics of faults caused by unbalanced and misaligned rotor faults are similar. In order to effectively identify the two rotor faults of centrifugal pump rotation， the influence of location selection of different measuring points on distinguishing faults is effectively understood. Sensors are arranged on the inlet flange of centrifugal pump for signal acquisition， and the time-frequency domain characteristics of the original signal are extracted. The random forest algorithm is used to screen out 6 features with high importance， and the classification results obtained by the random forest are used as the input of PSO-SVM， so as to distinguish the faults of normal， misaligned rotor and unbalanced rotor. At the same time， the fault recognition rate of this method is compared with that of traditional PSO-SVM. The results show that the PSO model has fewer iterations and higher recognition rate， and the recognition rate of faults reaches 99.36%.

In order to explore the influence of the uncertainty of seismic load and structural resistance on the seismic performance of offshore wind turbine support structure， this paper establishes a simplified nonlinear numerical model of tower-pile foundation-soil by using OpenSEES software. The active learning reliability method based on Kriging Model and Subset Simulation Method （AK-SS） is combined with the Capability Spectrum Method （CSM） to study the reliability changes of support structures under different seismic impact conditions in the service life， and the influence of the thickness， buried depth， diameters， and internal friction angle of sand on structural reliability. The results show that AK-SS is more accurate and efficient than other reliability calculation methods such as Subset Simulation Method （SS）. The mode combined distributed loading mode （SRSS） is suitable for the offshore wind turbine support structure controlled by multiple modes. The rare earthquake condition is the dangerous control condition of the structure， and the mud surface displacement exceeding the critical value is the main failure mode. However， for any failure mode， the structure meets the target reliability requirements before the end of the service period. Compared with the buried depth， the thickness and diameter of the foundation are the control factors of the seismic performance of the structure. The geometric dimension of the pile foundation should be reasonably selected in the design.

With the wide application of offshore wind turbines with large diameter monopile foundation， the axial bearing characteristics of pile foundation and the influence of soft soil in complex geological conditions need to be further studied. The finite element software ABAQUS was used to carry out a series of numerical calculations in this study. Firstly， the different evaluation criteria of ultimate bearing capacity are compared， and the sensitivity analysis of the influence of soil parameters was carried out. Finally， the influence of location and thickness of soft soil layer on bearing characteristics was discussed. The calculation results show that the vertical bearing capacity determined by the load-displacement curve of the pile top is significantly smaller than that obtained by the settlement control standard. The friction angle of soil has an important influence on the vertical bearing capacity， and the increase of elastic modulus can effectively reduce the axial settlement of monopile. The closer the soft soil is to the pile end， the greater the decline of the axial bearing capacity of monopile. At the same time， as the thickness of the soft soil layer increases， the axial bearing capacity will further decrease and show a three-stage attenuation law of “acceleration-uniform speed-uniform speed”.

In order to meet the requirements of construction and bearing capacity， the measure of the variable diameter of the pile body is often used for the monopile foundation of offshore wind turbines， and the variable diameter section may have an impact on the vertical bearing characteristics of pile foundation. A numerical model of a variable diameter monopile was established by the finite element analysis software ABAQUS， and a series of numerical simulations on the vertical bearing performance of variable diameter monopiles and the influence of their size parameters on the vertical bearing capacity were carried out. The numerical analysis results show that the variable diameter characteristics have little influence on the axial force distribution of the pile compared with the pile with the same diameter. With the increase of vertical load， the proportion of each bearing component of the two types of monopiles remains unchanged at first， and then the proportion of external side friction resistance decreases， while the proportion of internal side friction resistance and pile tip resistance increases. Increasing pile diameter at bottom of variable diameter pile can effectively improve the vertical bearing capacity and increase the proportion of the external side friction resistance. Increasing the upper length and the length of the variable diameter section has no obvious effect on the vertical ultimate bearing capacity of the pile foundation， but will lead to the decrease of the proportion of the external side friction resistance and the increase of the proportion of the internal side friction resistance.

The connection mode between the tower and monopile of the offshore wind turbine has an important impact on structural safety. Based on an offshore wind power project， the influence of the aerodynamic damping of the wind wheel on the dynamic response of the wind turbine structure is studied by numerical analysis method. The natural vibration characteristics and dynamic response characteristics of the structure under different connection modes between tower and monopile are analyzed， and the change of grouting connection effect with elastic modulus of grouting material is compared. The results of numerical analysis show that the aerodynamic damping of the wind wheel has obvious influence on the dynamic response of the wind turbine structure， which should not be ignored in the analysis of the wind induced response of the wind turbine during operation. The top displacement of the tower in grouting connection is smaller than that in variable diameter connection， and the elastic modulus of the grouting material in the grouting connection has no obvious effect on the grouting connection effect.

Based on a practical offshore wind power project， the influence factors of axial bearing performance of monopile in heterogeneous layered foundation are studied by numerical method and optimization suggestions are put forward. The results show that the axial force of pile increases slowly from the pile top to the mud surface， and decreases significantly with the increase of buried depth under mud surface. The proportion of each component of axial bearing capacity changes gradually with the increase of load applied to pile top， and the internal and external side friction resistance shows a trend of "dislocation play" with the increase of load applied to pile top. The external side friction increases evenly with the increase of pile depth in space， while the internal side friction mainly is mobilized in the lower part of monopile. Pile diameter and buried depth have great influence on axial bearing capacity. The grinding of pile body can effectively improve the axial bearing capacity of pile， especially the external side friction resistance， and reduce the axial force of pile body with grinding. In practical engineering， pile diameter and buried depth should be determined by comprehensive consideration of various factors， and the external surface of monopile near the pile end can be treated with grinding to improve the axial bearing capacity of the monopile.

In this study， the dynamic sliding mode controller of hydraulic turbine governing system is designed based on the sliding mode control method to address the chattering problem of hydraulic turbine governing system in sliding mode control. Firstly， a mathematical model of hydraulic turbine governing system considering a super long headrace tunnel is established and the dynamic sliding mode controller is designed. Then， the controller parameters are optimized by a hybrid optimization algorithm of particle swarm optimization and gray wolf optimization （PSOGWO）. Finally， the dynamic sliding mode controller is adopted for trajectory tracking experiments of hydraulic turbine governing system with sinusoidal and step signals which are used to evaluate the superiority and effectiveness of different controllers. The simulation results indicate that the designed dynamic sliding mode controller not only improves the control performance of the hydraulic turbine governing system and the convergence time of trajectory tracking， but also can significantly reduce the chattering effect of sliding mode control and the error of trajectory tracking.

Temperature control and crack prevention of roller-compacted concrete （RCC） dams are the key technical problems in the construction of projects. The material parameters of RCC dams have significant spatial variability due to the large pouring concrete surface， uneven rolling quality， and heterogeneity of concrete. The deterministic calculation is adopted in the traditional temperature and stress analysis of concrete dams，which ignores the influence of parameter spatial variability， resulting in unreasonable simulation of temperature and stress field. Based on the random field theory and the center point discrete method， a finite element simulation method of spatial variability of concrete thermal parameters is proposed in this paper. The case study of TJ dam shows that the average effect of the maximum temperature field and maximum tensile stress field considering the spatial variability of thermal parameters is basically consistent with the deterministic results. The spatial variability of thermal parameters significantly affects the maximum temperature and maximum stress of the dam concrete structure. The temperature and stress at some positions of structures in the random temperature and stress field exceed the allowable value， which means that the temperature control measures proposed based on the traditional deterministic temperature stress analysis results may be dangerous. The random temperature and stress analysis method proposed in this paper provides methodological support for the formulation of temperature control measures of gravity dams during the construction period.

In view of the easy availability of sound data of industrial equipment， the sound data is collected for experiments such as load rejection during the start-up test of a hydraulic unit， and the collected sound data is analyzed by RMS， spectrum and spectrogram. Based on the waveform， spectrum and spectrogram， a neural network is selected as an auxiliary means， and the spectrogram is used as a training sample to enter the input layer of the neural network to obtain voiceprint features to realize the classification and scoring of test samples. The results show that different load conditions and tailgate leakage accidents can be correctly identified in the test. This research will help to establish a machine voiceprint feature map library for the whole and important key components of electromechanical equipment in hydropower stations.

The negative damping characteristics of hydropower units are the intrinsic cause that induces ultra-low frequency oscillations of hydropower dominant power systems. Accurate and efficient quantification of the damping coefficients of units is crucial to the positioning and control of the dominant units of ultra-low frequency oscillations. To address the problem that the existing damping quantization methods for nonlinear system units are difficult to balance the operational simplicity and calculation accuracy， this paper analyzes the damping characteristics of single and multi-machine systems based on the damping torque theory and proposes a novel fast quantization method for damping coefficients. On the one hand， the quantified results of damping are compared with the theoretical values to verify the calculation accuracy of the method. On the other hand， the experimental analysis of ultra-low frequency oscillation of a multi-machine system and the measurement data of actual power stations are used to verify the validity of the method.The results show that the method is accurate and simple， and it can provide an effective technical means for the damping study of strongly nonlinear systems and the online evaluation of the damping in ultra-low frequency oscillations.

With the development of CFD and computer technology， many scholars have begun to use numerical simulation methods to conduct a lot of detailed research on the hydraulic characteristics of stepped spillways， but there is no consistent method for evaluating the accuracy of their calculations.In this paper， three grid sizes ranging from dense to coarse are used to numerically simulate the air-water two-phase flow on a stepped spillway by using Flow 3D^? software， to provide a general method to evaluate its calculation accuracy.Firstly， the grid size is optimized by calculating the grid convergence index （GCI）， which can shorten the calculation time while ensuring the calculation accuracy. Then， by using the physical model test measurement results as a reference， the accuracy of the numerical simulation calculation results under the recommended mesh size is evaluated. The results show that using the same mesh refinement factor can greatly simplify the calculation process of GCI. It is recommended using a grid size with a global GCI less than 5%. Although slightly lower than the calculation accuracy for pure water flow， Flow 3D^? software still has high calculation accuracy for the key hydraulic parameters of the air-water two-phase flow on the stepped spillway.

In order to explore the black-box details of the FLOW-3D bubbly flow model， the effect of the model parameters including the critical Weber number， critical capillary number， initial bubble diameter， drag coefficient， and Richardson-Zaki coefficient multiplier are investigated based on the experimental data of uniform flow in a 45° steep chute. It is discovered the bubble size is dominated by the critical capillary number， whereas the critical Weber number only exhibits a certain effect near the aerated flow surface. The drag coefficient and Richardson-Zaki coefficient multiplier have a significant influence on simulation results， while the effect of the critical capillary number， the critical Weber number and the initial bubble diameter is relatively negligible. A drag coefficient or Richardson-Zaki coefficient multiplier more than the default value will enhance the turbulence and thereby increase air entrainment， and values less than the defaults have even more significant effect. Therefore， when aerated flow is simulated by using FLOW-3D， more attention should be paid to the calibration of the drag coefficient and Richardson-Zaki coefficient multiplier to improve model accuracy.

The filling method of high face rockfill dam should be divided in stages. The selection of filling height difference will have certain influence on the deformation of the dam body. FLAC3D is used to carry out three-dimensional numerical simulation of Altash face rockfill dam， and the stress deformation of the dam body is analyzed when the height difference between the upstream and downstream fill body is 5， 10， 15， 20， 25 and 30 m under the form of reverse elevation downstream fill. The results show that the greater the height difference is， the greater the stress deformation of the dam body is， and the worse the stress state of the face plate is. When the height difference is 30 m， the maximum vertical settlement of the dam body is 84.8 cm， the horizontal displacement of the downstream side is 12.9 cm， the maximum principal stress is 2.23 MPa， and the deformation inclination of the downstream characteristic point is 1.02%， exceeding the critical deformation inclination， shear failure may occur. Overall consideration， when designing the filling scheme of high face rockfill dam， great attention should be paid to the selection of the height difference between upstream and downstream filling， and it is recommended that the height difference be less than 30 m.