To evaluate the influence of hydraulic and meteorological factors on the occurrence of the water bloom in Xiangxi River in summer， the chlorophyll A concentration at Xiakou （perennial backwater area） and Pingyikou （fluctuation backwater area） was monitored daily in the season of water bloom from August to September in 2021， and the temperature， solar radiation， rainfall， wind speed， air pressure， humidity and discharge of Xiangxi River were obtained synchronously. The effects of hydrometeorological factors on algal community structure were evaluated by generalized additive model （GAM）， random forest importance analysis and canonical correspondence analysis （CCA）.The results showed that the discharge of Xiangxi River was the most important factor affecting the algal biomass， and the algal biomass decreased significantly when the flow exceeded 100 m³/s. The algal biomass at Xiakou was positively correlated with air temperature， solar radiation and the wind speed， and the importance decreased successively. The algal biomass at Pingyikou was significantly correlated with rainfall and solar radiation. There was a significant positive correlation between wind speed increment and algal biomass increment at Xiakou， indicating that high wind speed was likely to boost algal aggregation in the backwater area. The results of this study indicate that hydraulic and meteorological factors are important factors predicting the occurrence and development of water bloom， and provide a basis for the forecast and early warning of the bloom.

The meso process of the barrier dam break is the scouring and transport movement of particles under the action of water flow. In essence， it is the interaction between unsteady overtopping flow and uneven earth rock materials in the breach， which belongs to a special form of sediment movement. The material of the barrier dam has strong heterogeneity and a wide grading range. The laws of incipient motion and transport are quite different from those of uniform sediments. If the existing theory of river sediment movement is directly applied to the calculation of the dam break accurately， the results will be different from the actual ones. In order to calculate the sediment incipient velocity under this condition， the exposure angle of sediment particles is analyzed. The bed slope， the longitudinal and transverse exposure angles of sediment particles are introduced. Based on the sediment rolling model， the instantaneous incipient velocity of sediment particles calculated is converted into the vertical average velocity of the section. The calculation formula of the incipient velocity of wide graded sediment is established， the rationality of the calculation formula is verified and the sensitivity is analyzed. The main conclusions are as follows： the incipient velocity of uniform and non-uniform sediment is selected for calculation， and compared with the measured data， it shows that the formula in this paper can accurately reflect the incipient law of sediment with the bed slope and particle exposure angle to a certain extent. There is a negative correlation between the bed slope and the incipient velocity of sediment particles. With the increase in the bed slope， the incipient velocity of sediment particles generally shows a decreasing trend， but the influence degree is affected by the particle exposure degree. With the increase in the sediment exposure degree， the influence of the bed slope on the incipient velocity gradually increases. There is a negative correlation between the transverse and longitudinal exposure angles of sediment particles and their incipient velocity， and the incipient velocity decreases with the increase in the transverse exposure of particles. When the studied particles are in the exposed state， ignoring the hydraulic elements and the surrounding water flow structure， whether the particles start or not will be mainly controlled by the particle size. The influence of the longitudinal and transverse exposure angles of the particles on the starting velocity of the particles is different. The transverse exposure angle of the particles has an exponential function relationship with the starting velocity， and the influence on the starting velocity gradually increases with the increase in the exposure angle. The relationship between the longitudinal exposure angle of particles and the starting velocity presents an S-curve. With the increase in exposure angles， the influence on the starting velocity first decreases and then increases. In addition， the composition of soil and stone materials at the mouth of the dam is very complex， and the particle shape， size， density， relative position are very different. To calculate the incipient transport of sediment at the breach accurately during overtopping， it is necessary to carry out further research on the generalized values of relevant parameters such as the exposure of sediment particles on the surface of the breach and the transport calculation method.

Habitat quality is an important indicator reflecting biodiversity. Under the background of high-quality development， studying the evolution and driving factors of environmental quality is of great significance for regional sustainable development and ecological security maintenance. Based on the five-phase land use data in the Chishui River Basin from 2000 to 2018， the InVEST model assess habitat quality isused， and its spatial differentiation characteristics isexplored byusing hot and cold spot analysis.In addition， the influencing factors of the spatial distribution of habitat quality are explored by means of geographic detectors. The results show thatin terms of time， the habitat quality of the Chishui River Basin shows a trend of increasing first and then decreasing. The analysis of hot and cold spots shows that habitat quality and habitat degradation are spatially characterized by “weak upstream and strong downstream”. Geographical detection results show that land use is the dominant factor affecting the habitat quality of the Chishui River Basin， and the Chishui River Basin is affected by the synergistic effect of natural and socioeconomic factors. The results clearly identify the key areas of habitat quality protection and the degree of influence of different factors on habitat quality， which is helpful to provide a theoretical basis for watershed biodiversity conservation strategy and high-quality development management decision-making.

Eco-environmental quality is a comprehensive representation of ecosystem elements， structures， and functions in time and space， reflecting the interaction of various limiting factors， landscape elements， and eco-hydrological processes. Therefore， the correct understanding and evaluation of the regional ecological environment are significant to constructing ecological civilization and ecological and environmental protection in China. Irrigation agriculture is an important food security area for the economic and social development of the Chinese Loess Plateau. Under rapid economic development， its fragile regional ecological environment needs to conduct a systematic research on the ecological security evaluation of the main agricultural irrigation areas on the Chinese Loess Plateau. In recent decades， the Jinghui Canal Irrigation District has achieved agricultural development and produced some ecological and environmental problems， such as surface water and groundwater environmental problems and soil environmental problems. Therefore， this paper takes Jinghui Canal Irrigation District as the research object， conducts research on the evolution characteristics of the ecological environment during the development process of the irrigation area （2000-2020）， monitors possible ecological environment problems， and analyzes the possible causes. This paper uses the remote sensing ecological index （RSEI） to analyze the changes in the ecological environment quality of the Jinghui Canal Irrigation District. The RSEI index can comprehensively， quickly， and objectively reflect the regional ecological environment quality level. The results show that the RSEI value of Jinghui Canal Irrigation District has first decreased and then increased in the past 20 years. The area of good ecological quality grades has decreased by 30.19%， the area of medium ecological quality has increased by 1.19 times， and the area of poor ecological quality has increased by 56.79%. In the Jinghui Canal Irrigation District， 71.82% of the area ecologically has degraded in the past 20 years， 15.61% of the area with no noticeable change， and 12.56% of the area with ecological improvement. The RSEI value of the cultivated land is generally higher than that of the construction land area. The RSEI value of the cultivated land area has decreased by 9.09%， and the RSEI value of the construction land has decreased by 9.26%. Although the ecological quality of Jinghui Canal Irrigation Distract has recovered somewhat since 2010， the overall level is still not good. There is minimal land cover such as forests， grasslands， water bodies， and wetlands， and further improvement is required. The irrigation area’s forests， grassland， and water wetlands are too low. The Jinghui Canal Irrigation Area needs to expand many ecological construction areas， such as forests and grassland， to better restore ecology. In addition， adjusting the planting structure and developing ecological agriculture increases vegetation diversity and enhances ecological stability. This research is of great significance to the ecological environment protection and sustainable agricultural development of Jinghui Canal Irrigation District.

Rural ponds play an important role in the rural spatial pattern and overall appearance. High-quality governance of rural ponds is an important means of beautiful rural construction. In the context of rural revitalization， reconciling the properties of rural pond water and shoreline， evaluating the governance level of rural pondscomprehensively， finding out their spatial distribution characteristics， mastering their adaptability to the laws of economic and social development， and putting forward targeted management strategies are the basis for improving the quality of rural ponds. Taking Longbei Area of Longyou County as an example， this paper constructs a rural pond’s quality evaluation system from the perspective of water-shoreline synergy， using TOPSIS model， index correction model and spatial agglomeration to study the governance level and distribution characteristics of rural ponds， and formulate corresponding promotion strategies. The results show that： ① the management and protection of water， the development and utilization of shoreline and the comprehensive index of Longbei Area are at the med-low level， but there are great differences among villages.And this phenomenon has a certain positive correlation with economic and social development. ② The type of water-shoreline synergy in Longbei Area include high-synergy， medium-synergy， mild-synergy and antagonism， and the number of corresponding villages accounts for about 8∶31∶27∶18.The comprehensive level is generally low， mainly in moderate and mild coordination. ③ The governance level of rural ponds in Longbei Area shows significant agglomeration and difference characteristics in overall and local space， which changes from high level in the southeast to low level in the northwest. ④ Aiming at different types of rural ponds with different quality levels， combined with some of the pond regulation schemes being implemented， the governance strategy of “classified measures” is proposed to form a rural pond governance system， which helps to improve the regulation level of rural ponds.

Regarding the Heihe River Basin as the research object， based on the harmony theory and sustainable development theory， aiming at coordinating the ecological construction， economic and social development and optimizing the allocation of water and soil resources， the harmony evaluation index system of the“water economy ecology” system in the surface water overexploitation zone is established， and the different degrees of harmony are divided into five levels by using the linear membership method. According to the coordinated development goal of “water economy ecology” in the Heihe River Basin and combined with the future planning， 14 evaluation indexes that can reflect the current situation of water resources， the degree of development and utilization of surface water， agricultural irrigation， the level of economic and social development and the status of ecological environment are determined， so as to provide a basis for the harmony evaluation of the basin. The comprehensive index evaluation method is used to calculate the comprehensive harmony degree of the system under different scenarios in different level years in the Heihe River Basin. The calculation results show that although the overall harmony degree shows an upward trend under different scenarios， the harmony degree is lower than 0.4 in 2020， which can not reach the general harmony. In 2030， the harmony degree of scenarios I and II will be less than 0.6， while the harmony degree of scenarios III and IV will be more than than 0.6. The harmony degree of scenarios III and IV is significantly better than that of scenarios I and II， reaching the harmony level. In scenarios III and IV， the development and utilization rate of surface water will be controlled within the threshold of 75.0% by continuing to adjust policies. By 2030， the development and utilization rate of surface water will be 70.7% and 68.3% respectively， 60.57% and 62.97% lower than that in 2015， making the Heihe River Basin withdraw from the surface water over development zone. In order to ensure the coordinated and common development of water resources， social economy and ecological environment in the Heihe River Basin in the future， in view of the high development and utilization rate of surface water resources in the basin， this paper suggests adjusting the crop planting structure， vigorously developing the area of efficient water-saving irrigation and increasing industrial water-saving efforts based on the core of the strictest water resources management system –“three red lines”while maintaining the growth rate of planned GDP， optimizing the allocation of water resources， greatly reducing agricultural water consumption and effectively reducing the utilization rate of surface water conservancy can realize a virtuous cycle of water resources and water ecosystem and ensuring the healthy and sustainable development of watershed ecology. Although the harmony evaluation mathematical model established in this paper is in the exploratory stage， it quantitatively describes how to coordinate the development of water resources， social economy and ecological environment， provides data support for the governance of the basin， providinga reference basis for the future development of the Heihe River Basin.

Precipitation is a key element in the water cycle process. Selecting an appropriate precipitation time series characteristic analysis method is the premise to find out the variation trend， sudden change year and cycle period of precipitation in the target area. In this paper， the calculation methods commonly used in the analysis of precipitation time series characteristics are classified and summarized. By analyzing the characteristics and applicable conditions of different methods， the rationality of introducing mathematical statistical methods into precipitation analysis is expounded. Based on the daily precipitation data of Wuhan from 1951 to 2017， Mann-Kendall test method， linear regression method， 5 a moving average， cumulative levelling method， Morlet wavelet analysis are selected for calculation. The results show that the precipitation in Wuhan has a significant upward trend， affected by climate change， human activities and other factors， the precipitation has abrupt changes in periods around 1954， 1980， 1998， and 2010. In the recent 67-year precipitation sequence， two main precipitation changes cycles of 50-year and 10-year appeared. The reasons for the change of precipitation are analyzed. Considering the influence of the western Pacific subtropical high， the precipitation in Wuhan is concentrated in summer and the interannual variation of precipitation is more severe. It is believed that the urbanization process has also interfered with the precipitation in Wuhan， and the total regional precipitation and precipitation intensity have increased. It is expected that the rainfalls in Wuhan will continue to maintain a stable upward trend in the future， and the probability of heavy precipitation events in summer will increase. The calculation results confirm the reliability of the above algorithm by analyzing the reasons for the changes in precipitation， which can be used for the analysis method of precipitation time series characteristics in other regions for reference.

As a major maize-growing region in China， it is particularly important to investigate the sensitivity and response mechanisms of maize growth， development and yield to extreme precipitation events in Jilin Province. Based on the daily maximum and minimum temperature and precipitation data of 24 meteorological stations in Jilin Province from 1961 to 2019 and the maize yield data of each station， this paper uses five-year moving average， Sen slope， Mann-Kendall nonparametric test and other methods to analyze the spatio-temporal variation characteristics of extreme precipitation events and maize yield in Jilin Province. And Pearson correlation analysis and Boruta algorithm are used to quantitatively determine the impact of extreme precipitation events on maize yield. The results show that the Sen slope values of heavy precipitation （R95p）， total precipitation per rainy day （PRCPTOT）， number of heavy rain days （R20） and normal daily precipitation intensity （SDII） are 0.301 mm/a， -0.18 mm/a， 0.31 d/a and 0.27 mm/（d·a）， respectively， which show an upward trend except for PRCPTOT. It indicates that extreme precipitation events gradually increase. The actual yield per unit area and trend yield of maize show an upward trend. The climatic yield of maize fluctuated in the range of -1 802.24~1 579.04 kg/hm²， and the interannual difference is great. During the fifty-nine years， the relative climate yield of maize has 11 good years， 10 bad years， and the rest years are normal years. Maize climatic yield and extreme precipitation indices are positively correlated in the northwest and eastern regions， but negatively correlated in the south. Combined with nonlinear fitting curve analysis， it can be seen that when R95p≥190 mm， PRCPTOT≥610 mm， R20mm≥8 d， the climatic yield of maize decreases gradually. R20 and R95p are more important to maize climatic yield， indicating that maize yield is more sensitive to extreme precipitation days and extreme precipitation. The results of this study are helpful for Jilin Province to put forward targeted agricultural adaptation measures to improve the level of food security.

To clarify the long-term hydro-thermal law in Guizhou Province， as well as to serve the construction of demonstration zones for ecological progress in this area， and to serve water resources development and utilization in Guizhou Province， this paper takes research on the hydro-thermal change law in this area in the last 60 years， by using the in-situ data from 31 national standard stations of the last 60 years. The spatial clustering method is applied to classify the whole area into 3 regions based on their hydro-thermal conditions. Mann-Kendall Test， Pettitt Abrupt Test are applied to analyze the trend of the precipitation， temperature and dryness and to check the abrupt points further. Also the Morlet Wavelet Analysis is applied to prove that there is periodical laws in Guizhou Province. Finally， the long-term distribution characteristics and evolvement trend of the hydro-thermal conditions can be concluded in Guizhou Province and the three regions. Results show： ① there are abrupt points in temperature while no apparent trends in rainfall. Both of them show specific law of the three areas， which differs from each other. ② There are three remarkable periodical laws composited in precipitation， with a length of 22 years and 18 years. In addition， there is a third periodical law in medium-temperature and high–rainfall zone and high-temperature and medium-rainfall zone. While only two inconspicuous periodical laws in temperature with length of 18 years and 15 years. These periodical laws weakened around 1975 and 1985， separately for precipitation and temperature. ③ Dryness of Guizhou Province showed a slight decrease trend with unapparent abrupt points. ④Temperature and rainfall in low-temperature and low-rainfall zone rose a bit， while those of high-temperature and medium-rainfall zone rose significantly. Medium-temperature and high–rainfall zone showed a rise in temperature and a fall in rainfall. The high-temperature and medium-rainfall zone can have more water resources in the future， with better utilization conditions compared to the low-temperature and low-rainfall zone and the medium-temperature and high-rainfall zone.

With the development of urbanization and the improvement of residents’ living standards， water-saving in urban residents’life has become the focus of water-saving work. The domestic water use of urban residents is subdivided into seven parts： drinking water， cooking water， washing water， environmental cleaning water， laundry water， bathing water and toilet flushing water. Based on the theory of rigid， elastic and extravagant water use hierarchy， this paper constructs a hierarchical water demand evaluation model for residents， and carries out parameter calibration through questionnaires， calculates the hierarchical water consumption of each water consumption behavior， and analyzes the water consumption of urban residents at three levels horizontally and vertically. The research results show that： ① Laundry and bathing water accounted for 54% of the total water consumption in 2016 and 60% in 2020， both exceeding 50%， and laundry and bathing water was the main component of flexible water and luxury water. ② In 2016， the per capita rigid， flexible， and luxury water consumption accounted for 51%， 33%， and 16% of the total per capita water consumption， respectively； in 2020， the per capita rigid， flexible， and luxury water consumption accounted for 48% of the total water consumption， 33% and 19%respectively. The proportion of rigid water consumption per capita will decrease， the proportion of flexible water consumption per capita will remain unchanged， and the proportion of luxury water consumption per capita will increase. ③ The per capita rigid water consumption in economically developed areas （Shijiazhuang City and Baoding City） in Hebei Province is smaller than that in less developed areas （Zhangjiakou City and Chengde City）， and the per capita flexible and extravagant water consumption is more than that in economically underdeveloped areas. It can be seen that the more economically developed areas are the less rigid water consumption per capita， the more flexible and luxury water consumption. The research results are of great significance to the management and prediction of urban domestic water use.

Taking the inflow from Baise Reservoir in Yujiang River Basin as the object， stepwise multiple regression（SMR） model， artificial neural network（ANN） model based on hydrometeorological factors and chaotic theory（CT） model， nearest neighbor bootstrapping regressive（NNBR） model， wavelet analysis（WA） model， artificial neural network-autoregressive model based on time series are used to forecast the annual， monthly and decadal scale inbound runoff from Baise Reservoir for the mid-term and long-term runoff forecasting. Then four evaluation indexes， namely， average relative error， passing rate， TS score and root mean square error（RMSE） are used to evaluate the accuracy of the prediction results of the above six models， and a comprehensive index analysis system is formed by objectively assigning weights to the above four indexes based on the theory of entropy weight method to determine the optimal model for the mid-term and long-term runoff forecasting of incoming runoff at different scales and forecasting periods in Baise Reservoir of the Yujiang River Basin. The results show that， the average relative error of each model is relatively large， and the corresponding pass rate and TS score indexes are all at excellent levels. In the monthly scale forecasting process， the forecast accuracy of each model in the non-flood period is higher than that in the flood period. Based on the characteristics of each model and comprehensive index analysis， the neural network-autoregressive model can be used in the annual-scale Mid-term and long-term runoff forecasting process， the chaos theory model in the monthly scale mid-term and long-term runoff forecasting process， and the artificial neural network model （meteorological factor） and wavelet analysis in the decadal-scale mid-term and long-term runoff forecasting process according to different forecasting periods. The mid-term and long-term runoff forecasting is carried out by artificial neural network model （meteorological factor） and wavelet analysis for different forecasting periods， thus providing technical support for the formulation of future mid-term and long-term scheduling plans for the Baise Reservoir in the Yujiang River Basin.

Soil water content is an important parameter affecting the hydrological cycle and climate change. Compared with optical remote sensing， radar remote sensing is not affected by meteorological factors such as clouds and rain， and can providea continuous observation， which is an effective way to obtain soil water content information on a large scale. In order to analyze the influencing factors and variation characteristics of radar backscattering signal on bare soil， and to explore the soil water content retrieval method based on Sentinel-1A radar data， an observation experiment is carried out in the typical agricultural area of Nanyang Basin. AIEM theoretical model is used to simulate the radar backscattering coefficient under different incident angles， root-mean-square height， correlation length and soil moisture content， the influence of each parameter on the radar backscattering coefficient is analyzed. The BPNN model is trained with both simulated data and measured data， and the inversion results are verified by measured data. The results show that the effect of surface roughness on soil water content inversion accuracy cannot be ignored. Under different polarization modes， the R ² of simulated microwave backscattering coefficient between BPNN model and traditional theoretical model reaches 0.99. The results show that the R ² and RMSE are 0.72 and 0.033 g/cm³， respectively， between the BPNN predicted and measured values. Therefore， the combination of C-band microwave remote sensing and BPNN model can estimate soil moisture content on bare surface accurately and efficiently. The research results will provide effective scientific support for the fields of agricultural irrigation management， environmental change monitoring， and hydrological cycle，which has important application value and practical significance.

Jinsha River is rich in water energy resources and is an important water source in the Yangtze River Economic Belt. The analysis of temporal and spatial evolution characteristics of drought in Jinsha River has an important guiding significance for water resources management planning and agricultural production in the lower reaches. Based on the monthly precipitation and temperature data of 28 meteorological stations in the Jinsha River from 1960 to 2020， the standardized precipitation evapotranspiration index （Standardized precipitation evapotranspiration index） at annual and seasonal scales is calculated， and the temporal variation and spatial distribution characteristics of drought frequency at different levels at seasonal and annual scales are quantitatively analyzed. The randomness and stability of spatial and temporal distribution of annual meteorological drought are analyzed by the cloud model. The results show that on the annual scale， the Jinsha River is mainly characterized by light droughts and moderate droughts， with high frequency of light droughts and low frequency of severe droughts. On the seasonal scale， the drought frequency of the four seasons is about 30%， mainly in spring and summer. In terms of spatial distribution， the occurrence frequency of drought is high in Lijiang Area.The results of cloud model analysis show that the temporal distribution of SPEI index is more discrete than the spatial distribution， and the heterogeneity is more unstable. In terms of time distribution， the difference of drought degree between stations increases with the interannual variation， and the unevenness tends to be unstable. In terms of spatial distribution， the hyperentropy value decreases with the increase in entropy value， and the site with lower expectation fluctuates more with respect to the annual average drought degree， and its drought degree unevenness is more stable.

Developing economy， global warming， ever-changing climate and the regional hydrological cycle. bring severe challenges to ecological protection， soil and water conservation， and water resources protection in the middle Yellow River Basin.In this study， the adaptability of 20 global climate models （GCMs） in the Middle Yellow River Basin is evaluated in the historical period （1961-2005）， the top six climate models with better adaptability are selected， and the weighted average method is applied to generate an ensemble global climate model （EGCM）. The performance of EGCM in reproducing precipitation and temperature of MYRB is assessed based on observations （temperature and precipitation）. Under Representative Concentration Pathways （RCP） scenarios RCP4.5 and RCP8.5， the climate changes are projected by EGCM in the future period （2021-2065）. The results show that， compared with other climate models， ACCESS1.3， CSIRO-Mk3-6-0， IPSL-CM5A-LR， IPSL-CM5A-MR， MIROC5， and MRI-CGCM3 can better reflect the climate characteristics of the middle Yellow River basin. The EGCM can project the overall variations for climate variables from annual and monthly perspectives. Compared to the historical period， the EGCM projected increases in the mean annual precipitation and annual extreme precipitation are about 5% and 12.5% in the future period， respectively. The study also reveals that the temperatures are projected about 1.94 and 2.41 ℃ under RCP4.5 and RCP8.5 scenarios separately.

As an indispensable and important resource for human survival and social development， water resources are of great significance to coordinate carbon emission control and promote high-quality economic and social development.Based on the relevant data of 9 prefecture-level cities in the Tuojiang River Basin from 2007 to 2017， the super-efficiency SBM model is used to measure the green efficiency level of water resources in the Tuojiang River Basin.On this basis， the GTWR model is used to explore the impact of water use structure， technological progress， level of opening to the outside world， water resources endowment and government regulation on the green efficiency of water resources in the Tuojiang River Basin from the perspective of spatial and temporal differences. The research on the governance mechanism of water resources green efficiency ispromotedfurther in different spatial scopes， and provide an effective basis and scientific reference for the governance of regional water resources green efficiency in my country.The results show that： ① The distribution of green efficiency of water resources in the Tuojiang River Basin has obvious spatial and temporal differences. In the time dimension， the level of water resources green efficiency fluctuates greatly， but the overall trend is upward. In the spatial dimension， it gradually decreases from south to north.② Different influencing factors have different degrees of influence on the green efficiency of water resources in the Tuojiang River Basin.The regression results of the OLS model and the GTWR model both show that the level of opening to the outside world has the greatest impact， followed by technological progress， and the impact of water use structure， government regulation and water resources endowment is less.③ There are significant temporal and spatial differences in the degree of influence of different influencing factors on the green efficiency of water resources in the Tuojiang River Basin， and the direction and intensity of each influencing factor in different years and regions are very different.The research conclusion is conducive to promoting the coordinated and healthy development of water resources in the Tuojiang River Basin， and solving the dilemma of unbalanced development of regional water resources.

Global climate models are widely used in future climate simulation and assessment， and the accuracy of regional climate simulation determines the reliability of research conclusions. In order to explore the ability of different ensemble methods to simulate precipitation and temperature， based on the historical data of 19 climate models in Coupled Model Intercomparison Project Phase 5， the simulation abilities of each model on climate in Poyang Lake Basin are compared， and the optimal model is selected.Later， based on the set arithmetic mean and Bayesian model mean （BMA） method， four Multi-model ensemble， all-model equal weight ensemble，preferred model equal weight ensemble，all-model BMA ensemble and preferred model BMA ensemble， are constructed to evaluate the ability of each ensemble to simulate climate change in Poyang Lake Basin. The results show that： ① Single model and ensemble have better ability to simulate air temperature than precipitation； ② On the annual scale， the all-model equal weight ensemble and the preferred model equal weight ensemble underestimate the annual mean temperature and precipitation of the basin， while the all-model BMA ensemble and the preferred model BMA ensemble can describe the annual mean climate of the basin better， and the preferred model BMA ensemble is better than the all-model BMA ensemble. On the monthly scale， the full-model BMA ensemble has a good simulation effect in both the periodic and validation periods of temperature and precipitation. ③ The temperature simulated by full-model BMA ensemble and preferred model BMA ensemble are high in the south and low in the north， high in the east and low in the west， and rainfalls are high in the east and low in the west and high in the north and low in the south， compared with the all-model equal weight ensemble and the preferred model equal weight ensemble， the BMA ensemble can better reproduce the overall characteristics of precipitation and temperature spatial changes in the basin. This paper recommends using the BMA ensemble method or correcting the simulated values of the equal weight ensemble to improve the accuracy of the multi-model ensemble simulation.

The self-cleaning mesh filter is a new type of filter. In order to improve the sewage discharge efficiency of the sewage system， the theoretical expressions of the swirling power and adsorption suction of the self-cleaning mesh filter sewage system are established， and the influencing factors of the swirling power and adsorption suction are determined. Numerical simulation of the sewage process of self-cleaning mesh filter is carried out by CFD method. The velocity cloud diagrams and the pressure cloud diagrams are obtained respectively. The results show that the maximum flow velocity difference between suction nozzles 1~4 in the sewage system is 2.96 m/s and the maximum pressure difference is 3.65 kPa， which leads to uneven sediment adsorption in the sewage system and reduces the sewage discharge efficiency of the filter. Combined with theoretical analysis and numerical simulation results， 6 groups of optimization schemes are designed. The opening widths of nozzles 1~4 of the sand suction assembly are 0.2， 0.4， 0.6 and 2 cm， respectively， and the solution with the opening diameter of the rotary nozzle of 2 cm is the recommended optimal solution. In this scheme， the flow velocity distribution of each suction nozzle is more uniform， the flow velocity is significantly improved， and the pressure difference between the inlet and outlet of the filter is increased， which is beneficial to improving the sewage discharge efficiency.

There are serious sediment wear problems in the water pump units of water intake pump stations along the Yellow River in China. The research object of this paper is a double suction centrifugal pump. The particle motion law and wear characteristics in the pump are predicted by solid-liquid two-phase flow numerical simulation. The results show that the flow rate has a significant effect on the motion and wear characteristics of the particles in the runner. Under different flow conditions， the wear position and wear rate in the runner are obviously different. The total wear rate of blade wall changesis positively correlated withthe flow conditions and increases with the increase in the flow. Under the condition of small flows， the vortex and secondary flow in the runner have a great influence on the trajectory of particles. The existence of vortex will change the particle concentration distribution and aggravate the local friction and wear. The research results of this paper provide a theoretical guidance for the prediction and design of the pump internal wear， and have important academic significance and engineering value.

This paper studies the application of BIM+GIS technology in reservoir engineering， and focuses on the main process framework of BIM+GIS technology application in the feasibility study stage.By taking the GJ reservoir project as an example according to the characteristics and difficulties of the project， such as comparison and selection of cascade two reservoirs and multiple dam sites， many disciplines involved， and lack of information in the early stage， this paper cannot easily collect basic data， short survey and design cycle and heavy workload， or carry out three-dimensional collaborative design and BIM+GIS technology application research in the feasibility study stage. By using GIS+ UAV technology， this paper quickly extracts the river system of the basin， draws up the water level of the reservoir and the development plan， quickly extracts the land data of the flooded area， collect topographic data and establish a three-dimensional geological entity model. It standardizes the three-dimensional forward collaborative design process， optimizes the structural tree of collaborative design， carries out the forward collaborative design of hydraulic engineering， electromechanical metal structure and safety monitoring， and quickly counts the quantities of works， integrates finite element calculation and analysis， construction simulation， three-dimensional display and structural drawing. The concept of full life cycle will be carried out throughout， from feasibility study， preliminary design， detailed construction drawings to operation and maintenance stages， to meet the requirements of one-time modeling and full life cycle application， improve the added value of the model， provide a guidance for the application of bim+gis technology in reservoir engineering， and improve the refinement and information management level of the project.

During the large-flow water conveyance period of the Middle Route Project of South-to-North Water Diversion， the wake vortex alternation in the downstream of the tail pier and the large fluctuation of the water level in the channel body have occurred in some aqueducts， which seriously affect the stability and structural safety of the project. In view of the proposed tail pier shape optimization scheme of “gradually shrinking and lengthening tail pier ” to break the tail vortex and reduce the water level fluctuation， this paper adopts RNG k-ε model and VOF method to study the effect of different tail pier types and tail pier lengths on wave elimination control， and determines the appropriate engineering measures. The results show that the elliptical tail pier has the best wave attenuation control effect among all types of common pier shapes. When the pier is lengthened to 8 m， the wave attenuation control effect is remarkable， which can effectively improve the flow pattern and hydraulic characteristics of the flume. When the length of the tail pier exceeds a certain range， the reduction effect of water level fluctuation in the trough section is improved slightly. It is recommended that the length of the pier should be about 8 m， taking into account the effect of the controlling water level fluctuation and the minimum requirements of engineering investment.

To optimize the flow state of the inlet forepool of the lateral pump station and eliminate the influence of the bad flow patterns on the pump suction， this paper usesnumerical calculation to analyze the flow patterns of the inlet sump of the pumping station， based on which， the rectification scheme is proposed to arrange diversion grid with different sizes at the inlet of the inlet sump， and the flow state of the inlet pool after rectification is analyzed. It can be seen from the results that the corresponding rectification effect is achieved after the arrangement of the guide grid， which can make the flow stream flow into the inlet pool relatively smoothly through the guide grid， improve the bias flow phenomenon in the 1~4# inlet pool， and create a good performance for the feed pump.After a comprehensive comparison and analysis， the rectification schemewith “3+2” type combination layout form is adopted. This rectification scheme can stabilize the uneven coefficients of the five inlet tanks and reduce the uneven coefficients of flow velocity compared with those of the original scheme. The rectification effect is obvious.

In order to study the nitrogen transformation law of saline soil， this paper takes the typical saline soil in Hetao Irrigation District（Inner Mongolia Autonomous Region） as the research object， and sets six salt levels （S ₁=2.01 dS/m， S ₂=6 dS/m， S ₃=12 dS/m， S ₄=16 dS/m， S ₅=20 dS/m， S ₆=25 dS/m） based on isotope tracer technology. 7.14 μmol/g is added to the soil of each salt level respectively.Isotope labeled ammonium nitrate （¹⁵NH₄NO₃， NH₄ ¹⁵NO₃， ¹⁵NH₄ ¹⁵NO₃） is used as soil nitrogen source. The concentrations of ammonium nitrogen and nitrate nitrogen and the corresponding atomic percentage of ¹⁵N are measured at five time points （4， 24， 72， 144， 288 h） during the experiment. Combined with the experimental data and the principle of isotope dilution， based on the first-order kinetic equation， the models including ammonia volatilization （v）， the first stage of denitrification or dissimilatory reduction to ammonium （d ₀）， the second stage of dissimilatory reduction to ammonium （d ₁）， the second stage of denitrification （d ₂）， mineralization （m）， the first stage of nitrification （n ₁）， the second stage of nitrification （n ₂），the nitrogen transformation models of saline soil are established for 10 soil nitrogen transformation processes， including ammonium nitrogen assimilation （i_a ）， nitrate nitrogen assimilation （i_n ） and heterotrophic nitrification （h）. The established model reflects the processes of nitrogen transformation in saline soil and better simulates the trend of experimental observations.In addition， the R ² of the fitting curve between the first-order kinetic constant of the model and the salt is more than 0.65 （except ammonia volatilization）， in which the fitting curve of K_{n 2} and salt ［K_{n 2}=（39.59（lnS）²-244.27lnS+393.86）×10^-3］ has the highest correlation（R ² =0.98， Δ=0.017）.

In order to optimize the design type of the straight pipe outlet channel，this paper establishes a three-dimensional pump device model which geometric scale is 11 bytaking Tonglvlarge low lift pump stationpumping sub-station as an example， uses hexahedral mesh divides the calculation domain， and calculates the full flow channel with steady flows. The numerical calculation is carried out to explore the water flow performance of the outlet channel with different bottom upturn angles. The calculation results show that the hydraulic performance of the bottom horizontal outlet channel is relatively general， and the adjustment effect on the internal flow is not obvious.With the increase in the upturning angle of the bottom， the hydraulic performance of the outlet channel shows a trend of first priority and then gets worse. There is a threshold angle for the optimal hydraulic performance， which is 1.5°. When the upturn angle is the threshold angle，the eddy flux in the front section of the outlet channel has a significant decrease， and the flow velocity uniformity in the rear section is the highest.Different bottom upturn angles have a great influence on the water flow performance of the straight pipe outlet channel. Using a suitable bottom upturn angle can improve the hydraulic performance of the outlet channel， enhance the water flow adjustment.The research results provide a certain reference for the hydraulic design of the straight-pipe outlet channel.

The Loess Plateau region has a serious shortage of water resources， and the study of soil moisture characteristic curves has important practical significance for improving water efficiency and saving water resources， but the direct test of measuring soil moisture characteristic curves faces many problems such as difficult operation technology， time-consuming and laborious， so it is necessary to make scientific and reasonable predictions of soil moisture characteristic curves.In order to improve the accuracy of the prediction model of soil moisture characteristic curve in the Loess Plateau area， the loess of the test site in five counties and cities in Shanxi Province was compared for the model. Based on the BP neural network algorithm， the prediction models of Gardner empirical model parameters and Van Genuchten empirical model parameters were established respectively， and the prediction models of Gardner empirical model parameters and Van Genuchten empirical model parameters were compared and analyzed according to the prediction results of the measured database.The results show that the average value of the relative errors of the two parameters after modeling and verification of the Gardner empirical model is less than 4% in the BP neural network prediction model of the empirical model parameters established， and the average of the relative errors of the two parameters after the modeling and verification of the Van Genuchten empirical model is less than 5%. It can be seen that whether it is the modeling training database or the validation database， the prediction model accuracy of Gardner empirical model parameters is slightly higher than that of Van Genuchten empirical model parameters.At the same time， compared with the Van Genuchten experience model， the expression of the Gardner experience model is simpler， and the meaning of the parameters is easier to understand， which is also more conducive to the learning and application of grass-roots workers related to farmland water conservancy.Therefore， this paper proposes thatthe loess moisture characteristic curve prediction modelbe established in the Loess Plateau region， the Gardner empirical model be more appropriate， and the results of this paper can provide supplementary and practical proof for the theoretical study of the moisture characteristic curve in the Loess Plateau region.

Vibration trend prediction of hydropower units helps to ensure the safe and stable operation of the unit. However， due to the complexity and non-stationarity of vibration signals， accurate and effective prediction becomes a problem. This paper uses the advantages of variational modal decomposition and neural network in dealing with non-stationarity and nonlinearity， combined with error correction methods， and establishes a combination model of vibration trend prediction. First， the original signal is decomposed by VMD， and then a GA-BP network is established for each IMF component to predict， and the obtained results are superimposed to obtain the vibration signal prediction result. Then， the error between the synthesized signal of each IMF component and the original signal is also predicted by using the VMD-GA-BP model， and the prediction result is added to the vibration signal prediction result to obtain the final prediction result. Demonstration experiments on the proposed model using the data of a domestic hydropower station show that the model proposed in this paper has higher prediction accuracy.

With continuous changesin business demands and storage technologies， how to store， process and apply data scientifically has become a major problem facing all walks of life. In view of the current situation and problems of hydropower plant data storage， such as slow query rate， low security， and rapid increase in the cost of data storage， this paper introduces Dameng Database System， and comprehensively uses distributed real-time database and relational database to store and manage data. Research on intelligent data storage strategies of hydropower plants from real-time data storage， historical data storage， data storage encryption and others provides innovative， scientific and effective strategies for the intelligent data storage of hydropower plants.

Dam deformation analysis is an important component of researching dam deformation regulation and ensuring dam safety. Support vector machine algorithm is integrated to optimize the fractal interpolation model. According to the characteristics of dam deformation time series， a hybrid model of fractal interpolation and support vector machine is established by optimizing vertical scale factor and kernel function. Deformation data of No 8 Observation Point in a concrete gravity dam is analyzed as an example， a hybrid model of fractal interpolation and support vector machine is established to fit and predict the deformation time series. The calculation results show that the hybrid model has higher accuracy than the corresponding singular-model， and can be applied to analyze dam deformation.

In order to realize shared concurrent personnel training and improve the training efficiency of turbine rotor fault， a hydraulic turbine rotor fault simulation system based on virtual simulation is designed. The foundation layer transmits all relevant data such as the foundation and fault of the turbine rotor to the application layer through the network interface， switch and other equipment. Based on the data， the application layer establishes the three-dimensional modeling of the hydraulic turbine rotor by using VRP modeling control program and 3ds max， and optimizes the model color based on the visual attention mechanism. The details of the hydraulic turbine rotor are displayed through the online simulation module of this layer. After the rotor fault is diagnosed by support vector machine， and the results are transmitted to the management layer. The management can present the fault simulation of hydraulic turbine rotor model through a variety of equipment and complete the virtual scene interaction through VRML interaction mechanism. The test results show that the system has good three-dimensional modeling effect of hydraulic turbine rotor， and the color visual effect of the model is good. Obtaining hydraulic turbine rotor fault diagnosis results can provide reliable support for fault simulation， present accurate fault simulation results to students， and meet the training application needs of multi-personnel sharing and concurrent interaction.

Aiming at the safety and stability of small earth-rock dams with downstream slope-wall composite structure， the current code theory regards the retaining wall as a part of the dam structure to evaluate the structural stability， which has certain limitations. The shear strength index is difficult， and the empirical value is often used in engineering. In order to accurately evaluate the stability of the composite structure and clarify the main influencing factors of the instability of the combined structure of the slope and wall， this paper regards the dam body and the dry stone retaining wall as independent structures， and uses the Geo-Studio finite element software to first use the Morgenstern-Price method to analyze the normal. The stability of the downstream dam slope under operating conditions， and then based on the distribution of pore water pressure and the x-direction stress and elevation distribution curve at the contact surface between the dam body and the retaining wall， the acting load on the contact surface is obtained， and the anti-sliding and anti-overturning stability and safety are calculated. The analysis results show that the ratio of the height of the retaining wall to the dam body and the slope ratio of the downstream dam slope are the main factors affecting the stability of the composite structure.

In the reinforcement project of the Xiyanghe Reservoir， a newly built spillway will lead the discharge flow into the downstream riverbed before Jingxin Expressway through the curved section of the outlet channel， with a turning angle of 54°. In the hydraulic model test of initial design， it was found that the water flow in the canal is obviously inclined to the left and shows wavy boundary with backflow near the sidewall meaning that the flow pattern in outlet channel was poor， which cause the outflow to spread to the left side and scour the bridge pier of the expressway. The downstream riverbed was severely scoured， which could not meet the requirements of energy dissipation and scouring prevention. In order to solve the problem， FLOW-3D software was used to conduct numerical simulation of the optimization of the outlet channel shape and hydraulic model test was also conducted， so as to verify the feasibility of the optimization. The result shows that： using the rectangular section with flat slope outlet channel can narrow the water better than the initial design， which can also make the backflow disappear and improve flow pattern. The flow velocity in the outlet channel increased obviously after the optimization of outlet channel shape. Therefore， different schemes are compared for the downstream anti- scouring measures， and feasible schemes are recommended.

High internal pressure buried steel pipe is faced with prominent deformation and anti-sliding stability problems at the turning point of the pipeline. In this paper， the finite element numerical model of the buried steel pipe is established based on the actual condition of a high-head water conveyance project. The influence of the pipeline laying mode and anchor block arrangement on the stress and deformation of the steel pipe is studied. The results show that under the action of high internal water pressure， the large convex deformation occurs at the large turning point of the buried steel pipe due to the weak constraint of the soil around the pipe， which leads to the slippage of the steel pipe. The temperature rise will strengthen the deformation trend and is more unfavorable to the steel pipe. Even if there is no expansion joint in the buried steel pipe pipeline， the steel pipe and the soil can have a certain relative slip， which can release part of the temperature stress and reduce the influence of temperature. In buried steel pipe pipelines， the deformation and axial slip of the steel pipe can be effectively controlled by setting several anchor blocks in places with severe terrain fluctuation. It is unnecessary to set an anchor block at each turning point， otherwise， the engineering quantity is increased， and problems such as uneven settlement may be induced.

Correct identification of dynamic parameters of hydraulic turbine rotor system is the key to research onthe reliability and stability of hydraulic turbine rotor system， which is of great significance to improving the operation safety of the hydraulic turbine unit. Based on the importance， the basic characteristics of dynamic parameters of hydraulic turbine rotor system are divided and determinedin this paper. The relevant dynamic parameters and algorithms are embodied in the hydraulic turbine， bearing and disk-shaft models. The disk structure is determined as the core structure of the on-orbit identification method. In addition， the frequency-domain identification method， the dynamic parameter identification method， and the parameter identification method based on intelligent algorithm are analyzed. The application strategy of on-orbit identification method is proposed based on the traditional identification methods， and the method of reducing the error of identification results is also proposed. Finally， the accuracy and stability of the on-orbit identification method are verified by comparative experiments. The results show that compared with the traditional instantaneous power calculation identification method and the electromagnetic axis identification method， the adaptive capacity of the on-orbit identification method is improved by 0.5 points， and accuracy is improved by about 0.3 MW.

A　turbine was selected as the research object in this paper， and the working state of water turbine under different flow state was determined by analyzing the rotation state. The average velocity of runner cross section was determined by calculating the velocity difference between front and rear of cascade. At the same unit speed and efficiency， the relationship between flow capacity and unit flow rate was analyzed to optimize cascade density. Simultaneously， the relationship between blade twist Angle and unit speed with unit flow rate was analyzed， and the relative radius of section of rim and hub was determined to optimize blade twist Angle parameters. The axial velocity of the cylindrical section of the runner was calculated， and the blade thickness parameters were optimized. The simulation results showed that under the condition of hub cavitation erosion and blade cavitation erosion， the final running speed of hydraulic turbine was 2.2 and 6.1 m/s faster than that before optimization， which had a good optimization effect.

Aiming at the problems of difficult data sharing in the enterprise’s business system and excessive manpower input in report making， this paper proposes an intelligent report analysis system based on intelligent information flow. The report data integration process based on BI business intelligence information flow transforms the data into ordered information for sharing. Combined with XML technology， the standardized management of all kinds of metadata is realized. Template RDL file isdefined， the overall model of report migration isbuilt， and report information isloaded into XML file to complete report format migration.Cosine similarity is used to evaluate the similarity between different measures to realize statistical decision pattern recognition. The analysis of hydropower station statement data shows that the system can intelligently complete report form development and decision analysis on the premise of ensuring the accuracy of data processing and analysis.

Reservoir resettlers are an important part of China’s rural population， and the 14th Five-Year Plan for Public Services points out that the well-being of people’s livelihood should reach a new level， so how to comprehensively improve the happiness of reservoir resettlers is an important part of the 14th Five-Year Plan. Based on happiness economics， this paper takes non-agricultural employment of reservoir resettlers as the research object， constructs the index system for measuring reservoir resettlers’ happiness， and uses the combination of AHP-entropy weighting method to compare and analyze the impact of employment location differences on reservoir resettlers’ happiness. The results show that income and family relationship are the main factors affecting reservoir resettlers’ happiness， and indicators such as work status， living conditions， convenience of life， infrastructure and policy fairness are also in a more important position， while consumption situation， social welfare， social status and neighborhood relationship do not have significant effects on reservoir resettlers’ happiness； the happiness of local non-farm employment reservoir resettlers is higher than that of reservoir resettlers working outside， and the individual characteristics of the two groups with higher well-being differ significantly. On this basis， the following suggestions are made： skills training should be carried out continuously to improve the competitiveness of reservoir resettlers’ employment； special industries should be developed vigorously to encourage young reservoir resettlers to return to their hometowns for employment and business； equalization of public services should be effectively guaranteed to improve reservoir resettlers’ quality of life.

Geotechnical engineering risk decision-making can quantitatively consider uncertainty and is widely used in engineering practice. A risk-based decision-making model and method are proposed for slope monitoring design based on the pre-posterior analysis. To address the computational difficulties in evaluating the value of information （VoI） for pre-posterior analysis， an efficient calculation method is proposed in this thesis， which improves the practicability and applicability of risk-based decision-making method for slope monitoring design based on the VoI theory. The proposed method is illustrated by a rock slope monitoring example. Results show that the pre-posterior analysis effectively identifies the optimal monitoring plan， and hence provides a useful tool to facilitate slope monitoring design.