Peri-urban areas are special areas formed in the period of rural areas changing to cities and towns. It has been vigorously developed during the past few decades because of urbanization and industrialization， and rapidly caught everyone’s eyes. However， diverse pollutants brought by complex sources， ranging from farming， breeding， living， to production and processing， inescapability damage the surrounding water environment and the whole basin ecosystem. In order to curb water pollution in peri-urban areas and cut down the total amount of pollutants flowing into river originally， this study selects middle and lower areas of the Four-lake basin as a research object， not only investigating all pollution sources and calculating the amount of pollutants， but also optimizing the structure of planting and breeding as well as the scale of urban and rural areas in the future. In this paper， Concentration Method and the Improved Export Coefficient Model（IECM） based on transfer reduction are used to calculate the amount of input pollutants from all point and non-point sources during the year 2008 to 2018. Then， spatial-temporal variations characteristics of input-river pollutants and the key pollutant sources are concluded and identified by data visualization， indicating that the agricultural planting and breeding in Honghu City are one of the most significant sources of input river pollutants. What’s more， Interval Fuzzy Multi-objective Programming Model（IFMOP） is used to optimize the planting structure as well as urban and rural scale in 2030. Model parameters are inexactly set to simulate the uncertain situations in the future， such as climate， agricultural and industrial management， environmental protection policies. The results show that the input TP and COD pollutants in research areas during 2008 to 2018 increased by 3.86% and 11.11% respectively， while the input NH₃-N and TN pollutants reduced by 14.91% and 0.4%. The main export area of input pollutants transferred from Jianli City to Honghu City. Most of input pollutants came from rural sources， instead of urban sources， in decades. Secondly， there will be an excellent effect on water conservation and pollution control in the year 2030， by optimizing the planting structure and county scale. With high level of water conservation and pollution control， the water consumption per ten-thousand yuan of GDP in Jingzhou region and Qianjiang region would decrease by 42.2% and 61.7% respectively， as well as the input TN， TP， COD and NH3-N pollutants would decline by 47.9%， 50.5%， 56.2% and 57.3%. Thirdly， dry farming and crayfish-rice planting modes would gradually replace paddy field to become the main planting modes in the study areas； the amount of livestock and poultry production as well as rural population would decrease by 20.9 and 48.5%~49.4%， the amount of aquaculture production， urban population and industrial added value would respectively increase by 8.9%， 76.2%~77.7% and 183.4%~183.9%.

Constructing inter-basin water transfer ecological compensation mechanism for inter-basin water transfer is one of the effective ways to adjust the interest relationship and promote sustainable development in the region. Public’s willingness is an important basis for establishing the ecological compensation mechanism of the inter-basin water transfer. Based on theoretical exploration， field investigation and model analysis， the willingness to pay （WTP） value and influencing factors of ecological compensation of inter-basin water transfer project are analyzed in Jinnan， Shandong Province， the water-receiving area of the eastern route of the South-to-North Water Transfer Project. The WTP value is 206.29 RMB /（person·year） obtained through the combination of non-parametric and parametric methods. Bayesian network model is employed to explore the influencing factors， it is found that educational background， per capita monthly household income， the recognition of the importance of the project to the city or the country and whether the project has a positive impact on your life have the greater influence on WTP. Then， SWOT matrix analysis method is adopted to put forward incentive mechanism from the perspectives of internal public background and external environmental policies.This study is to provide reference for the construction of ecological compensation mechanism of inter-basin water transfer project， and to put forward countermeasures and suggestions for social capital to participate in water conservancy construction management.

Intensive human activities have led to significant changes in land use types， which will have an impact on the landscape and ecosystem health of the basin. By using the land use map data of 2000， 2010 and 2020， the changes of land use， landscape pattern index and ecosystem service value in Fen River Basin are modeled and calculated， and the ecosystem health assessment of Fen River Basin is carried out at the county scale based on PSR model. The results show that in the past 20 years， the construction land in Fen River Basin has increased sharply by 3.64%， while the cultivated land area has decreased significantly by 4.51%. The decrease of cultivated land is mainly transferred to construction land， forest land and grassland， and the increase of construction land mainly comes from cultivated land and grassland. The PD of construction land and cultivated land in the basin has increased by about 23%， indicating that the degree of landscape fragmentation of these two land types has increased in recent 20 years. SHDI of the overall landscape level of the basin shows an upward trend， while PD and LSI first increase and then decrease， which reflects that the degree of land use has increased， the impact of human activities has intensified， and the landscape in the basin has a fragmentation trend. There are certain differences in the ecosystem health status of the river basin in different time and space. The regions with good ecosystem health status showed an increasing trend from 2000 to 2020， but with the development of urbanization， the ecosystem health pressure of population gathering areas such as the surrounding areas of Taiyuan and the lower reaches of Fen River is still large. The results of this study can provide a theoretical basis for environmental protection and ecological management of the basin.

As the dredged slurry is treated by straw drainage combined with vacuum preloading， the straw drainage will inevitably degrade， thus changing the cultivation performance of the dredged slurry after vacuum preloading. To clarify the influence law of the degradation of straw as a drainage body on the cultivation performance of dredged slurry during vacuum preloading， a large-scale model test of vacuum preloading of dredged slurry with straw as the vertical drainage body is carried out. By measuring the distribution of organic matter and nutrient elements in different positions of dredged slurry after vacuum preloading， the influence of straw drainage body degradation on the cultivability of the dredged slurry is discussed， which can provide technical support for straw drainage used in the ecological treatment of dredged slurry. The results show that compared with untreated dredged slurry， straw degradation would increase the contents of organic matter， carbon （C）， nitrogen （N）， phosphorus （P）， and potassium （K） in the treated slurry， and reduce the carbon nitrogen ratio （C/N）. At the same depth， the organic matter content in the dredged slurry decreases with the increase in the distance from the drainage body. At the same distance from the drainage body， the variation of organic matter content in the dredged slurry with the increase in depth is small， which is less than 1.0%. Additionally， the contents of carbon （C）， nitrogen （N）， phosphorus （P）， and potassium （K） in dredged slurry show different trends with the increase in depth and distance from the drainage body. However， when the distance from the drainage body reaches 30 cm， the content of nutrient elements in the dredged slurry tends to be stable.

In recent years， a kind of new purification technology of polluted river water， the artificial floating island has been widely used. This technology is pollution-free in the whole process of the water treatment， but its negative effects on water resistance have been becoming increasingly evident. In this paper， a general physical model experiment is conducted by considering the application characteristics of floating islands in rivers. Based on the experimental data， this paper systematically analyzes the damming effect upstream of artificial floating islands， defines the damming coefficient to characterize this effect， and investigates the influential factors and changes rules of the damming effect. The methods of dimensional analysis and orthogonal design tests are used， combined with sensitivity analysis. According to the analysis， the main influencing factors of the damming effect of artificial floating islands are identified. Based on the Least Squares Method， a multiple regression analysis on the relationship between the main influencing factors and the damming coefficient is carried out and a mathematical expression is obtained. The results show that the presence of floating islands causes the phenomenon of water level enhancement upstream and water level reduction downstream. The magnitude of the damming coefficient is related to the factors of floating island size， river depth， floating island draft， river width and distance from the floating island. The damming coefficient is positively related to the Froude Number， the relative width of the floating island （the ratio of side length of floating island to channel width ） and the relative draft depth （the ratio of draft depth to river depth）， respectively. And the above positive relations tend to the power functions.

River ecological water demand is the minimum water consumption that must be guaranteed to maintain the stability of ecological environment function in the river， which can provide a scientific and theoretical basis for river ecological environment governance and rational development and utilization of water resources. Due to the phenomena of continuous bottom freezing and cutoff in winter， the contradiction between the development and utilization of water resources and the ecological environmental water demand which intensifies the river of the cold regions in northern China. So an important problem is how to determine the ecological water demand of rivers in cold regions. According to the variation characteristics of river runoff in cold regions， considering the freezing period and non-freezing period， and selecting the monthly average runoff with ninety-five percent assurance rate and the multi-year average monthly runoff as indicators， this paper improves the annual distribution method of river ecological water demand. Taking five main hydrological control sections in the Huma River Basin in the high latitude region as the research object， the runoff data is taken in total of sixty-one years， measured sections from 1956 to 2016 are selected， and the basic ecological water demand of the main control sections of the Huma River is calculated by using the improved intra year distribution method， and the calculation results are compared with those of Montanan （Tennant） and those of other methods. The results show that： ① the ecological water demand of the sections of the main hydrological stations in the Huma River Basin in the flood season （wet season） accounts for 25.8%~27.8% of the annual average runoff in the same period for many years. The cross-section ecological water demand of each main hydrological station in non flood season （normal season） accounts for 19.1%~24.0% of the annual average runoff in the same period over the years. The analysis and calculation results are consistent with the river state corresponding to the evaluation standard of Montana method （Tennant） and the ecological function goal defined by the concept of basic ecological water demand of the river. ② The improved intra year distribution can well reflect the natural runoff of rivers in the northern cold region during the flood season， the non-flood season and the real change process and law of low water and even continuous bottom freezing in the freezing period， which can meet the ac tual needs of the river ecological function protection target for runoff in the northeast cold region， and meet the annual dynamic demands of the river ecological hydrological process for runoff. As a result， it can be popularized and applied to the calculation of the basic ecological water demand of rivers in the cold region. The actual demand of the river ecological function protection target for the runoff can be applied to the calculation of the basic ecological water demand of rivers in cold regions.

Research on the migration and transformation patterns of heavy metal pollution in watersheds is one of the key instruments for effectively preventing and controlling heavy metal pollution and protecting the quality of the ecological environment in watersheds. Complex mechanisms with multiple sources and pathways are the characteristics of heavy metal transport and transformation in the watersheds. Accurate modeling of heavy metal migration and transformation processes in the watershed is the foundation and primary approach for studying the migration and transformation of heavy metal pollution.It is crucial to consider atmospheric， land surface， and water space from the perspective of the integrity of the river basin， to clarify the mechanisms， processes， and fluxes in each system， and to achieve a systematic analysis of changes in heavy metal water quality from integrated point and non-point sources of pollution in order to model and analyze changes in heavy metal concentrations accurately. This paper gives a thorough overview of the sources， processes for the transport and transformation of heavy metals in the atmosphere， soils on the surface of the land， and river water bodies in the basin. It also systematically introduces the development of models for the transport and transformation of heavy metals in the basin. Future research will concentrate on improving the coupled model of heavy metal transport and transformation in the basin and fully coupling terrestrial surface processes with river hydrological sediment processes， heavy metal transport and transformation processes， and meteorological process influences. Additionally， it is expected to increase environmental risk management and precise environmental management in the region while providing new insights on how to predict， prevent， and regulate heavy metal contamination in the basin.

Ecological water demand is an important research direction in the fields of ecology， hydrology， environmental science， etc. The ecological restoration of rivers or the development and utilization of water resources require preliminary studies on the ecological water demand of rivers. How to scientifically determine river ecological water demand is a significant premise and basis for protecting river ecosystem and rationally allocating river water resources. At the present time， there are innumerable methods for calculating the ecological water demand of rivers. The wet perimeter method is a widely used hydraulic method for calculating the ecological water demand of rivers. The wet perimeter method is convenient and speedy to establish a reliable wet perimeter-flow relationship， but it is difficult to calculate the ecological water demand in ungauged watersheds. In order to solve this problem， this paper employs the aerial photogrammetry technology of Unmanned Aerial Vehicle （UAV） to obtain the large section shape of the river channel. The important hydraulic parameters， such as roughness and hydraulic slope， are acquired by analyzing and processing UAV images. Astable wet perimeter-discharge relationship is established with the Manning formula. The slope method is used to determine the curve inflection point， and the minimum ecological water demand of the river is calculated with reference to the inflection point. Two cross-sections （Huangta and Lianghekou） of the Nanhe River Basin in Qionglai City are selected as study sections to calculate the ecological flow. The conventional calculation approach with the Tennant method based on historical flow data is used as a comparison and reference to judge the rationality of the calculation results. The results indicate that the ecological flow of the two sections calculated by the wet perimeter method are 9.38 and 5.33 m³/s， respectively， while the ecological flow calculated by Tennant method is 11.96 and 6.6 m³/s. The two results are close and consistent with the flow distribution law， which proves that it is feasible to apply UAV technology to the wet cycle method to calculate river ecological water demand. The method for calculating river ecological water demand is feasible， providing a new way for calculating river ecological water demand in areas lacking data and an important basis for water resources development and utilization and water ecological protection. However， since UAV technology cannot measure large underwater sections， for the watersheds without hydrological observation stations nearby， how to carry out a reasonable cross section generalization and coupling with the above-water section when applying the wet cycle method， and how to verify the rationality of the calculated ecological flow and other issues need further research.

This summer， China’s Yangtze River Basin suffered the most severe meteorological and hydrological drought since 1961 under extreme heat， and the Yangtze River roaming beaches ran dry over a large area， seriously affecting the carbon cycle of the riverbank wetland ecosystem. An incubation experiment was conducted by using the sediments selected from Baguazhou wetland in Nanjing to investigate the effects of drying and rewetting on wetland sediments GHG emissions and to explore the corresponding influencing mechanism based on three-dimensional fluorescence spectroscopy （3D-EEMs） and other methods under two different types of temperature（20 ℃ and 30 ℃） and three different moisture gradients （fully submerged， semi-submerged and dry）. The results under different temperature treatments show that warming promoted carbon dioxide （CO₂） emissions （P<0.05） and methane （CH₄） emissions （P>0.05）， and the total CO₂ equivalent of cumulative emissions from the three sites at 30 ℃ is 987.74 mg/kg， which is 1.62 times higher than that under the 20 ℃ incubation treatment. And the sediment at Site A contributed the most to the total emissions （63.36%）. The results under different moisture circumstances show that the CO₂ equivalents of cumulative emissions under the same temperature treatment are from high to low： fully submerged treatment > semi-submerged treatment > dry treatment， and the CO₂ equivalents under fully submerged treatment are 9.97 times higher than those under dry treatment at 30 ℃ incubation treatment. The CO₂ equivalent of sediment greenhouse gas emissions under high temperature and high water level conditions can reach more than 28 times of that under low temperature and dry environment， in which the contribution of CO₂ emissions is 99.7%. The results of the study have important implications for assessing sediment carbon emissions and formulating carbon reduction policies under the influence of long-term drought and extreme precipitation frequency in the future.

It is of great significance for the ecological protection and high-quality development of the Yellow River Basin to explore the coupling coordination relationship between ecosystem services and human activity intensity in the Yellow River Basin and its influencing factors. Unfortunately， there is a relative lack of research on integrating the human activity intensity into the correlation analysis of ecosystem services to explore the coupling coordination between the two， especially in the Yellow River Basin. In this paper， based on multi-source data such as remote sensing and socio-economic statistics， the spatial and temporal variation characteristics of ecosystem service values and human activity intensity in the Yellow River Basin from 2000-2018 are assessed by using the modified equivalent factor method and the human activity intensity method. Then the spatial and temporal evolution of the coupling coordination relationship between them are revealed by using the coupling coordination degree model. Finally， the dominant driving factors affecting the change of the coupling coordination relationship between ecosystem service values and human activity intensity are discussed by using the geographical detector model. The results show that： ① The ecosystem service value in the Yellow River Basin showed an increasing trend from 2000-2018， with an increase of 8.492 7 billion yuan during the whole study period， and showed a spatial distribution pattern of low ecosystem service value in the eastern municipalities and high ecosystem service value in the central and western prefecture-level cities of the Yellow River Basin. ② Most of municipalities in the Yellow River Basin showed an increasing trend of human activity intensity from 2000-2018， indicating that the human activities in the Yellow River Basin are increasingly interfering with the ecosystem， and showed a spatial pattern of decreasing human activity intensity from southeast to northwest. ③ The coupling degree between ecosystem service value and human activity intensity in most municipalities of the Yellow River Basin was at the stages of friction and high level of coupling， and the coupling coordination degree was mostly between barely coordinated and basically coordinated. ④ The results of geographical exploration showed that economic density， construction land ratio， rainfall and NDVI were the dominant influencing factors driving the changes of coupling coordination degree between ecosystem service value and human activity intensity in the Yellow River Basin. The results not only enrich the knowledge of the relationship between ecosystem services and human activities， but also provide an important scientific basis for the sustainable development of the ecosystem in the Yellow River Basin.

Flood encounter in the main stream and tributaries， tributaries and tributaries， upper and lower reaches aggravate the severe situation of flood control in the upper reaches of the Yangtze River.The frequent occurrence of rainstorm and flood disaster in the basin seriously affects the stable development of the coastal area. It is necessary to analyze the law and situation of flood encounter comprehensively and systematically. Based on the hydrological statistical analysis method， the flood encounter rules of ten different combinations of the main stream and tributaries， tributaries and tributaries， upstream and downstream of the upper Yangtze River Basin are analyzed from the aspects of flood encounter times and time， peak encounter and magnitude of maximum 7-day and 15-day flood process encounter， and maximum 7-day and 15-day flood process overlap days. Then the severity of flood peak， the severity of maximum for 7 days and 15 days flood process， and the overlap degree of maximum for 7 days and 15 days flood process are sorted and analyzed by using the improved five-element connection number set pair situation sorting method.The results show that， when a flood happens， the overall situation of peak and flood volume of various flood combinations in the upper reaches of the Yangtze River is not serious， but the overlapping degree of the maximum 7-day and 15-day flood processes is at a high level， which shows that the flood lasts for a long time and the process flood volume is large. In particular， the overlapping degree of the maximum 7-day flood volume of Wujiang River and the mainstream of the Yangtze River at Yichang Station is especially serious， which brings great flood control pressure to Yichang Station and its downstream Jingjiang flood diversion area. The improved five-element connection number set pair potential ranking method retains 181 logically established potential levels， quantitatively depicts the connection trend between flood encounter indicators and severity levels from the angles of equal potential， balance of potential and reverse potential， and quantifies the severity of flood encounter into different potential levels meticulously and accurately， which is helpful to quickly judge flood control priorities and provide a decision-making basis for implementing scientific dispatching.

Many studies can be found regarding river flood and urban flood induced by heavy rainfall. However， o few are focused on the compound flood caused by them. The mechanism of the compound flood process and the measures that could be taken to mitigate its impact need a systematic research. By taking the river flood happening in August 2020 in downtown city of Chongqing， the flood characteristics including the flood area and depth have been simulated by using the proposed modeling system CUFM （Compound Urban Flood Model）. By comparing the results by using MIKE 21， the flood extent of the latter is more serious and it cannot reproduce the overflow flood through the pipeline. Taking the Dashaxi Region in Nan’an District of the downtown city as the study area， the compound flood process and its rationale have been analyzed numerically. With the increase of the rainfall return period， the flood area also expands gradually. The reason can be partially attributed to the jacking at the outfall and pipe overflow. Besides， the topography decreases from the southeast to the northwest which forces the mountainous runoff flowing to the low-lying area， but due to the river flood， the runoff cannot go into the river or be collected by the surcharged pipe system. Finally， the response relationship between the variation of flood volume and the rainfall pattern under the impact of the river flood has been simulated and discussed. It shows that under the circumstance of small rainfall return periods， the rain peak occurrence does not affect the flood volume but the rain with early peak occurrence would result in a rapid flood increase. With the increase in rainfall return period， the rain peak has a great impact on the flood volume， the rain with a later peak occurrence would produce higher flood peak and the flood peak comes later. The conclusion of the research indicates that in case of small rainfall return period， precautions should be taken against the rain with early peak occurrence which may speed up the increase in flood， and for large rainfall return period， preventive actions need to be taken to mitigate the impact brought by the rain with later peak occurrence.

The runoff process is a vital part of the earth’s hydrological cycle. Scientific and accurate prediction of monthly runoff inflow is of great significance for water flow scheduling， water resources planning and management in the basin. However， due to the complexity of the runoff process and the influence of human activities， it is very difficult to accurately capture the variation law of the monthly runoff time series in a changing environment. Because of the two problems in the prediction of monthly runoff time series， the prior information identification in the sample data is not thorough enough， and the time step embedding dimension is difficult to be effectively and adaptively selected. This paper designs a model for monthly runoff time series based on VMD-PSR-BNN. Based on the good robustness of variational mode decomposition （VMD） algorithm to noise and the characteristics of accurate decomposition of time series signals， the monthly runoff time series is regarded as a time series signal， and the VMD method is used to decompose the monthly runoff time series into multiple relatively stationary intrinsic mode function （IMF）. Then， each IMF is reconstructed based on the phase space reconstruction （PSR） theory， and the Bayesian neural network （BNN） based on variational inference is used to predict each reconstructed IMF. Finally， the prediction results of each BNN are aggregated and reconstructed to obtain the final prediction result. The monthly runoff time series from 1953 to 2018 of two hydrological stations in Xianyang and Huaxian in the Weihe River Basin are selected for case analysis. The results show that the prediction results of the two hydrological stations based on the VMD-PSR-BNN model can reach the first-class standard of hydrological forecasting， and have a good fitting effect for the extreme values ??in the sample， which provides a new method reference for the prediction of monthly runoff time series.

Groundwater drought could cause non-negligible harm to groundwater system， social industries and ecosystems which depend on groundwater. It is of great significance to accurately predict groundwater drought. As case studies in the typical regions with less human influence in Hunan Province and Sichuan Province in the Yangtze River Basin， groundwater droughts in typical regions are predicted by using the key influencing factors， such as natural net recharge （P-ET）， landuse and landcover， as predictors of gated recurrent unit （GRU）， which is a deep learning model， and support vector machine （SVM）/multiple linear regression （MLR）， which are machine learning models， respectively. It adopts the groundwater storage anomaly （GWSA） derived from GRACE as the output of the models， and consequently calculates the groundwater drought index based on GRACE. In addition， this paper also explores whether meteorological variables affecting P-ET are suitable as input variables. The main conclusions are as follows： ① In Hunan， a typical region in the Yangtze River Basin， the MLR has the longest forecast period of GWSA， and the forecast period of SVM is the shortest. During the forecast period， GRU has the best prediction performance and SVM has the worst prediction efficiency. In terms of input variable selection， adding meteorological variables that affect P-ET improves the prediction performance of SVM and MLR models for GWSA， but reduces the prediction performance of GRU model. In terms of groundwater drought prediction， the case in which the MLR model excludes meteorological variables affecting P-ET shows a better ability to capture groundwater drought dynamics. ② In Sichuan， a typical region in the Yangtze River Basin， the predicted GWSA of all cases in the test period are close to the reference value， except for some peaks that cannot be caught in the middle and late stages. Adding meteorological variables affecting P-ET can improve the prediction performance of the three models for GWSA. In terms of groundwater drought prediction， using SVM model or MLR model and excluding meteorological variables affecting P-ET can achieve relatively satisfactory performance in groundwater drought prediction.

With the continuous advancement of urbanization， the contradiction between supply and demand of water resources has been escalating， and the water resources problem has become increasingly prominent， which has seriously restricted the healthy development of regional economy. Therefore， the quantitative evaluation of ecological carrying state of water resources can provide a scientific basis for the sustainable development of the region. Collecting the data of economy， population and water resources in Southeast Sichuan from 2005 to 2019， based on the model of water resource ecological footprint， the sustainable index of water resources in southeast Sichuan is calculated by analyzing and discussing its spatio-temporal variation characteristics. The results show that：① From 2005 to 2019， the overall trend of ecological footprint of water resources per-capita increased first and then decreased； the ecological carrying capacity of water resources fluctuated greatly， and its change trajectory was closely related to precipitation； the amount of water resources was ecological surplus， and water resources were in a state of sustainable development， which could satisfy the needs of current social and economic development. ② From 2005 to 2019， the water resources ecological footprint of 108 yuan of GDP decreased year by year， indicating that the regional water resource utilization efficiency gradually improved； the water resources load index was between grade II and III， indicating that the development and utilization degree of regional water resources was high， and there was no need to transfer water across the region； the sustainable index of water resources was between 0.7 and 0.9 all the year round， and the sustainable state was medium sustainable and strong sustainable. ③ From 2015 to 2019， there were spatial differences in water resources of ecological footprint， ecological carrying capacity and ecological profit and loss among prefecture-level cities. Leshan and Meishan were relatively rich in water resources， and there was a good coordination between economic development and water resources utilization； the ecological profit and loss of water resources in Luzhou and Yibin were in the middle-low level， and the ecological carrying capacity of water resources needed to be improved. In Zigong， Neijiang and Ziyang， the ecological carrying capacity of water resources were low， the ecological profit and loss of water resources were small and the ecological pressure of water resources were large.

Based on the daily data observed in 14 meteorology stations in the Yongding River Basin from 1957 to 2018， this paper analyzes the spatial-temporal characteristics of precipitation by using linear propensity estimation， anomalies analysis and wavelet analysis.The Rotated Empirical Orthogonal Function（REOF） method is used to divide characteristic zones and reveal the main correlative factors of precipitation in the basin through correlation analysis. Results show that under the background of global warming， the precipitation of the Yongding River Basin shows a decreasing trend with a rate of -2.88 mm/10 a with the average annual precipitation of 389.22 mm. From seasonal means， the precipitation in spring and autumn shows an increasing trend and the increase in precipitation is the most obvious in autumn with increasing rate of 3.75mm/10a.On the contrary， the precipitation in summer and winter shows a decreasing trend and the decrease in precipitation is the most obvious in summer with decreasing rate of -8.14 mm/10 a. Wavelet analysis shows that there are three cycles of 28， 15 and 4 a in the variation of precipitation， with 28 a as the main cycle. The main cycle time of precipitation in the Basin is 28 years. From spatial means， precipitation is significantly different， precipitation in the Basin decreases from the southeastern plain areas to the northwestern mountainous areas. The REOF analysis shows that first six modes can reflect the spatial distribution of precipitation in Yongding River Basin. According to the distribution of high load area in each mode，the Yongding River Basin can be divided into six zones： Zone Ⅰ is southwestern Datong Basin， Zone Ⅱ is northern Zhangjiakou， Zone Ⅲ is Yanhuai Basin， Zone Ⅳ is Beijing and northwestern Hebei Basin， Zone Ⅴ is northwestern Inner Mongolia mountains and Zone Ⅵ is Coastal plains.Among these zones， Zone Ⅰ， Zone Ⅳ and Ⅵ are affected by continental climate and monsoon climate， respectively. Zone Ⅱ and Ⅲ are significantly affected by local topography. The correlation analysis results show that the Southern Indian Ocean Dipole （SIOD）， evaporation， maximum temperature， sunshine time and scattering are significantly correlated with precipitation.

Reasonable flood limit water level can coordinate the contradiction between flood control and benefit， and produce double benefits of flood control and benefit. The flood limit water level and scheduling procedures of Fushui Reservoir have been in use since 1996， so it is necessary to study the flood limit water level of Fushui Reservoir. In this paper， according to the flood control needs of the basin under the new situation， different adjustment schemes of the flood limit water level of the Fushui Reservoir are formulated. The regulation and storage of the Fushui Reservoir and the evolution of downstream floods are simulated and calculated， and the flood control benefits and water storage benefits of each dispatch scheme are counted and compared. Finally， it is proved that the research method of flood-limited water level adopted in this paper is suitable for the study of flood-limited water level of reservoirs with important flood control tasks downstream.

Terrestrial water storage is the comprehensive reflection of precipitation， evapotranspiration， runoff， infiltration and other hydrological processes， it controls hydrological cycle processes at different scales. Analyzing the long-term changes of terrestrial water storage in the Qinghai-Tibetan Plateau and clarifying the impact of climate change can cause a scientific understanding of current water security risks and improve water resource managements in the Qinghai-Tibetan Plateau. This study utilizes the GRACE data and ISI-MIP2b simulations， combing multi-model weighing method with Mann-Kendall trend analysis to analyze the temporal and spatial changes of terrestrial water storage in the Qinghai-Tibetan Plateau during 1861-2005 and 2006-2099. Further， it investigates the impact of climate change on terrestrial water and groundwater storage through different scenarios. This study finds that： ① The GRACE data showed that the terrestrial water storage in the Qinghai-Tibetan Plateau presented a decreasing trend from 2002 to 2017， and the spatial heterogeneity of water storage changing is strong. The southern part of the plateau showed a decreasing trend and the northern part showed an increasing trend. ② The ISI-MIP2b multi-model simulations showed that the terrestrial water storage in the Qinghai-Tibetan Plateau during 1861-2005 exhibiting increasing trends （P<0.01） under picontrol scenario （PIC） and historical scenario （HIST）. Climate change reduced the increase rate of terrestrial water storage （0.50 km³/a）. In addition， the terrestrial water storage in most parts of the eastern and central of the plateau changed from an increasing trend to a decreasing trend under the PIC scenario due to climate change. ③ From 2006 to 2099， the trend of terrestrial water storage changed from an increasing to decreasing trend due to climate change. Terrestrial water storage showed an increasing trend under PIC scenario， while it showed decreasing trends under RCP2.6， RCP6.0 and RCP8.5 scenarios. Terrestrial water storage in most parts of the Three-Rivers Headwaters Region showed decreasing trends under the four scenarios， while it showed an increasing trend in the inner river basins under RCP2.6， RCP6.0 and RCP8.5 scenarios. The groundwater storage showed a decreasing trend under PIC scenario while it showed an increasing trend under other scenarios， and the higher radiation forcing scenario showed a higher increase rate.

Based on MODIS-NDVI and LST images of the growing seasons （April-October） from 2000 to 2020， the Vegetation Supply Water Index （VSWI） is used as the drought monitoring index to analyze the drought intensity and drought frequency characteristics of Guizhou Province by using a wavelet analysis， linear propensity rate， and center of gravity migration model to explore the relationship between agricultural drought and soil moisture and rainfall is explored to provide a reference for agricultural drought monitoring and drought relief in Guizhou Province. The results show that ① in the growing season （April-October） from 2000 to 2020， the VSWI in Guizhou Province showed a slow increasing trend， indicating that the drought was alleviated. The drought frequency showed a spatial distribution of “high in the west and low in the east”， and the drought level showed a drought zone from Qianxinan Prefecture to Anshun City to Guiyang City to Zunyi City， and the drought degree decreased from the axis to the northwest and southeast. The area of light drought showed a decreasing trend， the area of middle drought showed a decreasing trend， and the area of severe drought was less and fluctuated less.② There are two main oscillation cycles of agricultural drought， the first cycle is 7~9 years， with the center of oscillation in 2005； the second cycle is 15~18 years， basically throughout the study period， with the center of oscillation in 2011. There are cycles of about 8 and 16 years for agricultural droughts in Guizhou Province. ③ The average drought center of Guizhou Province in 21 years was located in Xingyi City （104.99°E， 25.03°N）， and the monthly drought center and annual drought center were concentrated in Guiyang （106.73°E， 26.58°N）， Bijie （105.28°E， 27.30°N） and Xingyi （104.90°E， 104.90°E）. 25.08°N）.④ The spatial relationship between VSWI and soil moisture was complex， but the overall positive correlation was observed. The lower the soil moisture was， the lower the VSWI was and the more severe the drought was. At the same time， the relationship between rainfall and agricultural drought is not completely positive. On the whole， the changing trends of rainfall and agricultural drought are similar.

The probability of extreme climate events is increasing under global warming， and compound extreme events have more serious impacts in society and environment than individual extreme events. By using daily precipitation observation and daily maximum temperature data from 639 meteorological stations over China during 1961-2020， this paper adopts the index of weighted average of precipitation （WAP） and the method based on relative threshold to identify flood and heatwave events， and investigates total frequency and probability of compound extreme flood-heatwave events occurrence within seven days， discusses the temporal variation characteristics of compound events in the different periods compared with individual extreme events， and analyzes the duration and average magnitude of heatwave in flood-heatwave event， this study can provide reference for the flood control and disaster reduction scheme in China. The research results are as follows： ① In recent 60 years， the compound flood-heatwave events occur at almost all stations， and show obvious spatial differences. The regions with high frequency of compound extreme events occurrence are mainly distributed in Yangtze， Southeast， Pearl and Northwestriverbasins； ② The total frequency and the regional average occurrence probability of flood-heatwave events over China showed significant increasing trends （P<0.01） from 1961 to 2020， which became larger and larger among different decades.The frequency and probability of compound events occurrence in different years varied greatly with the highest values in 2016 （261 times， 17.4%） and the lowest values in 1985 （8 times， 0.5%）， and the frequency and probability of occurrence has significant correlation； ③ Compared with individual extreme events， the increasing rate of flood-heatwave events is relatively significant.The ratio of the total number of flood-heatwave events during 1981-2000 and 2001-2020 against the total frequency of compound events during 1961-1980 increased from 1.26 to 2.96， and the increasing rate was most prominent in eastern Yangtze， Southeastern Pearl and Southeastern river basins； ④ Compared with heatwave events without flood before them， the longest duration and average magnitude of heatwave in flood-heatwave events were relatively short and small respectively， which show insignificant spatial differences among different basins.

In practical engineering， many rectangular thin-crest measuring weirs use thick concrete walls as the retaining wall of side contracted weirs， leading to the different thickness of the weir and the retaining wall. This change increases the safety of measuring weirs， but different from the standard situation in the specification， and may have a certain impact on overflow capacity. In order to study the calculation of discharge coefficient of rectangular contracted weir considering the thickness of retaining wall， the hydraulic experiments of contracted weir with 6 thickness ratios with contracted ratio of 0.5 are carried out while the nappe over weir is observed and recorded. The experimental results show that the thickness of the retaining wall of the contracted weir has an obvious influence on the discharge coefficient after comparison. Therefore， the calculation formula of the discharge coefficient of the contracted weir in the existing Measurement Specification did not express the influence of the sidewall thickness. Based on the experimental data， the calculation formula of discharge coefficient of contracted weir considering thickness ratio D/d and h/P is established by regression relationship method， which can be used as a reference in practice.

To study the changes of chlorophyll relative content （SPAD） in rice leaves under three water treatments and five nitrogen treatments， and to explore the feasibility of multispectral remote sensing technology for unmanned aerial vehicle （UAV） to retrieve rice SPAD. In this study， DJI Phantom 4 multispectral UAV was used to collect multispectral remote sensing images of rice canopy at jointing and booting stage， heading and flowering stage and milk ripening stage， and simultaneously measure the SPAD value of rice. Based on twenty-five spectral variables （five band reflectance and twenty vegetation indexes）， the retrieving model of rice SPAD at different stages is established by multiple linear stepwise regression （MLSR）， ridge regression （RR） and lasso regression （LR）. The results show that the best retrieving models of rice SPAD at three growth stages are established by lasso regression， and the best retrieving model of SPAD established at milk ripening stage has the highest inversion accuracy among the three growth stages， with coefficient of determination of 0.782， root mean square error of 1.217 7 and relative error of 6.611 3%. Therefore， this paper can monitor rice leaf SPAD by remote sensing， and provide a scientific basis and data support for rice precision irrigation and fertilization.

The low specific speed centrifugal pump has the characteristics of small flow， high head and low efficiency. In order to improve the efficiency of the low specific speed centrifugal pump under the condition of meeting the use requirements of the head， this paper optimizes the low specific speed centrifugal pump by modifying the meridian surface of the impeller， and then the blade outlet width， the inlet shroud placement angle， the inlet hub placement angle， the outlet placement angle and wrap angle are used as optimization parameters. Head and efficiency are selected as optimization goals. 40 groups of experiments are designed by using the optimal Latin Hypercube Design Method. BP neural network is used as the surrogate model between optimization parameters and optimization goals， and NSGA-Ⅱ multi-objective genetic algorithm is used to optimize the head and efficiency. After optimization， the hump phenomenon is suppressed by chamfering the impeller outlet. The final optimized centrifugal pump has an increase of 13 m in head and an efficiency increase of 8.07% under standard conditions.

For the multi-parameter calibration problem of the complex cascaded open channel water transfer project， the traditional trial-and-error method needs to obtain the optimal combination of parameter values based on the hydrodynamic model， which requires a large amount of computation. Therefore， this paper proposes a multi-parameter calibration method based on a genetic algorithm， which transforms the multiparameter calibration problem in the hydrodynamic model into an optimization problem with the calibrating parameters as the state variables. Then the combination calibration of the parameters is obtained by a genetic algorithm. The method is used to determine the roughness of the three channels and the flow coefficients of the three undershot gates in the “Xiheishan gate-Fenzhuanghe gate” section in the Middle Route Project of the South-to-North Water Transfer Project. The results show that the optimal combination calibration of the parameters can be obtained by one optimization process， the water level obtained by the simulation model by using the calibrated parameter values are relatively close to the measured water levels， with the average deviation less than 2 cm.

The particle composition of coarse-grained soil is complex， and it is difficult to accurately measure its permeability coefficient in practical projects， so it is particularly important to explore its empirical calculation formula. In this paper， through the particle gradation and permeability test of typical medium sandy soil in Yinchuan Plains， the influence of sand content on sediment permeability under the condition of particle grading is studied， and the correlation between permeability coefficient and gradation parameters is discussed. The empirical formula is revised. The results show that： when the sand content is more than 60%， the permeability coefficient increases linearly with the increase in sand contents； the permeability coefficient of coarse-grained soil is highly correlated with the non-uniformity coefficient Cu， R ² is 0.81； the empirical formula after introducing the non-uniformity coefficient Cu can better reflect the permeability coefficient and characteristic particle size of coarse-grained soil in Yinchuan Plains.

Improving the regulation and storage capacity of pipe networks is an important research topic in relieving urban waterlogging disasters. Studies have been conducted to design scheduling strategies with the single objective of reducing system overflow， lacking consideration of the loss and risk caused by frequent gate openings and closings.To address this issue， this paper proposes an optimal rolling control model for an urban sluice pump group drainage system with the optimization goal of reducing system overflow and gate opening and closing times， using the neighbourhood of The Hague in Norfolk as an exemplary study. The overflow volume of the optimal rolling control model is 31.2% lower than the value of static scheduling.The gate opening and closing times of this model are 59.8% lower than the dispatching scheme with the single goal of reducing the overflow， while the overflow of the drainage system has been reduced.The proposed method is helpful for the formulation of a dispatching scheme of urban drainage system in case of waterlogging.

Exploring the efficiency and influencing factors of agricultural water conservancy investment in the Yellow River Basin is conducive to alleviating the misallocation of agricultural water resources in the basin and promoting the high-quality development of agriculture in the Yellow River Basin. The MinDS model is used to measure the investment efficiency of agricultural water conservancy in the Yellow River Basin from 2014 to 2020， and combined with the kernel density estimation to explore the dynamic evolution characteristics of the spatial and temporal distribution of its investment efficiency， and finally a panel Tobit model is established to analyze its influencing factors. The results show that： ① The change trend of agricultural water investment efficiency in the whole country and the Yellow River Basin is basically the same， and the gap between the two is gradually narrowing. The regional differences in agricultural water conservancy investment efficiency in the Yellow River Basin are large. From 2014 to 2018， the pattern was downstream > midstream > upstream， and then it showed the characteristics of upstream > midstream > downstream. ② The overall increase in the efficiency of agricultural water conservancy investment in the Yellow River Basin during the analysis period， the degree of dispersion in spatial distribution has increased， and the absolute difference between provinces has gradually expanded over time. ③ Before 2018， the low efficiency of agricultural water conservancy investment in the Yellow River Basin was due to its lower pure technical efficiency， and after 2018， it was due to its lower scale efficiency. ④ The level of economic development and the degree of fiscal decentralization are positively correlated with the investment efficiency of agricultural water conservancy， while the income level of rural residents and the illiteracy rate of rural residents are negatively correlated with it. In order to improve the efficiency of agricultural water conservancy investment in the Yellow River Basin， the allocation of agricultural water conservancy investment resources should be optimized， the management system of agricultural water conservancy investment projects should be improved， and an external environment conducive to the improvement of agricultural water conservancy investment efficiency in the Yellow River Basin should be created.

In order to study the migration and distribution characteristics of contaminated cadmium Cd in typical paddy soil in Chengdu Plain during irrigation， the applicability of VG-TSM （two-point adsorption） model is verified. Based on the dynamic soil column test， three irrigation modes of exogenous Cd solution water injection+clear water leaching quota are designed to simulate the Cd migration characteristics under different pollution scenarios， and the VG-TSM model in Hydrus-1D software is used for fitting verification， prediction analysis and sensitivity analysis of soil column test results. The results show that the penetration ability of Cd in soil is affected by irrigation mode. The greater the water injection amount of Cd， the weaker the adsorption buffer effect of soil， and the higher the peak concentration. Through the fitting analysis of root mean square error RMSE， correlation coefficient R ² and average absolute error MAE， it is found that the simulated value is in good agreement with the measured value， which proves the rationality of the spatio-temporal migration model of Hydrus-1D-Cd solution. Extending the simulation time， it is found that the further analytical release characteristics of Cd in soil are consistent with the TSM model of chemical non-equilibrium solutes. Through parameter sensitivity analysis， the hydraulic characteristic parameters θ_S and K_S under the control of VG model， and the solute transport parameters ρ， K_d and f under the control of TSM model have a profound influence on the simulation output results. In addition， soil texture， soil column test scale， irrigation mode and other factors may also affect parameter sensitivity and cause irrational fluctuation of simulation results.

In allusion to the low accuracy of rubbing fault diagnosis of multi-stage centrifugal pump in engineering， a rubbing fault diagnosis method for multi-stage centrifugal pump based on optimized support vector machine （SVM） is proposed. The method can complete diagnosis with a small amount of sample data by extracting the most effective fault features from vibration signal to optimize the input sample quality of the model and optimizing the parameters of the model. The rubbing signal of the actual product is obtained through the fault simulation test-bed of multistage centrifugal pump， and an SVM model is constructed by extracting time-frequency domain characteristics and information entropy characteristics of vibration signal with ensemble empirical mode decomposition （EEMD）， features are selected with sequential feature selection （SFS） algorithm， and the parameters of SVM with grid search （GS） algorithm and particle swarm optimization （PSO） algorithm are optimized. The experimental results show that the proposed model has high recognition accuracy for rubbing fault of multi-stage centrifugal pump in engineering and has good practicality.It can provide a certain reference for the rubbing fault diagnosis of the multistage centrifugal pump.

In order to make full use of rainwater resources to deal with the problems of soil erosion and drought and water shortage in dry land rainfed agricultural areas， and to give full play to the important position of dryland in China's grain production， this paper focuses on the construction of high-standard farmland based on China's climatic conditions and crop planting practices. How to increase rainwater use efficiency， some effective measures are put forward from three perspectives： ① increase soil water storage capacity， that is， deep plowing to increase the thickness of dryland soil effective layer； ② increase soil effective water content， that is， to improve the soil structure and increase soil capillary pores； ③ increase supplementary water sources， that is， build small water source projects such as water cellars， pools， ponds， small dams and pumping stations； ④ increase the utilization efficiency of rainwater irrigation， that is， increase the micro-irrigation facilities equipped with simple water and fertilizer integration.

The two-phase flow model is used to simulate the cavitation of the double-suction centrifugal pump under different flow conditions， and the development process and performance evolution of the double-suction centrifugal pump are studied. The results show that with the development of cavitation， the head and efficiency of the double-suction centrifugal pump decrease significantly， and the cavitation in the impeller first occurs near the hub of the suction surface of the blade， and spreads to the plate and the outlet of the blade. In the judgment of critical cavitation， the efficiency reduction of 1% is more reasonable than 3% of the head decrease， but neither is suitable as the judgment basis for cavitation inception. Based on the development law of cavitation in the impeller， the efficiency reduction of 0.1% may be used as the judgment basis for cavitation inception of double-suction centrifugal pumps.

The vortex chamber is the main component of the vortex drop shaft spillway. To overcome the limitation of measuring cavity swirl in traditional model tests. The RNG k-ε turbulence model is used to numerically calculate the gas-liquid two-phase flow in the vortex chamber， and the hydraulic characteristics of the swirling flow in the vortex chamber are obtained. The calculation results show that the near-wall pressure in the vortex chamber is affected by the contraction section of the shaft and increases gradually with the elevation decrease. The pressure of the cross-section is symmetrically distributed along the radial direction and increases almost linearly with the radius increase. The pressure isolines on the cross-section roughly conform to the concentric circle distribution in the center of the vortex chamber， which is most dense at the air-water interface， and gradually becomes sparse toward the wall. The tangential velocity on the cross-section of the vortex chamber shows an axisymmetric distribution law， which increases with the increase in the radius， decreases with the increase in the radius at a certain distance from the wall of the vortex chamber， and then drops sharply to 0 somewhere near the wall. The axial velocity on the cross-section of the vortex chamber is the largest at the center of the section cavity， decreases first and then increases with the change in radius， and rapidly decreases to 0 at a specific position near the wall. Tangential and axial flow are the main types of three-dimensional swirling flow in the vortex chamber. As the flow moves， the flow changes from tangential flow to axial flow. The value of the near-wall swirl angle in the vortex chamber varies from 60° to 80°， and the significant value of the swirl angle in the vortex chamber indicates that the water flow in this area is mainly tangential. With the elevation decrease， the swirl angle decreases along the way， meaning that under axial gravity and with the movement of water flow， the flow in the vortex chamber changes from tangential to axial flow. The combined vortex index n reflects the internal flow characteristics of the spiral water flow in the vortex chamber. On the cross-section， the value of n increases gradually from cavity to wall in the range of -0.4~1， indicating that the water flow along the radial direction is a combined vortex movement transforming from quasi-forced to quasi-free vortex. In the axial direction， the range of free vortices decreases with elevation， indicating that the cavity vortex is dominated by quasi-free vortices and transformed into quasi-forced vortices.

The welding forms of the stiffening ring and pipe wall of penstock include the butt weld and fillet weld. The fillet weld is more widely used in practical engineering because of its low welding difficulty.However， scholars often simplify or directly adopt the form of the butt weld in the simulation calculation of external pressure resistance stability of penstock， ignoring the impact of fillet weld connection， which is inconsistent with the engineering practice and causes some errors. In this paper， the three-dimensional finite element software ANSYS is used to simulate the force transfer mechanism of penstock and stiffening ring when fillet weld and butt weld are used， the influences of the two weld forms on the external pressure stability of penstock are compared， and the influences of different leg heights of the fillet weld on the structural stability of penstock are explored in order to provide some reference and basis for the actual construction of the project.

Cellulose fiber， polypropylene fiber and reinforced dense （crack resistant） agent are added to normal panel concrete to form crack resistant panel concrete. Experimental studies are carried out on its mechanical properties， durability， dry shrinkage and early crack resistance. And the influence law of crack resistant materials on the performance of panel concrete is analyzed. The results show that the three anti-crack materials can improve the tensile， impermeability， frost resistance and early crack resistance of concrete to varying degrees. They can obviously reduce and restrain the dry shrinkage deformation of concrete.It has no significant effect on the compressive strength of concrete at each stage， and has a certain reduction on the elastic modulus of concrete. Cellulose fiber can best improve the ultimate tensile value， axial tensile strength， dry shrinkage deformation and early crack resistance of concrete. Reinforced dense （crack resistant） agent can best improve the impermeability of concrete. The research conclusion can provide a reference for the mix proportion design of panel concrete.

With the continuous promotion and improvement of the power spot market， the diversification of power generation side subjects makes the bidding environment of power generation subjects more intense. The establishment of the bidding unit is conducive to improving the ability of power generation enterprises to resist the risk of market bidding. This paper analyzes the impact of different river basin hydrological conditions， multi-element development subjects and the scale attribute of power stations on the bidding of power generation enterprises. By taking the three main factors of power generation enterprises and grid access points as indicators， this paper proposes a bidding unit construction method based on density peak clustering， and the method is applied to 67 power stations in the main river basins in Southwest China. The results show that the construction of bidding unit is of practical significance to improve the bidding capacity of hydropower. The unit scheme is relatively consistent with the unified dispatching unit specified by the power grid， which verifies that the model is reasonable and feasible. It can provide a new idea for power generation enterprises to participate in power spot market bidding.

The roof drainage system is one of the important auxiliary systems of hydropower units. It plays an important role in the safe operation of hydropower plants. Evaluating the health status of the roof drainage system is a necessary measure to ensure the safe operation of the unit. The drainage system is decomposed into multiple levels， combined with data mining to extract the state characteristic indicators that characterize the health state of the system and establish health samples， use the AHP weight method to give weights and build a health assessment model based on the degree of deviation of the health reference value to accomplish the turbine roof drainage system. The health status assessment， combined with the actual operation data of the roof drainage system of the actual hydropower station， verifies the effectiveness and feasibility of the method.

The prevention and control of river oil pollution has become the focus of social attention. The discharge of oil leakage from hydropower stations is one of the causes of pollution. In view of the problems existing in the hydropower stations and the shortcomings of the existing treatment methods in the oil pollution absorption link， a new set of oil pollution control device for leakage water-collecting well of hydropower station combining software and hardware is designed and developed. Semi-floating dynamic balance overflow floating oil suction tank is adopted to adapt to the thickness change of the floating oil layer， so as to prevent excessive suction of water leakage. The rear design of the pump can avoid oil emulsification caused by mixing oil， which is also conducive to oil-water separation. The device has been successfully applied to Hubei Xinglong Water Control Project to solve the problem of oil leakage control.

Scientific and reasonable evaluation of the social adaptability of the Three Gorges migrants is very important for maintaining social stability and promoting the sustainable development of the migrants. Firstly， combined with relevant literature， field research data and expert opinions， this paper establishes the evaluation index system of social adaptability of Three Gorges migrants. Then， OWA-AHP method， principal component analysis method and game theory fusion weight method are used to determine the weight of each index. At the same time， GRA， KL distance and TOPSIS method are combined to construct a new form of relative entropy （KL distance） instead of European distance and a new form of relative closeness to rank and evaluate the evaluation objects. Finally， the emigration of the Three Gorges in Guangdong Province is used as an example. The results show that the model can objectively reflect the social adaptability of the Three Gorges migrants， and the evaluation results are consistent with the actual situation， which verifies the effectiveness and practicability of the model. The research results， index system and evaluation model in this paper can provide effective ideas for the social adaptability of reservoir immigrants.

The hydro-wind-photovoltaic hybrid energy system is an important way to build China’s new power system and to peak carbon dioxide emissions by 2030 and achieve carbon neutrality by 2060. The advantages include orderly developing renewable energy combined with natural resources condition at power sending terminal， effectively improving the consumptive ability of power grid for wind and photovoltaic energies， and significantly increasing the utilization rate of power transmission channel and the competitiveness of electricity price. The hydro-wind-photovoltaic hybrid energy system， with a total installed capacity of more than 10 million kW， is mainly driven by cascade reservoirs. However， due to the combination of wind and photovoltaic energies with hydropower， cascade reservoirs are faced with more difficult challenges， including larger input uncertainty， new operation constraints， and more complex coordination. Moreover， existing studies vacillating in a wide range of research spectrum are applied to the limited real-world projects with small installed capacities， and are not summarized systematically yet. Therefore， based on plenty of investigations in excellent work by international experts and scholars， this paper intends to provide the state-of-the-art review of hydro-wind-photovoltaic hybrid energy system， involving its development and utilization， its planning and designing， and its regulation and operation. The main research problems are also summarized， and then future potential suggestions are discussed. Accordingly， this paper will provide helpful technical suggestions and ideas for the development and management of the hydro-wind-photovoltaic integrated renewable energy bases listed in China’s 14th five-year plan.

In order to accurately predict the long-term operation behaviour of concrete-faced rockfill dams of pumped-storage power stations， the unified generalized plasticity constitutive model for coarse-grained dam materials is modified by introducing a modulus factor with a positive second derivative， which can improve the model’s behaviours in simulating the “hysteresis loop” during the unloading-reloading process and reflecting the modulus’s gradually decrease during unloading. Meanwhile， the model’s effective scope of application is extended to the post-peak softening stage through incorporating functions related to the stress ratio and the plastic shear strain. Based on the laboratory triaxial experimental data， the model’s effectiveness is validated. Results show that the modified model can better reflect the “hysteresis effect”， “Ratchet effect” and softening of the coarse-grained materials. In addition， the explicit expressions of the yield surface under the model parameter β equal to unity are supplemented， which can be used for finite element numerical analysis of long-term behaviour prediction of pumped-storage rockfill dams.

Rivers originating from the Himalaya contain a large amount of sediment， which inevitably causes erosion wear and damage to the hydropower plants， seriously decrease the life time of the turbines and operational stability of the hydropower plants. A Francis turbine runner of Jhimruk Hydropower Plant in Nepal， which has been operating at large opening for a long time， is used in this study. By combining numerical simulation and wear-resistant optimization design of the turbine runner， its performance and erosion characteristics are analyzed. The results show that the three designing schemes reduce the average erosion rate of the blades without reducing the efficiency of the turbine. By changing the flow direction on the blade surface， the vortex pattern in the passage is changed， which weakens the cross flow on the pressure side of the blade， so the erosion rate of the runner is reduced. In this research， the inlet shape conforming to the linear function （scheme II） is the best for wear resistance， by which the erosion rate is reduced by 35%. The research results provide a reference for the wear-resistant design of hydraulic turbines operating at large opening conditions.