Changes in hydrological conditions are the main factor in the function of river ecosystems. In view of the changes in the hydrological situation of the Minjiang River Basin caused by the construction and operation of water conservancy projects， the representative hydrological station， Gaochang Station at the intersection of the Minjiang Tributary Dadu River and the mainstream downstream of the Minjiang River is selected for 62 years （1956-2017） daily flow data by using the Mann-Kendall Method， Cumulative Anomaly Method， mean difference T test method， and sliding T test method to analyze flow characteristics， and consider the hydrological project construction to split the hydrological indicators before and after a sudden change， and select the ecological hydrological indicator change range method （IHA-RVA） and hydrological change degree method to comprehensively evaluate the changes in the hydrological regime of the Minjiang River， and qualitatively analyze its impact on fish in the lower reaches of the Minjiang River. The results show that from 1956 to 2017， the average annual flow of the Gaochang Hydrological Station in the Minjiang River Basin showed a downward trend； the mutation year occurred in 1993. Through the analysis of the ecological and hydrological indicators before and after the sudden change in hydrological situations， the overall hydrological change in the Minjiang River Basin is 45%. As for moderate change， the change degree of the hydrological index， the rate of decline reached 100%； the qualitative analysis of the changes in fish composition before and after the mutation shows that the types and quantities of fish resources have declined to a certain extent， which proves the series operation mode of reservoirs in the Minjiang River Basin and have a greater impact on fish diversity. This study can provide a reference for the ecological restoration and sustainable development of the Minjiang River Basin.

The Yalong River Basin is an important hydropower energy base in our country. In the context of global warming， it is of great significance to study the characteristics of precipitation changes in the Yalong River Basin and predict future trends in precipitation. In this paper， SDSM is used to downscale the GCM global climate model data to simulate the future precipitation changes in Yalong River Basin. Through trend analysis， M-K trend test and mutation test， Morlet wavelet analysis and other methods， the temporal and spatial trends and characteristics of precipitation in the Yalong River Basin in the historical period and the future three concentration path scenarios are analyzed. The results show that the annual precipitation in the Yalong River Basin in each period shows an increasing trend， the increase range is RCP8.5 scenario>RCP4.5 scenario>historical period>RCP2.6 scenario. Its spatial characteristics are expressed as the increase in upstream precipitation higher than downstream. There are certain differences in the seasonal changes in the amount of water falling in different periods. Except for the RCP2.6 scenario， there is a sudden change in precipitation increase in each period of the basin. The sudden change in the upstream of the historical period is 1986， and there is no significant change in the downstream. In the future， the abrupt years are mostly concentrated on the mid-range period （2041-2070）.Regarding cyclical changes， the historical period of the basin and the cyclical changes under the RCP2.6 scenario are more significant， and there are multiple cycles at the same time： 1~4 a short cycle and 4~8 a medium cycle. In the RCP4.5 and RCP8.5 scenarios， the frequency of periodic occurrence is higher， and both are short periods of 1~4 a， indicating that in the future， these two scenarios will show the characteristics of a long cycle duration and short frequency cycle changes.In general， the results simulated by the SDSM statistical downscaling model can well reflect the trend of precipitation changes in the Yalong River Basin. The statistical analysis method is used to conduct a specific research on the characteristics of future precipitation changes， which can be used to rationally plan the water in the Yalong River Basin. This paper provides a scientific basis for resource utilization， optimized reservoir dispatch and power generation dispatch.

Drought has been a major natural disaster for mankind since ancient times. Even today， with the development of science and technology， the disastrous consequences caused by droughts are still everywhere. In this paper，the evolution characteristics of the drought and its correlation with circulation in Henan Province from 1970 to 2019 are analyzed by using the methods of standardized precipitation evapotranspiration index （SPEI）， Mann Kendall test and cross wavelet analysis. The results show that based on SPEI value， the climate in Henan Province has gradually become arid in recent 50 years. In terms of spatial variation， the drought in spring， summer and winter is significant in the northwest and relatively humid in the southeast. From the circulation correlation， the North Atlantic Oscillation （NAO）， Arctic Oscillation （AO） and Southern Oscillation （SOI） have a strong correlation with droughts in spring， summer and autumn in Henan Province， and the Pacific Decadal Oscillation （PDO） and SOI have a strong inter-annual correlation with droughts in Henan Province.

In recent years， affected by climate change， extreme rainstorm events occur frequently in urban areas of the Loess Plateau， causing many urban waterlogging and other water disasters， which seriously affects the social and economic development of the region. In this paper， the urban storm flood simulation model （Seorm Water Management Model，SWMM） is constructed in the gully region of the Loess Plateau to study the process of urban flood formation after the occurrence of extreme rainfall events with different design frequencies. The simulation results show that when the design return period of rainstorm is more than 2 years， some roads will be waterlogged， and the waterlogging will increase with the increase in the design return period. Affected by the buried depth， pipe diameter， number of inlets， topography， geology and other factors of drainage network， the runoff in some areas increases， and the flood overflow time and water depth increase. It is considered that the main causes of waterlogging in urban areas of the Loess Plateau have heavy rainstorm intensity， small infiltration and insufficient water collection capacity. In order to promote the construction of sponge city and improve the ability of flood control and disaster reduction， it is necessary to comprehensively consider the drainage status of the pipe network and the distribution of simulated ponding points， carry out the design and construction of drainage pipe networks of key ponding nodes， and promote the construction of sponge city.

In this paper， the change of land use in the Ganjiang River Basin from 1990 to 2019 is analyzed， and the effect of land use change on water production in recent 30 years is studied by using the InVEST model. According to the results， the water production in the Ganjiang River Basin presents an m-type variation year by year， with more water production in the north and east， and less water production in the west and south， the results of scenario simulation show that the transfer of arable land and forestland as well as the transfer of construction land in Ganjiang Basin will promote the increase in water production， and the transfer of water area will promote the increase in water production. Rainfall is the main factor affecting water production， but it is not controllable， so it is practical to study the controllable land use change and to explore the change and influence of land use change on water production， it is of great significance to regional land use planning and water resources management.

To explore the possible impact of climate change on the hydrometeorologicalprocesses and provide the reference for flood prevention and disaster reduction in Yuanjiang River Basin， this paper obtains the outputs of five GCMs announced by CMIP6 from 2041 to 2100. Then， monthly precipitation and temperature under SSP126， SSP245， SSP370 and SSP585 paths are generated through the M-BCSD downscaling method. Moreover， the impact of climate change on the runoff at the basin outlet is forecasted by back-propagation neural network （BPNN） with cross validation skill. The results indicate that the M-BCSD method has better applicability in Yuanjiang River Basin and the BPNN is able to predict the monthly runoff effectively. In general， the mean annual rainfall， temperature and runoff have an increasing trend within the periods of 2041-2100 with the maximum increase of 24.6%， 20.4% and 10.2% respectively. As for the seasonal scale， the runoff decreases in spring and increases in fall. As for the monthly scale， the runoff decreases in April and increases in November. Under different path scenarios， the changes of the hydrometeorological elements are basically consistent but their amplitudes are different.

Water resource is a prerequisite for the development of the arid regions in Northwest China. The fluctuation of water resources utilization efficiency and price in Xinjiang has a significant impact on its economic and social development. Based on the input-output table data of Xinjiang in 2017， this paper uses the input-output method to compile the input-output table of water resources based on values and build a value model， which makes up for the deficiency of other methods by means of micro-analysis. The results show that there is still room for improving the utilization efficiency of water resources in Xinjiang. When the price of water resources rises， the price of products in various sectors of the national economy will rise， which will have a negative impact on the economy of Xinjiang. Further research shows that when the prices of water resources rise at the micro-level， output prices of agriculture， forestry， animal husbandry， fishery， transportation， post and telecommunications， public services and other sectors increase significantly. At the macro-level， the primary industry witnesseses the biggest increase in output prices. At present， there is still room for adjustment of water resource prices， so we should make full use of price means to strengthen water resource allocation and serve economic development.

Targeted at the limitation of the typical solution set （TD） model， which is only applicable to stationary random series， a new monthly runoff stochastic model， this paper proposes the complementary set empirical mode decomposition （CEEMD-TD） model. Taking three typical hydrological stations in the Yellow River Basin as an example， a monthly runoff stochastic model of the CEEMD-TD model is established， and the simulation effect of the stochastic model is evaluated by examining the main statistical parameters of the section. The results show that the absolute value of the relative error of the statistical parameters of the CEEMD-TD model simulation sequence and the measured sequence in each typical hydrological station is small， indicating that the CEEMD-TD model can maintain the actual measurement in the simulation sequence of each typical hydrological station. The main statistical characteristics of the sequence provide an effective simulation method for the random simulation of monthly runoff.

The traditional design flood estimation method assumes that the flood peak and the flood volume are at the same frequency， without considering the correlation between the two flood characteristics. Furthermore， when the design flood region composition under a specific return period is estimated， although the traditional method is from the most unfavorable point of view， it is impossible to quantitatively describe the correlation between the floods in each subarea. Therefore， in this paper， Copula function is used to deduce the design flood peak and flood volume at different frequencies which consider the combined effects of flood peak and flood volume， and then obtains the design flood process at different frequencies. The marginal distribution of flood components in each area is established and the most suitable Copula function between components in each area and design section is preferred which consider the spatial correlation between each flood zone and Huayuankou section， and then explore the most likely design flood region composition. It shows that the design results obtained by considering the correlation between flood elements in this study are slightly higher than those deduced by traditional methods under the same return period. The method in this paper can qualitatively and quantitatively describe the design flood region composition in the study area so as to obtain the design flood results that consider both the correlation of flood characteristics and spatial correlation at the same time， which are more objective and more consistent with the actual situation of design flood region composition in the basin.

Three sub-products （IMERG-E， IMERG-L， IMERG-F） of the IMERGV06 and two sub-products （TMPA-V7， TMPA-RT） of the TMPA 3B42V07 are evaluated against the gauge data from 2008 to 2017 in Nanliujiang River Basin. The results show that： ① On the daily scale， IMERG has better correlation （CC） and stability （RMSE） than TMPA for spatial scale. As the temporal scale is increasing， the differences between IMERG and TMPA products narrow， and TMPA-V7 gradually surpasses the near-real-time products of IMERG. From the spatial scale， the southeast stations have a relatively weak correlation and the southernmost stations have poor stability. ② For one satellite product， the relative error （RB） between 15 gauges varies greatly， but for one gauge， the difference between five products is not significant. On the basin scale， the deviations of the post-real-time product are lower than those of the near-real-time products. IMERG-F tends to overestimate rainfall slightly， while IMERG-E and IMERG-L tend to underestimate rainfall to a higher degree. ③ The trends of the three categorical indicators （POD， FAR， CSI） with thresholds are similar at the basin and station scales. The ability of TMPA to detect light rainfall is relatively weak， while IMERG has been improved markedly. The detection performances of the five products on the rainstorm are not ideal and the distribution of the values of each station is more dispersed. Generally， IMERG-F can basically replace TMPA products in the Nanliujiang River Basin.

The evaluation of rural river ecological condition is the basis of rural river ecological management. According to the characteristics of rural rivers， the evaluation index system of rural river ecological conditions is constructed from six aspects： river function， river form， river environment， river ecology and landscape， river management and comprehensive evaluation. The integrated order relationship analysis-entropy weight method obtains the combined weight of each index. An established fuzzy matter-element evaluation model is used to comprehensively evaluate the ecological status of rural rivers in Jiangsu Province. The results show that the ecological conditions of rural rivers in Jiangsu Province are generally good， but some rural rivers still have poor ecological conditions， and there are regional differences in the ecological conditions of rural rivers in Jiangsu Province. The evaluation results are basically consistent with the actual situation.

Based on 694 farmer survey data in Jiangsu Province and Hubei Province， this paper uses hierarchical regression and Bootstrap method to empirically analyze the influence path of farmer’s participation on ecological policy gains and social policy gains. The results show that： ①The participation of farmers has significantly improved the sense of ecological and social gains， and part of the mediating effect on ecological gains and social gains through government trust， accounting for 29.89% and 18.97% of the total utility， respectively. ②Formal systems play a positive role in regulating the influence of government trust on social gains， and informal systems have a positive regulating role in the influence of government trust on ecological and social gains. Therefore， this study proposes that rural environmental governance should strengthen the trust of farmers in the government， require institutions to empower farmers to participate in and empower farmers， to activate the endogenous motivation of farmers to participate， and moreover， it is necessary to use informal systems to reach a consensus on collective governance in the village， strengthen the network of farmers and the government， and enhance farmers’ sense of policy gains.

Deflected flow， as one of undesirable flow patterns， may scour river beds and banks seriously. Experiments are conducted at a symmetric multi-gate sluice model with different large expansion ratios and Froude numbers. The LSPIV （Large-Scale Particle Image Velocimetry） technique is adopted to collect the velocity data of free surface downstream. This study aims at the flow deflection features on the condition of symmetric inflow and outflow. The results show that the velocity distribution at the cross sections display an ‘S’ shape. The flow dynamic axis is deflected obviously. It is classified into three reaches according to the differences of the dominant factors on the whole deflected flow zone. In general， as Froude number increases， the reach dominated by the total outflow width tends to shrink， while the reach influenced by the enlarged boundary width downstream tends to expand. The deflected ratio of flow is a function of Froude number and expansion ratio by the method of regression analysis， and the deflected ratio increases with Froude number and expansion ratio within limits. The maximum of deflected angle is less than {\mathrm{20}}^{°}. These achievements are instructive to putting forward the improvement measures of undesirable flow patterns.

In order to evaluate current river health and identify the causes of river damage， based on four criterion layers， including hydrology and water resources layer， physical structure layer， water quality layer and biology layer， this paper constructs a river health evaluation model based on fuzzy logic. The model takes Yongding River Basin as the study area. And then the sensitivity analysis of indicator layer and criterion layer is carried out on the basis of the evaluation results to find out the most effective repair measures. The results show that the health of the lower reach of Sanggan River is better than that of other river reaches， which is rated as sub-healthy. The upper reaches of Sanggan River， Yanghe River and Yongding River are rated as unhealthy. Among four criterion layers， the biology layer is the worst， which is unhealthy， indicating that the water ecology of the basin limits the survival and reproduction of aquatic species. The most sensitive indicators and criteria focus mainly on water quality and biology， which are the most effective factors that can improve the overall river health level in a short period of time.

The effect of nitrate loading on water has been a hot issue at home and abroad. Clarifying the main sources of nitrate load in water is the basis for accurately formulating nitrogen pollution control and emission reduction strategies. Taking Qianxia Lake for example， this paper analyzes the variations of nitrate and its main sources qualitatively by monitoring the hydro-chemical characteristics and nitrogen and oxygen isotope composition of nitrate of lakes， with the addition of the nitrogen and oxygen isotope composition of various sources （precipitation， domestic sewage， fertilizer， sediment and surrounding soil） in this study. On this basis， the stable isotope model MixSIAR is used to quantify the different contributions of every nitrate source. The results show that： ① the downstream of Qianxia Lake is greatly affected by livestock manure or urban domestic water， and its sources of nitrate are mainly from the organic nitrogen affected by human activities with high stable nitrogen isotope flowing to water by nitrification； ② the nitrate for the lake from surrounding soil， domestic sewage， fertilizer， sediment， and precipitation accounts for 87%±9.7%， 9.0%±5.9%， 2.5%±1.5%， 1.2%±0.8%， 0.3%±0.4%， respectively. The transfer and transformation process of nitrate in Qianxia Lake is mainly nitrification under the effect of human activities. Therefore， the nitrate produced contains a higher nitrogen stable isotope value. This study can provide a scientific basis for nitrogen cycle， transfer and transformation in deep lakes.

By using the ANSYS FLUENT numerical simulation software， the Navier-Stokes equation as the governing equation， based on the finite volume method， this paper adopts the standard k - ε turbulence model to establish a numerical analysis model. Under the condition of constant density， numerical simulation study is carried out on the water flow characteristics of three kinds of rigidly submerged vegetation open channels with thick stems. The results show that the experimental results are compared with the numerical simulation calculation results， and the calculated velocity values are in good agreement with the experimental values， which verifies the correctness and feasibility of the numerical simulation method. By analyzing the flow velocity distribution changes in the flow field， the increase in the thickness of the vegetation stems is obtained. By analyzing the vertical distribution of the flow velocity in the flow field， it is concluded that the slope close to vegetation has a smaller range of velocity change， and the water flow is more turbulent. As the distance from vegetation continues to increase， the vertical velocity change range increases significantly. The mixed turbulence effect of vegetation on the point flow field is weakened.

River and lake system is an important part of maintaining the natural ecosystem， and also an important support for social and economic development. The ecological connectivity engineering technology of river and lake water systems is an important way to make up for the shortcomings of ecological restoration projects. By elaborating on the connotation of river and lake system connectivity， the ecological connectivity engineering system of river and lake system based on the three-stream and four-dimensional ecological model is constructed， including vertical connectivity engineering technology， horizontal connectivity engineering technology and vertical connectivity engineering technology， and each engineering technology is specifically elaborated on for each connectivity dimension. The construction of the river and lake system ecological connectivity planning engineering technology system can provide a strong technical support for the national and water conservancy industry to carry out the work related to river and lake system connectivity.

In order to study the influences of C/N ratios and operational water level on the nitrogen removal effect in vertical subsurface flow constructed wetlands， with four ratios of C/N （2/1， 4/1， 8/1， 12/1） and three operational water levels （60， 40 and 20 cm） above the constructed wetlands bottom， 12 sets of simulated vertical subsurface flow constructed wetland experiments are carried out to analyze the nitrogen removal effect at different heights of 50， 30 cm and the water outlet with 10cm above the constructed wetlands bottom. The study results show that C/N has a significant effect on the removal of ammonium nitrogen （NH₄ ⁺-N）， nitrate nitrogen （NO₃ ^--N） and total nitrogen （TN） in vertical subsurface flow constructed wetlands with P<0.05. When C/N=4/1， the removal rates of NH₄ ⁺-N， NO₃ ^--N and TN along the way are the highest among the three operational water levels， which is the optimal C/N radio. With C/N=4/1 and the operational water level of 40 cm， the three nitrogen removal rates at different heights of the simulated vertical subsurface flow constructed wetland are the highest， with （98.16±1.10）% for NH₄ ⁺-N， （82.84±10.55） % for NO₃ ^--N and （85.92±8.34）% for TN. So the C/N ratio and operational water level at this time are the optimal combination for the three nitrogen removal effect. Operational water level has a significant effect on the removal of NH₄ ⁺-N and NO₃ ^--N in vertical subsurface flow constructed wetlands with P<0.05. With different C/N ratios， the nitrogen removal mainly occurs in the upper part of 50~60 cm when the operational water level is 60 cm. When the operational water level is 40cm， the concentration of three nitrogen changes little from 30cm to the water outlet， which is more stable than that at 60cm outlet. Therefore， increasing C/N and decreasing operational water level are beneficial to nitrogen removal in vertical subsurface flow constructed wetland system. The results in this study can provide a reference for the selection of optimal conditions for nitrogen removal in vertical subsurface flow constructed wetlands.

In order to explore the operating characteristics of the solar pump and reveal the transient flow mechanism of the solar pump， the output characteristics of the photovoltaic array and the pressure pulsation at the pump outlet with the instantaneous solar radiation changes to ±100 W/m² and ±200 W/m² are studied and analyzed by using the experimental test method. The research results show that compared with the increase in sunlight intensity of 200 W/m² and the transient increase in sunlight intensity of 100 W/m²， the time required for the photovoltaic array to reach the steady state is reduced by 2 seconds， and the time required for the pump outlet pressure to reach the steady state is increased by 0.5 second. With the increase in sunshine intensity， the output fluctuation of photovoltaic array decreases. The response time of pump outlet pressure pulsation gradually becomes shorter， and the sunlight radiation transiently increases. The output power of photovoltaic array significantly changes， and the transient response reaches a steady state within 3 s. As the basic solar radiation increases， the response time of pump outlet pressure gradually becomes shorter， and the time required for the system to reach steady state increases significantly. Under the low base solar radiation， the larger transient solar radiation increases， which is more likely to cause unstable pressure fluctuations at the pump outlet. With the decrease in the basic sunshine radiation， the outlet pressure of the pump decreases first and then increases and then gradually tends to be stable. With the increase in the basic sunshine radiation， the outlet pressure of the pump needs to spend more time reaching a steady state under the increase in large transient sunshine radiation.

To solve the issue that the traditional BP neural network predicts the amount of agricultural irrigation water， fall into the local minimum and select the appropriate learning rate with difficulty， this paper proposes an agricultural irrigation amount prediction model based on the genetic algorithm and the Adam algorithm to optimize the BP neural network in parallel. This model uses the global search characteristics of genetic algorithm to prescreen the BP neural network with initial weights and thresholds， and then uses Adam algorithm to realize the learning rate adaptation to the constant update of the parameter gradient. The meteorological data of 7 typical irrigation areas in the Longzhong Area of the Yellow River Basin and the measured irrigation data of corn are collected to train the model. At the same time， it is compared with the network model under the traditional GD method， GA method， and Adam method. The results show that the GA-Adam model reaches the preset accuracy only when the training times are 67 times and the training duration is 0.403 s； and the RMSE and MAE of the predicted value and expected value of the GA-Adam model are the smallest： 54.73 and 47.76 respectively. The coefficient of determination R ² is 0.81. In a word， the overall prediction effect of GA-Adam model is the best.

A pumping station forebay with excessive diffusion angle is more likely to result in bad flow patterns in the intake pool， which will affect the flow patterns in the inlet pool， worsen the water inlet condition of the pump，reduce the operation efficiency of the pump， and even affect the normal operation of the pumping station. Both numerical simulation and model test methods are adopted to do research on the flow patterns in the inlet pool for a pumping station with diffusion angle of 55° in the forebay by setting diversion pier in the front pool. The results shows that the wedge diversion pier could play a diversion role well in the inlet of the forebay， and reasonable arrangement of the combined symmetrical wedge diversion pier could effectively improve the flow patterns in the forebay.This kind of diversion pier is simple in structure and small in engineering quantity， so it is easy to popularize and apply it.The research results have a certain reference value to rectify the flow patterns in the forebay for similar pumping stations.

In order to propose a more accurate forecast methods suitable for the reference crop evapotranspiration of rice in Jiangxi Province， this paper uses the PM formula and the historical meteorological data of 26 meteorological stations to calculate ET ₀， and uses this as a reference value to calibrate the Hargreaves-Samani （HS） model， the Blaney-Criddle （BC） model and the McCloud（MC） model. Weather forecast data is used to evaluate the applicability of the three ET ₀ forecast models at various stations in Jiangxi Province. The results show that after parameter calibration， the average accuracy rates of ET ₀ forecasts of HS model， BC model and MC model at 26 stations are 86.63%， 85.81%， 87.12%， and the average absolute errors are 0.75， 0.80 and 0.76 mm/d， the average root mean square errors are 0.98， 1.00， 0.99 mm/d， and the average correlation coefficients are 0.76， 0.76， 0.78， respectively.16 stations recommend using the HS model for ET ₀ forecasting for the stations in Jiangxi Province， the HS model has the best forecast accuracy， followed by the MC model， and the BC model is the worst. On the whole， using the calibrated HS model for forecasting can provide more accurate ET ₀ forecasting data for irrigation forecasting and decision-making in Jiangxi Province.

This paper aims at the problem that the fall irrigation quota of drip irrigation farmland under mulch cannot be effectively determined due to the extremely uneven spatial distribution of water and salt and the significant effects of freezing and thawing in the seasonal freeze-thaw area. In response to this problem， based on the field experiment data， this paper uses the joint simulation method of HYDRUS-2D and SHAW model to simulate the soil water and salt dynamics under different autumn irrigation quotas under the conditions of the Yellow River water irrigation， and studies the single and multi-year autumn irrigation quota of drip irrigation farmland under mulch. The results show that： ① When the single year autumn irrigation is conducted， for mildly saline soil， the recommended autumn irrigation quota is 1 100 m³/hm²； for moderately saline soil， the recommended autumn irrigation quota is 2 100 m³/hm²； for heavily saline soil， the recommended autumn irrigation quota is 2 500 m³/hm² when only for the purpose of improving soil quality. ② When irrigating in autumn every few years， the non-saline soil should be irrigated in autumn at least once every 3 years. The recommended autumn irrigation quota is 2 000 m³/hm² for irrigation every three years， and the recommended autumn irrigation quota is 1 350 m³/hm² for irrigation every two years.The soil with mild， moderate and severe salinization must be irrigated in autumn every year.

Water content is the main reason for the deterioration of the thermal insulation materials’ thermal conductivity， compressive strength， permeability and other parameters. In order to analyze the hygroscopic characteristics of thermal insulation materials， this paper uses three kinds of commonly thermal insulation materials to conduct the isothermal hygroscopic performance tests. Based on the experimental results， the application of seven kinds of hygroscopic models is analyzed and evaluated. The results show that the isothermal hygroscopic properties of different insulation materials have obvious differences. The higher relative humidity is， the faster the hygroscopic rate is， and the longer time it takes to reach the equilibrium moisture content under the same condition. The moisture absorption of the FLK insulation material is 2 times of the PU， and 5 times more than that of the XPS. The fitting results indicate that the Peleg model can well describe the isothermal hygroscopic process of the three insulation materials. The results can provide basic data support for the study of thermal insulation material property deterioration mechanism and thermal-wet coupling analysis.

In recent years， water and sediment regulation of the Yellow River changes the diversion conditions of Xiaokaihe Irrigation Area， which makes the irrigation area’s water supply and ecological security threatened. Aiming at the problem that is the decrease indiverted water volume of the Yellow River， serious deposit， no place for desilting spoil and the function shortage of desilting basin， etc. The reconstruction canal head project and construction of sand transmission pipeline and other engineering schemes are put forward. In order to implement ecological protection and high-quality development in the Yellow River Basin， a series of operations and management measures have been proved to be effective including using sediment resources， dispersing sediment， improved land， and heavier regulation. In the practice and exploration of dealing with the increasingly prominent contradiction between supply and demand of water resources and curbing the degradation of ecological environment in Xiaokaihe Irrigation Area， some accumulated practices can provide reference for the irrigation area of the lower Yellow River.

In view of the problems such as excessive vibration of unit in the second phase of Yonghu Pumping station， strong vibration of local structure of workshop and serious wear of pump port ring， we carried out on-site inspection. Through the analysis and study of the field test results， the paper draws the conclusion that the high vibration of the unit is caused by the rapid shrinkage of the inlet taper pipe of the water pump， the strong vibration of the local structure is caused by the resonance caused by its natural vibration frequency consistent with the pump blade frequency， and the severe wear of the pump port ring is caused by the improper use of materials. According to the conclusion， the strong vibration of the pump station building disappears， the excessive vibration of the unit and the wear of the mouth ring are improved.

Based on an engineering example， the characteristics of pump-stopping water hammer in a pipeline system with a local convex point are analyzed in this paper. Then based on the working principles of the air valve and water hammer relief valve， the water hammer protection effects of three measures， including the ordinary air valve， air valve with the function of “fast in and slow out”， and ordinary air valve adding with water hammer relief valve， were compared and analyzed. The calculation results show that， compared with the ordinary air valve， the air valve with the function of “fast in and slow out” can effectively reduce the water hammer pressure caused by cavities collapsing by limiting the venting speed in the pressure raising stage， and has a better water hammer protection effect. The water hammer relief valve set at the place where the cavities collapsing first occurs can release the high pressure fluid in time， so it can be used as a water hammer protection backup measure after the failure of the function of the “fast in and slow out” the air valve.

Abstract： In order to clarify the effect of solar-power water lifting equipment in the application of water supply in Qinghai pastoral areas， this paper uses the solar water supply model to establish a pilot site for solar-power water supply in these areas. Based on the field test observation data， the equipment practical application of solar deep well water lifting， solar shallow well DC pump water lifting， and solar battery water lifting are analyzed. The results indicate that the daily water withdrawals of the battery-free water lifting equipment are the highest in July and August， and the lowest in December. The stable output characteristics also have battery equipment achieving the standard of three consecutive days without energy storage， and ensuring water supply needs. The guarantee rate of water supply for 3 types of equipment is 91.5%， 92.3% and 95.7% respectively， which can meet the annual water supply demand of water users in Qinghai pastoral areas. This paper can provide a theoretical basis for the promotion of clean energy water supply in Qinghai pastoral areas， which is of great significance to ensure safe water supply for pastoralists.

The geological conditions at the entrance of the discharge structure on the right bank of Lawa Hydropower Station are complicated. The maximum height of the excavated slope is about 220 m. After excavation， the slope foot has a high level of compressive stress and the stress concentration effect is obvious， which threatens the construction and operating safety of the discharge structure. The deformation， plastic zone and stress variation of slope during excavation， especially the influence of stress concentration at slope foot on slope stability， are analyzed by establishing the numerical models of slopes at different parts. The results show that the maximum compressive stress at the foot of EL2 654 m platform slope at the entrance of spillway tunnel is 18 MPa， which is 2.1 times higher than that at the main compressive stress before excavation. In order to ensure the stability of the rock mass at the foot of the slope， this paper studies the deformation and stress of the slope less than 2 709 m at different excavation slope ratios （vertical slope， 1∶0.3 and 1∶0.5）. The results show that the excavation volume and the deformation of the slope are both small and the stress concentration at the foot of the slope obviously decreases when excavation slope ratio adopts 1∶0.3.

Baihetan Dam Site is characterized by complex geological and structural conditions. The unloading effect of rock mass is strong and the number of faults， dislocation zones， deep fractures and other weak structural planes develops there. During the construction period， human activities have seriously damaged the stability of the high and steep slope， and affect the long-term safe and stable operation of the dam. Combined with the geological materials， this paper analyzes the monitoring data of the abutment slope during the construction period and studies the law of the slope deformation in different elevations of the abutment on both banks. Based on geological data， a three-dimensional finite element model of slope is built， and numerical simulation is carried out by FLAC3D software during slope excavation and support. The rationality of the numerical simulation results is verified by monitor data， and then the dam deformation law of the high and steep slope on both sides is studied according to the results of numerical simulation and in combination with monitoring data. The results show that both sides of the abutment slope is stable during the construction period.

The equipment supercooling problems have been observed in the operating condition of the air supply system in some pumped storage power stations. It is a critical safety risk for the air supply system when it is working with the compressed air. Especially for the different valves in the pipelines， which feature short-length and complex internal structure， usually cause air velocity increasing rapidly and temperature decreasing sharply， challenging the system sealing performance and connection strength. Since the numerical simulation researches about air supply system are still rarely reported， it puts forward the urgent need of some related researches. In this paper， the SA turbulence model is adopted for the transient full-channel numerical simulation research on the air supply system of pumped storage power stations. Present work puts emphasis on the extreme temperature decreasing phenomenon of the valves， occurring when the air supply system releases highly compressed air to drain the water out of the runner chamber. And some critical aspects of the above valve temperature-drop problem， including the occurrence location， drop level and mechanism are focused on and analyzed.

In view of the modal aliasing phenomenon that occurs when EMD is used to deal with the vibration signals of hydropower units which are coupled by multiple signals and noise， a fault signal preprocessing method is proposed based on differential empirical mode decomposition and energy characteristics.The signal is decomposed by differential empirical mode algorithm and then the energy matrix of each order differential signal is constructed. The simulation results show that the differential empirical mode decomposition can effectively avoid the mode mixing effect. The support vector machine is used to verify that the identification accuracy can reach 98% in the preprocessing of the guide bearing signal of the hydropower unit. This method has a good engineering application value in the application of complex coupling signal pretreatment of hydroelectric units.

A nonlinear finite element model of high head expansion water seal is established to simulate the mechanical performance and deformation characteristics of the rubber material during the water sealing process. The influence of back pressure， reservoir water pressure and other parameters on sealing performance of the expansion water seal are further investigated. Firstly， the uniaxial tension compression and pure shear test date of rubber material are used to curve fitting and the Mooney-Rivlin model parameters based on the least square method. The APDL programming language in ANSYS is used to determine the contact state of steel head and apply the cyclic loads from lateral water pressure. Secondly， the influence of the Mooney-Rivlin model with different number of parameters on the accuracy of the simulation is analyzed by numerical examples. The validity of the simulation is verified by comparing with the model experiment. Finally， the parametric studies are presented to explore variations of free expansion， contact stress and steel head offset with back pressure， reservoir water pressure and the distance between panel and pressing plate in different working stages.

Relying on the engineering problems caused by a landslide resurrection under the action of reservoir water， this paper aims at understanding the deformation and resurrection mechanism and critical conditions of the landslide， to provide a basis for environmental impact assessment and comprehensive disposal. By collecting the historical work data on the landslide area， the landslide identification is landslide. By using both a qualitative and quantitative analysis， this paper evaluates the landslide stability before and after water storage. By using multiple-phase ground surveys and safety monitoring， this paper evaluates the mechanism of the influence of hydropower water storage on the landslide surrounding environment based on the site situation. The main conclusions are as follows： ① The cognitive process of Luojiaping landslide are initially considered as a deformation， identified as a landslide at medium-term with its scope being determined. Finally， its scope and thickness are rechecked and corrected. ② Early Jinsha River water level is low， the leading edge of landslide being drainage， its overall stability is stable. Water reached 354 m in 2012， front edge of the slope was immersed， landslide resurrection caused existing construction and structures produced cracks， whose stability was less stable. Water reached 370 m in 2013， increasing deformation of the landslide resulted in expanding the cracks in the existing buildings and structures， its stability being critical. Continue storage to 380m， the Landslide deformation rate continues to intensify， its stability was critical. So the water storage level of 370 m can be considered as the critical water level for Luojiaping Landslide. ③ Environmental impact assessment is Shuisui secondary road and migration works before water storage can normally be used. Secondary roads， bridges and dwellings do not affect their formal functions， deformation increases to 370 m， cracks of existing buildings and structures are expanded， their functions are damaged. Some dwellings collapses to water storage level of 380 m. Environmental impact indirectly proves several stages of landslide resurrection， closely relating to the water storage of hydropower stations. ④ In-situ reinforcement disposal can only reinforce the landslide part above the secondary road， which has no effect on the underwater part. The above conclusions can provide an analogy basis for the adjacent projects in the reservoir area.

In order to solve the cavitation problem of turbine blades， this paper studies the technology of laser cladding anti-cavitation coating. The Co-based cavitation resistance cladding coating is prepared by laser cladding technology on the surface of 0Cr13Ni4Mo stainless steel， a common material for turbine blade. The microstructure， hardness and cavitation resistance of cladding coating are studied. The results show that the laser cladding process will produce slight thermal stress deformation of the blade， but it will not affect the actual use of the blade， and the thermal stress deformation can be controlled in a more reasonable range by adjusting the process parameters. The Co-based cladding coating has a good metallurgical bonding with the substrate. Its microhardness is 1.5 times that of the substrate. Under the same test condition， its cavitation weight loss is only 1/3 of the substrate.The application of this technology is expected to greatly improve the cavitation resistance of turbine blade under clean water environment and ensure the safe operation of the hydropower unit.