The soil which can be used in sponge city is improved by cotton stalk biochar prepared in 450 ℃. Three kinds of materials （biochar， sand and clay） are mixed in three models （fully mixing of biochar， sand and clay； mixing of clay and sand with layered biochar； layering biochar， sand and clay）. The research conclusion shows that the osmotic coefficient increases with the increase in volume ratio of sand and biochar. In different fully mixing of biochar， sand and clay models， the best removal effect of turbidity， ammonia nitrogen and total phosphorus in storm water runoff is obtained when the volume ratio of sand to clay to biochar is 2∶2∶1. The removal effect of 2∶2∶1 model on COD_Cr is lower than the 1∶1∶1 model. Furthermore， the research results of planting grass on the improved soil shows that the grass reduces the osmotic coefficient of improved soil， protects the structure of soil， has a positive effect of reducing turbidity， improve the removal stability of COD_Cr， ammonia nitrogen and total phosphorus and extends life cycle of improved soil. The effective solution of initial storm water runoff pollution is planting grass on the soil improved by biochar， which can control the non-point source pollution effectively caused by urban road storm water runoff.

Impeller outlet diameter D ₂， impeller outlet width b ₂ and impeller inlet diameter D_j are selected， excellent hydraulic models of sewage pump are combined， the law of head coefficient λ_H， flow coefficient λ_Q， velocity coefficient λ_v changing with specific speed are obtained. The corresponding empirical formula are determined， and the double-blade sewage pump with high efficiency and good anti-clogging performance is designed. The full flow numerical simulation of the designed sewage pump is carried out by using CFX， the pressure and streamline distribution in the impeller are obtained. The efficiency of the rated flow point of the pump is 76.53%， the head is 14 meters， the efficiency is higher than the national standard 10%. The design method has some reference value for the hydraulic design of double-blade sewage pump.

Based on the monitoring data of 8 water quality indexes of 26 monitoring sections in Huntai River Basin in the past 10 years， the temporal and spatial evolution characteristics of water quality in the basin are comprehensively analyzed， and the water quality changes are obtained. According to the recent water pollution situation， the main pollution sources of Huntai River Basin are determined as urban sewage discharge， industrial production pollution and some meteorological factors. The absolute principal component multiple linear regression analysis method is used to calculate the corresponding pollution contribution rate of each index， so as to provide countermeasures and basis for effective water pollution control in the later stage.

For the sediment siltation problem after the operation of Three Gorges， the sediment siltation characteristics of Three Gorges Reservoir Area are analyzed based on the measured data， and the flocculation effect of sediment under the hydrodynamics of Three Gorges Reservoir Area is simulated based on the indoor test. The results show that since the operation of Three Gorges Reservoir， the sediment inflow and outflow are in the trend of oscillating decrease， and the total siltation amount is increasing year by year； the annual average discharge ratio of Three Gorges Reservoir is 21.0%， and the overall decrease in the discharge ratio is influenced by many factors； the sediment siltation in the subsidence zone of Three Gorges Reservoir Area is influenced by the slope and elevation， the smaller the slope， the larger the sediment siltation amount， and the higher the elevation， the smaller the siltation amount. In the indoor test， it is clear that under the corresponding hydrodynamic conditions in the Three Gorges Reservoir Area， the sediment in the reservoir area can flocculate and settle rapidly in a short time， and the change of hydrodynamic conditions has a great influence on the flocculation and settlement of sediment particles in the Three Gorges Reservoir Area.

Black-odorous water can be said to be one product happening in the course of increasing economic and social development and accelerating urbanization process. Therefore， some cities have still been suffering from the dilemma of “Governance Repetition and Repetitive Governance” of black-odorous water. Nowadays， most of the current cases of governance for black-odorous water have been carried out from the following angles， inclusive of ecology and water-pollution control， without putting more eyes on the important role of various water-conservancy measures. Systematically sort out actual causes and progresses of urban black-odorous water， as well as actually-adopted governance measures therein， with combination of specific water-conservancy technical requirements existing in the course of governing black-odorous water， this paper makes a series of researches and finally proposes specific water-conservancy measures required in the practical governance of urban black-odorous water， including ensuring ecological flows， river regulation， inter-connecting river-system networks， restoring bank slopes and other water conservancy measures and technologies for the purpose of providing certain technical references for the subsequent governance of urban black-odorous water.

In recent years， lakes in different regions have changed in different types and degrees due to the increasing influence of climate change and human activities. This paper uses RS and GIS technology， based on the results of the first water conservancy survey and the 2019 GF-1 time series remote sensing image， the water body is extracted through object-oriented multi-scale segmentation combined with the bimodal threshold method， and visual observation is used in the secondary calibration. Interpretation to determine the type of lake change， and then derive the water area to quantitatively evaluate the lakes with an area of more than 1 km² that have changed， and perform statistical analysis on the type， level and quantity of the changes.The results showed that： ① About 814 lakes across the country have undergone unfavorable changes. The main types of changes include shrinkage， cultivated land encroachment， wetland encroachment， breeding land encroachment， other encroachment， accounting for 28.3% of the total number of lakes. ② The spatial difference of change types is obvious， the lakes in the north are mostly dried up and shrunk， the lakes in the south are mostly occupied by paddy fields and aquaculture. ③ Expansion lakes are mainly concentrated on Tibet and Qinghai.The research results provide the latest basic data for lake change monitoring and management.

Based on the fact that Huayang section of Jinjiang River， a typical encroached urban river， is blocked and flood discharge can not be improved by conventional methods， this paper proposes using large-scale culvert for flood diversion. It establishes MIKE hydrodynamic numerical model based on river topography， simulates and analyzes the influence of culvert cross-section size， entrance position and inflow angle on culvert flood diversion flow， water level elevation and flow velocity. The results are of guiding significance to solve the problem of flood discharge in Huayang section of Jinjiang River and the control of urban encroachment river.

In order to reveal the dynamic changes of the water environment carrying capacity of the Sanggan River Basin， water environment carting capacity indicator system’ s design consists of socioeconomic subsystem， water resource subsystem and water environment subsystem. The improved entire-array-polygon synthesis illustration method is used to evaluate the carrying capacity， the variation tendency of result is basically the same as that obtained by the fuzzy comprehensive evaluation method. Obstacle degree is used to analyze obstacle factors. The results indicate that the water environment carrying capacity of Sanggan River Basin is weak， comprehensive index is under 0.3 in 2011-2018， but present escalating trend， from 0.183 in 2011 advance to 0.237 in 2018. The carrying level of the water resources subsystem fluctuates greatly. According to the obstacle degree analysis， the obstacle factors affecting the water environment carrying capacity of this area are mainly concentrated on the water resource subsystem.

The Jingnan Four-inlet Regions of Yangtze River are located in the connecting part of Yangtze River and Dongting Lake. Due to special geographical locations， topographical conditions and water security problems in reality， regional flood control， drainage， water resource utilization and water environment protection have become a hot topic. Based on an analysis and study of the above issues， this paper summarizes and concludes the key evaluation index of water security， including the types of disaster control， water supply， ecological environment and water value in the Jingnan Four-inlet Regions of Yangtze River. Based on the hydrologic characteristics and current situation of various water projects in the Jingnan Four-inlet Regions and according to the social economic development planning and other special plannings， this paper proposes the key evaluation index in the Jingnan Four-inlet Regions of Yangtze River and the security threshold value of Anxiang station including： ①Flood control evaluation index is， when the flood of 1954 year happen， that the highest water level value of Anxiang Station would not exceeded 39.38 m. ②No obvious waterlogging occurs when the value of maximum 3-day rainstorm reaches 212 mm in Anxiang Station. ③During the key irrigation period， the water level value of Anxiang Station shall not be lower than 29.50 m. ④In each period， the flows in the Four-inlet Regions meet the requirements of ecological flow. ⑤The water quality in each river meets the requirements of Class Ⅲ . ⑥The water level value in Anxiang Station meets the requirements of minimum navigable water level value of 28.71 m. The paper also discusses the rationality of these threshold results. Such results provide scientific support for making the determination of comprehensive control， development and protection programme in the Jingnan Four-inlet Regions of Yangtze River.

Aiming at the problem of low accuracy of direct prediction due to the non-linear and unstable characteristics of runoff series， a new method based on double decomposition of runoff time series and least squares support vector machine （LSSVM） model is proposed for monthly runoff prediction. Firstly， the complete ensemble empirical mode decomposition with adaptive noise （CEEMDAN） is used to decompose the original runoff time series into a series of intrinsic mode function （IMF）. Then the technique of wavelet decomposition （WD） is utilized to decompose the high-frequency components to extract the implicit information from the original data more effectively. Each component is taken as the input of the LSSVM prediction model optimized by particle swarm optimization （PSO）. Finally， the prediction results of each component are superimposed and reconstructed to obtain the final result. Taking the monthly runoff at Changshui Hydrological Station in Luohe River Basin as an example， the verification results show that the proposed CEEMDAN-WD-PSO-LSSVM combination model improves the accuracy of runoff prediction better than that of the single model. The double decomposition conducted by CEEMDAN-WD is more powerful to detect the information of complex runoff series， and provide a new approach for forecasting the nonlinear and unstable monthly runoff time series.

The source region of the Yellow River， as an important flow producing area and water conservation area of the Yellow River basin， has an important influence on the realization of the overall goal of “strengthening the governance and protection of the Yellow River and promoting the high-quality development of the Yellow River Basin”. Based on SWAT （Soil and Water Assessment Tool） model， Mann-Kendall test and sliding T-test， the spatial and temporal distribution characteristics and change trend of precipitation， blue water volume and green water volume in the source region of the Yellow River from 1962 to 2017 are quantitatively analyzed. The results show that in the past 56 years， the average amount of green water in the source region of the Yellow River is more than 2.5 times that of the blue water. The green water increases in the whole basin， with the largest increase at the northwestern Maduo Station （1.0 mm/a）. Precipitation and blue water increases in the northwest， while decreasing in the east and southeast. In terms of spatial distribution， the distribution of precipitation and blue/green water shows an increasing trend from northwest to southeast. Precipitation change is the main factor affecting the temporal and spatial distribution of blue water. However， the green water in the basin is affected by both precipitation and air temperature， and its spatial distribution is quite different. The evapotranspiration in the northwest is less than that in the southeast， and the green water in southeast is the most abundant.

The anisotropy of soil hydraulic conductivity is widespread in nature， but the influence of such soil characteristics on runoff generation is not considered in most studies， making it difficult to reproduce the hydrograph of real flood events. In this paper， a physics-based model （InHM） is applied to Jianpinggou， a mountainous catchment in China， to simulate the rainfall-runoff process under different scenarios of anisotropic hydraulic conductivity. The results show that the anisotropy of soil hydraulic conductivity have a significant impact on the runoff process. With the increase in anisotropic ratio（Kr）， the peak discharge can be substantially elevated： when Kr is 10， it can be 70% higher than the isotropic base case. In addition， under the condition of larger Kr value， the peak occurrence time is also relatively earlier. These impacts can be attributed to the increased flow velocity both at the hillslope and under stream channel due to the larger Kr， which drains more soil water down the hillslope and recharges streamflow in the channel. Our results suggest that the anisotropy of soil hydraulic conductivity cannot be ignored， and reasonable consideration of anisotropy in hydrological simulation can improve the accuracy of rainfall runoff simulation， which has important application value for flash flood early warning and prediction.

In order to determine the matching relationship between water resources and social economic factors （e.g. GDP， population） in karst areas， this paper proposes a gini coefficient based on the structural weight of included angle， and compares it with traditional gini coefficients and gini coefficients based on the entropy of the region. Taking the statistical data of the typical karst area in Guizhou Province， China from 2000 to 2018 as an example， this paper uses the above three methods to analyze the matching characteristics between water resources and social economy of Guizhou Province， and the autocorrelation analysis is used to the corresponding time series of nine administrative regions in Guizhou Province， the spatial change of nine administrative regions in Guizhou Province based on spatial grouping analysis is also studied. The results show that the matching degree of water resources and GDP in Guizhou Province is stable in time， but different in space， while the matching degree of water resources and population gradually decreases in time， but the difference is small in space. Therefore， the suitable measures should be adopted according to the matching characteristics of different administrative regions and the relationship between water resources and social economic development should be coordinated.

The hydrological process of flooded wetlands is an important basis for maintaining its biodiversity and water resources regulation. The hydrological hysteresis of lake flooded wetlands is an important part of revealing lake hydrological process and water balance. This paper takes the Nanji Wetland and its adjacent lake areas as the research area， and uses the two-dimensional hydrodynamic numerical model of lake flooding， geostatistical analysis and numerical integration to discuss and analyze the relationship of water level， inundated area and hydrological connectivity. The results show that the typical flooded wetland of Poyang Lake has hydrological lag on the seasonal scale and on the scale of rising and falling events. What’s more， the degree of hydrological lag has significant interannual differences where the degree of hydrological hysteresis is stronger in wet years than normal and dry years. It is also found that the hydrological hysteresis is obvious in the rising period other than the recession period. Landform structure and flood storage and drainage are one of the main causes of hydrological lag， especially the numerous sub-lakes in the south of Poyang Lake may aggravate the hydrological lag of flooded wetlands. The nonlinear response relationship of water level， inundated area and hydrological connectivity indicates that it is urgent to strengthen wetland hydrological observation and reveal the characteristics of wetland hydrological connectivity in flood wetland water resources management and eco-hydrological research. The research results can provide an important basis and scientific reference for floodplain hydrology theory and wetland ecological protection and management.

Shiyang River basin is one of the regions where exist a very serious contradiction between supply and demand of water resources in China. And since 1950s， in practical engineering， some serious ecological and environmental problems have been detected in Shiyang River basin because the water resources and groundwater have been overexploited largely. In order to implement the strictest groundwater resource management system， the Shiyang River Basin Water Resources Scheduling and Management Information System Project， which was implemented in 2011， has established a groundwater monitoring system to monitor groundwater resources and implement real-time monitoring of the water consumption of the driven wells. It provides important information means and technical support for realizing the optimal allocation， unified scheduling and management of water resources in the basin， and further improves the level of water resources management and water use efficiency.

The amount of the water resources that can be provided by nature is limited， and at the same time the spatio-temporal distribution of the water resources in China is uneven， which leads to the contradiction between the supply and demand of water resources in Shiyang River Basin. Therefore， in view of this phenomenon， this paper first studies the allocation of water resources， calculates the amount of water resources in the basin， analyzes the current situation of water resources allocation in the basin， and then optimizes the model to rationally allocate water resources， so as to solve the contradiction between the upstream and downstream of the basin.

In order to give full play to the utilization efficiency of agricultural water resources and realize the sustainable development of agriculture in the central Yunnan water receiving area， the output of main crops is selected as the output index， the agricultural water consumption， the comprehensive irrigation quota， the planting area of grain crops and the agricultural population are selected as the input indexes. Taking 2008 and 2018 as the cross-section data， the static data envelopment calculation analysis is carried out， and the Malmquist dynamic analysis is carried out based on the 2008-2018 data series. The results of static analysis show that the utilization efficiency of agricultural water resources in the whole and each water receiving area in Central Yunnan is invalid， and show a downward trend in recent years. The results of dynamic analysis show that TFP index of agricultural water resources utilization efficiency is not more than 1， the average value is 0.911 6， and it has been declining in the past 11 years. As an important factor in leading the utilization efficiency of agricultural water resources， technology directly determines the change rhythm of total factor productivity to a great extent. The key to improve the utilization efficiency of agricultural water resources is to strengthen the construction of water-saving and cooperate with reasonable resource allocation.

The purpose is to reveal the vibration of the rotor system of centrifugal pump in case of coupling parallel misalignment. Firstly， the rotor system components are simplified， and the finite element model of the rotor system is established. Then， the influence of different parallel misalignment on the vibration characteristics of centrifugal pump rotor system is studied through a comparative analysis of vibration displacement spectrum diagram and axis orbit diagram. The results show that the ideal centering rotor system is dominated by radial vibration， the radial vibration frequency is 1 time of the rotation frequency， the axial vibration frequency is 1 time of the blade passing frequency， and the axis orbit is elliptical； the coupling parallel misalignment causes a large radial vibration of the shaft on the rotor system and the vibration characteristic frequency shows an obvious 2APF. The vibration amplitude increases linearly with the increase in the parallel misalignment； the axis orbit of the rotor system with the parallel misalignment shows a banana shape.

In order to explore the effects of drip irrigation on the growth of Lingwu Changzao in the Yellow River irrigation area in northern Ningxia and the reasonable irrigation pattern. In 2017 the experiment set the annual irrigation quotas were 2 925， 3 600， 4 275 and 4 950 m3/hm² four treatment， each treatment was repeated 3 times， a total of 12 test plots. In 2018， an additional treatment was added， the irrigation quota increased from 4 950 to 5 625 m3/hm²， and the annual irrigation quota was designed at five treatments， and each treatment was repeated 3 times for a total of 15 test plots. According to the 2017-2018 experiment， combined with the different depth soil moisture of Lingwu Changzao’s different periods， the soil irrigation water storage ratio and the yield， the comprehensive analysis that the Lingwu Changzao drip irrigation system was formulated as follows： the annual irrigation quota was 4 275 m3/hm²， 11 times of irrigation； the irrigation quota for growth period was 3 825 m3/hm²， 10 times of irrigation， among them， the elongate shoots period irrigation was 1 time， the irrigation quota was 450 m3/hm²； the squaring stage and florescence irrigation was 3 times， the irrigation quota was 300 m3/hm² every time； the young fruit expansion stage irrigation was 3 times， and the irrigation quota were 375， 375， 450 m3/hm² respectively； the fruits in white-mature period irrigation were 2 times， the irrigation water quota was 450 m3/hm² every time， the maturity period irrigation was 1 time， the irrigation quota was 375 m3/hm²； dormancy period （winter irrigation） irrigation was 1 time， the irrigation quota was 450 m³/hm². Under the above treatment， the yield of Lingwu Changzao was 11 184~16 080 kg/hm²， the water production efficiency was 1.90~2.90 kg/m³.

Remote sensing technology has been increasingly used in agriculture. This paper presents an improved support vector machine method to estimate saline-alkali soil from imagery obtained from UAV. Taking the first irrigation district at the Jingtai Electric Power Irrigation District of Gansu Province as an example，this paper uses Trimble refused UX5 fixed-wing uav remote sensing data in the study area， combining ENVI software based on supervised classification of five types of classifier （parallelepiped， minimum distance， neural network and maximum likelihood and support vector machine） to perform classification， accuracy compared with the result of classification， statistics and typical area saline-alkali land area is extracted. The classification results of the two regions show that support vector machine （SVM） is superior to other methods in extracting saline-alkali land information from uav remote sensing. The total accuracy of region 1 and region 2 classification is 94.66% and 96.55%， the Kappa coefficient is 0.936 1 and 0.957 3， and the proportion of saline-alkali land area is 43.5% and 36.1%， respectively. SVM classification can provide method support for accurate extraction of saline-alkali land information from uav remote sensing images in arid desert irrigated areas.

In order to explore the effects of different nitrogen fertilizer levels on the growth indexes and SPAD value of jujube under drip irrigation， and determine the appropriate local nitrogen application rate， the field experiment was conducted with 7-year-old jujube trees in Minqin， and four nitrogen fertilizer levels （407 kg/hm²， CK； 610 kg/hm²， T1；814 kg/hm²，T2； 1 020 kg/hm²，T3） were set as the treatment. The results showed that the SPAD value of leaves increased with the increase in nitrogen application rate in each growth period.The increase in nitrogen fertilizer can promote the growth of jujube bearing branches to a certain extent. Compared with CK， T3 treatment can increase the length of jujube bearing branches by 16.75 cm， an increase of 11.57%.Increasing nitrogen fertilizer can effectively improve the fruit setting rate of local jujube trees， and T3 has the highest fruit setting rate. Compared with CK and T1， the fruit setting rate increases by 3.69% and 3.06% respectively. T3 treatment has the highest yield， which is 162.99 kg/m² higher than CK treatment， with an increase of 24.76%. Through the comprehensive evaluation by using the membership function method， it is considered that T3 treatment （1 020 kg/hm² nitrogen fertilizer application rate） is the optimal treatment and is suitable for the local nitrogen fertilizer application.

This paper aims to put forward countermeasures for both agricultural water saving and emission reduction in Qilu Lake Basin. Data of statistical yearbook and lake water quality in Qilu Lake Basin from 2001 to 2014 are collected to analyze the influencing factors of lake water quality by common correlation analysis method and gray relational analysis method. Correlation analysis shows that population， vegetable yield， plastic film usage， agricultural gross output value and Potash scalar are very important factors of water quality for the lake. Factors， such as farmland area， Nitrogen scalar， phosphorus scalar and pesticide use are also important. Among all the factors， the yield of grain crops has the least impact on water quality. Field surveys of farmland non-point source pollution and farmland water use in Qilu Lake Basin were carried out in 5 towns at the end of 2019. Results of surveys showed the annual average water consumption， fertilizer use， pesticide use and film use were 4.00， 8.86， 3.96 and 5.63 times of the national average level respectively. Therefore， countermeasures， such as adjusting agricultural planting structure， reducing vegetable multiple cropping index and adopting water-saving irrigation technology are helpful to reducing irrigation water consumption. Also， the construction of three defense-line system are very important for agricultural non-point source pollution control， which includes field water and fertilizer regulation， ecological ditch interception， pond weir and regulation and storage belt purification and reuse.

The purpose of this study is to explore the moisture and salt transport regularity of saline-alkali land in Xinjiang and Jiangsu reclamation areas under the drip irrigation. Through the drip irrigation experiment in the rain-proof soil tank， taking drip irrigation flow and soil texture as control factors， Xinjiang sandy loam and Dongtai silty loam are selected as typical soils， with four flow treatments （ 0.4， 0.7， 1.0 and 1.3 L/h） to study the effect of drip irrigation flow on the moisture and salt transport of saline alkali soil with different texture. The results show that ① with the increase in drip discharge， the average moisture content of the soil in each treatment first increases and then decreases； the moisture content of sandy loam reaches the maximum at 1.0 L/h flow rate and that of silty loam at 0.7 L/h flow rate； ② the closer the soil is to the emitter， the higher the salt leaching rate； the 0~25 cm soil layer is salt leaching area and the 25~35 cm soil layer is salt accumulation area.In 0~15 cm soil layer， The salt transport trends of the two soils are the same， and both decrease first and then increase with the increase in flow. The migration of total salt and Na⁺ shows that the average content of sandy loam is the lowest at a flow rate of 1.0L/h， and the leaching rate of silty loam is the highest at 0.7 L/h. The Cl^- leaching rate in silty loam soil is highest when the flow rate is 0.7L/h， but there is no obvious law between flow rate and Cl^- migration in the sandy loam soil； ③ The optimum drip irrigation flow rate is 1.0 L/h for sandy loam in Xinjiang and 0.7 L/h for silty loam in Dongtai according to the soil moisture and salt leaching conditions. The results can provide a basis for formulating a more reasonable irrigation system for drip irrigation system in Xinjiang and Jiangsu reclamation areas.

In order to understand the formation mechanism of terminal water price of different users， and provide a reference for the comprehensive reform of agricultural water prices in Jiangxi province， Ganfu Plain irrigation district was selected from 2016 to 2017 for a survey on cost， current water price and users’ bearing capacity. Ecological water was included in the survey as one of the users. According to research results， the users are divided into agricultural water users， non-agricultural water users， and ecological water users. Apportion coefficient method is used to calculate the terminal water price of different types of users. The reasons for the change of terminal water price that include ecological water use in the large scale irrigation are analyzed. Finally， according to the water user affordability the executable water prices range in Jiangxi Province are put forward. The results will provide a reference for the agricultural water price reform in irrigation area.

In order to improve the water production efficiency of crops and alleviate the agricultural water crisis， the regulated deficit irrigation mode is adopted to rehydrate the tomatoes after a certain period of drought during the flowering and fruit-bearing period. By measuring the photosynthetic parameters and chlorophyll fluorescence before and after depletion-rewatering， the physiological performance， yield and water use efficiency of tomatoes under drought-rewatering mode are analyzed. a control， 3 drought periods， 3 irrigation gradients， a total of 10 treatments are set up. The control group has always maintained the soil moisture content of the field water holding capacity of 90%~100%， and the 3 drought periods are continuous droughts for 7， 14 and 21 d， and then re-watering. 3 kinds of irrigation gradient treatments keep the soil moisture content at 80%， 60% and 40% of the field hold respectively.The results show that under short-term drought stress of 7 d and 14d， the Fv/Fm and Fv/F0 of tomato leaves decrease with the increase in stress， and recover after rewatering， except that the soil moisture is 80% of the field water holding capacity. -60% treatment can roughly restore to the control level， the rest of the treatments can not restore the state before the drought， However， each treatment after 21 days of continuous drought is more inhibited， and it can not fully recover after rewatering. During the short-term drought stress of 7 and 14 d， Ci gradually decreased， Gs decreased， and Ci recovered rapidly after rewatering， indicating that the decrease in Pn is mainly caused by stomatal restriction. In the 21 d drought treatment stage， the Ci of each regulated deficit treatment is different from Pn and the decrease in Gs， on the contrary， increases Ci compared with the 14 d drought treatment， indicating that the continuous drought for 21 days will produce non-stomata limiting factors that will reduce the Pn of tomatoes. The WUE of the soil moisture content of 80% and 60% of the field water holding capacity after 7 days of drought is higher than that of the control group by 4.44% and 1.90%. It shows that controlling the soil moisture content at 80% to 60% of the field under drought conditions 7 d is conducive to improving the water use efficiency of tomatoes.Therefore， drought treatment reduces the photosynthetic performance of tomatoes， and rewatering after drought has a positive effect on improving the water use efficiency of tomatoes.

The axis detection of hydraulic turbine is the basis of operation， installation， maintenance and axis adjustment of the hydraulic turbine. The principle and implementation technology of an intelligent detection system of the hydraulic turbine axis based on the arm and ant colony optimization algorithm is studied in this paper. Firstly， the hardware composition and working principle of the intelligent detection system of the hydraulic turbine axis based on ARM microprocessor are introduced in detail. Then the principle of axis deviation detection based on the ant colony optimization algorithm and the software implementation technology suitable for ARM microprocessor are deeply studied. Finally， an application example of the device is given. Theoretical analysis and application examples show that the system has the advantages of high intelligence， high precision and high real-time.

In 2019， Southwest power grid was asynchronously interconnected with Central China power grid.Combined with operation condition of primary frequency modulation in governor opening mode of hydropower unit， this paper introduces the power regulation and primary frequency modulation of hydropower units before and after asynchronous networking of southwest power grid， analyzes the problems existing in the primary frequency modulation of the governor opening mode，puts forward a method for distinguishing the primary frequency component and monitoring regulation component of hydropower power variation in governor，discusses the optimization strategy of primary frequency modulation in governor opening mode. The conclusions can be used as a reference for improving the function of governor opening mode of hydropower units.

Yunnan Province is rich in small hydropower resources， among which cascade small hydropower stations account for a large proportion of the whole small hydropower generation. These cascade small hydropower stations are daily regulating hydropower stations. There are obvious differences between the optimal operation of cascade reservoirs in the basin and the common cascade hydropower stations controlled by large regulating capacity leading hydropower stations. It is difficult to use the algorithm and model of traditional cascade hydropower stations to realize the optimization of reservoirs. Aiming at this problem， based on the research background of optimal operation of daily regulation cascade hydropower stations， the general drawing steps of multi factor cascade dispatching diagram is discussed， and the key of the steps is analyzed. Around the key factor screening of small hydropower station optimal operation， the related factors are further described. Based on the analysis process of optimal operation， taking Jinshuihe three-stage small hydropower station located in Jinping County of Yunnan Province as an example， the selection method of key factors for daily regulation hydropower station operation is discussed in depth， and the effectiveness of the method is verified by the comparison of water head and water amount benefits.

In order to improve the robustness and dynamic quality of the controller， an optimal sliding mode controller is designed for the optimal control of the hydro-turbine governing system. Firstly， the basic mathematical model of each subsystem of the hydro-turbine governing system is introduced. Based on the system mathematical model， the algebraic equation is locally linearized by using Taylor's expansion formula， and the state space equation of the controlled object of the hydro-turbine governing system is obtained by ignoring the second order and high order infinitesimal. Secondly， the sliding mode controller is designed according to the state space equation and the new sliding mode manifold， and the parameters of the controller are optimized based on the proposed mixed objective function. Finally， the optimal sliding mode control strategy of hydropower plants under power control mode is studied by taking an extra-large hydropower station in China as the experimental object. The robustness of the designed sliding mode controller is verified by experiments of parameter perturbation， disturbance response and noise interference under the weak stability condition of the unit， which lays a theoretical foundation for the practical application of sliding mode control in hydropower units.

Backfill empty phenomenon maybe happen after backfilling for underground penstocks of hydropower stations. The empty range and depth are important references for whether the underground penstocks need supplementary grouting. This paper selects representative pipelines of a certain project， and uses the three-dimensional non-linear finite element method to calculate the sensitivity of their stress conditions in terms of empty range and depth. Then the calculated results are compared with the resistance limit of the material to obtain the allowable empty range and depth of the steel pipe， and the impact of the backfill empty range and depth on the force of the steel pipe structure are scientifically evaluated.

Due to the noise error in the monitoring process of concrete dam displacement， the intelligent algorithm is prone to overall fitting， local minimum value and slow convergence speed. In order to solve the above problems， this paper uses the ensemble empirical mode decomposition （EEMD） method to decompose the measured displacement values to obtain the components IMF and residual R with different frequencies. Then， the components and residual terms are trained by recurrent neural network （RNN） to obtain the mapping relationship between environmental variables and time effect and IMF and R. Finally， the predicted response values of each component and residual term can be obtained by the mapping relation obtained from the model， and the predicted value of displacement can be obtained by summation with equal weight. In the process of RNN training， harmony search algorithm （HS） is introduced to optimize the RNN， systematically de-noising， and a certain probability limit function is used to disturb to get the optimal solution. Thus， the weights and thresholds of RNN are optimized and the robustness of the model is improved. Taking a concrete dam as an example， the results show that HS-EEMD-RNN model has higher accuracy of overall fitting and prediction， and less overfitting degree. Compared with EEMD-RNN model， HS algorithm can significantly improve the accuracy of its model， and has high precision in predicting the sudden jump value of displacement hydrograph.

The safety and stability of power plants and power grids are closely related to the operating status of hydropower units. The forecast of the unit status trend makes up for the insufficiency of fault diagnosis as an after-the-fact decision， and the occurrence of accidents can be avoided by detecting fault signs in advance through predictions. Based on EEMD and neural network theory， this paper proposes a state trend prediction model for hydropower units. Taking the vibration state trend prediction of a domestic two power plants as an example， the vibration signal of the unit is firstly decomposed by EEMD， and then the GA-BP prediction model is used to predict the operation trend of each IMF component. The final prediction signal is the accumulation of the prediction results of each component. The experiment results show that the model can effectively predict the vibration state trend of the unit， which is more accurate than other methods.

Taking a hydropower station in China as an example， a mathematical model of load rejection process of hydroelectric generating units is constructed under the uncertain framework. Based on this model， an Extended Fourier Amplitude Sensitivity Test is introduced to quantify influences of input parameters on the system response， and sensitivity characteristics of input parameters relative to the rotational speed， water hammer pressure and surge in the surge-chamber during the load rejection transition are obtained. It can be concluded that the flywheel torque has the most significant effect on the maximum speed appreciation. At the same time， it can be found that the uncertainty of each parameter will obviously affect the sensitivity to the water hammer pressure， but will not affect the sensitivity to the surge in the surge chamber.

The baffle of the Weir-bottom hole combined fishway divides the Fishway into a continuous stepped pool， which increases the energy dissipation of the water in the pool and creates the upstream flow pattern of fishes. However， the different shapes， size and layout of weir and bottom hole will lead to the change of flow characteristics， and the layout of weir is an important feature that needs to be carefully considered.Taking a weir-hole combined fishway as the research object， a three-dimensional mathematical model is established to study the characteristics of the partitions of the Fishway pool room. The velocity distribution and flow structure in the fishway are optimized by changing the relative position p/B of weir. The results show that when the water depth in the fishway is 2 m， different weir layouts have a great influence on the flow structure of the pool room. Compared with the weir crest gaps staggered left and right in the original plan， when p/B = 0.6， the main stream in the pool room is clear， the range of return zone is relatively small， the maximum velocity at the weir and bottom hole is less than 1.0 m/s， and the maximum turbulent kinetic energy is 0.06 m²/s²，which can basically meet the upstream requirements of four major fishes and other cash fishes. In practical application， the optimal solution to P/B can be found according to the engineering practice.

The cemented material dam is a new type of dam that has been studied extensively in recent years. This type of dam has many significant advantages such as over-topping， relatively little waste， and ideal environmental protection. At present， there are relatively few research results on the characteristics of dam construction materials and an analysis of dam body structures.This paper combines the weathering material of the Xijiang Dam to conduct a mix ratio test and dam stress-strain analysis. The research results show that when the proportion of strong weathering material in the mixed aggregate is less than 60%， the compressive strength of the cemented sand and gravel can meet the requirements of the preparation； under all working conditions， the overall stress level of the Xijiang Dam is low and uniformly distributed， while meeting The “Technical Guidelines for Cemented Granular Dam Construction” SL678-2014 stipulates that the compressive safety factor is no less than 4. The research results broaden the selection of materials for cemented sand-gravel dams and provide a theoretical basis for the Xijiang Dam Project.

The amount of coagulation in the process of water purification in water plants is influenced by multiple water ingress factors， and the law of change presents a highly nonlinear pattern difficult to control. Based on the RBF optimized by PSO， a dynamic model of nonlinear high-dimensional mapping water plant with error reverse propagation is established. Compared with the single RBF model， the average relative error is reduced by 3.05%， the maximum relative error is reduced by 0.198 6， and has a faster iterative convergence speed，and also has good adaptability to the water plant of different processes.

The influence of various parameter changes of the vertical air vessel in the long-distance water conveyance system on its water hammer protection ability is analyzed and discussed. By taking a water supply project as an example， the Extended Fourier Amplitude Test （EFAST） method is used. The maximum positive pressure， the minimum negative pressure and the maximum reversing speed of the pump in the accidental pumping condition are taken as the results of the air vessel water hammer protection. An analysis of the parameter is based on the global sensitivity of the air vessel water hammer protection effect when the reference value is ±50%. The results show that the main parameters that affect the maximum water hammer pressure of the air vessel are the diameter of the connecting pipe， the volume of the air vessel and the gas-liquid ratio； the main parameters that affect the lowest negative pressure are the diameter of the connecting pipe， the outlet local resistance coefficient， the gas-liquid ratio and the length of the connecting pipe. The main parameters that affect the maximum reversing speed of the pump are the diameter of the connecting pipe， the gas-liquid ratio and the volume of the air vessel in order. Among them， the diameter of the connecting pipe between the air vessel and the main pipe is the most sensitive parameter that affects the maximum pressure， the minimum negative pressure and the maximum reverse speed of the pump.