Water resources management is a key issue in China's national governance. The investigation and management of water resources in Ireland is very distinctive， which has important reference significance for the governance of water resources in China. Therefore， this study selects Ireland water resources survey and management work as a case example， and investigates separately from the dimensions of water resources management mode， relevant legislation， water resources protection education， public participation mechanism， water resources survey and evaluation content and mechanism， and water resources major strategic plans. The results show that Ireland has rich experience in data informatization， visualization and data sharing， strategic planning， design and deployment， monitoring network construction， formulation of laws and regulations， water resources management and supervision， public education and participation mechanism construction. Combined with the existing problems of water resources management in China， the following suggestions are put forward： continue improving data information management and sharing water resources investigation and evaluation； paying attention to the formulation， layout and improvement of medium and long-term strategic planning of water resources investigation suitable for different perspectives， strengthening the implementation supervision and achievement evaluation mechanism construction of water resources investigation and evaluation， strengthening the education and publicity of water resources protection， and encouraging the public to participate in the whole process of water resources survey and management， hoping to provide reference for water resources survey and management in China.

Vegetation cover changes affect the formation and evolution of runoff， and then affect the regional hydrological cycle. In this paper， the normalized vegetation index （NDVI） is used as the indicator of vegetation coverage to analyze the temporal and spatial changes of vegetation coverage in Shandong Province from 1998 to 2018， and its relationship with runoff. The Copula function is used to construct a two-dimensional combination distribution of NDVI and runoff. The results show that from 1998 to 2018， NDVI showed an increasing trend in time and space， and runoff depth was positively correlated with NDVI in Shandong Province. Under the combined influence of NDVI and precipitation， runoff depth decreased by 30% around 2011 in Shandong Province. Through goodness-of-fit test， Gumbel Copula function is used to construct the two-dimensional joint distribution of runoff depth and NDVI. With the increase in runoff depth and NDVI， the joint probability value and return period of the two increases. The joint probability value and return period of different combinations of runoff depth and NDVI can be determined by the contour map. The research results are of some guiding significance to the sustainable development and utilization of water resources and the formulation of development planning.

In order to improve the accuracy of runoff prediction， a runoff forecasting hybrid model named LMD-QPSO-CRJ is developed for monthly forecasting featured with strong non-stationarity and non-linearity. Firstly， the runoff data is decomposed with Local Mean Decomposition to reduce noise， and Variational Mode Decomposition （VMD） is employed to further decompose the first high-frequency component. Secondly， Quantum Particle Swarm Optimization （QPSO） is utilized to optimize the parameters of the Cycle Reservoir with Regular Jumps （CRJ）. Finally， the LMD-QPSO-CRJ model is established. The model is applied to the monthly runoff prediction of Fenhe Reservoir Station and Shangjingyou Station in the upper reaches of Fenhe River. LMD-QPSO-CRJ model is compared with other models such as the single QPSO-CRJ model and CEEMD-QPSO-CRJ model for a comparative analysis. The results show that the MAE value and RMSE value of the LMD-QPSO-CRJ model has reduced by 32%~40% and 23%~31% compared with the single QPSO-CRJ model， by 11%~26% and 11%~18% compared with CEEMD-QPSO-CRJ model during the validation period. The NSE value of the LMD-QPSO-CRJ model is close to 1. The results highlight the LMD-QPSO-CRJ model with great prediction accuracy， the model can be used to guide practical production and construction.

In order to analyze the relationship between water resources utilization and economic growth quantitatively in Shaanxi Province， based on the theory of water resources ecological footprint，this paper analyzes the decoupling relationship and makes decoupling predictions between the two. The results show that the water resources ecological footprint and economic growth in Shaanxi Province are in a state of decoupling from 2005 to 2018， but they have not been completely decoupled. The relationship between water quality ecological footprint and economic growth has developed from expansive negative decoupling and weak decoupling to strong decoupling. From a comprehensive perspective， Shaanxi Province is in a state of weak water-based decoupling. Through forecasting， it is found that the decoupling relationship between water resources ecological footprint and economic growth in Shaanxi Province towards a benign development， while the decoupling intensity between water quality ecological footprint and economic growth is decreasing. From a comprehensive perspective， the contradiction between the decoupling of water resources utilization and economic growth is transformed from water quantity type to water quality type. Therefore， Shaanxi Province must increase sewage treatment efforts. According to the research results， this paper puts forward relevant suggestions for the decoupling development of water resources utilization and economic growth in Shaanxi Province.

The precision of snowmelt runoff forecast is affected by many factors. The temporal and spatial resolution and accuracy of snow information are very important factors. The products of snow retrieval using MODIS data are widely used in snowmelt runoff forecast because they are available and have relatively high spatial and temporal resolution. Actually， the available and applied product of snow retrieval using MODIS data is about snow cover information， and the time resolution is 8 days. To reduce the forecast error caused by lacking snow depth information， this paper establishes a regression model based on MODIS reflectance and factors affecting snow depth， and establishes the SRM model based on snow depth. The regression model can be used to retrieve snow depth， and the time resolution of snow depth is 10 days. The snow depth retrieval is used as the input of the SRM model based on snow depth， and is used as the adjustment to correct the calculated daily snow depth. The snowmelt runoff is calculated by variation of the snow depth with time， and meanwhile the daily snow depth is calculated by the variation of the runoff caused by snow melt. The snow depth retrieval and snowmelt runoff model based on snow depth are applied in Basin A in Xinjiang. The results show that the levels of accuracy of snow depth retrieval using MODIS were more than 85% in 2019 and 2020， and the Nash coefficients of runoff simulation in 2016-2020 were all more than 0.85. The simulation results show that the snow depth retrieval helps to describe the temporal and spatial distribution of snow， the SRM model based on snow depth can reflect the temporal variation process of snow cover more accurately， which will improve the precision of runoff forecast.

The water resource problem has become an important constraint of the economic development. Improving the efficiency of water utilization is helpful for the green and high-quality development. Under the concept of green development， the study integrates interval analytic hierarchy process （IAHP） and interval multi-attribute decision making model （IMADM）. According to the data of 17 secondary indicators in 10 years from 2009 to 2018， the green efficiency of water utilization （WUGE） in 11 cities of Shanxi Province is evaluated from the perspective of “economy-environment-society”. The evaluation results show that ① the green efficiency of water utilization is relatively high in cities in Shanxi Province. ② Taiyuan and Shuozhou have higher green efficiency of water utilization， and Linfen and Yuncheng have lower green efficiency of water utilization. ③ Through a comparative analysis， it is concluded that the results of the interval multi-index evaluation model proposed in this study are more convincing.

Based on the daily discharge data of five hydrological stations on the mainstream of Mekong River from 1960 to 2018， methods of Mann-Kendall test and sliding t-test are employed， and variation characteristics and trends of runoff are analyzed from multiple scales of year， wet and dry periods， and extreme days. The results show that： ① The annual runoff of the mainstream of Mekong River increases along the river way， and the inter-annual range of annual runoff for each station is relatively small. Except for an upward trend at Mukdahan Station， the other stations show a fluctuating decline trend， and most of them have abrupt changes in the mid-1990s. ② The monthly distribution of runoff is extremely uneven， with obvious wet and dry periods. The runoff in wet period accounts for about 80% of the total annual runoff. The inter-annual variation of wet period runoff increases at Mukdahan Station， but shows a declining trend at the other four stations. The inter-annual variation of runoff in the dry period at the five stations shows an upward trend， while the variation range varies greatly. ③ The extreme maximum runoff shows a non-significant upward trend at Mukdahan Station， and the other stations show a significant declining trend. The inter-annual variation for Chiang Saen and Luang Prabang Stations are more severe， and especially Chiang Saen Station is prone to extreme flood events. The inter-annual variation process of extreme minimum runoff at the five stations generally shows an upward trend， and the inter-annual variation for Stung Treng and Mukdahan Stations are relatively severe， and none of the stations are prone to extreme dry water events.

The available water resource is an important index to guide the utilization of water resources. Plain river network area is characterized by its dense river network and complicated regulation and storage mechanism， thus it is necessary to provide a calculation method of available water resources according to its characteristics. Taking Yancheng City as an example， this paper expounds the calculation method of available surface water resources in plain river network areas. Based on the regional features， the generalized reservoir model is put forward， and 12 computing scenarios （different water intake capacity； different guaranteed frequency） are established. The results show that：① Under the current water intake capacity of Yancheng， the available surface water resources under 50%， 75%， 90% and 95% guaranteed frequency are 6.06， 5.51， 5.03 and 5.21 billion m3 respectively.② The available surface water resources in Yancheng City diminishes with the decrease in inflow， and is limited by the regulatory capacity of water supply engineering. The calculation results indicate that the water shortage in Yancheng City can be alleviated by improving the water supply network.

The problem of suspension treatment of oil and gas pipelines has been highly concerned by engineering construction units and researchers. Research shows that the bionic grass can effectively reduce the flow rate， promote sediment deposition， and control the development of the pipeline suspension area. The velocity distribution of open channel flow with bionic grass is very complex.The height and spacing of bionic grass will affect the river flow velocity distribution. At present， the flow velocity in the open channels containing bionic grass is mainly studied by measuring the velocity variation in front， middle and back of bionic grass， but few effective measurements are made for the full velocity field. This paper describes the use of modern means of advanced test by using standard particle image velocimetry （PIV） measurements with bionic grass along the water channel to the vertical plane of the distribution of velocity field. The probability density distribution and spatial correlation of pulsating velocity in the open channel after bionic grass section is further discussed.

This paper carries out the model experiment for the planned Kumbak water division project under different topography and frequency flood conditions of the river channel. The result shows that before and after the construction of the project， the test river section is scoured along the river， and the scouring intensity of the upper section is more than that of the lower section. Under natural conditions， the scouring of the section in front of the sluice presents a “V” shaped channel. After the construction of the project， according to the different dispatching modes of the sluice， when the upstream flow is less than 800 m³/s， the scouring of the section in front of the sluice presents a “W” shaped channel， the lowest point of the section is located in the scour hole near the diversion wall and is 0.91 m lower than the bottom elevation of the sand-sluicing sluice. When the flow is more than 800 m³/s， the section shape in front of the sluice is relatively flat， the lowest point of the section is near the flood-discharging sluice and is 1.11 m lower than the bottom elevation of the flood-discharging sluice. The maximum backwater influence scope of the test reach is 3 660 m upstream of the gate site， affected by backwater and raising water level of the project， the long-term high water level and erosion leads to the decrease in the stability of the right bank.

The operation of the Three Gorges Dam（TGD） has significantly altered the flow and sediment conditions， causing responsive erosion and deposition adjustments in the middle and lower reaches of the Yangtze River. Based on the long series of flow， sediment and topographic data， the evolution characteristics of the Wuhan reach are analyzed， and the responsive adjustments of the typical reaches to the changes in the flow process under the influence of the reservoir are clarified. The results show that since the impoundment of the Three Gorges Dam（TGD）， intensive erosion in the Wuhan reach has been mainly concentrated on the medium flow channel. In recent years， the diversion ratio of the right branch during the dry season increases， and the size， plane position of the Tianxing bar are relatively stable. Compared with the non-reservoir situation， the current dispatch mode greatly reduces the peak flow and prolongs the duration of the intermediate discharge， resulting in a slightly higher diversion ratio of the right branch that medium flow tends to and a slightly larger area of the Tianxing bar. The research results can provide references for the optimal operation of the Three Gorges Reservoir and the governance of the middle and lower reaches of the Yangtze River.

Hanjiang River Basin is the water source for the Middle Route Project of South-to-North Water Diversion Project in China. The research on soil erosion in Hanjiang River Basin of Shaanxi Province is of great significance to the South-to-North Water Diversion Project in China. Moreover， the research results can also provide a theoretical basis for the soil and water conservation project of the local government. In this paper， RUSLE model and GIS are used to calculate the soil erosion modulus of Hanjiang River Basin in Shaanxi Province by using the daily precipitation data from 8 meteorological stations from 2000 to 2015， DEM data with 90 m resolution， MODIS NDVI data with 250 m resolution and soil type maps data. Then， differential characteristics of the soil erosion are analyzed from two dimensions of time and space. Results show that： ① during 2000-2015， the annual average soil erosion modulus of the study area fluctuated greatly， which increased in 2000-2011 and decreased in 2011-2015. In space， the high value of soil erosion modulus was mainly distributed in the north and southeast of the basin， while the low value was distributed in the central plain and basin of the basin. ② The soil erosion in the study area was mainly micro erosion， mild erosion and moderate erosion， in which the micro-erosion and mild erosion showed a downward trend， while the other intensity of soil erosion showed a weak upward trend. ③ The soil erosion in the northwest sample area was mainly micro-erosion and moderate erosion， in the Northeast sample area is mainly very strong erosion and severe erosion， and in the southeast sample area is mainly micro-erosion and moderate erosion. In addition， the soil erosion modulus in Counties of Zhenba， Ziyang， Langao， Xunyang， Baihe and Zhenping is relatively high， which should be paid attention to by relevant departments to improve their soil erosion status. Returning farmland to forest and grassland in a targeted manner， establishing ecological protection zones， implementing water conservancy projects at designated locations， and maintaining water and soil are still effective measures to reduce soil erosion in the future.

The bottom-permeable partition wall is an engineering measure commonly used to improve the flow conditions in the entrance area of the approach channel. As it’s difficult to deal with the bottom-permeable in the two-dimensional mathematical model of the conventional water depth average， the improvement effect in the physical model was once studied. In this paper， the overall physical model test of the Bazizui hub is carried out， and the detailed flow conditions of the entrance area under walls of different length are determined. The two-dimensional flow of the permeable partition wall is established based on the equal area method. The mathematical model， compared with the physical model test results， shows that： ① in the shield wall area， the calculated values of the flow velocity vector and the transverse velocity are more important than the actual values； ② Outside the barrier wall cover area， the calculated values of flow velocity vector and transverse velocity are very close to the actual values； ③ The equal-area permeable method can solve the problem so well that it is difficult to simulate a transparent partition wall in two-dimensional numerical calculations.

Dike engineering is an effective method for flood control and disaster mitigation. Considering the potential ecological problems such as water loss and soil erosion brought by dike construction， the ecological health evaluation is of important significance to the determination of ecological restoration objectives. Based on the average connection number and triangular fuzzy number， an ecological health evaluation model in dike interference area is proposed. The average connection number is obtained by coupling the connection number based on the discrete value and the connection number dependent on the continuous value. In the optimized connection number expression， triangular fuzzy number is introduced to quantitatively express the difference coefficient， so as to describe the fuzziness between adjacent grades. The application of the proposed model in the typical dike bid sections in the main stream of Amur River shows that the ecological health condition in section 5 is the worst， and the ecological health condition after dike construction in section 1 displays the most evident changes. In addition， effective soil thickness and vegetation coverage rate are the main influencing factors. The model is valuable for popularized application in the ecological health evaluation and ecological restoration guidance on the interference area of the similar water conservancy project construction.

In this study， according to the data of sediment change along the channel and estuary of the lower reaches of the Yellow River， the coastline is extracted by satellite remote sensing data. The relationship between river channel change and delta change in the lower reaches of the Yellow River in the past 40 years is analyzed by using statistical principle and remote sensing image analysis. The hysteresis response model of the river channel is solved by using the Grey Wolf optimization algorithm to explore the evolution of the lower reaches of the Yellow River and the siltation change of the estuary under the change of water and sediment of the Yellow River. The model shows that the ratio drop of the Xihekou section will decrease year by year with the change of river course， and the final value is 0.145.

In order to adapt to the runoff distribution characteristics of seasonal rivers in China more reasonably， the original dynamic calculation method is improved. Before calculating the ecological water demand of the river， the reliability， representativity and consistency analysis of the natural runoff data is done， and the calculation period is divided according to the division standard of wet， normal and dry period. Meanwhile， based on the ratio of annual average monthly runoff with 90% guarantee rate and annual average monthly runoff， the ratios of the same periods are calculated， and the ecological water demand can be determined combined with the monthly average runoff. Taking Xiadaiji station in the Songhua River basin as an example， the ecological water demand of the station is calculated by using the improved annual dynamic calculation method. The calculation results are compared with those of the original annual dynamic calculation method， the monthly minimum value method， the flow duration curve method and the 90% guarantee rate method. The Tennant evaluation standard is used to evaluate the calculation results. After comparative analysis， it is found that the ecological water demand calculated by the improved annual distribution method better reflects the annual distribution characteristics of river runoff， which conforms to the changeable rule of river flood. It can also better meet the survival needs of aquatic organisms in the river in the dry period， which is more conducive to the river habitat as a whole.

Different start-up strategies of hydropower units will lead to different hydraulic transition processes. In view of the requirements of simple and reliable start-up process of hydropower units by hydropower stations and view of the requirements of simple and reliable start-up process of hydropower units by hydropower stations and the requirements of starting rules， this paper uses particle swarm optimization （PSO） to conduct an optimization study on the startup conditions of hydropower units. Taking a domestic large-scale hydropower station with dual generators and common tailrace tunnel as the research object， considering the objective function composed of the speed overshoot and the speed ITAE index， this paper optimizes the parameters of the start-up strategy of the combination of the first and second sections of the guide vane and the PID and fractional PID， and carries out the transition process simulation experiment. The experimental results show that， compared with other start-up strategies， the two-stage opening law of the guide vane combined with the fractional PID controller can obtain a smaller optimal objective function value. The dynamic performance of the transition process such as the pressure at the end of the volute and the maximum draft tube pressure is better， and it can reach the steady state faster.

Freeze-thaw cycle tests on basalt are carried out to study the change of the physical and mechanical properties and the characteristics of characteristics. The durability of physical and mechanical indexes of rock under freeze-thaw cycles is analyzed by attenuation model. The results show that ① the mechanical properties of basalt decrease significantly under the freeze-thaw cycles. The damage deterioration of the rock mainly occurs during the first 20 freeze-thaw cycles， and the damage deterioration weakens as the number of freeze-thaw cycles continue to increase. ② The fitted relationship equation of each physical and mechanical index with the number of freeze-thawing is obtained by statistical analysis of the test results. ③ The strength and characteristic stresses of basalt under freeze-thawing are in good agreement， and the values of their sensitivity parameters are also close， which are suitable for rock freeze-thawing durability analysis.

The cofferdam of the upstream of Dongzhuang Reservoir has to be filled in three months. Due to the limitation of topographical and geological conditions， it is difficult to construct cofferdams with local materials. The type of cofferdam is selected between RCC and CSG. Two options are considered for the selection of cemented aggregate： artificial aggregate and excavated gravel. Due to the large cross-section of the cemented artificial aggregate cofferdam， the unit cost of artificial aggregate is high and the investment is basically the same as that of the RCC cofferdam. Using excavated gravel as aggregate can shorten the process of crushing and screening and the cost of waste gravel disposal， greatly reducing the project investment. Seven sets of grading tests have shown that the particle size content of greater than 300 mm is 1.9% to 15.3%， and the particle size content of greater than 200 mm is 5.2% to 28.3%， which makes it possible to use the excavated gravel as cementitious aggregate. After eight group proportioning tests， the compressive strength of the specimens is more than 11 MPa in 28 days， far exceeding the design strength of 4 MPa， which can be further optimized by reducing the amount of cementitious material and adjusting the water-cement ratio. It is the first of its kind in China to use excavated gravel instead of natural gravel or artificial aggregate to construct cofferdam of cemented material to meet design requirements， with the advantages of waste residue reduction， environmental protection， simple structure， convenient construction， safety and economy， which reduces investment by up to 40%.

The bank slope of reservoir is prone to deformation under long-term circulation of reservoir water fluctuation， which may lead to the cracking and even failure of the dam. Therefore， slope deformation has important influence on the safety of the arch dam. Jinping I Hydropower Station has experienced six fluctuation cycles of the reservoir water. The rheological inversion calculation of the slope deformation is conducted based on the monitoring data， and the long-term deformation of the slope is predicted. In development， the deformation and stress conditions of the arch dam under the conditions of normal water level of 1 880 m and dead water level of 1 800 m and different slope deformation are studied. The results show that the overall deformation of the arch dam was minor from the impoundment to July 2020. Furthermore， it is revealed that the tensile stress area of the abutment above the elevation of 1 800 m of the right bank decreased significantly， which means that the stress state of the arch dam has been partially improved. On the other hand， during the stage from July 2020 to the convergence of the slope after the long-term deformation， the deformation of the abutment groove slope will be small， the transverse deformation increment of downstream side of the left arch end will be less than 1.2 mm， and the magnitude and distribution range of the tensile stress of the arch dam will not change obviously. Therefore， from the reservoir impoundment to the convergence of the slope after the long term deformation， the stress and strain values of the arch dam are in a reasonable range， and the stress and strain of Jinping I high arch dam are generally in the safe operation state of elastic work.

In order to identify and evaluate the social stability risk of water conservancy and hydropower projects， a fuzzy grey correlation fault tree model for risk assessment is established. The model uses triangular fuzzy number to represent the fuzzy probability of the basic event； calculates the fuzzy probability of the top event and the fuzzy importance of the basic event； takes the fuzzy importance of the basic event as the reference column， takes the characteristic matrix composed of the minimum cut set as the comparison column， and calculates the grey correlation between the fault mode represented by the minimum cut set and the top event by calculating the correlation coefficient. A case study of Qianping reservoir shows that resettlement is the main risk factor of the reservoir construction， which is in line with the reality of reservoir construction. The model is suitable for dealing with complex system problems， and can provide reference for the social risk assessment of water conservancy and hydropower projects and the establishment of scientific early warning mechanism.

The traditional method of vibration division for hydropower units adopts the limit value stipulated by national standard through variable load test， without considering the difference of threshold value caused by unit type and operation environment. Based on the data-driven and limit learning machine （ELM）， a model for the vibration division of hydroelectric generating units is proposed， in which the stable operation data of hydroelectric generating units are applied to the vibration division， based on the data of steady state under all working conditions， the model of vibration region division is trained， and then the efficient and accurate division of vibration region is realized. The practical application shows that the vibration zoning model based on data-driven and ELM has the advantages of fast and efficient acquisition of effective data of on-line condition monitoring system， the wide coverage range and high reliability are of great significance to guide the actual operation of power plants.

Affected by the coupling of mechanical， electrical and hydraulic factors， the vibration signal of hydropower unit exhibits obvious nonlinear and non-stationary characteristics， which is a typical fractal signal. This paper proposes a signal feature extraction method for hydropower units based on multi-fractal and binary gravity search algorithm to optimize the probabilistic neural network （PNN）. The signal feature is extracted by the multi-fractal analysis method， and the binary gravity search algorithm is used to reduce the dimension of the feature. The vector input is recognized by PNN and compared with the feature vector before dimension reduction and the feature vector is extracted by using EMD fuzzy entropy. The results show that the method proposed in this paper can accurately extract the characteristics of unit vibration signals， improve the accuracy of unit status identification， and provide a theoretical basis for improving the safe and stable operation of the power station.

At present， the power regulation mode and frequency regulation mode of hydropower stations mostly adopt the same PID controller. When the working conditions are changed， the setting parameters of the primary frequency modulation should be changed frequently. In this paper， a power-frequency control method with reference model is put forward by analyzing the dynamic characteristics of control method. This method uses a reference model to obtain the adjustment value of the opening after the primary frequency modulation action according to the current head and target power and uses PID control to improve the adjustment accuracy. The simulation test under the frequency step signal and the actual frequency signal shows that the new method has the advantages of fast regulation speed and good regulation characteristics when fixed regulation parameters are used under different working conditions. It can satisfy the requirements of the local power grid assessment.

The interlayer staggered zones and faults are widely distributed in Baihetan Hydropower Station in Jinsha River Basin， China. The columnar joints basalts found in left bank and riverbed are abundant in fissures. Complex distribution of groundwater table perplexes the seepage state of the dam site area. In late May 2020， water gushed in the foundation drainage galleries of 17&18# dam sections， with maximum gush of water up to 410 L/min. On-site sampling for hydro-chemistry analysis， tracking changes of gush water amount， referring to hydrological data of recent months and consulting previous engineering geology datum and hydro-geological data are done for comprehensive analysis of gush water sources and gush water leakage paths， which confirms that deep fissures water in the left bank is the main gushing water source. The columnar arthritic basalts in the P₂ β ₃ rock formation， and layers C₂， C₃， C_3-1 are the main leakage paths. Proposals are offered for arranging seepage state monitoring during impoundment and normal operation stages with reference to this conclusion.

Hexi Corridor is located in the northwest inland with dry climate， sparse rainfall and intense evaporation， and the unreasonable development and utilization of water resources leads to the serious soil salinization in this area. According to the natural disaster risk theory and the formation mechanism of soil salinization， the index system for risk assessment of soil salinization in Hexi Corridor is established， and the risk evaluation model is constructed by using entropy combination weight and weighted comprehensive evaluation. The danger， exposure and vulnerability of soil salinization induced by water resources development and utilization in Hexi Corridor are analyzed by GIS technology. On this basis， the risk evaluation and zoning of soil salinization are carried out. The results show that the degree of water resources development and utilization is closely related to the risk of soil salinization. High and very high risk areas are distributed in the middle and lower reaches of the plain areas， and the eastern part is more serious than the western part.

Based on the problems existing in traditional open channel flow measurement methods， such as large error， inaccurate measurement results， complex measurement method， which is not conducive to popularization， and in view of the characteristics of open channel flow measurement， combined with the construction project of intelligent water metering and control system of Taohe water supply project， a rectangular multi-layer ultrasonic flow measurement technology based on cross-section average velocity method is systematically studied， and the integrated whole package is adopted innovatively. The design ensures the stability and accuracy of flow measurement technology. The calculation principle， design structure and engineering application examples of rectangular multi-layer ultrasonic current measurement technology are emphatically introduced. Through the application of the research results to the open channel measurement in Taohe Irrigation Area， the application effect is good.

Obtaining crop water requirement information is the basis of agricultural irrigation management and optimal allocation of water resources. In order to explore the use of public weather forecast information to predict reference crop evapotranspiration， this paper is an attempt to use PM model and HS model as the basis for quantitatively transforming weather forecast information to predict reference crop evapotranspiration so as to solve the problem of water demand forecast in typical areas. By using Wuhan as the typical study area， the daily forecast data of Wuhan Station from March 16， 2020， to April 15， 2020， daily for seven days in the future are collected. The results show that the predicted value and the standard value have the same trend in different forecast period， MAE of the two methods in 1~2 days forecast periods are 0.69 and 0.76 mm/d， RMSE are 0.91 and 0.905 mm/d respectively， which basically meet the precision requirements of water demand， while with the increase of forecast period， the accuracy is decreasing. The comparison between the two methods shows that the correlation coefficient of HS is always higher than that of PM and the prediction during later period is more stable. The main PM error is caused by the actual sunshine hours. HS method is recommended when the prediction accuracy of actual sunshine hours is poor. This method has good physical basis and data is easy to obtain.

This paper establishes a research framework of endowment characteristics，transaction costs and contract selection， clarifies the behavioral logic of contract conclusion of farmland infrastructure， and uses three cases with different characteristics of farmland infrastructure endowment for verification. The results show that the regional space and governance stage have an impact on the public endowment of farmland infrastructure. The different public attributes of farmland infrastructure will lead to the difference in transaction costs between explicit contract and implicit contract. According to the principle of cost minimization， strong and weak public endowment farmland infrastructure respectively concluded different contract forms. This paper puts forward some suggestions， such as respecting the choice of subject contract， guiding them to enter into explicit contract at the right time， giving full play to the complementary advantages of explicit contract and implicit contract， and choosing contract form according to local conditions.

Nowadays， drainage and irrigation pumping stations generally have the problem that the working flow of the pump set is greater than the pipe network system needs， and the pump is working at a point deviating from the optimal working condition. The transformation of the frequency conversion control system is too expensive， and cutting the outer diameter of the impeller causes a serious drop in the lift of the centrifugal pump， which is not conducive to the parallel operation of the centrifugal pumps. For the pumps of the Yellow River irrigation generally uses steel blade and welded impellers. If it is before welding， cutting the blades and moving the shroud of the impeller axially can easily change the hydraulic performance of the centrifugal pump. The medium specific speed double-suction centrifugal pump is taken as the research object， the front cover of the impeller axially is moved to change the shape of the impeller flow channel. The trend of the external characteristics of the centrifugal pump changing with the movement of the front cover is analyzed by numerical simulation， and the change mechanism of its performance is analyzed by studying the internal flow field. The results show that as the distance between the front cover and the rear cover of the impeller decreases， the head of the centrifugal pump decreases， and the H~Q curve moves downward and becomes steep. The axial translation of the front cover of the impeller makes the centrifugal pump η~Q curve move to the small flow condition as a whole， and the maximum efficiency and the width of the high efficiency zone remain approximately unchanged. By studying the changes of the flow field in the centrifugal pump and theoretical analysis， the mechanism of the head and efficiency of the centrifugal pump changing with the movement of the front cover is obtained. Moving the front cover of the impeller axially can reduce the flow rate of the centrifugal pump while maintaining a higher head and efficiency， which has certain engineering value.

The research aims at investigating the suitable maize sowing date under the maize mono-cropping system in the Hebei Low Plains. Zhengdan 958 is used in the field experiment with four sowing dates （May 5， May 20， June 5 and June 20）. The plant height， leaf area index， net photosynthetic rate， grout characteristics， yield and water use efficiency of maize are studied. The results show that the plant height and leaf area index of maize increase first and then decrease with the delay of the sowing date， with June 5^{treatment being the maximum and May 5 treatment being the minimum. After pollination， the net photosynthetic rateof June 5 and May 20 treatment is higher， and the net photosynthetic rateof May 5 and June 20 treatment is lower. Logistic curve can well simulate the corn grain grouting process simulation， In June 5 treatment， the average filling rate is the highest， the maximum grouting rate and the duration of the rate-increasing period are higher， which promotes the maximum 100-grain weight and the number of grains per ear. There is little difference in water consumption of maize between treatments， and the WUE first increases and then decreases with the delay of sowing date. The water use efficiency of June 5 treatment is the highest. Planting maize in suitable time （June 5） in the Hebei Low Plains is beneficial to plant growth， yield formation and water use efficiency.}