The mitigation effect of eco-ditch with controlled drainage and matrix dam on nitrogen runoff losses from paddy fields was investigated by field experiment. Based on the data observed after paddy field surface drainage in the yellow maturity, the nitrogen concentration changes and nitrogen removal mechanism of the eco-ditch with controlled drainage and matrix dam were monitored. We carried out a field experiment of eco-ditch with controlled drainage and matrix dam in 2017. The experimental site was located in the CaoWei Village of the Hongze County. The controlled drainage gate and matrix dam were set in the ditch at the side of strip field (9.6ha) and irrigation canal flow through the another side. The controlled drainage gate was reinforced concrete structure. The elevation of ram was set same to the strip field. The matrix dam consisted of six dams located in the 2m downstream of controlled drainage gate. The padding of first and sixth dams were stone with particle size of 2-3cm, which were set for energy dissipation and stabilizing the matrix dam. The padding of second and third dams were zeolite about 2cm, which were set for adsorbing nutrients. The padding of fourth and fifth dams were elastic solid material, which were vector of biological film. The paddy fields drainage water was held in the eco-ditch by controlled drainage gate. The nitrogen in drainage water reduced again by matrix dam after overflowing from the controlled drainage gate. Due to the surface drainage and lateral seepage from paddy fields, the high water level in the eco-ditch was remained during the observation stage. The drainage water overflowed from the controlled drainage gate everyday. During the five days paddy fields drainage water held in the eco-ditch, water samples were collected every day at the upstream of controlled drainage gate and downstream of matrix dam, respectively. Then, total nitrogen (TN), ammonium nitrogen and nitrate nitrogen concentrations in the water samples were analyzed, respectively. Results showed a combination of controlled drainage and matrix dam may be an effective method for mitigating nitrogen runoff losses from paddy fields. The eco-ditch with controlled drainage and matrix dam obtained 58.20% TN removal. The organic nitrogen was main form of TN in drainage channel water body after paddy field surface drainage in the yellow maturity, the mean ratio of organic nitrogen /TN was 78.14%. The removal of inorganic nitrogen was 11.89%, which was much lower than that of TN. Reductions in TN concentration were primarily due to the organic nitrogen removal in the eco-ditch. The nitrogen mitigation capacity of controlled drainage was higher than that of matrix dam. The removal of TN under controlled drainage was 46.24%, higher than that under matrix dam (8.19%).

In order to find out the development law, distribution characteristics and main causes of the salinization of the Hongsibao Irrigation District in Ningxia, the remote sensing images of the irrigation districts in 1994, 2003, 2008 and 2015 were used as research data, and the maximum likelihood theory was used to accurately classify the irrigation land. The development trend and main causes of secondary salinization of irrigation land were analyzed. The results showed that the area of salinized arable land in the study area increased from 13.44% in 1994 to 21.75% in 2015. The area of light saline-alkali land increased fastest, moderately and severely. Site investigations showed that the local high-salt soil parent material provided conditions for soil salinization, and the unique local climatic conditions and long-term extensive irrigation mode accelerated the development of soil salinization. Therefore, through the comprehensive management model to achieve the regulation and control of water and salt in irrigation districts, it can also provide countermeasures for the efficient use of land resources and the treatment of saline-alkali land in similar irrigation districts.

The technical measures of preventing silt deposition in muddy water pipeline irrigation system provide technical support for the application of pipeline irrigation technology in the canal irrigation area．． The spiral flow is produced by the action of the hydro－cyclone to reduce the deposition rate． The model test has been applied to the research to observe the spiral flow characteristics produced by guide vanes with different diameter－height ratios in hydro－cyclone． The spiral pipe flow is regarded as two parts． One is Poiseuille flow forced by pump on axial direction． Another produced by external pressure vane is circumferential Coutte flow，and the flow velocity is decomposed into axial velocity，circumferential velocity and radial velocity． It shows that the pressure of the testing section will increase if the diameter－height ratio of guide vanes gets higher，the pressure of hydro－cyclone will grow larger when it was located in the downstream of testing section than the upstream． The axial velocity in the downstream of the testing section will increase firstly but then decrease as the rise of guide vane diameter －height ratio． And the axial velocity of cross section is similar to logarithmic distribution． In the central region，that is，in the range less than 2．5 cm from the pipe axis，the axial velocity is larger and relatively uniform，which belongs to the core region of the spiral flow． In addition to this range，the flow velocity changes rapidly due to the viscosity of the liquid，which belongs to the transition zone and the bottom zone of viscosity． The circumferential speed in the downstream of testing section would decrease firstly but then increase as the rise in guide vane diameter－height ratio． In the mainstream region of r1＜r＜r2( r1 is less than 2．5 cm from the pipe axis，r2 is less than 3 cm from the pipe axis) ， the circumferential velocity has the characteristics of the velocity distribution of the forced vortex，and the velocity of the region is larger and the rotation intensity of the flow is intense． In the quasi free vortex zone of r＜r1 and r＞r2，the velocity value is relatively small，especially on the pipe wall，whose circumferential velocity is the minimum． The radial velocity in the downstream of the testing section will decrease gradually with the rise in guide vane diameter－height ratio． By studying the vorticity field，the size and distribution of the vortex in the test cross section are obtained，and the physical essence of the fluid motion is further recognized．

At present, agricultural water price comprehensive reform is steadily advancing on the national scale. This article takes the research and development of agricultural water price comprehensive reforms management information system developed by HuaiTouTaLa reservoir irrigation area in DeLingHa city as an example, which introduces the overall structure and functions of the management information system in detail, and analyzes the service-oriented SOA architecture of the management information system based on the key technologies such as event-driven service and big data analysis service and so on; practical application shows that by using Internet technology, internet of things technology and cloud computing platform, the management information system of agricultural water price reform in irrigated area, including monitoring, control, measurement and information technology, can be built. While saving water and increasing efficiency, the formation mechanism of reasonable water price can be established to strengthen the construction of irrigation and water conservancy infrastructure, to solve the operation and maintenance expenses of irrigation and drainage projects, ensure the benign operation of irrigation and drainage projects, effectively solve the "last kilometer" problem of irrigation and water conservancy, improve the efficiency and benefit of agricultural water, and promote the modernization of irrigation area and sustainable development of rural economic.

In recent years，secondary salinization of the lower reaches of the Yellow Ｒiver has been repeated and gradually intensified， causing damage to agricultural production and ecological security． This paper takes the Xiaokaihe Irrigation District of the Yellow Ｒiver Delta as the study area． Based on the soil salt content and Landsat8 OLI multi－spectral imagery，the spectral curve characteristics of soil samples are analyzed． According to the diagnostic index method，the band reflectance data with larger diagnostic index is an independent variable and the salt salinity is the dependent variable，and the soil salt inversion model is constructed by multiple linear regression model and BP neural network model． The results show that the higher the degree of soil salinization，the lower the spectral reflectance of the image and the highest reflectance is in the near－infrared． The inversion accuracy of BP neural network model is better than that of the traditional multiple linear regression model． It＇s Ｒ2 is 0．980 8 and ＲMSE is 1．059 5，the average relative error is 15．4%，and the fitting accuracy is high，which can provide a basis for the salinization treatment in the irrigation district．

In order to understand the sensitivity of ET0 in the Guhai Yangshui Irrigation District of Ningxia to the disturbance of meteorological factors，the concentric station in the irrigation area is used as the research area． According to the daily weather datas of the concentric station from 1961 to 2016，the Penman－Monteith formula is used to calculate ET0，the Mann－Kendall Trend analysis method is used to explore the trend of ET0 and meteorological factors in Guhai Yangshui Irrigation District of Ningxia． Sobol global sensitivity analysis method is used to analyze the sensitivity of ET0 to various meteorological factors． The results show that the entanglement of ET0 in the past 56 years is 1980，the ET0 and meteorological factors from 1981 to 2016 are both increasing compared with 1961－1980． The annual variation characteristics of the total sensitivity coefficient of meteorological factors are basically the same in 1961－ 1980 and 1981 － 2016，and the characteristics of the first－order sensitivity coefficient in these two periods are diverse and uncertain． In the interannual variation trend of the first－ order sensitivity coefficient of each meteorological factor，the first － order sensitivity coefficient of average temperature，maximum temperature，minimum temperature，relative humidity and sunshine durations showed a downward trend，and only the first－order sensitivity coefficient of wind speed upward．

In order to explore the effects of different moistube irrigation method on jujube growth, the experiment set two irrigation pressures (0.01MP, 0.02MP) and three different irrigation methods. The results showed that: the water consumption and supply are generally balanced of the 10~60cm soil layer by jujube main absorption roots distribution range, and the soil moisture content is maintained between 70% θf and 75% θf. The largest irrigation water amount of jujube in the growing period was S2 , followed by S1 and S3.The intensity of water consumption was the largest in S2, followed by S1, and the smallest in S3.In the annual growth, the growth of each treatment ground diameter was S2> S1>S3, the new shoot growth of each treatment was S1>S2>S3, S3、S1 and S2 was extremely significant between the difference treatment of jujube diameter and new shoots growth, and the difference between S1 and S2 was not significant. According to this, the optimally moistube irrigation scheme of jujube in the annual growth was S2, and S1 was second; take the monthly growth as the target, the optimally moistube irrigation scheme was S2 in May, June, July and August, and the S3 treatment was optimal scheme in September.

In response to the problem of micro-irrigation equipment clogging caused by irrigated crops containing yellow water in the Yellow River Irrigation Area, a non-all-flow filtration method was used. In the case of 5cm constant head (sand sediment volume 2kg/m3, influent flow rate 0.69 m3/h), “PVC perforated water filter pipe + non-woven fabric + quartz sand + soil” filter device, the device is equipped with three sets of processing: vertical water pipe (treatment 1), short horizontal water pipe (treatment 2), long horizontal water pipe (treatment 3) Experimental Study on non-all-flow Filtration of Sandy Water in Irrigation Area of the Yellow River. The results show that: (1) Observing the flow rate of filtered water per unit time and unit length, the maximum flow rate of treatment 2; (2) The low sediment concentration of the filtered water of the device can meet the water requirement for micro-irrigation; （3）the particle size of sediment particles in the filtered water is smaller , Can be used for micro irrigation.

The calculation of runoff concentration for ungauged watersheds is especially crucial in the flood forecasting of hills. Although the present concepts about geomorphologic instantaneous unit hydrograph have proposed the solution, convergence velocity describing flow characteristic in a watershed is required to be estimated. Here 155 source watersheds have been selected, and in order to represent the real average confluence velocity of the basins, the optimal velocity can be obtained by determining the optimum utilization ratio of the watersheds. Spearman Correlation Analysis, Grey Relation Analysis and Random Forests model were used to analyze the correlation between topography and geomorphology parameters and the optimal representative mean velocity in 117 watersheds randomly picked out from total subsequently. Results obtained indicate that the highest-level stream length and the highest-level stream elevation difference are more important topographical factors that affect flow velocity. The formula established between the optimal flow velocity of the watershed and the terrain and geomorphic factors is tested in calibrated and the remaining validated watershed, where performance shows the correlation coefficient are 0.557 and 0.588 respectively. Application of the formula shows better results when transferred to Dingan river in Hainan Province. The results indicate that the proposed technique has perfect fitting accuracy.

With the rapid development of economy and society, the main contradictions in Chinese society have been transformed into the contradiction between the people's growing need for a better life and the insufficient imbalance in economic and social development, as an important foundation and support for economic and social development, the problems faced by water resources are becoming more and more serious. Taking Jiangxi Province as an example, the insufficient research and Analysis on the imbalance of water security guarantee in three aspects of flood control security, water supply security and water ecological security in Jiangxi Province are carried out. It is concluded that the imbalance of water security in Jiangxi Province is mainly reflected in three aspects: First, there is an imbalance between the demand for regional water security and the allocation capacity of river water; second, there is an imbalance between the development and utilization of water resources and the protection of water ecology, and the contradiction between development and protection is prominent; third, there is an imbalance in the development of water infrastructure between the types of projects and urban and rural areas. The insufficiency of water security is mainly reflected in three aspects: First, the development of water infrastructure is still inadequate; second, the optimal allocation and economical utilization of water resources are inadequate; third, industry management still needs to be further strengthened.

The emergence of the critical state of the water resources system usually leads to the occurrence of abnormal events in the water resources system，and there is no consensus on the existing research on the determination of the critical state of the water resources system． Based on the AWＲI ( Aggregate Water Ｒesource Index) ，the CVI ( Critical Value Index) is proposed to comprehensively assess the sudden and abnormal degree of water resources from the early stage to the later stage． At the same time，the threshold CVIt is defined and calculated as the criterion for screening the critical state of the water resources system in the basin． Taking the upper Hanjiang river basin as an example，the monthly CVI index of the basin from 1992 to 2017 is obtained，and the critical month is determined by means of CVIt ． The results show that the CVI can better reflect the occurrence of abrupt water resources system anomalies． It is conducive to identifying sudden water resource anomalies and contributing to emergency management of the watershed water resources system by using the CVI index to discriminate the critical state of the water resources system of certain river basin．

After the construction of water replenishment project and river barrier in Wulungu lake, the briny water backflow in the Buluntuo sea appeared in Jili lake, which accelerated the salinization process of Jili lake and threatened the habitat maintenance and species survival and reproduction of Jili lake. From the perspective of hydrodynamics, combined with the water level change of Wulungu lake in the last 60 years, this paper analyzes the reasons of backflow of Wulungu lake；by means of numerical simulation, the hydrodynamic characteristics of the peak stage of reverse irrigation in lakes under wind flow, stimulation flow and compound drive were investigated, and the quantitative conditions of reverse irrigation were summarized. It is found that the wind current produced by northwest wind is the source of lake backfill, and the change of water intake and water level distribution by water replenishment project is the direct cause of lake backfill. When the water level of Jili lake is 0.3m higher than that of Buluntuo sea and the proportion of the recharge flow and the inflow flow of Wulungu lake is lower than 4.6, the lake will not reverse irrigation. In April and May, the proportion of the recharge flow and the inflow flow of Wulungu lake is far lower than 4.6, which can alleviate the problems of habitat fragmentation and lake irrigate.

The water temperature distribution in the reservoir area has an important impact on the water ecological environment and the growth of aquatic organisms． To explore the water temperature stratification structure of Hongjiadu Ｒeservoir under different floods，the water temperature model of Hongjiadu Ｒeservoir is established by EFDC model． The water temperature distribution at the front end of the reservoir dam is analyzed，and the temperature difference between the three－day flood，five－day flood and seven－day flood under the surface of the reservoir and the reservoir depth of 5，20，40 and 80 m is analyzed． The results show that: Hongjiadu Ｒeservoir 7 has an obvious water temperature stratification in the dam front section in October and October． The water temperature gradually decreases with the increase in water depth，and the temperature of the upper water body is large，and that of the lower layer is small． There is a temperature difference between the surface of the reservoir and the water at each depth and the flood duration and β． The values are all related． The better the mixing degree of the reservoir is，the smaller the temperature difference is，and the longer the temperature difference is，the longer the temperature difference is． The EFDC model can better simulate the water temperature stratification structure before the Hongjiadu Dam，and has high practicability and reliability． The research structure can provide a scientific basis for the rational operation of the reservoir．

In order to analyze the influence of design storm pattern on urban waterlogging, MIKE URBAN model was used to simulate the node flood of urban drainage pipe network of a waterlogged zone in the central city of Chengdu. Design hyetographs with different patterns and return period are considered. The total overflow, the node flood time series of a waterlogged well and the spatial distribution of waterlogging are analyzed. By comparing the simulation results, it is found that the lower storm peak position coefficient may cause a larger total overflow when the return period is greater than 20 years, and also more serious waterlogging degree of a waterlogged well, but the influence decreases with return period increasing. When the storm peak position coefficient is higher, the number of overflowed wells are greater, the level of the waterlogging disaster are higher, and the waterlogged area are larger. While demonstrating the effects of storm pattern on pipe network node flood, this paper verifies the rationality of the design storm pattern of the urban central city in Chengdu, which is refer to The Hydrological Manual of Sichuan Province, and may help the work of urban drainage planning and waterlogging prevention.

Based on the water quality observation data of a water plant in Hebei Province，this paper establishes a probabilistic artificial neural network ( PNN network) model based on MATLAB，and predicts and classified the water quality with three important indexes: pH value，NTU ( turbidity) and oxygen consumption． The experimental prediction model is a parallel algorithm based on Parzen window，which developed form the probability density function estimation method and Bayes classification rule． This experiment compares PNN neural network with BP neural network． The results show that the prediction accuracy of PNN neural network model is 21% higher than that of BP neural network model，and the prediction time is 2．141 s shorter than that of BP network model． It shows that PNN neural network model has reasonable feasibility for water quality prediction and classification，and has higher application value in water quality prediction and classification．

Phosphorus is an essential nutrient for every organism on the earth． It is also a potential water environmental pollutant which can cause eutrophication of water bodies． The removal and recovery of phosphorus from wastewater can not only reduce the eutrophication of water bodies，but also realize the recycling of phosphorus resources． Most researches are focused on phosphorus removal for large －scale urban wastewater treatment worldwide，and less concern about phosphorus removal technology for rural domestic wastewater． This paper reviews the technology of phosphorus removal and recovery of domestic wastewater，especially the technology suitable for small－scale sewage treatment in rural areas，including chemical precipitation method，biological method，adsorption method，artificial wetland method，etc． The advantages and disadvantages of various methods are analyzed． The feasibility of its application in small－scale sewage treatment projects in rural areas is also analyzed．

Diagnosing and evaluating the ecological environment vulnerability of drinking water source in karst area is of great significance for maintaining the water supply safety and ecological health of urban water source. Taking the drinking water source of Pushezhai and Jinquanhu in Kaili City as an example, this paper diagnoses and analyzes the ecological environment vulnerability of the study area by constructing the evaluation index system, using the fuzzy comprehensive evaluation model, ENVI4.8 and ArcGIS10.2 software. The results show that the ecological environment of drinking water sources is in a moderately fragile state. The moderately vulnerable area occupy the largest area, accounting for 48.97% of the total area, indicating serious ecological environmental problem. The vegetation coverage of drinking water source protection area is relatively low and unreasonable agricultural production and service activity is concentrated. The hydrometerorological function group is an important factor affecting the fragility of the ecological environment, followed by the water source pollution function group. The Euclid approach degrees of the two major drinking water sources are 0.3 307 and 0.1 218 respectively, which indicates that the ecological environment development status of the drinking water source in Pushezhai is relatively good. Finally, the countermeasures for the conservation of the ecological environment vulnerability of drinking water source are proposed.

The application of ozone disinfection in water supply is becoming increasingly popular, while it has the shortcoming of poor continuous disinfection. Concerning the regeneration of microorganisms in the water supply network after ozone disinfection, the reason and the danger of regeneration of microorganisms in the water supply network are analyzed. Besides, the influencing factors for the stability of microorganisms in ozone disinfection are interpreted on the basis of an overall study of the relevant research both at home and abroad. It has proposed that measures should be adopted such as standardizing the scope of application, controlling the addition of ozone, restricting the concentration of nutrients and adopting high-quality water supply pipe when using ozone disinfection to keep the stability of microorganisms in the water supply network. In this way, the tap safety in microorganisms of the drinking water can be guaranteed.

In this paper, the large eddy simulation method is used to simulate the pressure flow through the sluice in the upper and lower reaches. The effects of different gate bottom edge structures on the pressure distribution, flow chart, pressure time history and pressure power spectrum of the flow through the gate are systematically simulated. The results show that the low pressure zone of the bottom edge of the three groups with dip angle moves downstream towards the bottom edge of the gate, and only the first group has a negative pressure zone directly below the bottom of the gate, while the other three groups have a certain inclination angle. It can guide the flow through the gate to a certain extent. There will be three swirls at the beginning of the four gates. As time goes on, the vortex moves upstream. The first gate has no angle at the bottom edge of the gate, and there are two swirls in the backflow zone when it is finally stabilized. The other three gates have a back-and-forth tilt angle, and the last three vortices compose a large vortex, so there is only one vortex in the backflow region. This conclusion provides a basis for the study of the influence of different gate bottom edges on the swirl of water flow.

Silt solidification treatment technology is an important method to solve the problem of clearing silt in dike in the north of dongting lake and realize the reclamation of silt. Based on the analysis of test data of filling roadbed with silt solidified soil after dredging of ditches and ditches in anxiang county, north dongting lake, this paper discusses the physical mechanical properties and microstructure of silt solidified soil formed by cement and sodium metaaluminate solidified silt. The results show that the cement content has the greatest influence on the compressive strength of the silt solidified soil. The primary and secondary relationship is the cement content, > mud content, > curing agent content. The optimal ratio is 9.6kg mud content, 1.07 kg cement content and 0.43g curing agent content. It can be seen from the scanning electron microscope that sodium metaluminate can greatly promote the hydration reaction of cement, and its products can significantly improve the binding force between particles in the solidified sludge. According to the research results,the construction procedure for filling subgrade with silt solidified soil from ditch in North of Dongting Lake was put forward, which provided a basis for promoting the resource utilization of silt.

The design of hydraulic engineering foundation pit is highly professional and risky, and has high dependence on the experience of designers. Thus, to reduce the experience dependence of the designers, improve the efficiency of the foundation pit design and determine the design parameters of the foundation pit quickly and reasonably, the orthogonal test table is introduced to arrange the test scheme aiming the reliability and economy of the structure of foundation pit support. Through statistical analysis and multiple comparison of the experimental results of orthogonal test, the optimal scheme can be quickly fixed. This research takes the foundation pit support of gravity retaining wall of cement-soil pile in deep soft soil area as an example. It selects the width of the retaining wall, the embedded depth, the depth and width of the soil reinforcement in the passive area as the variable factors of orthogonal test. Then the variance analysis of the test results is carried out and the main influence of the related design targets is determined. Through multiple comparison, the optimization of the design parameters of the foundation pit design is completed rapidly. Finally, the design flow chart of the foundation pit based on the orthogonal test is given, which can provide a useful reference for the design of similar foundation pit.

Aiming at the problem of accidental shutdown of axial flow pumping station with siphon outlet channel under super hump condition, a mathematical model is established based on transient flow theory. Taking Jinkou pumping station as an example, the effects of shutdown speed, pre-closing opening and static head of fast gate on accidental shutdown are analyzed. The results show that the maximum water hammer pressure, reverse flow rate and reverse speed of the pump increase with the increase of closing time under the condition of super hump; the greater the degree of pre-closing the gate, the smaller the maximum water hammer pressure, the smaller the maximum reverse flow rate and the maximum reverse speed; the larger the static head, the greater the maximum water hammer pressure, the maximum reverse flow rate and the maximum reverse speed. The bigger the gate is, the more 70% of the gate is pre-closed and the gate is closed linearly for 120 seconds to prevent water hammer damage during over-hump shutdown in Jinkou Pumping Station.

Abstract：In order to improve the hydraulic performance of volute mixed-flow pump under multi-operating conditions, this paper chooses some design parameters of volute combined with NSGA-II optimization algorithm, takes hydraulic efficiency and head as criteria, and carries out multi-objective optimization of volute of mixed-flow pump by numerical simulation technology. A set of Pareto optimal design parameters are obtained by Isight platform. Combined with the hydraulic performance comparison test, it is found that the hydraulic efficiency of the mixed-flow pump under the optimized design condition is increased by about 3.02% and the lift is increased by about 2.81% compared with the prototype pump. The high efficiency area of the mixed-flow pump is widened, and the feasibility of the optimization method is verified. From the results of internal flow field simulation, it can be concluded that the area of the eighth section of the optimized volute mixed-flow pump decreases by 1.296%, increases the setting angle of the tongue and the length of the diffuser, weakens the vortex and inverse flow phenomena at the tongue, and improves the hydrostatic pressure distribution in the volute. The results have certain reference significance for the volute design of this kind of mixed-flow pump.

The air consumption calculation formula for one brake in Mechanical and Electrical Design Manual for Hydropower Station has defects: the calculation results are inconsistent with reality，and the actual air consumption of the generator braking system is far lower than the theoretical calculation value in the manual． The use of continuous air supply method for the selection of braking air supply equipment has many drawbacks，such as oil emulsification caused by frequent start and stop of air compressor，excessive volume of air tank and excessive capacity of air compressor resulting in equipment waste，the air tank volume and air compressor capacity do not match with each other． To solve this problem，the volume method to calculate the air consumption for one brake is carried out，and the air consumption variation range with the generator capacity is given by this paper． The formula for air tank volume and air compressor capacity is optimized and the reasonable matching relationship between them is summarized． Furthermore，the recommended value range of the air consumption for one brake for large and medium－sized pumped storage power stations is summarized in this paper． Based on an analysis of specific examples，the scientificalness and practicability of the new method and the new formula are verified here． 

There is a bulb tubular turbine installed hydropower plant having serious problems of unit vibration, which particularly results in cracks of the runner room. It needs to find out the main factors to cause hydraulic vibration of the unit so as to provide with theoretical basis for optimal operation of the plant. This paper, applying three testing means, namely model test, CFD test and prototype test, makes a research on characteristics of water pressure fluctuation and finds out the reasons of the turbine’s vibration. The results show that the main frequency of pressure fluctuation is 4X which is blade number multiplied by rotation frequency, and the vibration amplitude increases following the opening of the blade. It draws a conclusion that rotor-stator interaction is the main factor causing vibration and the fatigue failure caused by slot jet impingement is the main inducement making cracks of runner chamber.