Irrigation district is one of the critical units of natural-artificial water cycle systems． But the irrigation return flow，as an important indicator of the irrigation water use efficiency，has become one of the hottest issues worldwide． In this study，we summarize the primary research productions of irrigation return flows，and the results show that the conception of irrigation return flows can divided in its broad sense and narrow sense，because of different understandings of the artificial water cycle Furthermore，the irrigation return flows are influenced by artificial factors such as irrigation water quantity，irrigation methods，and natural factors such as precipitation，soil properties，ground water levels． But the main influencing factors of the irrigation return flows changed with the different irrigation district． In addition，we further discuss the quantitative prediction methods of the irrigation return flows by using the irrigation return flows index method，mathematical statistics method and numerical simulation method．

In this paper，the multi-objective optimization model of water resources carrying capacity for irrigation district is established under the condition of water -using quantity control，based on the structural features of water use in irrigation districts as well as the dynamic relationship among water resource，ecological environment and social economy． Economic and social development scale supported by water resources system is calculated out in Ganfu Plains Irrigation District in the status year and the programming years． Meanwhile，we evaluate the water resources carrying capacity by using relative bearing index and regional coordinated development index． The results show that comprehensive bearing index of water is more than one owing to abundant water supply in the status year，which indicates that water resources carrying capacity in Ganfu Plains Irrigation District has not been fully exploited． But the index is less than one under the condition of waterusing quantity control in the programming years，which shows that the water resources can not underpin economy and social development． The water resources carrying capacity is enhanced when the configuration of agricultural water is optimized，so optimizing configuration of agricultural water is an effective measure to improve the water resources carrying capacity． Ｒegional coordinated development index is more than 0．99 under the optimizing configuration of agricultural water and controlling pollutant emissions，to really realize win -win between economic development and environmental protection．

Northeast China has been one of the most important major grain producers，where agricultural production is closely related to national food security． In recent years，northeast China has undergone successive droughts，posing a tremendous threat to agricultural production． Therefore，drought monitoring and timely pre-warning is extremely important． This study is based on NDVI～ TS method and linear mixed models and uses MODIS remote sensing data as input． The land surface temperature ( LST) and the normalized difference vegetation index ( NDVI) are selected from MODIS products to retrieve vegetation canopy temperature and then compared with ground observations of maize canopy temperature measured by handheld infrared thermometer in Lishu County，Jilin Province． Ｒesearch results show that the retrieval canopy temperature accords well with observed data and performs better in the middle and later growing period． The canopy temperature retrieval method used in this study can provide a relatively accurate estimation of crop growing conditions and help in the timely agricultural irrigation in Northeast China．

Based on the structure of impact sprinkler PY20，a gas suction pipe is inserted in the middle position of sprinkler＇s tube to achieve the impact sprinkler multifunction． As the fixed and rotating impact sprinkler working at the low pressure，the gas suction pipe can carry about air，liquid fertilizer，liquid chemicals，pesticide etc． Liquid-gas volume flow ratio and liquid-liquid volume flow ratio are adopted to measure the suction capability． The experiment is carried under different working pressures． With the same flow rate at the working pressure，the research of impact sprinkler and multifunctional impact sprinkler are compared，the hydraulic performance and the combination uniformity coefficient that is arranged for square in different interval distances are studied． The following results have been achieved: With the increase in working pressure，the curves of liquid-gas ratio and liquid-liquid ratio decline and the results tend to a certain value，the suction flow rate of gas or liquid increases． At different working pressures，the sprinkler with and without aeration has the same jet range，but the jet range of the sprinkler with liquid suction is about 1m shorter than that of the impact sprinkler PY20． It has a significant effect on water distribution improving at the front and middle range of water jet when gas or liquid sucked in． At the same time，the precipitation and the impinging force at the end range of water jet significantly reduce significantly． When the multifunction impact sprinkler is used in combination irrigation，the best combination distances which are both 1．2Ｒ will be superior to impact sprinkler PY20． The best combination distance is 1Ｒ． Moreover，network expenditure cost related to irrigation will be cut down．

To clarify the spatial and temporal distribution characteristic of reference crop evapotranspiration (ET0) change and the cause for ET0 change, ET0 during 1959～2015 was estimated with FAO-56PM equation by the daily climate data of 19 meteorological stations in Guizhou Province. The trend and spatial distribution characteristic of ET0 in Guizhou Province were analyzed by MK trend test and IDW interpolation method. The sensitivity of ET0 to climate factors was analyzed by partial derivative method. The attribution of climate factors for ET0 was analyzed by sensitivity analyze combined relative change rate of annual ET0. The result indicated that ET0 in Guizhou Province showed different trends and distributed characteristic. The annual ET0 performed the negative trend from southwest to northeast during 785mm～989mm. The relative humidity was the most sensitive variavle ,while the sunshine duration was identified the main driving factor for the annual ET0 change in Guizhou Province. The corresponding scientific measures should be taken according to its driving factors for the region with increasing ET0. The study was helpful for alleviating the contradiction between water supply and demand. In addition, the result can provide guidance for crop planting structure adjustment and rational water resource allocation.

In recent years, with the development of urbanization and industrialization in North China, the security ofagriculturalwater supply is facing up with tremendous challenge.Based on statistics data from 1997 to 2011, this article chooses Hebei as representative region to analyze the main influencing factors and problems of agricultural water security in North China in terms of amount of water resources, agricultural acreage and irrigation area, irrigation quota, industry comparative efficiency, population structure and agricultural water quality,and suggestions for the security of agricultural water supply are proposed as well.

In order to find the suitable moistube＇s buried depth for tomato growth，yield and quality，three different kinds of moistube buried depth treatments incuding T1 ( 10 cm) ，T2 ( 15 cm) ，T3 ( 20 cm are ) are set up，and surface gravity irrigation is set up as control． The effect of various treatments on growth indexes such as plant height，stem diameter，leaf area and physiological indicators such as photosynthetic rate，transpiration rate，chlorophyll content，and yield and comprehensive quality of tomato are investigated． Ｒesults are given as follows: ①As entering flowering and fruit enlargement period，the growth indexes of all moistube buried treatment are higher than CK treatment except for the leaf area of T1 less than CK，all growth indexes of T2 treatment are maximum． The order of photosynthetic rate are T2＞T1＞CK＞T3． The order of transpiration rate are T2＞T3＞T1＞CK．The order of stomatal conductance are: T2＞ T3＞ T1＞ CK． The order of intercellular carbon dioxide concentration is T1＞T3＞CK＞T2． ②The individual fruit mass of all moistube buried treatment are higher than CK treatment，T2 treatment has a maximum yield． ③ The order of comprehensive quality evaluation value is T2 ＞ T3 ＞ T1 ＞ CK． Our study concludes that 15 cm is the appropriate moistube＇s buried depth when tomato is planted．

An automatic underground orbital weighing lysimeter system is developed to solve the low degree of automation and reliability and vulnerable to weather conditions of small weighing lysimeters.This system can automaticly operate through the PC software.The moving weighing device can realize independent measurement for different experimental cylinders and its location in the basement excludes the impact of heavy wind or rain. System test shows the observation accuracy for evapotranspiration (ET) is 0.028mm,and the ET calculated by the weighing system coincides with the one calculated by moisture content, proving the data monitored by the system is accurate and reliable.The system can be used to study crop water requirement and response mechanism of different water stress, soil water balance, etc.

To determine the change of environment in the Hengduan Mountains of scientific and efficient irrigation system，this paper uses MATLAB programming calculation processing of the Hengduan Mountains 1960－2013 31 meteorological stations monthly meteorological data to get monthly reference crop evapotranspiration in the Hengduan Mountains． The temporal and spatial distribution of reference crop evapotranspiration in the Hengduan Mountains is revealed by GIS，complete correlation analysis，EOF analysis and MOＲLET wavelet analysis． The results show that the spatial characteristics， the Hengduan Mountains 1960 - 2013 average annual reference crop evapotranspiration was 945． 20 mm． The northwest and northeast of the Hengduan Mountains reverse change trend is obvious． The time characteristic，the Hengduan Mountains＇ average reference from 1960 to 2013 in increments was 4．5 mm/10 a． The main period of Hengduan Mountains average annual reference crop evapotranspiration was 27 a，the average crop seasons in the Hengduan Mountains reference evapotranspiration in winter are consistent with the Hengduan Mountains＇ average annual reference crop evapotranspiration cycle．

Based on saline -alkali field soil water infiltration experiments in northern Shanxi Province，200 measured samples of Philip infiltration model parameters were obtained，with the help of MATLAB software． The multivariate nonlinear model was established． Soil temperature，organic matter content，moisture content，dry density，clay and silt content were used as input factors and in which infiltration rate and steady infiltration rate of Philip infiltration model parameters were used as output factors． The accuracy of prediction model was tested by measured data． The results show that the relative error of prediction parameters is less than 10%，and the forecast model accuracy is within acceptable range． On the one hand，the establishment of multivariate nonlinear prediction model of saline-alkali land Philip infiltration model parameters provides technical means for the prediction of saline -alkali land irrigation technical parameters． On the other hand，the establishment provides theoretical basis for improved methods of the saline-alkali land．

Based on the laboratory experiment data of ammonia volatilization，Elovich model，BP neural network model，GABP model are established and the predictive effects of the three models are compared． It shows that the three models can meet the requirements of simulation accuracy，the average relative error，correlation coefficient，determination coefficient between the predicted results and the measured value of GABP model is the best in the three models． The GABP model has high prediction accuracy and good stability，it is well described in the dynamic process of ammonia volatilization and provided accurate scientific basis．

Modern water resources of “internet +” bring important influence for promoting the development of traditional irrigation to modern irrigation. Smartphone is an important carrier of “internet +”, location accuracy has direct influence on information accurately of the little-scale irrigation information collecting. To realize information sharing and map database of little-scale irrigation, the author works out Andriod-based information collecting system. This article analyzes the internal & external accord precision of cell location. The test results show that precision of cell location is 0-6m, and it can satisfy the requirement of information collecting with little-scale irrigation. It proves the reliability of collecting information with Andriod-based information collecting system.

An Analysis is made of some problems of traditional algorithm of rainstorm intensity formula． In traditional algorithm of rainstorm intensity formula，the first objective function is making sampling error minimum and the second is making statistical error minimum． An optimization algorithm named comprehensive error method with one objective function is put forward． The optimization algorithm takes the sum of sampling error and statistical error as objective function． The constraint condition is both sampling and statistical error less than an allowable value which can be set． 32 annual rainfall data of a city are used as a calculation sample． According to the error control model of traditional algorithm and comprehensive error method，four parameters formula with P ?Ⅲ distribution and exponential distribution are deduced． As a kind of comparison and verification，five parameters and six parameters formula under the P?Ⅲ distribution are deduced．The result shows the comprehensive error method is better than traditional algorithm．

Flux at Wuzhou cross section during dry season have index significance on ecology of the middle and lower reaches of the Xijiang Ｒiver，water supply and inhibition of saltwater intrusion at delta of the Pearl Ｒiver Estuary． By using the base flux for ecological need and inhibition of saltwater intrusion as control indexes，the progresses of utilizing the storage capacity between normal water level and limited for flood control of the Longtan and Yantan reservoir were numerical simulated by using the whole hydro-dynamic mathematical model of river nets and cascade reservoirs of the middle reaches in Xijiang Ｒiver． It shows that flux at Wuzhou cross section were improved remarkably by dispatch of the Longtan reservoir alone or allied with the Yantan，however there was little effect on flux improvement of the section by only operation of the Yantan reservoir． If the leading regulation role of the Longtan reservoir upstream and auxiliary function of other cascade reservoirs were taken full advantage during cascade reservoir scheduling for flood control，water supply and ecology，the reaction time can be shortened greatly for these demand and the efficiency can be improved significantly． The feasibility of using the abandoned water of the Longtan reservoir before flood season for demands downstream was also confirmed in the research．

Taking Hebi City as the research object，this paper selects seven evaluation indices include per capita water supply，modulus of product water，water consumption per million GDP，modulus of water supply，modulus of water demand，the irrigation ratio of farmland and ecological water use ratio，which greatly affects water resources carrying capacity in Hebi City． Then the water resources carrying capacity of Hebi City is evaluated through the use of the fuzzy comprehensive evaluation model． The results show that from 2008 to 2014，the comprehensive average score of water resources carrying capacity was 0．422 4，which belongs to weak carrying capacity． The carrying capacity increases first and then decreases，and part of transfer water is put into use which improves the carrying capacity in Hebi City． But the shortage of water resources still exists． Therefore，it is still important to optimize and utilize water resources．The purpose of this study is to provide reference for the development and utilization of water resources．

Since the launch of the GRACE (Gravity Recovery And Climate Experiment) gravity measurement satellites in March 2002, it has provided more than 10 years of observation data of the earth’s gravity field. The overall distribution of water resources will be obtained by measuring the fluctuation of gravity caused by water resources in different regions of the earth, which provides a new method for monitoring the surface layer or deep layer water reserves. This paper systematically reviews the research progress of GRACE satellite data for domestic water resources reserves. The GRACE gravity satellite and its exploration in the domestic lake basin, river basin and plateau glacier are mainly introduced. And analyzing the characteristics of water reserves in China from the climatic factors and socio-economic factors, and also discusses the technical bottlenecks, possible solutions and future prospects of GRACE in the study of China's water resources reserves.

The Hebei Plain is one of the region with serious contradiction between supply and demand of water resources in China. Based on the daily data of groundwater depth collected in 11 monitoring sites from 2008 to 2014, this paper analyzed shallow groundwater dynamic variations in different regions of the Hebei Plain. The results showed that the average groundwater depths gradually decreased from the region of the piedmont plain to the region of the central plain, due to difference in groundwater exploitation. The fluctuation of inter annual groundwater level was no more than 3 meters in the region of the central plain. The groundwater level gradually decreased in the region of the piedmont plain. But it rose in some special area close to the reservoir because the increase of water storage of the reservoir and the decrease of the wheat planted area and the increase of precipitation. In the piedmont plain, the highest water level of these observed sites were in the period from February to March and the lowest were in the period from July to August, respectively. Meanwhile, highest water level in the period from April to June and lowest in September in the region of the central plain, respectively. The duration, changing rates and intra-annual distributions of the period of water level increase and decrease with great variations, due to the spatial differences of groundwater exploitation, land use, topography and landform, etc.

In order to explore the relationship between the coordinated economic development and utilization of water resources in Guizhou Province，the statistical data in Guizhou from 2006 to 2015 is used to calculate the water footprint and water footprint evaluation indicators and build harmonious development decoupling evaluation model to evaluate the relationship between water resources utilization and economic coordinated development． The result shows that water footprint falling volatility trend on the whole in 2006－2015 of Guizhou Province，the agricultural water is the main part of water footprint average accounting for 57．83%． In agricultural water，the water footprint of food crops and vegetables than the average accounted for 38．42% and 41．96%．The water resource self-sufficiency rate，water resources pressure index and water scarcity index were high． The relationship of GDP growth and water resource utilization in the fluctuation transformed the weak decoupling primary coordination to strong decoupling quality coordination on the whole． Based on the above conclusions，by changing the consumption structure，the trade structure of virtual water，and the industrial structure is optimized to further promote better coordinated development between economic growth and utilization of water resources in Guizhou Province．

The warning index of critical rainfall is an important gist in warning and forecasting of mountain torrent disasters in small watershed. In order to analyze the effects of antecedent soil moisture content （Pa）to critical rainfall, this paper calculated critical rainfall of three soil moisture content by using the inverse-water level，which was aimed at small watershed of Ungauged Basins in the south of Shaanxi. The results showed that it was accordance with the actual circs better by calculateing the designing peak flow with rational formula. The cirtical rainfall decreased with increasing of Pa under different soil moistures. The effects of Pa to critical rainfall was increscent with the growth of the time. The inverse-water level method is simple and easy, and it is applicative in small watershed of Ungauged Basins in the south of Shaanxi.

Flood forecasting is an important non-engineering measure in flood control and disaster reduction，and it is very important to select proper hydrological model in flood forecasting． The Dahuofang Ｒeservoir is an important water conservancy project in Liaoning Province，and its geographical location determines the importance of its flood control status． BP neural network and genetic algorithm coupled Dahuofang model ( DHF) is used to establish a semi -distributed flood forecasting model to improve the original lumped Dahuofang model and its application in Dahuofang Ｒeservoir，improve prediction efficiency and get better forecasting results． Forecast results show that the forecast effect is good and it can be applied to formal forecast．

This paper calculated design peak discharge of 1% frequency flood in ShiKan River Basin of Qingyuan city using synthetic unit hydrograph and rational formula. Six assessment indexes were considered in order to establish flash flood risk assessment model, including design peak discharge, elevation, slope, soil type, density of population and land use types. GIS and AHP Integrated Method was applied to demarcate risk level in ungaged small basin. The results show that the higher risk area is concentrated in the midstream and downstream of the river and both sides of the 200m range; design peak discharge is an important index for flash flood risk assessment; GIS and AHP integrated method is effective and fast to assess the flash flood risk in ungaged small basin. The evaluation results coincide with the actual situation of the basin, which could provide reference for risk mapping of flash flood in China.

The SCS-CN model is a widely used surface runoff evaluation method. It can improve the runoff forecasting ability by determining the numerical value of the runoff curve number(CN),which is important for effective development and utilization of water resources and flood disaster. Computing the watershed comprehensive CN value by rainfall-runoff inverse method and automatic optimization method of parameters in Songbai station of Hubei Province. The measured rainfall runoff data of 1983-2012 were divided into calibration period (1983-2003) and validation period (2004-2012).According to the cumulative precipitation of the first five days to determine the classification of the flood and obtain the integrated CN value of the basin with different antecedent moisture condition, and then the CN value obtained is used for repetitive validation flood. The results show that comprehensive CN value obtained by the two methods can be used for the flood forecasting in this basin with considering antecedent moisture condition, and the latter method is more accurate.

This paper used Daluze and Ningjinbo flood detention basin as an example, based on 2-D unsteady flow mathematical model, the flood variation process of the fifty-year frequency flood under current conditions were analyzed by using MIKE FLOOD software. And then the model test of Huanshui village and Aixinzhuang village were verified by using”96.8” historical flood submerged data. The simulation results are basically tallies with other related studies, the simulation result is reasonable. This model provides basis for plotting the flood risk map, which provides important basis for safety construction planning of flood storage and detention area.

The Movable-Bed Model was used to study the characteristics of scouring and deposition of the Lower Yellow River overflow at the condition of different boundary and different flow. Also the feasibility program which to control the overflow and let it to the floodplain was explored. The results show that, in plan boundary conditions , the flood process that the maximum peak flow is 8000m3/s is the best one. In that condition the scouring volume is Largest , flood controllability is best and the Inundation area is small. If there are big overflow the the flood process that the maximum peak flow is 8000m3/s is a good choice in the Lower Yellow River. In the reach of Jiahetan to Gaocun the Dongming floodplain and Changyuaner floodplain can be used to flood detention.

The objectives of this study were to investigate the characteristics and controlling factors of stable oxygen and hydrogen isotopes during the thaw period in seasonal freezing area． Ｒesults show that δD and δ18O of snow were －9．33% and －1．28%，respectively，which were lowest among all the water samples，and the variability was maximum． The δD and δ 18 O of soil water and groundwater influenced by precipitation before freezing period were uniformly located beside the local meteoric water line，and the variability was minimum． Freeze－thaw process controlled the temporal variation of δD and δ18O of stream water by influencing the evaporation and mixing of snowmelt water and soil water． The land uses greatly influence the space variation of δD and δ18O of soil water and groundwater． The soil water of maize land was mainly from precipitation，and the surface soil water suffered stronger evaporation，thus the δD and δ18O was rich in surface soil water and then decreased with depth． The soil water and groundwater in paddy land was mostly from irrigation water，which has experienced great evaporation before infiltrating into deep soil，thus the δD and δ18O was rich． On the contrast，the surface soil water in paddy land mostly came from precipitation and snowmelt water，as a result，the δD and δ18 O was poor． Affected by paddy land groundwater，ice melt water and evaporation，the δD and δ18O of the main stream was obviously richer than that in tributary，and this difference was related to the activity of water cycle in the watershed．

In order to overcome the current application difficulties，the applicability and defluoridation effect of MgO adsorbent under lowfluoride and high -fluoride groundwater are studied in this paper． Ｒesults show that MgO adsorbent possesses good applicability and can remove fluoride below the drinking water standard＇s limit value with low adsorbent dose 0．3 g /L． Meanwhile，MgO adsorbent also adsorbs a lot of coexistence competitive anions，especially bicarbonate and sulfate． These coexistence competition anions have a significant effect on the reused performance of MgO adsorbent． The regeneration method under the condition of deionized water with NaF can hardly satisfy the actual demand of high-fluoride groundwater． As for the regeneration method，it is necessary to consider the desorption and regeneration of fluoride but also the desorption of bicarbonate，sulfate and chloride and thus releasing more adsorption sites．

With the impoundment of the Three Gorges and the economic development of the local，the water quality becomes progressively worse． Setting the runoff，non-pointnitrogen ( TN) and non-point phosphorous ( TP) as indexes，the distributed hydrological model SWAT wasused to simulate the water environment． After setting different governance scenarios on reducing pollution，the corresponding measures were proposed． The results shows: ①The correlation coefficients of runoff and sediment，total nitrogen and total phosphorus were 0．87，0．98 and 0．89respectively，which shows runoff is the main way of loss of nitrogen and phosphorous． ②The wet-period contributes more than 80% non-point source pollution in a year，showing a strong relationship between season and non-point source pollution． ③Different land-use shows different abilitieson outputting the non-point source pollution，followed by agricultural land( rice) ，grassland and forest land from large to small． ④Five different Best Management Practices( BMPs) showed that returning farmland to forest and filter strip can both reduce the nonpoint source pollution effectively．

In order to broaden the adaptability of Tennant method, the method of using flow reduction or return to revise different types of river flow is put forward in this paper aiming at the large difference between the location of water compensation urban river and natural river, and typical annual flow was used to replace the multi-year average flow, so as to improve the Tennant method. The improved Tennant method is applied in rivers such as Xiaoqing River and Qi River. The application results show that the improved Tennant method applied in natural river can better reflect the natural hydrological regime, which is conducive to ensuring the existence and development of ecological habitat environment such as river flow velocity, water surface width and water depth; its application in water compensation urban river can better reflect the characteristics of water use within the water supply area, which tends to meet the demmand of the economic, social and natural development in this drainage area. The overall results show that the improved Tennant method is more reasonable, and it takes into account the water demand of different types of rivers, which broadens the application of Tennant method and provides a new idea for the calculation of ecological base flow of river.

With the in situ direct shear testing method suggested by ISRM, comparative studies on the tests and selections of design shear strength parameters for rock foundations based on the codes between China and America are made. The studies show that the test methods of shear strength for rock foundation in Chinese codes coincide with America’s and the direct shear test is the most popular. However, there are some differences including preparation of specimens and application of load in the experimental process. Besides, when lack of tests data or in the feasibility study and the preliminary design stage, the selections of design shear strength depend on the experimental result of the similar project in both China and America. Whereas, when having sufficient tests data, design shear strength for rock mass are generally selected on the basis of results of laboratory direct shear tests and in-situ direct shear tests, whose conservative values are determined by lower bound of the experimental scatter plot. Lastly, take an American project for an example, which demonstrates the value guaranteed rate is a little higher than the experimental result (78.7%) of small specimens ruled in codes of China.

Irrigation engineering concrete surface crack need good performance curing sealing materials to reduce the waste of water resources． In order to select better curing agent C，we modify PTN sealing materials by using three different kinds of curing agents． The experimental results show that the modified material surface drying and actual dry time is shorter than the control group 3 h and 5 h， respectively． The tensile strength reaches 2．62 MPa，and it is higher than the control group 1．91 MPa． The elongation of break is 1112%，and it is higher than the control group 761%． Tensile elongation of break reaches 586% when the tensile bond strength is 1．59 MPa． The authors establish the relation of material hardness and tensile properties，and it can test the tensile properties of PTN． The results in this paper can save water irrigation，and it has certain practical application value to surface cracks in concrete engineering irrigation．

Focusing on the issue that there is a vertical vortex at the vertical intake of ChemabiＲeservoir Project，the paper studies the impacts of water velocity at the vertical and the submerged depth on the vortex，the paper proposes the scheme to vanish the vortex by building a vortex elimination construct． The result indicates the vortex elimination construct consisted of 12 vortex and a cover plate vanishes the vortex completely without affecting the discharge capacity and increasing much work for the project． The study result can provide a reference for the arrangement of vortex elimination measures of vertical intakes．

In order to save the investment of concrete rectangular canals, by comparing the quantities of different lining materials, selection method is given for different lining materials of mall rectangular concrete canals based on the structure calculation theory, especially for the small rectangular irrigation canals in water conservancy projects. According to the situation of small rectangular irrigation canals in Jiangsu Province, by using this method, the cost of different cross section of rectangular canals in different lining material like C25, C30 plain concrete and C25 reinforced concrete are compared. On this basis, the selection of the lining material of the small concrete rectangular canals under different side wall height is suggested, which can be a reference for the selection of lining material of small rectangular canals.

Special geographical conditions make the western region formed many narrow valleys, construction of high RCC arch dam in these narrow valleys can saving cement, simplify operational procedure, speed up the construction speed and low cost etc. During the construction and operation period, narrow valley high RCC arch dam may be in danger through penetrating crack caused by excessive thermal stress. One way to solve this problem is to set up the structural joints in the dam. Lizhou RCC arch dam height is 132m, it’s the world class high RCC arch dam. In this paper, according to the results of geomechanical model test, it is necessary to set up the joints. And then though three-dimensional finite element analysis model is used to establish the three-dimensional finite element analysis model of Lizhou RCC arch dam, to study and evaluation of the joint program in the stress and deformation characteristics of the dam during the normal operation period. On this basis, by overloading to model failure, study on damage characteristics of different joint forms under the dam cracking. To find a better solution to the dam joint and provide some reference for engineering design.

Three-dimensional finite element numerical analysis method is used to simulate the mechanical behavior of the pier structure under the combined action of multiple loads. The structural deformation of the middle pier, prestressed anchorage zone stress, the law of stress and deformation around the flat hole and the change rule of the tensile stress distribution condition with the load condition are studied. The reasonable initial reinforcement scheme is studied according to the weak position of the prestressed pier. The results show that prestressed concrete piers have a good effect and the cable arrangement is reasonable. The stress and deformation distribution of the whole piers meet the design requirements under various load combination effects. The research results of this paper not only play an important role in the optimization of the structure design of prestressed concrete pier and the layout scheme of cable, but also provide important reference for similar engineering design and safety evaluation.

The velocity head is an important hydraulic parameter，which can reflect the energy of flow to a certain extent． In order to explore the changing rule of the velocity head，this paper introduces the relative velocity head concept for stepped spillways by comparing the velocity head of the corresponding smooth spillway． The hydraulic model test on skimming flow has been conducted by using four different chute slopes of 26．6°，33．7°，38．7°and 51．3° at a step height of 0．5，1．0，2．0 m，focusing on the relationship of the velocity head and relative velocity head with the length of flow path，step height，unit discharge and bottom slope． An analysis of the datum shows that the relationship of velocity head of stepped spillways with those hydraulic parameter are complex while the relative velocity head of non-uniform flow is in linear with flow length，and the linear correlation coefficient between them is 0．994 8 ～ 0．998 8． The straight slope increases with the decrease in the unit discharge，and the step height and bottom slope also have an influence on the relative velocity head that increases with it，especially the bottom slope． The result shows that it is necessary to explore the relative velocity head and the unique linear relationship provides a significant basis for exploring further hydraulic characteristics of stepped spillway．

The blasting vibration effect in the construction of the diversion tunnel of a hydropower station was simulated on the basis of equivalent application method of blasting load and dynamic finite element method. Representative feature points were selected and the characteristics of vibration displacement, velocity and acceleration were analyzed, moreover, the vibration and attenuation law of different explosion center distance parts were also analyzed, stability safety factors of Danba landslide before and after construction blasting were calculated by using GeoStudio and the influence of blasting vibration on the stability of Danba landslide was proved. The results show that the closer the distance away from the explosion source, the greater the vibration frequency and amplitude of the particle, and the vibration attenuation is also faster. When the distance is large enough, the horizontal and vertical vibration amplitude value are about the same and vibration effect caused by blasting at this time is very small. The peak velocity of the vibration velocity is the fastest in the explosion center distance of 15m, and in the range of 100m, the peak value of vibration velocity is less than 0.2cm/s. The stability safety factor calculated by the two methods, the limit equilibrium method and the finite element method, can meet the requirements. Tunnel blasting has no harm to the safety and stability of Danba landslide.

The bridge backwater compression channel，bridge group of superposition of backwater effect will cause a hazard to flood control under a heavy traffic． By using two-dimensional shallow water equations of hydraulic elements along the average water depth，the method of plane 2D water mathematical model is established to evaluate and study the compression degree，traffic，and the influence of roughness of single bridge backwater，and the numerical simulation is carried out on the Jiangjun Bridge，on the Tielu Bridge and Yong＇an Bridge＇s backwater situation． By comparing the standard formula calculation results and the measured data，the accuracy of the model is verified． At the same time，the degree of compression representing the numerical simulation method of the impact of river bridges is versatile，this method can be popularized and applied to the general arrangement of bridge site selection and bridge crossing．

In order to improve the unit efficiency, a small hydropower plant in Guizhou finally realizes the optimal active power control allocation and establishes a unit efficiency on-line monitoring system by using multi-channel ultrasonic flow measurement technology. This paper focuses on the system function and program design and implementation methods and so on. After the system was installed and debugged in a small power plant in Guizhou, all the functions were tested, and did efficiency test at the same time. This system can use a variety of methods to achieve efficiency curve fitting, and can be compared, the overall has a certain degree of innovation.

In order to overcome the difficulty of ascertaining the structure and probability of Bayesian network application in the fault diagnosis of hydropower units, this paper studies the fault tree transform into Bayesian network model. In this paper, we first compare these two models, and verify that the Bayesian network method and the AND-OR gate fault tree analysis method are the same. Then the generator fault model of the existing fault tree structure is transformed into a Bayesian network model, using the histogram to compare the prior probabilities determined by the experts system and through the Bayesian network reverse reasoning to obtain the posterior probability of bottom events when the top event failure, verify the most likely events to cause the system failure, provide the basis for the reliability design and fault diagnosis for the complex system.

The doubly fed adjustable-speed unit has a significant benefit to the grid frequency modulation，with the controllable active power flow during the pumping mode． It has been used in some under construction unit in China． A proper process is the key point to guarantee pumped start-up success，which has not been well designed in China． The rotor differences between fixed-speed unit and adjustable-speed unit are discussed in this paper． With the experience of traditional unit commissioning，three proper processes of pumped start -up are proposed． The SFC start-up，back-to-back start-up，and self-starting are three feasible ways to start up in pumped storage rotation． The processes of SFC start-up and back-to-back start-up are modified，depending on the fixed-speed pumping start-up processes． Ｒelying on the analysis of the self-starting principle，a realizable start-up process is presented for the self-starting mode，to make every part of the adjustable-speed units cooperate well with each other，and to improve the success rates of self-starting．