In order to reveal the seasonal freeze-thaw effect of land cover on temporal and spatial variation of soil temperature，this paper sets up three treatments，including the bare land ( LD) ，straw mulching ( JG) and plastic film mulching ( DM) ，and the change of soil temperature in different depth of freezing thawing process is analyzed by means of mathematical statistics and grey correlation degree． The results show that: the effect of plastic film mulching on soil temperature is significant; the effect of straw mulching on soil temperature is different at different stages． At freezing stage，straw mulching reduces soil loss of heat and has a warming effect on the soil; at melting stage， straw mulch reduces the heat exchange between the ground and atmosphere and inhibites the increase of soil temperature． Plastic film mulching and straw mulching can stabilize the soil temperature changes． Throughout the freezing -thawing period，both the two kinds of mulching have impact on soil temperature，the treatment of 0 ～ 20 cm has a great effect on soil temperature，while for the treatment of 20 ～ 90 cm，the soil temperature increase with the increase of soil depth and the fluctuation of soil temperature decreases gradually． The research results provide the basis for the selection of the surface coverage measures in seasonal frozen soil area． 

Jingyuan county of Gansu province was selected as a research object． Based on the observation data of soil moisture，temperature and precipitation in crop growing season from 1981 to 2000 in agricultural meteorological stations，statistical analysis methods，Mann-Kendall method and Least square method were applied to analyze the data of the surface soil ( 0 ～ 50 cm) ，the spatial and temporal variations of soil moisture and the response of different crops soil moisture to climate change are studied． The results showed that the surface soil moisture change rule in each layer was basically consistent to the same crop types; however，the soil moisture change in each layer was greatly different for different crop types; the multi-years average soil humidity in different depth has a certain relation with the planting of crops type; therein，the soil moisture change process of spring wheat was convex type with the change characteristic of low to high to low from top to bottom; while the soil moisture variation of spring corn was concave type with the change characteristic of high to low to high from top to bottom． The relationship between air temperature and soil moisture was different due to different planting crop types and soil depth． The relationship between precipitation and soil moisture has nothing to do with planting crop types and soil depth，but the relationship have certain otherness for the types of crops and the sensitivity of soil depth． While the relationship between soil moisture and runoff has opposite characteristic for different crop types．

In order to explore the relationship between soil water repellency and moisture content，change rules of sand water repellency under different moisture content was studied through indoor test by using the water drop penetration time method，and the theory analysis of contact angle change was conducted based on the ideal soil particle model． The results showed that: with the increase of water content，the sand water repellency showed a single peak curve trend of first increase and then decrease with 1．5% ～ 2% moisture content as the turning point; the higher the intensity of sand water repellency，the bigger the peak value of WDPT，the smaller corresponding moisture content value，and the lower the threshold moisture content of water repellency． There are differences between water drop penetration time method and contact angle method for soil water repellency，and the essence is that the two methods evaluate the water repellency from two different aspects，namely the permanence of water repellency and the strength of water repellency． The above results can lay a foundation for the research of water repellent soil．

In order to explore the feasible ways to measure soil water content by using soil image gray level data and Monte Carlo method， Helan County of Ningxia Yellow Ｒiver Irrigation Area is selected as the research area，soil picture is gathered and the gray probability of soil image is analyzed，then a mathematical model，with the soil moisture content as output and the soil image gray -values as input，is established，the soil moisture is calculated by Monte Carlo Method，and the calculation value is compared with the measured value． The experimental results show that: ① using Monte Carlo method to measure the soil moisture content reduces the analysis of complex nonlinear model，the calculation of some additional first or higher order sensitivity coefficients，and the computational complexity． ② The accuracy of the measurement depends on the number of Monte Carlo tests． The more accurate the Monte Carlo test，the more accurate the soil moisture measurement． ③ The results of using Monte Carlo method to analyze the spatial distribution pattern of soil water content are accorded with the actual situation of soil water content in the study area．

Fluent software was used to simulate the internal flow field of the automatic screen filter by porous jump model and Realizable k-ε model. The difference of pressure drop between the inlet and outlet of the numerical simulation and the physical experiment is 6.77%, which indicates that the numerical simulation is accurate. After analyzing the filter internal flow field, found that main part of the pressure drop is filter screen. Some vortex zones in the outlet pipe, distribution of velocity and pressure are uneven, keep the filter area unchanged, respectively to simulate the flow field of the filters when the outlet pipe and tank angle is 75 °, 60 °, 45 °, 30 °. the results showed that:?α?has a greater influence on the flow field of outlet pipe, but has little effect on other area as well as the pressure drop between the inlet and outlet. With the decrease of the angle α?, the upper outlet pipe, distribution of velocity and pressure are more uniform; The vortex on the left of the outlet pipe disappear gradually, but the vortex on the right of the outlet pipe increase gradually. The angle between the outlet pipe and tank is not the main reason affect the main reason for the flow field, so structural optimization should carried out from the filter screen.

The Mathematical model of soil water infiltration under subsurface drip irrigation condition is established based on the principle of non-saturation soil water dynamics． The mathematic model is solved numerically by using the HYDＲUS -3D software． Compared with the actual infiltration process，the simulated infiltration process is in agreement with actual infiltration process． The relative error is less than 10%． Generally speaking，simulated results can reflect the regulation of soil water movement with drip irrigation and can provide the theory guidance for drip system design．

Crop water requirement is determined on the basis of the norm of irrigation. The crop evapotranspiration is the key parameter. Due to the large water demand of tea plants during growth period, determines the reasonable irrigation water quota of tea plants is very necessary. On the basis of Penman-Monteith equation, drawing lessons from the calculation method of modified P-M equation in greenhouse, and we were proposed the calculation model of tea plantsevapotranspiration in greenhouse based on conventional meteorological data and growth index. The tea plants evapotranspiration in greenhouse was calculated and analyzed by using modified P-M equation and ET0(Tea) (March 10 to April 10, 2016). The model is verified by the principle of water balance. Our results showed that the simulation results of these parameters and computed results are respectively approximate and they have the same varying trend. And the ET0(Tea) has better performance on sunny day than on cloudy day. This algorithm has theoretical correctness and feasibility in practice. Therefore, the calculation model can be used as a decision making basis for tea plants irrigation in greenhouse in northern China.

In order to study the feasibility of fuzzy mathematics in optimizing the irrigation scheme of summer maize，the improved analytical hierarchy process combined with fuzzy comprehensive evaluation method is used to evaluate the summer corn water consumption and yield characteristics under different irrigation lower control limit． And the summer corn planting test results under non -sufficient irrigation in Zhengzhou area is combined for analysis． The results show that when the lower irrigation control limit is 70% of the field capacity，the yield and water use efficiency of summer corn are the highest，the fuzzy comprehensive evaluation result is accorded with the experiment result． Therefore，the fuzzy comprehensive evaluation model based on improved analytic hierarchy process can be used for evaluating the water - saving irrigation and the optimization of irrigation scheme，and can provide theoretical support for the application of fuzzy comprehensive evaluation in water saving irrigation．

Aiming to give suggestions and supports for choosing appropriate micro-irrigation methods for Lycium barbarbum L． cultivation in Zhongning area of Ningxia from modern water -saving micro -irrigation methods，a field experiment including 4 micro -irrigation methods， namely surface drip irrigation，surge irrigation，subsurface irrigation and cantilever drip irrigation，was carried out to evaluate the effects of different micro-irrigation methods on the distribution of water and nutrient in the trial soil and the yield of Lycium barbarbum L．． The results showed that: under the same water amount，soil water under surge irrigation had much more potential on lateral movement with an increase of soil water content of 8．82% compared with initial value，which significantly contributed for the highest average soil water content( SWC) of 14．49% in the whole soil profile，compared with the other 3 micro-irrigation methods． However，there was no significant difference of the average SWC，the soil water distribution and the SWC increment between surface drip irrigation，subsurface drip irrigation and cantilever drip irrigation． Furthermore，surge irrigation and cantilever drip irrigation methods had much more effect on nutrients transportation and leaching intensity in root zone than surface drip irrigation and subsurface irrigation methods． Nevertheless，subsurface irrigation and cantilever drip irrigation methods could likely cause nutrients accumulation in no-root zone to some extent． What’s more，Lycium barbarbum L． under surface drip irrigation and surge irrigation methods got better growth index and more yield than the other two methods． As a result，the best growth index and the highest yield of Lycium barbarbum L． were obtained under surface drip irrigation，which attributed to better water-fertilizer coupling． So，surface drip irrigation can be preferred irrigation methods for Lycium barbarbum L． in Zhongning area of NingXia.

Various maize varieties have different drought resistance capacity． Therefore，using a constant irrigation scheduling for different maize varieties will result in a decline of irrigation water use efficiency． In this study，a field experiment was carried out in Yellow river district in 2013 to study the response of 6 staple maize varieties to different irrigation regimes，including irrigation after sowing，irrigation after sowing and at jointing stage，irrigation after sowing and at jointing and filling stage，under adequate rainfall condition． The results showed that the major water consumption layers were distributed at 20～ 40 cm soil depths at filling stage; the ZD909 type consumed the greatest amount of soil water ( 434 mm) ，followed by DH605 type ( 411 mm) ，and the ZD958 type ( 352 mm) was the smallest one; XY335 type and ZD 958 type had the highest water use efficiency of 28 kg/( hm2 ·mm) ，followed by DH605 type and XD20 type，while the ZD909 type had the smallest water use efficiency of 23 kg/( hm2 ·mm) ; the grain yield of DH605 type and XY335 type was increased by 13．0% and 14．2%， respectively，due to the application of irrigation at filling stage，compared to that of no irrigation application treatment; however，supplemental water irrigated at filling stage exerted no significant effect on grain yield increase for ZD958 type and XD20 type． So it can be inferred that under adequate rainfall amount in Yellow river district，a high grain yield can be obtained for DH605 and XY335 with irrigation after sowing stage and at filling stage，while a single irrigation after sowing stage may be enough for ZD958 and XD20 to successfully complete its life cycle． 

Design an effervescent nozzles, the mixing chamber pressure characteristicsthe atomizer has been studied by utilizing an experimental setup. The effects of different structures on the critical pressure characteristics were investigated. The factors affecting the critical pressure of the mixing chamber were analyzed. Experimental results show that the critical pressure ratio is only related to the structure of the nozzle. The critical pressure ratio increases with the increase of area ratio. The smaller outlet diameter, the greater the critical pressure ratio. Influence of ventilation mode on critical pressure ratio is very low. Added a vortex core, critical pressure ratio increases. The convergence angle has little effect on the critical pressure ratio. The variation rule of critical pressure ratio in the critical condition of different structure effervescent nozzle is determined, which provides the basis for the design and safe and reliable operation of the effervescent atomizer.

Water resources has become the important strategic resources for human survival，at the same time，agriculture is a water intensive industry，which is impacted by the water resources conditions most． The scientific evaluation and detection of the vulnerability of agriculture to water shortages is crucial for agriculture safety． Based on the analysis of the factors affecting the vulnerability of agricultural to water shortages，this study chooses the indictors from two parts，namely sensibility and resilience． Also，the net virtual water trade volume of agricultural products is innovatively included in the indictors，the water input and output flow form and accounting model is established，and the vulnerability of agricultural water shortages in Jiangsu is analyzed． In the end，the advices to reduce the vulnerability of agricultural water shortages in Jiangsu are given．

In order to understand the water quality of Dongzhai Harbor in different areas and time periods and its pollution reasons, we have collected 42 samples from aquaculture ponds , protected area wharf water, mangrove forest, mangrove ditch ,the mangrove forest outer sea in the dry and rainy season, and determined the contests of COD、DO、BOD5、NH3-N、TP, and the water quality based on AHP fuzzy evaluation model and gradient space analysis method to carry on the comprehensive evaluation and analysis. Results show that：（1）Whether the single factor pollution value analysis or fuzzy evaluation ,showed that the water quality in the dry season was greater than that in the rainy season, especially BOD5 and TP performance is the most prominent; (2)whatever the dry season and rainy season from land to sea with the increase of space distance, water pollution tends to decline ;(3) The pollution of aquaculture ponds is the most serious, it shows that the aquaculture pond is the main pollution source of the water body in Dongzhai Harbor ;(4)Residents offshore fishing has roiled effect, it also can affect the water quality of Dongzhai Harbor.

Based on the unsaturated soil water dynamics theory，by means of computer simulation，a three-dimensional axial-symmetrical model under subsurface flow root irrigation is established by using HYDＲUS-3D software． Soil water movement is simulated with the aid of Galerkin finite element method． The model is validated through the contrast of measured values with simulated values of the soil moisture． The results show that the relative error between simulated and measured values is less than 10%，which indicates that the predictability of the model is acceptable． This study can provide theory guidance for flow root irrigation system design.

in order to provide a theoretical with different irrigation with fertilization treatments to support for improving water and nitratenitrogen use efficiency of Jatropha curcas L． Four watering levels［T1: 100%ET( ET: Evapo-transpiration) ，T2: 80%ET，T3: 60%ET，T4: 40%ET］and three nitrogen fertilization levels ( N1: 0 g / kg，N2: 0．4 g / kg，N3: 0．8 g / kg) were designed． Test results showed that: From the difference between the two soil nitrate nitrogen mass fraction，it showed T2＞T3＞T1＞T4． Compared with T1N3，T2N2 saved 20% of irrigation water，saved 50% of nitrogen fertilizer dosage，the water use efficiency increased by 26% and the N apparent recovery fraction and N uptake efficiency were increased by 149% and 26%，respectively． Water use efficiency and nitrogen absorption efficiency showed two curve relationship with nitrogen application rate，and reached the maximum at low nitrogen level． So the treatment of T2N2 is more favorable to the absorption of nitrogen fertilizer．

The study on the transportation law of soil water and salt is the important basic content of the water and soil environment field． In this paper，the migration law of water and salt in paddy soils under the condition of different saving water measures，such as the plastic film irrigation，the shallow wet irrigation and the shallow water irrigation，is studied，and the vertically distributional of the water and salt in soil in spring is measured and analyzed． The soil salinity is measured by the conductivity method and the Soil moisture is measured by the drying method． The results shows that the trend of soil electroconductibility is the same in Xiqing District of Tianjin; the electroconductibility of soil layer above 50 cm is gradually reduced，while the electroconductibility of soil layer below 50 cm changes not much; the salinity of the surface is migrated to the ground during the leaching process，so the electroconductibility of the surface becomes smaller．

In recent decades，with the global climate warming，the frequency of extreme weather events is increasing rapidly，which seriously affects the survival of human beings and the sustainable development of society． The extreme drought events have a great impact on the ecosystem health of rivers． It is of great significance that maintaining the survival，conservation and biodiversity of the species to ensure ecological base flow in extremely dry conditions． Taking Weihe river of Baoji Section as an instance，Tennant and minimum daily mean discharge method are adopted to calculate ecological basic flow on the once-in-a-century drought． Ｒeferencing the daily flow analysis of Baoji Section in Wei river on the drought year of 1929，it is obtained that the ecological basic flow is 2．51 m3 / s and the duration time is 10 days． This study not only has important scientific value，but also plays a guiding role for the health of river ecosystem in arid areas of Northwest China

Sanjiang Plain is the core area of national commodity grain base, sample area of green food production and leading area of high efficient ecological agriculture. Ecosystem health problems in Sanjiang Plain relate to sustainable development of regional agriculture and national food security. In this paper, aiming at the problem of ecosystem health in Sanjiang Plain, the evaluation index system was established, and the projection pursuit evaluation model based on particle swarm optimization was used to evaluate the ecosystem health of Sanjiang Plain. The evaluation results showed that the overall ecosystem health of Sanjiang Plain had a trend of deterioration, and the health status of different sub regions was different. The ecological environment of Sanjiang Plain is becoming more and more serious. Therefore, it should be accelerated governance to maintain sustainable development in the region.

In order to solve the problem of precision irrigation in greenhouse，this paper designs a set of intelligent irrigation system based on the modified Penman-Monteith equation． The system selects the light sensor，temperature and humidity sensors，and soil moisture sensors to collect environmental parameters in greenhouse，the data is transmitted by the data collector to the host computer，the crop evapotranspiration in different growth stages is calculated with irrigation model，and the evapotranspiration value is converted into irrigation amount，the irrigation command is issued through the host computer to control the operation of the constant pressure controller and the opening and closing operation of solenoid valve． The remote operating system is connected with the base control system by GPＲS，which can realize parameter setting，real-time data display and query，and controling irrigation mode． The experimental results show that the system can realize automatic control of precision irrigation，and the system is stable and reliable，easy to operate，suitable for precision irrigation in greenhouse．

Micro irrigation technology can realize precise irrigation for crops． The intelligent micro irrigation technology based on ZigBee technology can effectively solve the irrigation problems in arid and water deficient areas and realize the sustainable development of agriculture． This paper presents a low power micro irrigation system，which uses solar power and effectively saves energy． The system can effectively solve the problems，such as the wide distribution of the control points，the long -distance wireless communication and short battery life． It significantly improves the crop irrigation water use efficiency，realizes the intelligent automatic control and improves work efficiency．

Due to the problem that it is difficult to reach the optimal design of current farmland irrigation pipeline project and the cost of agricultural irrigation water supply is too high，the nonlinear optimization model of farmland pressure pipe system is established in terms of water users by taking pipeline length，pipe diameter，pump head as variables，the minimal water supply cost and the annual cost as objective function． According to the principle of single point of water supply，the enumeration method is adopted for pipe network layout optimization combined with the designers ＇ experience and the practical project． On the basis of this，genetic algorithm is used to optimize the pipe diameter，the most economical pipe diameter combination and the pump head are obtained． Finally，the minimal water supply cost scheme is selected as the optimal design scheme． The C++ and Matlab programs are written and verified by engineering examples． The results show that this method can determine the overall optimization scheme of farmland pressurized piping system quickly and effectively，and meet the requirements of farmland irrigation while reducing the water supply cost and effectively protecting the interests of water users． 

The application and research status of trace -quantity irrigation and moistube -irrigation technique are reviewed in this paper， including the water-saving and yield increase effect on crops，irrigation technical parameters，movement of soil water，as well as computing simulation of the above two techniques． Comparative analysis between the two techniques is conducted． What＇s more，the existing problems and the proper advices for the future development of the above two techniques are discussed，which can be helpful for irrigation workers．

Water-saving management contract is a new type of water-saving，in which technical and financial support is provided by watersaving company and the profit is shared by participants． Although it has a broad prospect for development，the lack of profit distribution mechanism has become the main obstacle for promotion． In this study，firstly，the core participants of water-saving management contract are determined by Mitchell scoring method． Secondly，the analytic hierarchy process is applied to construct evaluation system and evaluates the importance of water-saving service company and water-using company in water conservation project to get their respective weight vector． Then the equitable entropy model is built and it is proved that water-saving profit is closely related to both the importance weights and resource input contribution． Finally，through the example analysis，it is found that water-saving service company and water-using company are in the dominant position and the profit will flow from water-using company to water-saving service company．

In order to solve the problem of the right of water right work in Qing'an County. According to the total amount of water that can be allocated,allocated the Initial water rights of domestic water, Ecological water, Non - agricultural production water, Reserved water and the agriculture water, introduced the purpose and significance of the work. Finally, this paper described the registration and certification of the work. The spatial extent of water resources of Qingan City cunty is determined, and the ownership of water rights and the rights and obligations is cleared.