Long-throated flume provides a cost effective, high robustness and low head loss structure for measuring flow in open channel. In order to optimize the contraction ratio design and understanding the sediment deposition characteristic of long-throated flume to provide reference for its application in flow measurement in sediment flow channels, in this paper, three dimensional fluid dynamics software was used to simulate the characteristics of water flow and sediment in the long-throated flume with different contraction styles. On the premise of verifying the reliability of the numerical model, the contraction ratio of flume was determined to be 0.36~0.40 for the style of only with side contraction, 0.40~0.72 for the style of only with vertical contraction, and 0.36~0.73 for the style of with both side and vertical contraction, respectively. When the flow contains sediment, the simulation results showed that the sediment mainly accumulated on the upstream of long-throated flume near the channel, and the order of sediment thickness was as follows: the style of only with side contraction < the style of only with vertical contraction < the style of with both side and vertical contraction. The study shows that the style with both side contraction and vertical contraction has high flexibility. From the view of siltation, the style with only side contration is optimal. The conclusions can provide technical reference for design and selection of long-throated flume in a large number of Yellow River irrigation areas in China.

In order to study the soil moisture and soil temperature of plantations and natural forests in the rainy season in the rocky desertification area of Huajiang River, the dynamic changes of soil moisture and soil temperature of Zanthoxylum bungeanum, Koelreuteria bipinnata. and Broussonetia papyrifera were analyzed by in situ monitoring and general statistical methods. The results showed that: ①the mean soil moisture content was Zanthoxylum bungeanum (34.7%) > Koelreuteria bipinnata. (33.8%) > Broussonetia papyrifera (33.4%). The mean soil temperature was Broussonetia papyrifera (29.3 ℃) > Koelreuteria bipinnata (27.9 ℃) > Zanthoxylum bungeanum (27.3 ℃). The variation coefficients of soil moisture content of Zanthoxylum bungeanum, Koelreuteria bipinnata and Broussonetia papyrifera were 0.13, 0.15, 0.13, respectively. The variation coefficients of soil temperature content were 0.04, 0.04, 0.07, respectively. ②Pearson correlation coefficients between soil moisture and soil temperature in different layers of Zanthoxylum bungeanum, Koelreuteria multipinnatifida and Broussonetia papyrifera were as follows: 0.275, 0.468, 0.441, respectively, for 0~5 cm; 0.307, 0.474, 0.462, respectively, for 5~10 cm; 0.165, 0.450, 0.398, respectively, for 10~20 cm; 0.181, 0.405, 0.520, respectively, for 20~40 cm; except for 10~20 cm and 20~40 cm of Zanthoxylum bungeanum, there were a significant negative correlation (P<0.01). The conclusions is as follows: Zanthoxylum bungeanum has higher soil moisture content, less time variability and least influence by soil temperature than Koelreuteria bipinnata and Broussonetia papyrifera. It has better soil moisture conservation benefits and can continue to be cultivated and managed as the best tree species for controlling rocky desertification.

At present, there is a lack of overall optimization of the flow channel structure of the jet pulse nozzle and the design and research of the driving structure based on the spraying characteristics. In order to solve this problem and promote the industrialization process of this type of domestic nozzle and the development of subsequent series of nozzles, in this paper, the overall structure optimization design of the jet pulse nozzle was carried out, the driving plate structure affecting the rotation and water distribution of the jet pulse nozzle was first designed and tested, and the defects of complex drive mechanism and easy corrosion aging of spring was solved. The driving plate structure is the key factors affecting the hydraulic performance of the jet pulse sprinkler. While at present, there is a lack of drive structure design and research based on spray characteristics. In this paper, a "claw-type" drive plate structure was proposed through the combination of four factors and four levels of hydraulic performance test and verification. The orthogonal test was carried out, and the results showed that the primary and secondary order of the influence of the structural factors of the "claw" driving plate on the spraying uniformity of the jet pulse sprinkler was as follow： the bottom width of the triangular driving plate, the length of the driving plate, the inclination angle of the driving plate, and the width of the driving plate. The optimal structure is as follows： the bottom width of the triangular drive plate is 7 mm, the length of the drive plate is 18 mm, the inclination angle of the drive plate is 14°, and the width of the drive plate is 11 mm.

In order to explore the distribution characteristics of soil moisture and nutrients under well-type water-saving irrigation, in this paper, the 6-years-old apple was taken as the test material and the well-type water-saving irrigation method was used to carry out field experiments. Three irrigation gradients were set: low water [W₁,99 m³/(hm²·times)], medium water [W₂,148.5 m³/(hm²·times)], high water [W₃,198 m³/(hm²·times)] and three fertilization gradients were set: high fertilizer [F₃,225 kg/(hm²·times)], medium fertilizer [F₂,150 kg (hm²·times)] and low fertilizer [F₁,75 kg (hm²·times)]. The treatment of no fertilization control with irrigation amount of W₃ was set as CK treatment. The spatial distribution characteristics of soil moisture and nutrients in apple orchards under well irrigation and fertilization were analyzed. The results showed that: Under well irrigation, soil water mainly distributed in the surface layer of 0~60 cm, mainly moving horizontally, and the moving distance expanded with the increase of irrigation amount. Under W₁ treatment, soil water could not reach the surface layer of 80 cm, and W₃ treatment had the largest moisture content and the widest distribution range. The horizontal distribution of soil nutrients was small near the shaft pipe, and the maximum nutrient content was reached at 40~80 cm with the increase of horizontal distance. In the vertical direction, nutrients mainly gathered in the soil surface, and decreased with the increase of depth. The available phosphorus was mainly distributed in the 0~40 cm surface, while the available potassium could be migrated to the 80 cm surface. By comparing the grading standard of soil abundance and deficiency, the nutrient content in the upper soil of apple orchard was rich within 0~40 cm, and the nutrient increased with the increase of irrigation and fertilizer amount. The nutrient content in F₃W₂ treatment was rich, while the nutrient abundance and deficiency in other treatments were at a medium level. Compared with traditional drip irrigation, well irrigation and fertilization can effectively increase the migration distance of soil water and nutrients. Well irrigation technology can ensure the normal water and fertilizer demand of fruit trees and can be promoted as a new water-saving technology. F₃W₂ treatment has the highest nutrient content and can be used as a reference for irrigation and fertilization.

In recent years, China has vigorously promoted water-saving irrigation projects, but it has not fully met the requirements of efficient water-saving. In the new era of "water saving priority", the evaporation prevention of water source (reservoir) will become one of the water saving research directions in arid and semi-arid areas. At present, the research on the evaporation inhibition effect of PE Floating ball has been relatively comprehensive, but the cost is high when arranged in remote mountainous areas. In order to find a more economical anti-evaporation material, this paper mainly studied the inhibition effect of EPS Floating balls on the evaporation of small water bodies. Five kinds of EPS solid Floating balls with different diameters of 10mm, 40mm, 80mm, 120mm and 150mm were selected to carry out outdoor evaporator tests in Turpan, Xinjiang. A total of six cylindrical evaporators were used to calculate the evaporation of each evaporator in non-freezing months, to calculate the evaporation inhibition rate of EPS Floating balls with different diameters in non-freezing months (March to October) of the year. Among the five diameters, the 40 mm Floating ball had the highest evaporation inhibition rate of 76.31%; the evaporation inhibition rate of the 10 mm Floating ball was the lowest of 59.57%. The relationship between the diameter of the floating ball and the evaporation inhibition rate was not a linear function. By analyzing the influence of surface water temperature and space body humidity on evaporation in the evaporator, it was found that the evaporation of still water surface was more sensitive to the relative humidity of space body under the coverage of EPS floating ball. After 10 months of outdoor test, the durability, water absorption, frost resistance and corrosion resistance of the selected EPS floating ball under the conditions of immersion and exposure met the requirements of long-term use, and was more economical than PE floating ball. The test further improved the selection scheme of the diameter of anti-evaporation floating ball. In small water bodies, artificial ponds and small reservoirs where the area is not vulnerable to strong winds, EPS solid floating ball with a diameter of about 40 mm should be used to reduce water evaporation.

In order to investigate the mechanism of nitrogen and phosphorus loss from paddy fields in plain polder areas, this study took the Fangxi Lake watershed in Jiangxi Province as a typical study area and carried out a study on the spatial and temporal variation of nitrogen and phosphorus concentrations in paddy drainage at different scales. The results showed that the highest mean concentrations of total nitrogen and ammonia nitrogen were found in May and July; the change trend of nitrate nitrogen was first decreased and then increased, with the lowest concentration occurring in August; the change trend of total phosphorus concentration was first increased and then decreased, with the highest value occurring in August; the ratio of ammonia nitrogen/nitrate nitrogen in drainage showed a general increase and then decrease over time, with the largest ratio occurring in August. On the spatial scale, the median values of total nitrogen, ammonia and phosphorus concentrations in drainage water were as follows: dry ditch scale > field scale > watershed scale > bucket ditch scale. The spatial and temporal variation of nitrogen and phosphorus concentrations in farmland drainage was complex and varies greatly at different stages of rice fertility and at different spatial scales. Therefore, it is necessary to strengthen nutrient and water management in the field during the planting process and reasonably control the drainage time. It is recommended to drain water after 16 days of fertilization. The overall rainfall process presents a change trend of "down-up-down". It is suggested that the flood water in the paddy field should be discharged within 2~4 days.

In order toexplore the multi-objective simulation optimization model for water resources allocation in canal well combined irrigation area considering both water quantity and quality issues, a multi-objective simulation optimization model based on FloPy and Pymoo were developed, in which groundwater numerical simulation model MODFLOW and solute transport model MT3D were used to simulate groundwater level fluctuation and pollutant diffusion process caused by irrigation pumping. Four objectives, including irrigation benefit, crop water productivity, groundwater level fluctuation and pollution diffusion, were considered, and two multi-objective genetic algorithms of NSGA-Ⅱ and NSGA-Ⅲ were adopted to solve the problem, and the application effects of the two methods were comparably analyzed. The multi criteria analysis and evaluation method TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) was adopted to determine the suitable irrigation solution, which can reduce the groundwater level fluctuation by 56% and 43% in normal and dry years, and reduce the pollution diffusion area by 54% and 40% respectively.

Studying the velocity distribution law of wide shallow trapezoidal open channel can simplify the flow measurement process, improve the accuracy of flow measurement, and promote the work efficiency of irrigation area. In this paper, the velocity, discharge and section area were measured by acoustic Doppler profile current meter. The orthogonal distance regression algorithm was used to fit the relative velocity and the relative water depth to the quadratic parabola function. The influence coefficient formula of vertical velocity distribution in wide and shallow trapezoidal channel was obtained by linear fitting. The distribution law of transverse velocity was summarized and combined with the measured data, the range of influence coefficient of transverse velocity distribution was obtained by linear fitting, and its exact coefficient was determined by comparing multiple sets of data. By undetermined coefficient method, the coefficients of average velocity of cross-section and velocity of perpendicular surface were obtained. Taking the ratio of the actual velocity to the average velocity as the relative velocity, the R ² values of the fitting velocity distribution law of the wide and shallow trapezoidal channel section were all above 0.937, showing a good correlation. The average velocity distribution of the measured line in the wide shallow trapezoidal channel conforms to the power function distribution. The influence coefficient of transverse velocity in wide shallow trapezoidal channel was obtained and the velocity distribution formula of transverse velocity was verified. In transverse relative position of the range of 0.2<(B-2 d)/B<1, the error was less than 5%. The relationship between the surface velocity of the vertical line and the average velocity of the section in the wide shallow trapezoidal channel was derived. The section flow of the main channel in the wide shallow trapezoidal channel AB was verified. The error between the measured flow and the calculated flow was less than 5%, which met the requirements of the water measurement standards and could be used for water measurement in irrigation area.

A torque-type open channel flow measurement method was proposed in view of the current situation of large number of lateral and field canals, gentle bottom slope and abundant irrigation cement sand in the northern irrigation area. In order to explore the theoretical relationship between the torque of the flow measuring round rod to the fixed point, water depth and flow under the impact of water flow of a rectangular open channel, the flow measurement model of a circular rod was analyzed theoretically by using the principle of flow around a cylinder, and the semi-empirical relationship between torque, water depth and flow was obtained by combining with the velocity area method, which was calibrated in an indoor rectangular open channel. The experimental results showed that the torque-type open channel flow measurement method had a high accuracy of flow measurement. The average relative error between the calculated flow and the measured flow was 1.212%, the maximum relative error was 3.18%, and the relative error was less than 5%, which met the requirements of water quantity in irrigation area. This method has the advantages of low head loss, low cost and high accuracy, which provides a new method for measuring water in irrigated areas.

Irrigation area and its spatial distribution information are very important in water management in irrigated areas. The traditional method of extracting irrigated area consumes a lot of manpower and material resources and time, which can not satisfy the modern management of irrigated area. Since the application of remote sensing technology in the study of irrigation area extraction, after decades of development, there have been a lot of research results. However, in the current remote sensing technology applied in irrigation area extraction, most of the cutting-edge methods adopt multiple sensor data or long time series data, which are often targeted at a specific area, and it is difficult to be specifically applied in the actual irrigation area. In order to extract irrigation area and distribution accurately and efficiently in the practical application of irrigation area management, a neural network algorithm based on multi-temporal difference data of optical satellites was developed in this paper. The experimental field in Huantai County, Zibo City, Shandong Province was taken as the study area. Firstly, random forest was used to sort the importance of all bands of Sentinel-2 satellite data and some indices related to soil water content and vegetation. The importance ranking results were different in different geographical conditions, so the combination of bands and indices suitable for this region could be quickly obtained by using importance ranking. In this study, the band or index with high importance was selected as the input layer of the neural network model to extract the irrigation area, and then the extraction results were tested according to the actual sample data, and the overall extraction accuracy of the irrigation area reached 76.7%. The Kappa coefficient was 0.74. In addition, the vegetation coverage of the study area was graded, and the precision changes of irrigation area extraction results under different vegetation coverage were analyzed. Among them, the accuracy is higher in medium and high vegetation coverage areas. Most of the study area is an agricultural area, with winter wheat and summer corn as the main crops. The data used are satellite images in mid-to-late March. The vegetation coverage of the study area is relatively high in this period, which accords with the result that the extraction of irrigated area has higher accuracy in the areas with medium and high vegetation coverage under the situation in this area. The research results of multi-temporal optical satellite data difference extraction of irrigation area proposed in this paper based on neural network can obtain the combination of bands suitable for the study area through importance ranking under different geographical conditions, and obtain higher accuracy of irrigation area extraction results.

Agricultural water shortage and extensive water use coexist, and the efficiency of water resources utilization urgently needs to be improved. Irrigation pipeline network is an important development trend of water-saving irrigation, but there are many difficulties in the design of irrigation pipe network system. Therefore, carrying out scientific and reasonable planning and design of irrigation engineering and seeking the scheme with minimum total investment of pipe network under the condition of satisfying irrigation water demand and various hydraulic conditions are important means to improve irrigation efficiency and utilization rate of agricultural water resources. In this paper, considering the constraints such as the capacity limit of the rotation irrigation group, the flow rate of the pipeline and the working pressure water, and taking the minimum sum of the pipeline cost and the power cost of the irrigation system as the objective function, a mathematical model was established which considered both the network layout and the network design of the irrigation pipeline. According to the characteristics of the model, a hybrid heuristic algorithm based on iterative neighborhood search was designed to solve the problem. Meanwhile, an actual irrigation project was optimized, and the upper limits of three different rotation irrigation groups were set, namely 120, 150 and 190 m³/h. The results show that in terms of working mode, because of the division of rotation irrigation group, the total flow of the irrigation network system is reduced, and the pipe diameter and the pump station head at the water source are reduced, thus reducing the pipeline cost and power cost. For the same example, the cost of irrigation network will also be different due to the different capacity limits of rotation irrigation group. There is an inverse benefit between the pipe cost and the power cost of irrigation system. In the pipe network design, it is necessary to reasonably set the upper limit of the capacity of the rotation irrigation group and the division method of the rotation irrigation group according to the irrigation area topography and node distribution characteristics, and select the most economical pipe network design scheme.

In this paper, the precipitation data of 10 meteorological stations in Changji area from 1961 to 2020 were used to calculate the standardized precipitation index (SPI-12 and SPI-3) at the annual and seasonal scales in Changji area, and the ability of the SPI index to evaluate the actual drought was verified. Trend analysis method, M-K mutation test method, wavelet analysis method and other methods were used to explore the characteristics of meteorological drought in Changji area. On this basis, the changes of drought frequency, drought intensity and drought coverage area at the annual and seasonal scales were analyzed. The results showed that the SPI index could characterize the drought characteristics of Changji area. From 1961 to 2020, the annual SPI value in Changji area showed obvious phased characteristics, the annual change trend showed the change and fluctuation of drying-wetting-drying, and the drying trend has been more obvious since the 21st century. The SPI in spring, summer and autumn in Changji area showed an insignificant wetting trend, but since the 21st century, spring and summer became arid year by year, and winter showed a significant wetting trend. The drought intensity was mainly light and medium drought in the whole region, and the drought intensity increased significantly in spring, summer and autumn since 2010. From 1961 to 2020, the area of drought decreased slightly, but since the 21st century, the scope of drought has expanded towards an expanding trend, and global drought and regional drought have become more frequent. In terms of periodic changes, there are multiple periodic oscillations of 3~5 a, 8~18 a and 20~30 a, and the "dry-wet" alternations become more frequent as the time scale decreases, but different time scales show different dry and wet oscillation rules.

In view of the practical problems of water shortage and low utilization rate of irrigation water faced by the development of silage maize in Hexi irrigation area, in this study, the water retaining agent (new ecological water retaining agent) developed by Shanghai Institute of Applied Physics, Chinese Academy of Sciences was used as the material to study the effects of new ecological water-retention agent application rate (CK:0 kg/hm², B3:45 kg/hm², B5:75 kg/hm², B7:105 kg/hm²) on soil moisture and photosynthetic characteristics, yield and quality of silage maize under drip irrigation. The results showed that: ①During the whole growth period of maize, the soil volumetric water content in 0~40 cm soil layer increased with the increase of water retaining agent application rate, and there was no significant difference between B5 and B7 treatments. The soil volumetric water content of silage maize in B5 and B7 treatments was 11.27% and 12.15% higher than that of CK treatment, respectively. ② The application of water retaining agent could significantly improve the photosynthetic performance of silage maize leaves. The chlorophyll content, net photosynthetic rate, transpiration rate, stomatal conductance and leaf water use efficiency of silage maize leaves treated with B5 were increased by7.67%, 58.32%, 32.94%, 35.22 % and 17.63 %, respectively, compared with CK treatment. There was no significant difference between B5 and B7 treatments. ③The application of water retaining agent could significantly improve the fresh grass yield, economic benefit and forage quality of silage maize. Compared with CK treatment, the yield, crude protein, crude fat and soluble carbohydrate content of silage maize treated with B5 were increased by 27.22%, 19.16%, 24.24% and 24.22%, respectively, and the content of acid detergent fiber and neutral detergent fiber were decreased by 12.14% and 7.73%, respectively. Therefore, 75 kg/hm² is the best application rate of the new ecological water-retaining agent for silage maize under film mulching drip irrigation in Hexi area.

Soil and water resources are the basic resources for food production, and agricultural output value is the driving force for promoting food production. On this basis, it is of great significance to explore the main influencing factors of food production in coastal areas and to define the coordinated development degree of food production and each influencing factor for evaluating the development status of regional food production and ensuring the sustainable and stable growth of grain output. Based on the data of grain crop yield, agricultural water and soil resources and agricultural output value, this paper constructed an identity model of grain yield, the LMDI index decomposition method was used to explore the main influencing factors of grain yield in Jiangsu coastal areas, and the coupling coordination degree model was used to explore the balance between grain yield and its influencing factors. The results showed that: ①the grain output in Jiangsu coastal areas showed a steady growth trend from 2009 to 2015, fell in 2016 and 2017, and resumed growth in 2018, with a total increase of 1.193 1 million tons during the period 2009-2020. ②From 2009 to 2020, the main factors affecting grain production in coastal areas were agricultural output value, water consumption of agricultural output value and grain multiple cropping index, agricultural water and soil resources and grain yield per unit area. The inter-annual variation of each factor showed positive and negative fluctuations, and the influencing factors of grain yield varied significantly between regions in different time periods. ③From 2009 to 2020, the coupling and coordination degree of grain output and various influencing factors gradually stabilized from serious incoordination to basic coordination and high-level coordination. Therefore, in the grain production increase plan, the government should adjust measures to local conditions, highlight the importance of agricultural output value and agricultural water use efficiency, promote the stable growth of grain planting area with the positive effect of agricultural output value, promote the benign adjustment of crop planting structure with the implementation of water-saving technology and the transformation project of medium-low yield fields, and realize the coordinated and sustainable growth of grain output, water and soil resources and agricultural output value.

Aiming at the difficulty of present contact flow meter for flow measurement, this paper proposes a non-contact flow calculation method. Since the average flow velocity of the perpendicular line and the average flow velocity of the section are approximately the same in the channel water flow, and the ratio of the average flow velocity of the perpendicular line to the flow velocity at the perpendicular water surface is a constant value, the flow rate of the open channel section can be calculated through the three sets of parameters, namely the constant value, the middle perpendicular water surface flow rate and the section area. In this paper, a rectangular nullah of the Dongshen Water Supply Project was taken as the research object, the average flow velocity of the perpendicular line was calculated by integrating the measured flow velocity on different perpendicular lines, and the flow velocity at the perpendicular water surface was calculated by fitting the flow velocity distribution formula of the parabolic function of the measured flow velocity, and the ratio of the average perpendicular flow velocity to the flow velocity at the perpendicular water surface was used as the flow coefficient. The results showed that the calculated flow rate based on the flow coefficient was very close to the measured flow, which indicated that the water surface one point method proposed in this paper could effectively reduce the difficulty of flow measurement while ensuring the accuracy of flow measurement. The calculation method of open channel flow based on one point method of water surface proposed in this paper has high precision, which can provide theoretical basis for real-time monitoring of channel flow in Dongshen Water Supply Project and rapid flow measurement in other irrigation areas.

In order to solve the problems of poor structure and low fertility of coastal saline-alkali land, and explore the influence of organic silicon compound fertilizer on soil physical characteristics of coastal saline-alkali land and summer corn yield, the field test of summer corn was carried out in Haixing County, Cangzhou, Hebei Province from June 2020 to October 2020. Five treatments were set up in the experiment, including local ammonium 600 kg/hm² (T1), silicone compound fertilizer 375 kg/hm² (T2), 750 kg/hm² (T3), 1 125 kg/hm² (T4), and basal fertilizer only blank control group (CK). By measuring the soil physical characteristics of 0~40 cm soil layer and corn yield, the improvement effect of organic silicone compound fertilizer on coastal saline and alkali soil was quantified, and the correlation between soil physical characteristics and corn yield was further analyzed. The results show that：the soil physical characteristics index and corn yield of 0~40 cm soil layer are significantly different. With the increase of silicone compound fertilizer application, the soil capacity decreases, soil porosity, field water holding, saturated water content and soil accumulated water absorption increase, and the yield increases accordingly. The effect of soil improvement and yield increase is T4> T3> T> T1> T2. There was a very significant correlation between bulk density, porosity, field water capacity and saturated water content. The physical properties of surface soil showed a very significant correlation with yield, while the correlation of lower soil was not significant, and the correlation decreased with the increase of soil depth. Applying organosilicon compound fertilizer to coastal saline-alkali land can effectively improve soil structure, enhance soil aeration and water retention, reduce the effect of salinity on corn growth, and thus increase corn yield.