Discussion On The Implementation Effect And Key Technology Of Low-pressure Pipeline Irrigation System For Grain Fields In Shanghai

As China's economy continues to develop,water conservancy has become an indispensable primary condition for modern agricultural construction,an irreplaceable foundation for economic and social development,and an inseparable safeguard system for ecological environment improvement.Farmland water conservancy is the foundation of agricultural production and development,an important infrastructure for agricultural and rural economic development,and a weak link in rural infrastructure.In recent years,Shanghai has vigorously developed low-pressure pipeline water-flooding technology in small-scale electromechanical irrigation areas in grain-growing areas,and has achieved significant economic benefits such as water saving,land saving,energy saving,and increased production.In the process of development,rice has not been fully considered.The characteristics of large and concentrated water consumption during the paddy field lack the technical model suitable for Shanghai,which affects the promotion and sustainable application of the technology.In this thesis,the following aspects are discussed in view of the current development of the water supply irrigation system for low-pressure pipelines in Shanghai.(1)Conducting a comprehensive and in-depth investigation of the low-pressure pipe irrigation project of the built grain field in Shanghai by means of issuing questionnaires,holding symposiums and on-site investigations,and water source,control scale and crop layout for the irrigation area of Shanghai low-pressure pipeline irrigation system.The irrigation project type,irrigation system construction,operation management status,etc.have a comprehensive understanding,summed up the three main forms of the city's low-pressure pipe irrigation project and its distribution.Through the analysis of typical cases,the successful experience of the implementation of the low-pressure pipe irrigation system in the city is summarized,and the existing problems are analyzed(2)In view of the problems existing in the current low-pressure pipe irrigation system in Shanghai,the typical irrigation area was selected,and the hydraulic performance simulation analysis of the system was carried out.The experimental equipment such as flowmeter and pressure gauge were arranged reasonably in the system,and relevant experimental research was carried out.Through simulation and experiment,the system operation conditions and design conditions are compared and analyzed,and the design methods such as system layout,pump selection and pipe diameter selection and the rationality of the design results are analyzed.The hydraulic performance simulation method proposed in this thesis is confirmed.It is applicable to both fully enclosed and open low-pressure pipeline irrigation modes;by designing different test schemes,optimizing system rotation irrigation system,monitoring system energy consumption,and understanding the effect of variable frequency controller in fully enclosed pipeline water irrigation.(3)Based on the characteristics of Shanghai Irrigation District,the main factors affecting the promotion and application of low-pressure pipe irrigation project in Shanghai were analyzed,and the technical integration mode,suitable control area and system construction standard for low-pressure pipe irrigation system suitable for Shanghai were proposed.On this basis,considering the different irrigation areas,different lifts and different layout forms of small electromechanical low-pressure pipeline irrigation districts in Shanghai,considering the project investment and operation cost,the trinity standardization design research of the low-pressure pipe irrigation system from the first part to the pipe network to the field was carried out.