Study On Flow Measurement And Control Integration Device Of Irrigation Channels

Irrigation channels take up the main form of irrigation in China, and to carry out the measurement of water in the canal system aims to strengthen the awareness of water conservation, and to push forward the irrigation quota and to improve the utilization coefficient of irrigation water for irrigation. Irrigation channel is one of the key technologies of developing water-saving agriculture and implementing efficient water use. With the rapid development of technology, water measurement technology in irrigated areas of some developed countries has been turned to integration of automatic control. Significantly affected by regional differences and due to the complex conditions of each large and medium-size irrigation district in China, the currently existing water-measuring devices cannot meet the new requirements of water measurement in irrigated areas. However, the characteristics of economy and stability reliability possessed by the weir flow measurement structure, is suitable for large-scale application in irrigated areas in China. Therefore, the channel water-measuring devices with a simple structure, precise measurement, high fitness, and convenient operation are of great significance for irrigation water saving and efficient utilization of water resources for sustainable development.In this paper, the two measuring and control systems are developed on the basis of flow measurement principle of rectangle thin-plate weir. Combined with automatic control technology, some features like simple structure, affordable price, reasonable accuracy, and the combination of measurement and control provided by the two systems can apply solar energy and battery to solve power supply problems of the systems, under the situations of field irrigated areas without power. The systems are capable of adjusting and controlling the weir head according to the desired watershed flow. After a thorough and systematic analysis of the hydraulic characteristics of the two measuring and control devices, the main research content and major conclusions are as follows:Firstly, the present research summarizes the latest development of technology and facilities of water measurement in irrigated areas, and the existing problems in China are also pointed out. Intending to overcome the shortcomings of the traditional water measurement devices, the present study has developed a new type of controlled channel flow measurement device with simple structure and high precision, and makes it easy for the silt and floating debris to go through. The laboratory experiment conducts an intensive research of the hydraulic characteristics of controlled channel flow measurement device, including the precision of flow measurement, the relationship between water level and flow, the head loss, and the submergence degree, etc. All of the above hydraulic characteristics provide technical parameters for the application of measuring flume in irrigated areas.Secondly, By utilizing the fundamental theory of traditional hydraulics and dimensional analysis, the stage-discharge relation of rectangle thin-plate weir flow channel intelligent measurement and control system is deduced, drawing the flow computing formula for further experimental verification. The results show that the precision of flow measurement of the two formulae conforms to the water measurement specification requirements of the water measurement facilities in irrigated areas. While the flow computing formula calculated by dimensional analysis is more concise and practical.Thirdly, the intelligent measurement and control system of rectangle thin-plate weir flow channel is based on the single chip closed-loop feedback control system. The intelligent control is achieved by artificially setting the flow and the yield of water, in order to maintain the constant flow rate of required weir head. It can be automatically set to block water when the task is completed, which may verify the feasibility of intelligent control.After the experimental study of two new types of measuring and control devices, results indicate that both of the two devices can meet the development requirements of modernization, automation and informatization in irrigated areas. The two devices are of significant value for large-scale promotion and have broad prospects to put into practical application.