Fundamental Research On The Application Of Low Flow And Micro-pressure Drip Irrigation Technology

Drip irrigation is one of the most water saving and high efficiency irrigation technology in the world, but its high cost limits the large-area application of this technology. To break the "expensive" and give full play to the advantages of drip irrigation technology, micro-pressure drip irrigation technology has been put forward by scholars. Micro-pressure drip irrigation technology gives a new way to drip irrigation technology development for the future. Aiming at existing problems in micro-pressure drip irrigation technology, a lot of basic research was made in the thesis. Through theoretical analysis, experimental research and numerical simulation, this thesis studied not only in the micro-pressure drip irrigation system itself, but also the effects of micro-pressure drip irrigation to soil water movement and crop growth. Thus, the thesis didn't only study irrigation on irrigation water; systematic research was made on the combination of water, soil and crop.On the basis of modern hydraulic theory, the quantitative relationsship between irrigation quality and working pressure, lateral length of run, lateral diameter and designed emitter discharge was systematically analyzed by experiment. According to the theoretical and expermeantal analysis, the goals of reducing the system cost and ensuring irrigation quality can be achieved by simultaneously reducing working pressure of drip irrigation system, appropriately increasing pipe diameter, appropriately reducing designed emitter discharge and pipe wall thickness. And the concept of low flow micro-pressure drip irrigation technology was put forward innovatively.In order to improve the design accuracy and ensure irrigation quality in the micro-pressure drip irrigation system, the impacts of drip irrigation system technical parameters on irrigation quality was studied. The method of determining the appropriate lateral diameter was initially established. The scope of the terrain was clarified for micro-pressure drip irrigation system. The measures of improving drip irrigation uniformity were proposed at the condition of micro-pressure. Taking account of the three deviation rates, a formula for computing the flow deviation rate was deduced on uniform slopes. And the method for designing irrigation unit of micro-pressure drip irrigation system was also put forward.For proving the feasibility and scientificalness of low flow and micro-pressure drip irrigation system, and also scientifically determining the appropriate emitter discharge, the experiment of soil water movement was conducted under low flow drip irrigation. According to non-saturated soil water dynamics theory, the mathematical model for soil water movement was established. And it was verified by experimental data. At the same time, based on numerical simulation, the method of determining the appropriate emitter discharge was proposed for drip irrigation system.However, any irrigation technologies should provide the crop required water to improve crop yield and water use efficiency. The effects of irrigation vary for the different irrigation technologies. Therefore, the effect of low flow drip irrigation to crop growth was studied in the thesis. The results show that, low flow and micro-pressure drip irrigation will be helpful to crop growth, and also improve crop yield and water use efficiency.In a word, low flow and micro-pressure drip irrigation technology, not only can reduce system cost, but also achieve the dual goals of water-saving and increasing yield. Thus, it has broad application prospects.