膜调控润灌在不同土壤类型下的技术参数确定OACSTPCD

[Objective]Membrane-regulated subsurface irrigation is a water-saving irrigation technique for water-scarce areas,and this paper is to experimentally determine its technical parameters for irrigation in soils with different textures.[Method]The studies were based on laboratory experiment and the HYDRUS-2D model.Infiltration of irrigation water into sandy soil,loam soil,sandy clay loam and silt soil under membrane-regulated irrigation was conducted experimentally with the dripping rate ranging from 0.9 to 3.2 L/h.The measured data were used to calibrate the HDYDRUS-2D model.[Result]The HDYDRUS-2D model can accurately simulate water flow in all soils under membrane regulated irrigation,with the relative errors less than 5%,the coefficient of determination and root mean square deviation being 0.97 and 0.007,respectively.The sandy soil was prone to leakage due to its elaborated hydraulic conductivity.In the membrane-regulated irrigation,adjusting the flow rate in the drip irrigation pipe was needed to improve irrigation efficiency in different soils.On average,the membrane-regulated irrigation worked well for all three soil types.At the end of the irrigation,the ratio of the water on the membrane to the total irrigation amount was more than 70%in all soils,indicating a reduction in water leakage loss.As the dripping rate increased,the proportion of water on the film in the loam soil decreased gradually;the dripping rate in irrigation for this soil should be controlled below a critical value.In the sandy soil,it was required to adjust the buried depth of the drip irrigation pipes to reduce leakage loss.The optimal dripping rate for the sandy clay loam soil and the loam soil was 2 L/h.As the flow rate increased,there was no significant change in the proportion of water on the membrane in the silt soil;the optimal dripping rate for the silt soil was 3 L/h.[Conclusion]Our experimental and numerical studies showed the optimal dripping rate for the membrane-regulated surface drip irrigation was 2 L/h for the sandy clay loam soil and the loam soil,and 3 L/h for the silt soil.