水平微润灌土壤水分运动数值模拟与验证

Numerical Simulation and Verification of Soil Water Movement under Horizontal Moistube-irrigation

【目的】进一步认识微润灌土壤水分运动规律。【方法】以非饱和土壤水分运动理论为基础,建立了微润管水平铺设方式下的土壤水分运动数学模型,利用SWMS-2D软件进行求解,采用室内试验及已有文献资料,对单位长度微润管入渗量、土壤湿润锋运移值、土壤湿润体体积和土壤剖面含水率等指标的实测值与模拟值进行了分析验证。【结果】入渗初期(24 h内),单位长度微润管入渗量模拟值与实测值之间存在一定差异,平均相对误差为11.7%;入渗后期(24 h后),模拟结果与实测结果一致性良好,平均相对误差为4.7%。微润管水平埋设时,土壤湿润锋沿微润管呈圆柱形分布,各时段的模拟值与实测值基本一致,平均相对误差绝对值为7.38%;土壤湿润体体积模拟值与实测值随时间的增加拟合性越好;土壤含水率等值线为围绕微润管的"同心圆",随着湿润体半径的增大而减小,微润管壁处土壤含水率最大。【结论】所建模型能比较真实地反映水平微润灌土壤水分运动状况,所建模型及采用SWMS-2D软件进行求解是可行的,采用数值方法模拟水平微润灌土壤水分运动过程是可靠的。

[Objective] The objective is to understand the soil water movement under moistube-irrigation. [Methods] Based on the theory of unsaturation soil water dynamics, a mathematical mode was established with the soil water movement under the way of moistube standard of laying and the SWMS-2 D software was applied to solve the model numerically. Based on the laboratory tests and the existing literature, the infiltration amount of a unit length micro tube, the transport value of soil wetting front, soil wetting volume and soil profile moisture content were analyzed and verified. [Results] There was a difference between the simulation results and measured values of moistube infiltration in per unit length, and the relative error average was 11.7% at the beginning of infiltra- tion. In the later period of infiltration, the simulation result agreed well with measured values and the relative error average was 4.7%. When the moistube was buried horizontally, the soil wetting front is a cylindrical distribution along the microtube. The simulated values of each time period were basically consistent with the measured values, and the mean relative error of the absolute value was 7.3 8%. The relationship between the simulated value of the volume of soil wetting body and the measured value became better as the time increasing. The contour of soil moisture content was the concentric circle around the moistube. With the increase of the radius of the wetted soil, the soil moisture content of the soil was the largest at the pipe wall of moistube.[Conclusion] The model can truly reflect soil water movement under the way of moistube standard of laying. The model and the SWMS-2D software can be used to simulate the soil water movement of the level moistube-irrigation.