沟灌土壤湿润体空间矩特征参数估算模型

Estimated model for spatial moment character parameters of wetted pattern under furrow irrigation infiltration

为进一步增加矩分析理论在研究沟灌土壤湿润体运移特性方面的实用性,采用数值模拟和理论分析相结合的方法,定量分析了土壤初始含水率、入渗水深、沟底宽和边坡系数等因素对沟灌自由入渗条件下土壤湿润体空间矩特征参数的影响,并建立了其与主要影响因素间的函数关系式。结果表明,土壤初始含水率、入渗水深和沟底宽对垂直向土壤水分分布的质量重心影响较大;水平向湿润锋的平均离散度主要受土壤初始含水率、入渗水深、沟底宽和边坡系数的影响,而垂直向对土壤初始含水率和入渗水深变化的敏感性较高;选取不同土壤质地对所建模型的可靠性进行了验证,结果表明所建模型估算不同入渗时刻的空间矩特征参数值与根据HYDRUS软件模拟结果所得计算值具有高度一致性,所有验证组合条件下两者相对误差绝对值均值均低于8.5%,且无显著性差异,说明所建模型估算沟灌土壤湿润体空间矩特征参数具有高度可靠性。研究结果可为沟灌灌水方案设计和管理提供理论基础和技术支撑。

In order to further improve the practicality of moment analysis theory on the study of the transport charac- teristics of wetted pattern under tow-dimensional infiltration of furrow irrigation, the effects of initial soil water content, water depth, bottom width and slope parameter on the spatial moment character parameters of soil wetted pattern under free infiltration were studied quantitatively by combination of numerical simulation and theoretical analysis method. The function relationship between the spatial moment character parameters of soil wetted pattern and the main influence factors was established. The results showed that the mass center of vertical soil moisture distribution is greatly influ- enced by initial water content, water depth and bottom width. The average dispersion of the horizontal wetted front is mainly influenced by initial water content, water depth, bottom width and slope parameter, while the average disper- sion of the vertical soil wetted front has higher sensitivity to initial water content and water depth. Then, the reliability of the model was further verified through several different soil textures. The results showed that the values of spatial moment character parameters estimated by the proposed model at different infiltration times agree well with calculated values based on the simulation results by the HYDRUS software. The mean absolute values of the relative error of all combinations were lower than 8.5%, and there was no significant difference, which indicated the proposed model can he used to estimate the spatial moment character parameters of soil wetted pattern under furrow irrigation with a high reliability. The results can provide theoretical basis and technical support for the design and management of furrow irri- gation.