一种沟灌累积入渗量简化计算方法

为简化沟灌二维累积入渗量的数值计算,采用理论分析和数值模拟相结合的方法,研究分析了土壤初始含水率、入渗水深、沟底宽、边坡系数、土壤质地和容重等因素对沟灌边界效应和拟合系数γ的影响,并建立了系数γ与主要影响因素间的函数关系式,提出了沟灌累积入渗量简化计算方法.结果表明,土壤初始含水率、沟底宽和边坡系数对沟灌边界效应的影响较小,而入渗水深、土壤质地和容重对沟灌边界效应的影响显著;拟合系数γ主要与入渗水深的变化有关,随入渗水深的增大呈现减小趋势,但对初始含水率、沟底宽、边坡系数、土壤质地和容重等因素变化的敏感性较低,可忽略其影响;建立了估算拟合系数γ的计算式,结合已有文献资料对其可靠性进行了验证,结果表明黏壤土和砂壤土不同入渗时间内,其沟灌累积入渗量计算值与实测值和HYDRUS软件模拟值具有高的一致性,说明文中所建公式估算拟合系数γ值可靠.研究结果可为简化沟灌累积入渗量的数值计算提供理论依据和技术支撑.

Simplified calculating method for cumulative infiltration of furrow irrigation

Theory analysis and numerical simulation combination method were employed for simplifying numerical calculation process of two-dimensional cumulative infiltration under furrow irrigation. By analyzing the impacting factors of initial water content, water depth, bottom width, slope parameter, soil texture and bulk density effects on edge effect and fitting parameter γ, a relationship between fitting parameter γ and the main influence factors was built and a simplified method for cumulative infiltration of furrow irrigation was proposed. The results show that the initial water content, bottom width and slope parameter have slight influences on the edge effect, however, water depth, soil texture and bulk density have greatly influence on it. Being closely related with water depth, fitting parameter γ decreases with the increase of water depth, but is less sensitive to the initial water content, bottom width, slope parameter, soil texture and bulk density, therefore those impacting factors can be ignored. Based on the references, the reliability of the proposed method in this paper is verified. The results show that the calculated values of the cumulative infiltration agree well with the measured values and simulated values by the HYDRUS. Therefore, it is reliable to estimate the cumulative two-dimensional infiltration with the proposed method under furrow irrigation.