用Philip模型参数推求湿润锋平均基质吸力S_f准确性

Validity of Average Potential Suction S_f of Wetting Front Calculated by Parameters in Philip Infiltration Equation

修改的适用自然降水入渗的Green-Ampt模型是模拟坡面降水入渗、产汇流的常用手段,该模型中一个重要参数——湿润锋平均基质吸力Sf的准确取值对提高计算精度有重要作用。在分析Philip入渗模型和Green-Ampt入渗模型的基础上,建立了两模型参数间的转化关系,并尝试用Philip模型参数间接推求Green-Ampt模型中的参数Sf。通过对积水入渗资料的处理和用降水产流资料进行准确性检验,结果发现,对黄土高原黑垆土而言,用Philip模型参数间接推求Green-Ampt模型中的湿润锋平均基质吸力Sf是可行的,与直接用Green-Ampt模型获得的Sf值具有相同的精度。

The modified Green-Ampt infiltration equation which is suitable to describe infiltration during an unsteady rain is widely used to simulate infiltration and runoff on the slope land. The average potential across the wetting front S_f is one of the most important parameters in it, whose validity is dependent on S_f. The theoretical relationships among the parameters of the Philip equation and Green-Ampt equation are analyzed, and parameter S_f in Green-Ampt equation can be calculated by the parameters values of the Philip (equation.) The infiltration experiments with surface ponding and unsteady rain were carried at the Changwu Agri-ecological Station in 1996, and the different values of S_f calculated by Green-Ampt equation and (parameters) of the Philip equation were obtained based on the infiltration data with surface ponding. The validity of different S_f~'s values was compared by the runoff data of unsteady rain on a plane via the modified Green-Ampt equation by Chu(1978). The results showed that S_f calculated by the parameters of Philip (equation) was valid for simulating the infiltration and runoff on a plane on the Heilu soil of the Loess Plateau.