Van Genuchten模型参数对降水入渗数值模拟的敏感性  

Effect of Parameter Sensitivity of van Genuchten Model on Numerical Simulation of Rainfall Recharge

作　　者：霍思远[1,2,3] 靳孟贵[2,3] 

机构地区：[1]长江大学资源与环境学院,湖北武汉430100 [2]中国地质大学盆地水文过程与湿地生态恢复学术创新基地,湖北武汉430074 [3]中国地质大学环境学院,湖北武汉430074

出　　处：《地球科学（中国地质大学学报）》2017年第3期447-452,470,共7页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学基金项目(Nos.U1403282;41602246)

摘　　要：详细分析不同评价指标下的van Genuchten方程参数敏感性,对于深入认识参数物理意义、合理确定参数值、提高降水入渗数值模拟准确性具有重要意义.用HYDRUS软件建立一维变饱和水分运移模型,以实际补给量、补给过程曲线和极限蒸发深度作为评价指标,采用单因素扰动分析法对van Genuchten方程各参数敏感性进行理论分析,进而选取多组参数实例,分析同一岩性类别下,不同土样土壤水力参数差异及其对入渗补给模拟结果的影响.结果表明:形状系数(n)、土壤进气值的倒数(α)与极限蒸发深度呈负相关关系,是影响极限蒸发深度的显著因素;饱和含水率(θs)、n、饱和渗透系数(Ks)对于入渗补给影响的敏感性较高,三者在实际土样粒径分布、干密度和孔隙性的共同影响下发生同向变动.合理的参数敏感性分析及数值模拟调参过程需结合土壤参数的物理意义来开展.The van Genuchten model is frequently used in expression of soil lithology and hydraulic feature of vadose zone. The included soil hydraulic parameters are sensitive factors in numerical simulation of rainfall recharge. It facilitates the understand- ing of the physical meaning of parameters, improving accuracy of numerical simulation of rainfall recharge and parameters reg- ulation to analyze the sensitivity of each soil hydraulic parameter. In this study, one-dimensional variably saturated flow models were established by using HYDRUS software. Simulations were run under conditions of multiple sets of parameters which are set in the principle of changing one parameter and keeping the others invariant to evaluate parameter sensitivity of van Genucht- en model by using actual recharge quantity, recharge process curve and maximum evaporation depth as the index. The case study chose multiple sets of measured parameters to evaluate the influence of parameter variation among different samples of the same lithology. The simulations results show that maximum evaporation depth is significantly affected by the n and a which are negatively related to it; 0~, n, and Ks have a high sensibility to the variation of vertical groundwater recharge, however they will change with porosity, grain size distribution and bulk density of soil at the same time. It is concluded that the reasona- ble analysis of parameter sensitivity can only be done in combination of the study of their physical meaning.

关 键 词：VAN GENUCHTEN模型 参数敏感性分析 降水入渗 数值模拟 HYDRUS 水文地质 

分 类 号：P641[天文地球—地质矿产勘探]