包气带弱渗透性黏土透镜体对降雨入渗补给影响的数值模拟  

Impacts of Low-Permeability Clay Lens in Vadose Zone onto Rainfall Infiltration and Groundwater Recharge Using Numerical Simulation of Variably Saturated Flow

作　　者：霍思远[1,2] 靳孟贵[1,2] 梁杏[1,2] 

机构地区：[1]中国地质大学生物地质与环境地质国家重点实验室,武汉430074 [2]中国地质大学环境学院,武汉430074

出　　处：《吉林大学学报（地球科学版）》2013年第5期1579-1587,共9页Journal of Jilin University：Earth Science Edition

基　　金：国家"973"计划项目(2010CB428802);国家自然科学基金项目(41172218;41272258)

摘　　要：大气降雨是华北平原浅层地下水的主要补给来源。长期过量开采地下水造成地下水位持续下降,使原来处于饱水带的透镜体位移到包气带中,形成了厚度大、非均质性更为复杂的包气带。厚层包气带中弱渗透性黏土透镜体对于降雨入渗补给的影响是关系到降水入渗过程及补给量评价的基本问题。用HYDRUS软件建立数值模拟模型,模拟探讨单次降雨条件下,透镜体埋深、宽度比、厚度等要素对入渗路径、入渗补给时间和入渗补给量的影响。结果表明:入渗过程中弱渗透性黏土透镜体两侧会形成较快的绕流;透镜体会减小补给峰值并延长总体补给时间,但不改变补给起始时间;透镜体埋深与极限蒸发深度的相对关系决定了潜在补给量的大小,透镜体埋深或因透镜体形成的上层滞水处于极限蒸发深度以上会减少潜在补给量。Rainfall recharge is a principal source of shallow groundwater in the North China plain. Long-term over-exploitation of groundwater has resulted in the decline of water table in the past decades which made some low-permeability clay lenses moved from saturated zone to unsaturated zone and thicker vadose zone with complicated heterogeneity. It is an essential issue for infiltration process and rainfall recharge estimation effected by low-permeability clay lens in thicker vadose zone. The HYDRUS Software Package is used to establish models mainly considering the buried depth, width and thickness of low-permeability clay lens and simulate the effect of the three factors on infiltration path, recharge time and recharge quantity under single rainfall event. The simulated results show that low-permeability clay lens will restrict vertical infiltration and form faster flow around the lens relative to flow inside of the lens. It will decrease recharge peak and delay recharge time, rather than altering the starting time of recharge. The potential recharge quantity is determined by the relationship between the buried depth of lens and the limit depth of soil evaporation, and it will decrease when the buried depth of lens or the perched water caused by the lens is above the limit depth of soil evaporation.

关 键 词：包气带 弱渗透性黏土透镜体 降雨补给 HYDRUS 数值模拟 

分 类 号：P641.131[天文地球—地质矿产勘探]