摘要
包气带作为连接植被与地下水的重要纽带,其岩性结构是影响地下水生态功能的主要因子之一,而包气带结构中的弱透水夹层对来自地面的入渗水流具有延迟滞后、局部蓄水作用(上层滞水),尽管该部分水量很小,但对于极端干旱区植被生态的维持具有一定供水意义。为了探究包气带岩性结构如何影响土壤含水率分布,设计了均质土柱(O)、单薄夹层土柱(A)、单厚夹层土柱(B)以及双夹层土柱(C)4个土柱,开展了室内层状非均质土柱释水实验和入渗实验;依据物理实验开展了变饱和水流数值模拟。实验过程中,粉土夹层结构导致水分在夹层内部和夹层上下界面处滞留,形成了水分聚集区;相较于O柱,A柱、B柱和C柱释水过程持续时长分别增加了290,500,780 h,持水量分别增加了6.20,7.90,7.83 cm;数值模拟结果表明采用修正后的van Genuchten模型能更好地模拟层状土含水率剖面。细粒土夹层对入渗水下移特征会产生明显阻滞效应,水分主要滞留在夹层内部和夹层上下界面处,夹层厚度增大、层数增多会导致夹层内和夹层界面处均滞留更多水分,通过引入虚拟变量和毛细高度修正van Genuchten模型,并将其对应的相对渗透率方程分为三段式,可有效提升层状土壤含水率剖面模拟精度。
[Objective]The vadose zone serves as a critical link between vegetation and groundwater,with its lithological structure being one of the main factors influencing groundwater ecological functions.However,the lowpermeability interlayer within the vadose zone structure has a delayed effect on the infiltration flow from the surface and local water retention(perched water).Although the water volume in this zone is relatively small,it plays a significant role in supplying water for maintaining vegetation ecology in extremely arid areas.To explore how lithological structure affects soil water content distribution,[Methods]four soil columns were designed:A homogeneous soil column(O),a thin interbedded soil column(A),a single thick interbedded soil column(B),and a double interbedded soil column(C).Indoor drainage and infiltration experiments were conducted on these layered heterogeneous soil columns.Numerical simulations of variable saturation flow were performed based on the physical experiments.[Results]The fine-grained soil interlayer structure causes water retention within the interlayer and at the upper and lower interfaces of the interlayer,forming a water accumulation zone.Compared with column O,the water release duration of columns A,B,and C increased by 290,500,and 780 h,respectively,and the water holding capacity increased by 6.20,7.90 and 7.83 cm,respectively.The numerical simulation results show that the modified van Genuchten model can better simulate the layered soil moisture profile.[Conclusion]The fine-grained soil interlayer has a significant retarding effect on the migration of water within the vadose zone,and water is mainly retained inside the interlayer and at its upper and lower interfaces.The increase in the thickness and number of interlayers leads to greater water retention within the interlayer and at the interlayer interfaces.The corresponding relative permeability equation is divided into three stages,which can effectively improve the simulation accuracy of the layered soil water content profile.
作者
王铭森
邓斌
张晚祺
孙志坚
刘延锋
张林
WANG Mingsen;DENG Bin;ZHANG Wanqi;SUN Zhijian;LIU Yanfeng;ZHANG Lin(School of Environmental Studies,China University of Geosciences(Wuhan),Wuhan 430078,China;Tianjin Geological Survey Center,China Geological Survey(North China Geological Science and Technology Innovation Center),Tianjin 300170,China;Hubei Institute of Water Resources Survey and Design Co.,Ltd.,Wuhan 430064,China;State Key Laboratory of Eco-Hydraulics in Northwest Arid Region of China,Xi'an University of Technology,Xi'an 710048,China;College of Environmental Science and Engineering,Ocean University of China,Qingdao Shandong 266100,China)
出处
《地质科技通报》
北大核心
2025年第3期296-308,共13页
Bulletin of Geological Science and Technology
基金
西安理工大学师资博士后科研启动经费资助项目(256082406)
天津市地质安全体检与风险评估示范项目(DD20243452)。
关键词
层状非均质
土壤含水率分布
数值模拟
定量刻画
土柱释水实验和入渗实验
粉土夹层
包气带
layered heterogeneity
soil moisture distribution
numerical simulation
quantitative characterization
indoor drainage experiment and infiltration experiment of soil column
silt interlayer
vadose zone
