包气带井回灌引起的非饱和-饱和流分析  

Analysis of unsaturated-saturated flow induced by a vadose zone well injection

作　　者：祁翠婷 詹红兵 郝永红[2] Qi Cuiting;Zhan Hongbin;Hao Yonghong(School of Geographic and Environmental Sciences,Tianjin Normal University,Tianjin 300387,China;Tianjin Key Lab of Water Resources and Water Environment,Tianjin Normal University,Tianjin 300387,China;Department of Geology and Geophysics,Texas A&M University,TX 77843-3115,USA)

机构地区：[1]天津师范大学地理与环境科学学院,天津300387 [2]天津师范大学天津市水资源与水环境重点实验室,天津300387 [3]美国德克萨斯农工大学地质与地球物理系,德克萨斯77843-3115

出　　处：《地质科技通报》2023年第4期118-129,共12页Bulletin of Geological Science and Technology

基　　金：国家自然科学基金地质联合基金项目(U2244214)。

摘　　要：包气带井回灌是人工补给含水层的重要方法。在回灌过程中,非饱和带水力参数的准确描述对于提高评价精度、增强回灌管理具有重要意义。目前已有的许多包气带井回灌的解析模型是基于Gardner土壤水分特征曲线模型(含二参数)建立的,随着三参数模型(MB模型)和四参数模型(MN模型)的提出,一个值得关注的问题是使用更加灵活的土壤水分特征曲线模型是否能提高回灌系统中非饱和-饱和流的模拟精度。本研究采用MN模型(Gardner模型和MB模型为其子集)建立了包气带井回灌模型,使用COMSOL Multiphysics对模型进行求解,所得解用于研究在回灌过程中非饱和带水力参数和地表通量对非饱和-饱和流的影响,并比较在回灌过程中基于不同土壤水分特征曲线模型所得到的水力响应。试验结果分析发现包气带井回灌引起的水力响应以及地表通量对回灌的影响均会受到非饱和带渗透性以及储水能力的影响,相对渗透系数指数ωk影响非饱和带渗透系数的变化,持水指数ωc影响非饱和带的储水能力,将指数参数简化为ωk=ωc=ω会在计算和预测包气带井回灌引起的水力响应时带来一定的误差。压力头阈值差b_(1)=ψa-ψk的绝对值较小时,对水头增量的影响也较小,此时将其简化为b_(1)=ψa-ψk=0所带来的误差也较小。本研究成果可以帮助学者们提高对包气带井回灌过程的认识,对于回灌方案设计、实施和管理具有重要的实际意义。[Objective]Vadose zone well(VZW)injection is an effective method of managed aquifer recharge(MAR).To improve VZW injection management,it is of great importance to accurately describe the unsaturated zone properties.Several analytical models have been developed for VZW injection based on the two-parameter constitutive model(Gardner model).As the three-parameter model(MB model)and four-parameter model(MN model)have been proposed,it is of interest to know whether the application of more flexible constitutive models is able to improve the analysis of unsaturated-saturated flow induced by VZW injection.[Methods]In this study,the MN model(which includes the Gardner model and MB model as subsets)was employed to establish a VZW injection model.The model was solved using COMSOL Multiphysics.The results are utilized to investigate the unsaturated-saturated flow induced by VZW injection for different values of the unsaturated zone properties to analyse the influences of the ground surface flux(GSF),and to compare the hydraulic responses based on different exponential constitutive models.[Results]The analysis demonstrates that the hydraulic response induced by VZW injection and the influence of ground surface flux are affected by the hydraulic conductivity and the water storage capacity of the unsaturated zone.The relative hydraulic conductivity exponentωk affects the change in hydraulic conductivity of the unsaturated zone.The moisture retention exponentωc affects the water storage capacity of the unsaturated zone.The approximation of ωk=ωc=ωwill result in some errors in the calculation and prediction of the hydraulic response caused by VZW injection.When the absolute value difference of the pressure head threshold b_(1)=ψa-ψk is small,its effect on the water head increment is small.In this case,it is reasonable to assume that b_(1)=ψa-ψk=0.[Conclusion]This study can help scholars improve the understanding of the VZW injection process and has important practical significance for the design,implementation and manage

关 键 词：包气带井 人工回灌 非饱和-饱和流 土壤水分特征曲线模型 

分 类 号：P641[天文地球—地质矿产勘探]