处理地下水模型单元疏干-湿润的两种算法对比研究  

Comparative study on two drying-rewetting algorithms of groundwater model cells

作　　者：陆文 陆垂裕[1,2] 何鑫 孙青言[1,2] 张博 贾仰文[1,2] LU Wen;LU Chuiyu;HE Xin;SUN Qingyan;ZHANG Bo;JIA Yangwen(State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,China Institute of Water Resources and Hydropower Research,Beijing 100038,China;Department of Water Resources,China Institute of Water Resources and Hydropower Research,Beijing 100038,China;Institute of Science and Technology,China Three Gorges Corporation,Beijing 100038,China)

机构地区：[1]中国水利水电科学研究院流域水循环模拟与调控国家重点实验室,北京100038 [2]中国水利水电科学研究院水资源所,北京100038 [3]中国长江三峡集团有限公司科学技术研究院,北京100038

出　　处：《水文地质工程地质》2024年第5期22-34,共13页Hydrogeology & Engineering Geology

基　　金：黑龙江省重点研发计划项目(JD22B001);流域水循环模拟与调控国家重点实验室自主研究课题(SKL2022ZD02);中国长江三峡集团有限公司员工科研项目(NBZZ202200616)。

摘　　要：在使用网格单元中心差分格式的地下水模型中,对地下水网格单元“疏干(干)-湿润(湿)转化”的模拟极易引发模型迭代不收敛等异常情况,很大程度上影响模型的应用。本研究使用理想案例和丹麦应用实例,综合比较了MODFLOW模型的试算法与COMUS模型的全有效单元法对网格单元“干-湿转化”问题的模拟能力及算法特性。结果表明:(1)试算法的参数组合选取对模拟的收敛性和模拟结果都有明显影响,使用试算法时需要不断优化参数组合以避免模型迭代不收敛或模拟失真等异常情况,很大程度上增加了用户使用模型的难度和时间成本;(2)全有效单元法的模拟结果比试算法的模拟结果更具可靠性,全有效单元法的作用等同于理论上最优的试算法参数组合,使用全有效单元法时用户无需进行复杂的参数组合工作,因此该方法能有效降低模型的使用难度与模拟结果的不确定性;(3)全有效单元法中单元间水平向水力传导度算法实现了可以与经典调和平均法相比较的数值计算精度,说明全有效单元法在不涉及网格单元“干-湿转化”问题的地下水模拟中同样具有应用潜力。综上所述,全有效单元法更适用于处理地下水模型单元的疏干-湿润转化问题,并且有望在地下水数值模拟领域中得到更为广泛的应用。When simulating drying-rewetting process of grid cells in numerical groundwater modeling using the block-centered finite-difference approach,the models is highly probable to run into non-convergence,which could greatly affect the applicability of groundwater models.This study used ideal case and practical simulation in Denmark to comprehensively compare the simulation capabilities and characteristics of two algorithms,namely the empirical trial(ET)method proposed by MODFLOW and the always active cell(AAC)method proposed by COMUS,in the drying-rewetting simulation.The results show that:(1)For the ET method,the selection of parameter combination has a significant influence on the model convergence and the simulation results.It is compulsory to continuously optimize the parameter to avoid model failures such as non-convergence and large simulation errors when using the ET method,which greatly increases the difficulty of groundwater model application and time cost.(2)The simulation results from the AAC method are more reliable than those from the ET method.Theoretically,the effect of the AAC method is equivalent to the optimal parameter set in the ET method.Therefore,parameter optimization is no longer needed in the AAC method,which can effectively reduce the difficulty of using groundwater models and meanwhile reduce the uncertainty of simulation results.(3)The numerical accuracy of the intercell horizontal hydraulic conductance in the AAC method is consistent with that of the classical harmonic average method,demonstrating that the AAC method can also be used in the simulation without the drying-rewetting process.In summary,the AAC method is more suitable for simulating the drying-rewetting process of groundwater model cells and is expected to be more widely used in groundwater numerical simulation.

关 键 词：地下水模型 网格单元疏干-湿润 全有效单元法 试算法 饱和-非饱和 

分 类 号：P641.2[天文地球—地质矿产勘探] P338[天文地球—地质学]