盆地地下水年龄空间分布规律  

Distribution of groundwater age in drainage basins

作　　者：蒋小伟[1] 万力[1] 王旭升[1] 李海龙[1] 

机构地区：[1]中国地质大学水资源与环境学院,北京100083

出　　处：《水文地质工程地质》2012年第4期1-6,共6页Hydrogeology & Engineering Geology

基　　金：中国地质调查局地质调查工作项目(1212011121145);中央高校基本科研业务费项目

摘　　要：地下水年龄蕴含了地下水循环与演化过程的信息,是研究盆地地下水循环规律的重要信息来源。利用实测示踪剂年龄校正地下水模型,是当前国际水文地质学研究的前沿与热点。在数值模拟计算中,地下水年龄有三种确定方法,分别是利用"活塞流"模型计算对流年龄、根据同位素浓度结合半衰期计算浓度模拟年龄和利用地下水年龄控制方程计算直接模拟年龄。利用地下水年龄控制方程计算的直接模拟年龄适合于从理论上分析盆地中的地下水年龄空间分布规律。研究发现,在各级次流动系统内,从补给区到排泄区,地下水年龄有整体上变老的趋势;盆地下游,地下水年龄在垂向上会发生突变,可作为识别不同级次流动系统的实用指标。研究还发现,驻点位置或者附近,地下水年龄存在一个偏大的峰值。这些规律可为利用地下水年龄校正盆地地下水模型提供理论指导。Groundwater age or tracer concentration is an important source of information in studies of groundwater circulation in large scale basins.Calibration of groundwater flow and transport models using groundwater age is a hot research topic in modern hydrogeology.There are three approaches to calculate model age.Advective age is based on the assumption of the piston flow model;concentration-based model age is calculated from the results of an isotope transport model,combined with the decay rate of the isotope;directly simulated age is obtained by solving the governing equation of age mass transport.Among them,directly simulated age is most suitable for analyzing age distribution in drainage basins.Results of directly simulated age show that groundwater age distribution is highly correlated with the development of groundwater flow systems.In each flow system,following the flowpath from the recharge zone to the discharge zone,groundwater age is increasingly older.In the lower reaches of a drainage basin,there is an abrupt change in groundwater age from the shallow to the deep,which is an excellent indicator of different flow systems.At or near the stagnation points,groundwater age has a maximum value.All of these findings are fundamental to calibration of groundwater models in large scale basins.

关 键 词：地下水年龄 盆地 地下水流动系统 年龄质量 直接模拟年龄 

分 类 号：P641.2[天文地球—地质矿产勘探]