地下水循环结构的动力学研究进展

由地下水补给、径流和排泄过程构成的地下水循环运动，是水文循环的重要组成部分，也是水文地质学的基本研究对象。地下水循环在空间上表现为不同结构单元的组合，存在以含水层特性为依据的介质结构和以渗流场为依据的动力结构2种划分方法。地下水流系统是动力结构意义上的地下水循环单元。近10年来，区域地下水流系统理论取得了显著进展，更加全面深入地揭示了地下水循环结构的动力学特性。通过对河间地块地下水流系统的研究，发现潜水面最高点并非地下水分水岭的准确位置。在盆地尺度上，系统研究了沟谷地貌、降水入渗强度、渗透性随埋深变化和盆地厚度等因素对潜水面波形与地下水循环动力结构的影响，初步发现了动力结构的周期性或趋势性演化特征。通过大规模流线路径的精细识别或驻留时间的统计分析，提出了三维地下水循环单元的划分方法。在水文地质效应方面，发现地下水循环的动力结构对地下水年龄的分布有重要影响。地下水循环的动力结构反映了不同补给区和排泄区之间的水力联系，在盆地尺度地球化学过程、流域尺度生态水文过程中发挥着关键作用，未来的研究重点是三维地下水循环的动力特性和演变规律。

Advances in dynamics of groundwater circulation patterns

As an essential part of hydrological cycle, groundwater circulation is a process including groundwater recharge, flow and discharge, which has been the primary research topic in hydrogeology.The spatial patterns of groundwater circulation are composed of different structure elements.There are two partitioning methods: the media structure determined from aquifer properties and the dynamic patterns determined according to the seepage field.A groundwater flow system (GFS) roles as a groundwater circulation cell within the concept of the dynamic patterns.In the last decade, significant advances have been achieved in the theory of GFSs, revealing groundwater circulation patterns in more comprehensive and deep ways.Studies on GFSs between parallel streams discovered that the top of water table is not the accurate position of groundwater divide.At the basin scale, the integrated impacts of the vale landform, precipitation infiltration rate, depth dependent permeability and basin thickness on the undulating shape of water table and groundwater circulation patterns were systematically investigated, with preliminary discovery on the evolution characteristics of dynamic patterns in periodicity and tendencies.Partitioning methods for three dimensional groundwater circulation cells were developed, according to fine-grained identification of paths or statistic analysis on residence times along a huge number of streamlines.For the hydrogeological effect, it has been found that the groundwater circulation patterns significantly influence the distribution of groundwater age.As an indication of hydraulic connection between recharge and discharge zones, groundwater circulation patterns play a key role in the geochemical processes at the basin scale and eco-hydrological processes at the catchment scale, which should be studied with more attentions on the dynamic and evolution behaviors of the three-dimensional groundwater circulation.