衡水地区深层地下水水化学特征及其演化过程

衡水地区多年超采深层地下水，形成了以衡水市区为中心的区域地下水降落漏斗，改变了初始的水动力场和水化学场。运用聚类分析、Piper三线图、Gibbs图、氯碱指数、离子相关关系方法分析了该地区历史时期和现阶段深层地下水的水文地球化学特征及其演化规律，探讨了水化学组分的来源及形成机制。结果表明：该地区深层地下水水化学演化受到了较大的人类活动影响，根据Q型聚类分析将研究区划分为补给、径流、排泄3个水化学分区。20世纪70年代到现阶段，随降落漏斗产生发展，研究区形成了新的局部补径排关系，加强了地下水对围岩的溶滤作用，导致研究区水化学场发生了变化，径流区地下水水化学类型由Cl·HCO3-Na、HCO3·Cl-Na和SO4·Cl-Na转化为SO4·Cl-Na和Cl·SO4-Na，排泄区地下水水化学类型由Cl·HCO3-Na和Cl-Na转化为Cl-Na。Gibbs图和离子关系显示，研究区现阶段深层地下水在降落漏斗影响下，水化学组分主要受岩石风化、阳离子交替吸附和脱碳酸作用控制。

Hydrochemical Characteristics and Evolution Processes of Deep Groundwater in Hengshui Area

The groundwater depression cone around Hengshui is formed from the over exploitation of deep groundwater, which changes the original hydrodynamic and hydrochemical fields. Cluster analysis, Piper and Gibbs diagrams, chlor alkali index and ion correlation method are used to analyze the chemical characteristics and evolution of deep groundwater in the Hengshui area. The results show that the chemical evolution of deep groundwater is substantially influenced by human activities. The study area is divided into the recharge area, runoff area and drainage area using Q type cluster analysis. A new route of groundwater supply, runoff and drainage, which strengthened the wall rock dissolution, is created with the development of depression cone since the 1970s. Major hydrochemical types of the runoff area have switched from Cl·HCO3 Na, HCO3·Cl Na and SO4·Cl Na to SO4·Cl Na and Cl·SO4 Na, whereas those of the drainage area have switched from Cl·HCO3 Na and Cl Na to Cl Na. Gibbs diagrams and ion correlation suggest that the present hydrochemical characteristics of the study area are mainly affected by the wall rock dissolution, cation exchange and decarbonation.