基于δD和δ^(18)O及水化学的永定河流域地下水循环特征解析

A Study of Groundwater Cycle in Yongding River Basin by Using δD,δ^(18)O and Hydrochemical Data

运用环境同位素和水化学成分作为水循环研究的示踪剂,揭示了永定河流域中下游地下水循环特征。通过现场调查并对浅层和深层地下水采样,进行室内水化学和氢氧同位素组成测定,分析了流域内深层和浅层地下水的氢氧同位素和水化学组成的空间分布规律和演化趋势,揭示了流域地下水循环特征。结果表明,降水是山前地下水的主要补给源,地下水在接受降水的补给后经过了不同程度的蒸发作用,山区受蒸发影响较小,平原区较大,尤其是平原区浅层地下水呈现出强烈的蒸发浓缩作用;水化学特征表现为自西部山区到山前平原至滨海平原,自浅层到深层,地下水的矿化度逐渐升高;平原区浅层和深层地下水含水层之间存在明显的越流补给现象;沿海地区未发现海水入侵现象。

By using environmental isotopes and hydroehemieal components as tracers in surveying water circulation ,this paper revealed the groundwater circulation characteristics in the Yongding River Basin.By field surveying and groundwater sampling in the shallow and deep aquifers,the hydrochemistry and hydrogen and oxygen isotope components were measured.Then the spatial distribution rule and evolvement tendency of δD and δ18O and hydrochemical components of the groundwater in the deep and low aquifers were analyzed for revealing the groundwater cycle characteristics in the Yongding River Basin.The results indicated that the main recharge source of the groundwater in the piedmont region is precipitation, and evaporation process of different degrees has undergone after groundwater recharge from rainfall in the basin. Feeble evaporation process has occurred in the mountain region and intene evaporation process in the plain region ,especially intense evaporation-concentration process for the groundwater in the shallow aquifer in the plain region.The hydrochemical characteristics of the groundwater manifested that the mineralization degree of the groundwater ascends gradually from the mountain region and the piedmont plain to the seashore plain ,and from the shallow aquifer to the deep aquifer.Evident inter-aquifer recharge phenomena exist between the shallow ground- water and the deep aquifer under the plain.While the phenomenon of seawater encroaching to the aquifer does not exist.