基于2H&18O和水化学成分的永定河流域地下水循环特征解析

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。

A Study of Groundwater Cycle in Yongding River Basin by Using δD, δ18O and Hydrochemical Data

By using environmental isotopes and hydrochemical components as tracers in surveyingwater circulation, this paper revealed the groundwater circulation characteristics in theYongding River Basin.By field surveying and groundwater sampling in the shallow and deepaquifers, the hydrochemistry and hydrogen and oxygen isotope components were measured.Thenthe spatial distribution rule and evolvement tendency of δD and δ18O and hydrochemicalcomponents of the groundwater in the deep and low aquifers were analyzed for revealing thegroundwater cycle characteristics in the Yongding River Basin.The results indicated that themain recharge source of the groundwater in the piedmont region is precipitation, and evaporationprocess 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 processin the plain region, especially intense evaporation-concentration process for the groundwater inthe shallow aquifer in the plain region.The hydrochemical characteristics of the groundwatermanifested that the mineralization degree of the groundwater ascends gradually from themountain region and the piedmont plain to the seashore plain, and from the shallow aquifer tothe deep aquifer.Evident inter-aquifer recharge phenomena exist between the shallow groundwaterand the deep aquifer under the plain.While the phenomenon of seawater encroaching tothe aquifer does not exist.