ABSTRACT

In many areas around the world, phreatic coastal aquifers are vulnerable to contamination and saltwater intrusion. This study aims to explore the hydrodynamic functioning of the coastal phreatic aquifer of the Urabá region, Colombia, based on the identification of hydrogeochemical processes and groundwater residence and transit times. Hydrodynamic data showed a fast response of the piezometric levels to precipitation with a maximum time lag of 48 h. Mean annual recharge was estimated at 19% with respect to precipitation. Another recharge mode is linked to infiltration from surface water, according to the hydrodynamic results. The main geochemical process identified is hydrolysis due to dissolved carbon dioxide, inducing silicate weathering and resulting in predominant HCO₃-Ca-Mg facies. Monitoring of δ¹⁸O and δ²H compositions combined with ³H, ¹⁴C, chlorofluorocarbons (CFCs) and SF₆ contents showed a fast recharge in the aquifer. Groundwater dating indicates recent waters mixed with older (>40 years) waters.

摘要

在世界许多地区，潜水的沿海含水层很容易受到污染和盐水的入侵。这项研究的目的是在确定水文地球化学过程和地下水的滞留和传播时间的基础上，探索哥伦比亚乌拉巴地区沿海潜水含水层的水动力功能。流体力学数据显示出压强水平对降水的快速响应，最大时滞为48小时。估计平均年补给量为降水量的19％。根据流体动力学结果，另一种补给模式与地表水的渗透有关。所确定的主要地球化学过程是由于溶解的二氧化碳引起的水解，导致硅酸盐风化并导致主要的HCO ₃ -Ca-Mg相。监测δ¹⁸ O和δ ^2对与组合ħ组合物³ H，¹⁴ C，氯氟烃（CFCs）和SF _6页的内容显示在所述含水层快速补给。地下水定年表明最近的水与较旧的（> 40年）水混合在一起。