Coastal aquifers are strategic and fundamental in the development of touristic areas. The coastal aquifer within the Manglaralto River Basin in Ecuador is essential, as it is the only source of water supply for a large part of the northern part of the Santa Elena province. It is a semi-arid region where high volumes of water are pumped from the aquifer, causing a significant drawdown of groundwater levels, thus affecting the water quality. This work aims to characterize the characteristics of groundwater in the coastal aquifer using hydrochemistry and stable isotopes to propose a hydrogeological conceptual model. The methodology for determining the chemical and isotopic characteristics of groundwater follows the following scheme: (i) studies of ionic concentrations using the Piper diagram, (ii) assessment of the origin of salinity through the Cl/Br ratio, the presence of seawater intrusion through the Hydrochemical Facies Evolution Diagram HFE-D, (iii) characterization of precipitation events using stable isotopes (¹⁸O and ²H), and, (iv) development of a hydrogeological conceptual model of the study area. The results indicate that in the basin there are mixing processes of the existing water in the aquifer with recharge water, direct cation exchange processes in the freshening process during recharge, and evaporation in the unsaturated zone. A conceptual model of the flow system in the basin is built, based on the mentioned processes. The main conclusions are: seawater intrusion is present in the areas of the wells located closest to the coast, urban activity through septic tanks is affecting the quality of the aquifer, and rainfall is highly relevant in the different hydrochemical and isotopic processes that operate in the basin.

中文翻译：

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曼格拉拉托河流域（厄瓜多尔）水域的水化学和同位素表征，有助于沿海含水层的管理

沿海含水层是旅游区发展的战略和基础。厄瓜多尔的曼格拉拉托河流域内的沿海含水层至关重要，因为它是圣埃伦娜省北部大部分地区的唯一供水来源。这是一个半干旱地区，从含水层中抽出大量水，导致地下水位显着下降，从而影响了水质。这项工作旨在利用水化学和稳定同位素表征沿海含水层中地下水的特征，从而提出水文地质概念模型。确定地下水化学和同位素特征的方法遵循以下方案：（i）使用Piper图研究离子浓度，¹⁸ O和² H），以及（iv）开发研究区域的水文地质概念模型。结果表明，该盆地存在含水层中现有水与补给水的混合过程，补给过程中的清新过程中的直接阳离子交换过程以及不饱和区的蒸发过程。基于上述过程，建立了流域内水流系统的概念模型。主要结论是：最靠近沿海地区的井眼中存在海水入侵，通过化粪池进行的城市活动正在影响含水层的质量，并且降雨在该地区开展的不同水化学和同位素过程中具有重要意义。盆地。