Coastal aquifers are complex groundwater bearing zones with multiple ways of interacting with seawater. Understanding of the main controls and evolution of such aquifers is essential for effective management of the groundwater. In this paper, a comprehensive study was conducted to characterize and identify the main factors and processes controlling the groundwater quality in some coastal aquifers through an integrated approach of Principal Component Analysis (PCA), Cluster Analysis (CA), geostatistical analysis and information entropy-based groundwater quality index coupled with detailed hydrogeochemical assessments. The PCA and CA yielded four clusters with distinct hydrogeochemical signatures (Cluster 1 and 2: freshwater influenced by rain, Cluster 3 transition zone and Cluster 4 marine influence/seawater intrusion or aerosol spray). Geostatistical analysis showed a wide variation in salinity from the coast to the inland while piper diagram revealed the evolution of the aquifers from Ca–HCO₃, Ca–Cl which correspond to natural recharge zone in the north, to mixed Ca–Na–Mg–Cl–HCO₃ representing transition and Na–Cl towards the coast. The water suitability assessment for drinking using entropy-based groundwater quality index showed that about 59.4%, 20.3%, 7.8%, 2.6%, and 9.9% of the groundwater sample were estimated to be excellent, good, average/medium, poor, and extremely poor water quality. Ion exchange mechanism, dissolution of minerals from the rocks and marine influence are the dominant processes controlling the groundwater chemistry in the area. Recommendations for groundwater resource management and future research needs have also been discussed.

沿海含水层是复杂的地下水承载区，具有多种与海水相互作用的方式。了解此类含水层的主要控制和演变对于有效管理地下水至关重要。本文通过主成分分析（PCA）、聚类分析（CA）、地质统计分析和信息熵的综合方法，进行了一项综合研究，表征和识别控制一些沿海含水层地下水质量的主要因素和过程。基于地下水质量指数以及详细的水文地球化学评估。PCA 和 CA 产生了四个具有不同水文地球化学特征的集群（集群 1 和 2：受雨水影响的淡水、集群 3 过渡带和集群 4 海洋影响/海水入侵或气溶胶喷雾）。₃，Ca-Cl 对应于北部的自然补给区，混合 Ca-Na-Mg-Cl-HCO ₃代表过渡和 Na-Cl 向海岸。使用基于熵的地下水水质指数进行饮用水适宜性评估表明，大约 59.4%、20.3%、7.8%、2.6% 和 9.9% 的地下水样本被估计为优、良、一般/中等、差和水质极差。离子交换机制、岩石中矿物质的溶解和海洋影响是控制该地区地下水化学的主要过程。还讨论了对地下水资源管理和未来研究需求的建议。