CSIR-National Geophysical Research Institute, Hyderabad, 500007, India.
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
Environ Sci Pollut Res Int. 2024 Sep;31(44):56272-56294. doi: 10.1007/s11356-024-34930-2. Epub 2024 Sep 12.
Seawater intrusion seriously threatens the quality of coastal groundwater, affecting nearly 40% of the world's population in coastal areas. A study was conducted in the Kamini watershed situated in the Udupi district of Karnataka to assess the groundwater quality and extent of seawater intrusion. During the pre-monsoon period, 57 groundwater and 3 surface water samples were analyzed to understand the impact of seawater on the groundwater and surface water. The analysis revealed that the groundwater in the study area is slightly alkaline. The weighted overlay analysis map indicated that 11% of the study area is unsuitable for drinking water due to the influence of seawater. The Piper plot analysis revealed that the groundwater is predominantly CaMgCl facies. The hydrogeochemical facies evolution diagram (HFED) showed that 62% of the groundwater is affected by seawater. The HFED and Piper plots also indicate that the surface water is also affected by seawater. These results are also supported by various molar ratios such as Cl vs. Cl⁻/HCO⁻, Cl⁻ vs. Na⁺/Cl⁻, Cl vs. SO/Cl, and Cl⁻/HCO vs. Mg/Ca, suggesting that the majority of the water sample has been affected by seawater. The saturation indices indicated that mineral dissolution has significantly contributed to groundwater salinization. The correlation between sulfate concentration and calcite and dolomite dissolution suggested the influence of seawater intrusion in the coastal aquifer. The process of reverse ion exchange mainly influences the groundwater chemistry according to chloroalkali indices. The total hazard index (THI) values of nitrate and fluoride exceeded limits, posing health risks to adults and children. Studies suggest that with time and space, seawater intrusion is increasing in some pockets of the study area, especially along the west coast.
海水入侵严重威胁沿海地区地下水质量，影响近 40%的沿海人口。本研究在卡纳塔克邦乌杜皮区的卡米尼流域进行，旨在评估地下水质量和海水入侵程度。在旱季前，对 57 个地下水和 3 个地表水样本进行了分析，以了解海水对地下水和地表水的影响。分析表明，研究区地下水呈弱碱性。加权叠加分析图表明，由于海水的影响，研究区 11%的地区不适宜作为饮用水。皮尔逊图分析表明，地下水主要为 CaMgCl 相。水地球化学相演化图（HFED）显示，62%的地下水受到海水的影响。HFED 和皮尔逊图还表明地表水也受到海水的影响。各种摩尔比（如 Cl 与 Cl⁻/HCO⁻、Cl⁻与 Na⁺/Cl⁻、Cl 与 SO/Cl 和 Cl⁻/HCO 与 Mg/Ca）也支持了这些结果，表明大多数水样已受到海水影响。饱和度指数表明，矿物溶解对地下水盐化有显著贡献。硫酸盐浓度与方解石和白云石溶解之间的相关性表明，海水入侵影响了沿海含水层。根据氯碱指数，反向离子交换过程主要影响地下水化学。硝酸盐和氟化物的总危害指数（THI）值超过了限值，对成人和儿童的健康构成了威胁。研究表明，随着时间和空间的推移，海水入侵在研究区的一些地区，特别是西海岸，正在加剧。
