This study attempts to learn the groundwater salinization mechanism in the large and well-populated coastal Gujarat alluvial plain under growing anthropogenic pressures. For this purpose, geochemical compositions and ⁸⁷Sr/⁸⁶Sr were analyzed in 53 groundwater samples collected in the three different seasons during 2016–2017. Additionally, surface water samples collected in each season from two nearby large rivers (Narmada and Tapi) and urban sewage discharge of Surat city were also analyzed. Excluding a few salinity hotspots (EC >8–18 mS/cm), the seasonal average of EC (~2.3–2.5 mS/cm) in groundwater shows little fluctuations negating evaporation as the major salinization process. Localized anthropogenic inputs as traced using NO₃ also fail to explain the widespread groundwater salinity. A strong marine influence on the groundwater salinity is revealed by an average Cl/Br of ~655 ± 104 mol/mol in groundwater (except a few outliers) falling close to the seawater composition. The lateral seawater intrusion at shallow depths is generally not supported by the freshening of coastal groundwater samples and generally seaward movements of shallow groundwater as indicated by regional piezometric heads. However, few (Ca)-Mg-Cl type groundwaters collected from north of the Narmada River fall in the piezometric depressions and hint at seawater intrusion and/or upconing of deep saline aquifers. The Sr isotope budget in most of the alluvial groundwater samples is controlled by the seepage groundwater–seawater mixing. Exceptional ⁸⁷Sr/⁸⁶Sr values owing to Sr inputs from different age terrains are found in the northeastern groundwater and a few groundwater samples collected downslope of ancient deposits in the central alluvium. The upconing of salty waters having marine signatures partly altered by aquifer–water interactions primarily governs the regional groundwater salinity, which makes the study area vulnerable to continued salinization by excessive groundwater extraction.

本研究试图了解在不断增长的人为压力下，人口稠密的沿海古吉拉特邦冲积平原的地下水盐碱化机制。为此，对 2016-2017 年三个不同季节采集的 53 个地下水样品的地球化学成分和⁸⁷ Sr/ ^{86 Sr 进行了分析。}此外，还对附近两条大河（纳尔马达河和塔皮河）在每个季节采集的地表水样本和苏拉特市的城市污水排放进行了分析。排除一些盐度热点（EC >8-18 mS/cm），地下水中 EC 的季节性平均值（~2.3-2.5 mS/cm）几乎没有波动，蒸发是主要的盐渍化过程。_{使用 NO 3}追踪的本地化人为输入也无法解释普遍存在的地下水盐度。地下水（除了少数异常值）接近海水组成的平均 Cl/Br 约为 655 ± 104 mol/mol，揭示了海洋对地下水盐度的强烈影响。浅层的横向海水入侵通常不支持沿海地下水样品的新鲜化和浅层地下水的一般向海运动，如区域测压水头所示。然而，从纳尔默达河以北采集的少量 (Ca)-Mg-Cl 型地下水落入测压洼地，并暗示海水侵入和/或深层盐水含水层的上行。大多数冲积地下水样品中的 Sr 同位素收支受渗流地下水-海水混合控制。优秀的⁸⁷在东北部地下水中发现了不同年代地形的Sr输入Sr/ ^{86 Sr值，并在中部冲积层古沉积物的下坡采集了少量地下水样品}。具有海洋特征的咸水的上升部分因含水层 - 水相互作用而改变，主要控​​制区域地下水盐度，这使得研究区域容易受到地下水过度开采导致持续盐碱化的影响。