Evaluation of seasonal and spatial variations in vulnerable zones for poor groundwater quality is essential for the protection of human health and to maintain the crop yields. With this objective, groundwater samples were collected seasonally (i.e., pre- and post-monsoon) from the Yellareddygudem watershed of Telangana, India. These samples were analysed for major chemical parameters (pH, TDS, Ca²⁺, Mg²⁺, Na⁺, K⁺, \({\text{HCO}}_{3}^{ - }\), Cl⁻, \({\text{SO}}_{4}^{2 - }\), \({\text{NO}}_{3}^{ - }\), and F⁻). Geographical information system (GIS) tools were used to delineate the seasonal and spatial variations for vulnerable zones related to the drinking groundwater quality index (DGQI) and irrigation groundwater quality index (IGQI). Geochemical facies and relations, Piper diagrams, and principal component analysis indicated that the weathering, dissolution, leaching, ion exchange, and evaporation were the primary processes controlling the groundwater quality seasonally. Human influences were the secondary factors. The TDS, Na⁺, K⁺, Cl⁻, \({\text{SO}}_{4}^{2 - }\), and F⁻ parameters were observed to be within the drinking water quality standard limits in most post-monsoon groundwater samples. However, the DGQI showed an increase in the number of samples with unsuitable quality for drinking in the post-monsoon period compared with the pre-monsoon period. The IGQI demonstrated that the number of samples with unsuitable quality for irrigation increased in the post-monsoon period compared to the pre-monsoon period. The differences in the vulnerable zones between the pre- and post-monsoon periods were due to variations in groundwater recharge, following the topography. Thus, the present study will help decision makers to plan groundwater treatment measures within vulnerable zones.

对脆弱地区地下水质量差的季节和空间变化进行评估对于保护人类健康和维持农作物产量至关重要。为此，从印度特兰甘纳邦的耶拉雷迪古德姆流域按季节（即季风前后）采集了地下水样品。这些样品进行分析的主要化学参数（pH值，TDS，钙²⁺，镁²⁺，钠⁺，K ⁺，\（{\文本{HCO}} _ {3} ^ { - } \），氯^- ，\（{\文本{SO}} _ {4} ^ {2 - } \），\（{\文本{NO}} _ {3} ^ { - } \），和F ^-）。地理信息系统（GIS）工具用于描述与饮用水地下水质量指数（DGQI）和灌溉地下水质量指数（IGQI）相关的脆弱地区的季节性和空间变化。地球化学相和关系，Piper图和主成分分析表明，风化，溶解，浸出，离子交换和蒸发是季节性控制地下水质量的主要过程。人为因素是次要因素。的TDS，钠⁺，K ⁺，氯^-，\（{\文本{SO}} _ {4} ^ {2 - } \），和F ^-在大多数季风后的地下水样本中，观测到的参数均在饮用水水质标准范围内。然而，与季风前相比，季风后时期的DGQI显示不适合饮用质量的样品数量有所增加。IGQI证明，与季风前相比，季风后时期灌溉质量不合格的样本数量有所增加。季风前后前后脆弱区域的差异是由于地形后地下水补给量的变化。因此，本研究将帮助决策者计划脆弱地区的地下水处理措施。