Simulation and Regression Models of Arithmetic Groundwater Quality Indices in Coastal Purba Medinipur, India: Seasonal Trends and Remedial Strategies

Seventy-one percent of the Earth’s surface is covered by water, with groundwater being one of the most important natural resources globally. In Purba Medinipur, the population growth rate has surged to ~0.75% per annum, outpacing that of West Bengal, due to agricultural and industrial development. Urbanization has led to an increase in the built-up area by 139.10% per annum, which has reduced the percolation of water into the groundwater table. Currently, 72% blocks are affected by salinity. Groundwater quality parameters such as pH, total dissolved solids (TDS), turbidity, iron, manganese, total hardness, and chloride were assessed over three seasons—pre-monsoon, monsoon, and post-monsoon—using 326 data points from 2015 to 2022. Turbidity and iron are the primary concerns for groundwater quality, contributing to pollution. Other parameters, including TDS and total hardness, were approaching acceptable limits across all seasons. Since 2021, turbidity has exceeded permissible limits during the pre-monsoon season, resulting from the dissolved minerals and seawater intrusion. The arithmetic weighted groundwater quality index has shown an increasing magnitude over time, indicating a decline in drinking water quality by 2030. The pre-monsoon season exhibits the most severely affected groundwater quality. Principal component analysis indicated that TDS and chloride are the major contaminants during the pre-monsoon, confirming seawater intrusion. In other seasons, metals like iron, TDSs, and manganese are significant contaminants. The hydraulic barriers, subsurface dams, and hybrid treatment can be adopted in the study area to abate the increasing groundwater quality concentration both on a yearly and seasonal basis.