Integrated groundwater quality assessment using Water Quality Index, complex fuzzy MCDM and GIS Techniques

Groundwater contamination, mainly caused by human activities, is a major environmental issue affecting the availability of safe drinking water. In this study, groundwater quality in Dharmapuri district, Tamil Nadu, India, was assessed using a complex Multi-Criteria Decision-making Model (MCDM). Physicochemical parameters, including total dissolved solids, nitrate, calcium, magnesium, sodium, potassium, chloride, sulphate, bicarbonate, fluoride, pH and electrical conductivity, were measured from 31 wells over the period 2015-2022. The Water Quality Index (WQI) was computed for each sampling location and spatially represented using GIS to classify groundwater into six categories: excellent, good, mediocre, poor, very poor and unsuitable for drinking. The WQI values ranged from 0.00 to 1.00 with a mean value of 0.5, indicating that the groundwater is generally suitable for drinking purposes in the study area. Statistical validation using descriptive measures and Z-score analysis confirmed the relative performance of sampling locations, highlighting significant deviations for high-ranking wells. The model showed strong predictive capability with an Area Under the Curve (AUC) value of 0.993, indicating excellent classification accuracy.