Application of groundwater quality index (GWQI) by Deterministic and Probabilistic Approaches to Assess Effect of Land Use Change on Groundwater Quality in the northern county of Iran: non-carcinogenic risk assessment

Abstract This study aimed to evaluate the groundwater quality, land use changes, and non-carcinogenic risk caused by F − , and NO 3 – ions in Babol county's drinking water. A total of 228 samples were collected from 38 drinking water wells between 2016–2021, and analyzed for various chemical parameters to determine the groundwater quality index (GWQI). The results obtained from the deterministic approach indicated that 74.6% of the water sources exhibited good quality, with a GWQI value range of 49.91 to 107.38. However, the Probabilistic Approach revealed that only 0.01% of the water samples demonstrated excellent quality, while the majority (98.37%) were classified as having good quality, with a smaller proportion (1.6%) considered poor. The qualitative zoning of GWQI showed that part of the studied area on the shores of the Caspian Sea and the north of the region is in an unfavorable condition. Principal component analysis (PCA) on parameters of chemicals showed three factors that account for 71.55% of the total variance in the groundwater quality data set. The land use results showed that in residential areas where the population is dense, a higher concentration of NO 3 − is observed. The study also found that the non-carcinogenic risk caused by F − and NO 3 − was below the risk limit (HQ < 1) for all age groups, except for infants in the wet season where 18.4% of the HQ F values were greater than 1. The results showed that NO 3 − concentration had the highest effect on the non-carcinogenic risk in all age groups. This study highlights the importance of monitoring and managing land use changes to maintain the quality of drinking water in Babol County.