An Integrated Approach of Hydrogeochemistry, Statistical Analysis, and Drinking Water Quality Index for Groundwater Assessment

Abstract

Groundwater is the major source of water for different purposes in many parts of Iran. Therefore, its quality assessment is of great interest. This research aims to consider the general conditions of groundwater for drinking purposes in a coastal aquifer by using an integrated approach of hydrogeochemistry evaluation and drinking water quality index. Statistical results of major cations (Ca2+, Mg2+, Na+ and K+), major anions (HCO3−, SO42− and Cl−), pH, EC and TDS concentrations show that the abundant cations and anions are in the order of Ca2+ > Na+ > Mg2+ > K+ and HCO3− > Cl− > SO42−, respectively. Chadha plot and Piper diagram point out Ca-Mg-HCO3 as the dominant groundwater chemical types in all sampling points in the recharge zone (Zone A), and the majority of wells in the central zone (Zone B) and the coastline zone (Zone C). Na-Cl hydrochemical facies in the eastern part of Zone C is related to saltwater intrusion from the Caspian Sea or the upconing of underlying connate water. The ionic ratios reveal that rock weathering and mineral dissolution, evaporation, the overuses of fertilizers, and the upconing of paleo-saline water control the chemical evolution of groundwater. The proposed drinking water quality index (DWQI) exhibits a poor quality of water in the north-east of the area, while the quality of groundwater falls in the “good” class in the south-west of the area. Generally, the quality of groundwater deteriorates from the south-west towards the north-east of the aquifer, and the eastern part of Zone B has the best quality of water for drinking purposes.