Assessment of Groundwater Quality in Gorgan Using the Groundwater Quality Index (GWQI)

Abstract

Water quality is a fundamental factor that influences all dimensions of ecosystems as well as public health. Numerous researchers emphasize that the provision of safe drinking water, proper sanitation, and efficient management constitute the three essential pillars of community health. Accordingly, the present study aimed to evaluate the groundwater quality index (GWQI) of rural drinking water resources in Gorgan County. A total of 13 sampling stations under the supervision of the Rural Water and Wastewater Company were investigated over a three-year period (2016–2018) to identify temporal trends in groundwater quality. Water samples were analyzed at the laboratories of the Rural Water and Wastewater Company and Golestan Institute of Higher Education using standard analytical methods. The GWQI index was employed to compare groundwater quality across the studied villages. Results revealed that Kaloo village exhibited the lowest GWQI value (37.41, classified as excellent), whereas Ghal’eh Mahmoud village showed the highest (277.39, classified as very poor). Overall, 49% of the groundwater samples were categorized as excellent, 46% as good, and 5% as poor to very poor in terms of drinking suitability. The findings highlight that groundwater in Ghal’eh Mahmoud requires treatment with respect to several chemical parameters, including hardness, turbidity, chloride, and sulfate. Concentrations of iron and fluoride in all drinking water sources remained below permissible limits. Nevertheless, the observed increase in certain parameters in recent years suggests the potential infiltration of wastewater, likely associated with the north-to-south topographic gradient of the region. In recent years, the increase in certain parameters indicates the potential infiltration of wastewater, likely influenced by the north-to-south slope of the area. This issue requires more comprehensive investigations.