Groundwater Quality Assessment Using Statistical and Spatial Approaches in a Rapidly Urbanizing Municipality of Kathmandu Valley, Nepal

ABSTRACT

This study evaluates the groundwater quality of Tarakeshwar Municipality, Kathmandu, Nepal. Groundwater acts as a primary source of water for various domestic uses for a significant portion of the population. This assessment was based on the field study method, where 49 groundwater samples were collected from densely populated areas of Tarakeshwar Municipality during the dry season (December–January). Physicochemical parameters such as pH, turbidity, EC, total hardness, Ca ²⁺ , Mg ²⁺ , Cl ⁻ , NO ₃ ⁻ , NH ₃ , SO ₄ ²⁻ , and alkalinity were determined in those samples. These parameters were evaluated with reference to World Health Organization (WHO) and NDWQS guidelines for drinking water quality standards. Descriptive statistics such as mean, standard deviation, minimum range, and maximum range were computed to determine the variations of each parameter in the study area. Pearson correlation analysis was used to identify the inter‐parameter relationships, which revealed statistically significant relationships among key physicochemical parameters, indicating both geogenic and anthropogenic sources of contamination. Simple linear regression further demonstrated that electrical conductivity (EC) is a strong predictor of change in total hardness, calcium, magnesium, chloride, sulfate, and alkalinity. GIS‐based spatial interpolation techniques were used to generate distribution maps and visually identify contamination hotspots across the municipality's wards. Based on the findings obtained from the research, it can be stated that the quality of groundwater found in some wards within Tarakeshwar Municipality is above the permissible values. Among the major findings, it was found that carbonic dissolution is the primary cause behind mineralization of the groundwater, whereas parameters such as iron, turbidity, total hardness, and ammonia are some of the parameters that require proper monitoring. Analysis of spatial data reveals that the southern and southeastern sections of the region are highly polluted with groundwater contaminants.