Comprehensive Assessment of Water Quality of a Transboundary River in Nepal Using Hydro-Chemical, Chemometric, Health Risk and Index-Based Approaches

Abstract

In this study, advanced hydro-chemical analysis, chemometric techniques, health risk assessment and various indices were used to comprehensively assess the water quality of Mahakali River, which is an essential water resource for Nepal and India. Most parameters measured in the water samples collected from 25 sites in the basin during the pre- and post-monsoon periods were found to be compliance with drinking water standards, except NH 4 + and Fe. The Water Quality Index values classified both the main river and its tributary (Chameliya River) as “unsuitable” for drinking. Nutrient pollution was found to be more severe in the tributary, which is much more affected by anthropogenic activities than the main river. Hydro-chemical analysis showed that the dominant water type in the basin is Ca–HCO 3 , which is mainly controlled by rock weathering. Apart from the magnesium hazard index, other irrigation indices confirmed that the surface water of the study area is suitable for agriculture. Chemometric methods provided deeper insights into the water chemistry of the basin by revealing pollution sources and relationships between parameters. Health risk assessment revealed minimal adverse health effects for children and adults exposed to NO 3 –N, Fe and F − . This pioneering study not only provides a holistic evaluation of water quality in a Himalayan glacier-fed river system but also establishes an innovative framework for sustainable water management in climate-sensitive regions worldwide.

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