Multivariate and Geospatial Analysis of River Water Quality in the Andhi Khola Basin, Western Nepal
摘要
The Andhi Khola River is a vital freshwater system in Syangja District, Gandaki Province, Nepal, serving as a primary source for drinking water, irrigation, fishing, and various other livelihood activities for local communities. This research seeks to evaluate the river's hydrochemical composition, overall water quality, and its appropriateness for drinking and irrigation through the application of multivariate statistics, water quality indices, and Geographic Information System (GIS) techniques. To achieve this, 22 hydrochemical parameters were analyzed in river water samples from thirteen sites. The water quality was generally found to be good, with most measured parameters meeting the permissible limits of both the National Drinking Water Quality Standards (NDWQS) and the World Health Organization (WHO). Hydrochemical facies classification using Piper and Durov diagrams showed that the river water is predominantly of the calcium-bicarbonate type, controlled mainly by carbonate mineral dissolution and precipitation processes, as supported by Gibbs and mixing plots. Water Quality Index (WQI) scores classified the water as "excellent" for drinking use across all sampling sites. Suitability for irrigation was evaluated using a set of standard indices such as Sodium Adsorption Ratio (SAR), Sodium Percentage (Na%), Magnesium Hazard (MH), Kelly’s Ratio (KR) and Permeability Index (PI). All indicators suggested that the river water is generally suitable for agricultural use, with only slight limitations noted at isolated stations. Multivariate statistical analyses, including Spearman correlation and cluster analysis, were applied to identify major controlling factors and to classify spatial similarities among sampling points. Geospatial analysis through GIS further enabled visualization of spatial variability and highlighted zones potentially impacted by anthropogenic activities. Overall, the integration of hydrochemical data, statistical evaluation, and GIS-based spatial mapping provides a robust framework for monitoring and managing river water resources. The findings emphasize the importance of regular water quality monitoring and underscore the Andhi Khola River’s critical role in supporting sustainable water use and achieving Sustainable Development Goal 6 (Clean Water and Sanitation).