Surface Water Quality Assessment of the Arkavathi Reservoir Catchment and Command Area, India, through Multivariate Analysis: A Study in Seasonal and Sub-Watershed Variations

The Arkavathi River, one of the major tributaries of the Cauvery River in southern India, is a major source of drinking water and agricultural irrigation to villages and townships in the region. Surface water quality distribution and characteristics of the Arkavathi Reservoir catchment and command area were evaluated using multivariate statistical analysis on 29 water quality parameters collected across 30 monitoring stations over a two-year, three-season period. Factor analysis (FA), agglomerative hierarchical clustering (AHC), analysis of variance (ANOVA) and t-tests were used to reveal strong links between parameters and to reveal significant variations in their concentration levels with respect to monsoon seasons and sampling locations across the sub-watersheds. Results from factor analysis showed strong groupings of specific parameters across seasons, while results from clustering revealed distinct clusters of sampling points around the river, upstream from the reservoir (where human activity is high), in the command area downstream from the reservoir (where irrigation activity is similar), in hilly regions towards the northeast of the study area and in the scrubland regions. Based on multivariate analysis findings, specific recommendations are made for water quality improvement in the reservoir catchment and command area.