Comparative evaluation of water quality zonation within Dwarka River Basin, India.

This study evaluates the thematic representation of drinking water quality of 211 habitations along the Dwarka River Basin (DRB), West Bengal, India. The dominant water type is Ca-Mg-HCO₃. Statistical analysis of the spatial dataset indicates a clustering pattern (with a nearest-neighbour ratio of 0.368 and Z score of 29.774). Two different techniques, spatial interpolation of water quality index (WQI) and composite water quality index (WQIC) of physico-chemical constituents, were implemented to compare their performance. The WQI_C indicates approximately 11.68% of the total study area is at non-permissible levels, whereas the normal WQI technique predicts about 1.64% of the area is in non-permissible zones. Spatial water quality zonation by means of the overlay technique was superior to the conventional WQI technique in precisely distinguishing the characteristics of the permissible area with respect to even a single WHO recommended water quality parameter. [ABSTRACT FROM AUTHOR]