ABSTRACT
In this study, the level of penetration of polluted riverwater on the adjoining aquifers were
carried out. Various tools such as Sodium Absorption Ratio (SAR), Wilcox diagram, United
States Salinity Laboratory (USSL) and Geographical Information System (GIS) were used to
evaluate the quality of water and its suitability for various consumption purposes. Results of
SAR show that many of the wells during premonsoon illustrate high values indicating the
unsuitable nature of groundwater for irrigation but during postmonsoon, SAR values found to
be decreased due to the dilution effect of precipitation by monsoon. Wells belonging to the
1 st layer demonstrates very high SAR value and the subsequent layers show diminished
values indicating the effect of percolation is not significant as the distance increases. Similar
results were found in the case of Wilcox diagram which also substantiates the results of SAR
that the wells pertaining to the 1 st layer is not suitable for irrigation whereas the 2 nd layer
wells display permissible to doubtful reflecting that some of the wells may be used for
irrigation. USSL and Wilcox result clearly state that the wells belonging to the 3 rd to 5 th layer
are suitable for irrigation. Spatial distribution diagram using GIS illustrate that the first zone
belonging to the 1 st layer is highly affected and the last zone (5 th zone) is the least affected
with regard to the percolation of the polluted water from River Noyyal. Overlay map shows
that the wells falling in the northern part of River Noyyal are less polluted compared to the
wells in the southern part.