Evaluation of the groundwater quality feasibility zones for irrigational purposes through GIS in Omalur Taluk, Salem District, South India

The present work is employed in Omalur Taluk (study area 538.10 km²), Salem District, Tamil Nadu, India. Eighty-nine groundwater samples were collected during pre-monsoon (May) 2011 and were analyzed for major cations and anions. The irrigational parameters like; EC, Kelley’s ratio, sodium absorption ratio (SAR) values, Mg²⁺ hazards, HCO₃ ^? and residual sodium carbonate (RSC) have been worked out to know the suitability of the groundwater for irrigational purpose. Wilcox diagram indicates that out of 89 samples, 39 samples belong to good permissible category and Doneen diagram revealed that 98.88 % of the groundwater samples fall in Class I. The plotting of SAR values in USSL diagram indicates that all the samples have low SAR value. Out of 89 samples, 44 samples were in C₃-S₁ field. This implies that no alkali hazard is anticipated to the crops. In 44 locations (49.44 %), samples fall within C₃-S₁ category. This category is suitable for irrigation purpose. However, the concentration of bicarbonate was in significant amount showing 82 % of sites under “increasing problem” and the 4 % sites under “Severe Problem” zones. Finally, the above-said results are taken into a Geographic Information System (GIS) platform. To understand the spatial distribution of unsuitable zones, ArcGIS was employed. The present work reveals that groundwater in the Omalur Taluk is of good quality and is suitable for all uses including interbrain water transfer in the region.