SOUNDHARYA, V. AND RAKESH SHARMA, T.
Abstract
Freshwater sources on Earth are vital for human life. However, water bodies are currently becoming polluted due to civilizational growth and various human activities. In the delta districts of Tamil Nadu, the quality of coastal groundwater is deteriorating due to factors such as human activities and seawater intrusion. This study evaluates the suitability of groundwater for irrigation in the Thanjavur and Tiruvarur districts. Groundwater samples were collected from 16 key coastal locations across three seasons (pre-monsoon, northeast monsoon, and post-monsoon); the physico-chemical properties of these samples were analyzed, and irrigation quality indices were calculated. In the post-monsoon samples, Sodium Adsorption Ratio (SAR) values at several locations (SG4 and SG7âSG16), Sodium Percentage at multiple sites (13.92â93.0%), and Permeability Index values at all locations (73.2â98.6%) exceeded their permissible limits. Similarly, Piper diagram analysis reveals the influence of Sodium (Na) and Chloride (Cl). Based on these indices, the study concluded that groundwater at many locations is unsuitable for irrigation during the post-monsoon period when compared to the pre-monsoon and northeast monsoon seasons.