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Artificial recharge is a technique used to recharge the groundwater resources which exploited by pumping for irrigation and drinking purpose. An artificial recharge structures are practiced in the hard rock regions of Tamil Nadu for groundwater restoration and also to enhance the groundwater quality. In the present study, an existing recharge structures in Thondamuthur block of was selected to assess the impact of artificial recharge structures in enhancing the groundwater quality. The considerable improvement in groundwater quality was observed due to the effect of artificial recharge structures. The maximum water quality improvement was observed near the artificial recharge structures at downstream side. The standard of irrigation water was improved during post monsoon period. Hence, it is recommended to recharge the groundwater artificially by constructing artificial recharge structures wherever feasible in the study area.

CTo assess the quality of ground water and its suitability for irrigation, a study was carried out during pre and post monsoon seasons of 2006-2007. In the present study, the ground water samples from open wells, bore wells and dug cum bore wells were collected in the Noyyal river basin that encompasses the urban and industrial stretch of Tirupur. The values of EC ranged from 0.41 to 15.95 dSm-1 and pH ranged from 7.61 to 8.61. Sodium dominated among the cations and chloride among the anions. The sequence of cations found to be Na + >Mg 2+ >Ca 2+ >K + and anions followed the sequence of Cl - > SO 4 2- >HCO 3 - >CO 3 2- . Salinity and sodicity classes were assessed as per Richards (1969). Very high salinity category (C4) dominated (56.90 per cent) and low sodium (S 1 class) (74.14 per cent) category recorded the major classes of salinity and sodicity respectively. Residual sodium carbonate and Residual Sodium Bicarbonate content classified under satisfactory with 68.9 per cent (<1.25 m.e L -1 ) and 87.93 per cent (<5 m.e L-1 ) respectively. Classification of the samples based on salinity and SAR indicated that 68.97 per cent of samples did not pose infiltration problem to the soils and 31.03 per cent will result in slight to moderate infiltration due to irrigation. It was found that 50 per cent of samples having slight to moderate (0.7 t0 3.0 dSm -1 ) salinity problem followed by 43.01 per cent under severe salinity (>3.0 dSm-1 ). Sodium and chloride toxicity were found in majority of the samples. Slight to moderate toxicity of sodium (SAR>9) was recorded by 67.24 per cent of samples which may cause accumulation of sodium over a long period.

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The irrigation water quality is gaining importance day by day due to the changes in the urbanisation and industrialisation which over utilise the under ground water. The ground water samples were collected from 15 revenue villages of Melur block, Madurai, Tamil Nadu during March, 2017 at variegated intervals, processed and analysed for the physico-chemical, anionic and cationic parameters to find out their quality by arriving calculated parameters viz., RSC (Residual Sodium Carbonate) and SAR (Sodium Absorption Ratio). Though the overall values lies well within the safe limit of water quality, the 25 percent water samples found to be alkaline, 42 percent found to slightly saline & two percent found to be critical in salinity levels. The highest value of 9.23, 2.62 dSm -1 , 3.52 and 8.51 of pH, EC, RSC and SAR were observed in the irrigation water samples. The good quality of 92.8 per cent, marginally saline 2.9 per cent and marginally alkali of 4.3 per cent of irrigation water samples have been recorded as per AICRP, 1989 classification.