Groundwater quality assessment and its suitability for drinking and agricultural purpose, Dindigul taluk, Tamilnadu, India

Groundwater samples of Dindigul taluk in the interior part of Tamilnadu, India were evaluated for groundwater quality and its suitability for drinking and irrigation purpose. Positive correlation of EC with most of the parameters suggests that salinity plays a vital role in the enrichment of other parameters. Comparing with the post-monsoon the samples from the pre-monsoon exhibit less quality but are suitable for drinking purposes except in north part of the study area. Almost all the samples come under the standard values and are suitable for drinking as well as irrigation purpose. The average value of TDS, Ca, Mg, Na, K, Cl, SO4, CO3, HCO3, F, pH, EC, TH, SAR, RSC and Na% for pre-monsoon are 923.35, 56.35, 60.11, 179.47, 29.41, 257.59, 99.53, 0.79, 343.91, 0.77, 8.09, 1598.82, 388.24, 3.79, 0.15 and 41.98. Similarly for the post monsoon the values are 664.94, 41.06, 44.45, 137.53, 10.24, 194.94, 53.88, 0.83, 271.21, 0.52, 8.06, 1175.29, 285.59, 3.42, 0.19 and 47.94 respectively. The TH and TDS values imply that the samples are hard to very hard type mostly during the pre-monsoon period. About 41% and 59% of the pre-monsoon have hard and very hard water respectively. Similarly, 64% and remaining 36% in the post-monsoon show hard and very hard water respectively. The very hard hardness of groundwater is due to the presence of alkaline earth such as calcium and magnesium. Northern area samples in the evaporation zone of Gibbs plot suggest the contamination of groundwater through surface processes such as irrigation return flow and some other anthropogenic impacts like domestic sewage disposal. Overall, the samples are suitable for irrigation purpose with an exception that samples with medium salinity and high sodium content were not suitable for irrigation purposes in any type of soil.