GIS-Based Suitability Measurement of Groundwater Resources for Irrigation in Thoothukudi District, Tamil Nadu, India

A detailed geographic information system-based study on hydrochemistry of groundwater in the Thoothukudi District of Tamilnadu, India has been carried out to assess the quality of groundwater for determining its suitability for irrigation purposes, where agriculture is the dominant economic activity. Hundred groundwater samples spread over the study area have been collected from hand pumps during PRM and POM, respectively. The abundance of major cations in groundwater is in the following order: Na+ > Ca2+ > Mg2+ > K+ and Na+ > Mg2+ > Ca2+ > K+ during PRM and POM seasons, respectively. The abundance of major anions is as follows: Cl- > IICO3- > SO42- > H4SiO4 > NO3- > PO4- > F- and Cl- > IICO3- > SO42- > H4SiO4 > NO3- > F- > PO4- during PRM and POM seasons, respectively. Geostatistical technique of ordinary kriging method was used to create spatial distribution maps. Spatial distribution of electrical conductivity, sodium percentage, sodium absorption ratio, residual sodium carbonate, magnesium hazard, and Kelly's ratio show that eastern part of the study area is unsuitable for irrigation purpose. Similar observations by USSL, Wilcox, and Doneen show that the majority of the samples are unsuitable for irrigation purposes during PRM compared to POM, due to the dilution effect after monsoon. All water quality parameters were correlated with each other.