ORIGINAL ARTICLE Spatial assessment of groundwater quality using water quality index and hydrochemical indices in the Kodavanar sub-basin, Tamil Nadu, India K. Kalaivanan 1 • B. Gurugnanam 1 • Hamid Reza Pourghasemi 2 • M. Suresh 3 • S. Kumaravel 4 Received: 25 January 2017 / Accepted: 8 June 2017 Ó Springer International Publishing AG 2017 Abstract The purpose of this study was to assess the drinking and irrigation groundwater quality in Kodavanar sub-basin, Dindigul and Karur region, Tamil Nadu, India. Water samples were measured according to the geological and hydrogeological aspects. Geographically, the study area is situated in 10°11 0 37 00 –10°27 0 30 00 N and 77°37 0 46 00 – 78°01 0 10 00 E with an entire area of 2255 km 2 . Overall, 82 groundwater samples were taken from bore wells and various physicochemical parameters and major ion chem- istry like pH, electrical conductivity, total dissolved solids, calcium, magnesium, sodium, potassium, bicarbonate, chloride, sulfate, nitrate, and phosphate were analyzed. According to the groundwater quality, Gibbs, United States Salinity Laboratory and Wilcox’s diagrams were plotted; and groundwater quality has been illustrated for domestic and agricultural purposes. Gibbs plot results showed that 87% of the sample falls under the rock dominance. Sodium absorption ratio 100%, sodium percentage 85%, and Kel- ly’s ratio 51% recommends that majority of the sample falls under the acceptable border of irrigation and drinking utility. Using geospatial analysis, the water-quality index was calculated. The result shows that most of the area comes under excellent (402 km 2 ) and good (1297 km 2 ) groundwater categories. Based on the studies, the quality of groundwater is safe for drinking purposes, but in a limited sample, which exceed the limit, due to anthropogenic activities. Keywords Groundwater Á Hydrogeochemistry Á Kodavanar sub-basin Á Water quality index Introduction The essential and natural resource for life on earth is water. According to WHO 1984, due to the poor quality of drinking water, the world is affected with 80% of diseases (Manivannan et al. 2011). The assessment of groundwater quantity and quality determined the sustainability of water resources. Due to gradual increase in the population, the demand for groundwater is growing day by day (Singaraja et al. 2015; Selvam et al. 2016). The economy and food production are interlinked with each other, depending mainly on the water availability, which in-turn is the deciding factor for the development of nations at various levels. This is acquired through two great natural causes, i.e., surface water, which includes freshwater lakes, rivers, streams, bore well water and groundwater (Paul Basker 2000; Magesh and Chandrasekar 2013). In developing nations, the supply of safe water for drinking purpose by the inhabitants is a major crisis undergone by the governments. In Kodavanar sub-basin, the scarcity of water is increased highly due to the rapid growth of the population and its socio-economic development. The study area is a hard-rock terrain depends mainly on atmospheric water during the northeast monsoon season. The surface-water & K. Kalaivanan kalai.geo87@gmail.com 1 Centre for Applied Geology, Gandhigram Rural Institute - Deemed University, Gandhigram, Dindigul, India 2 Department of Natural Resources and Environmental Engineering, College of Agriculture, Shiraz University, Shiraz, Iran 3 Department of Civil Engineering, Jayalakshmi Institute of Technology, Thoppur, Dharmapuri, India 4 Department of Earth Sciences, Annamalai University, Annamalainagar, Chidambaram, India 123 Sustain. Water Resour. Manag. DOI 10.1007/s40899-017-0148-x