Environmental Isotopes of Water as Potential Tool to Distinguish the Sources of Groundwater Recharge in a Semi-arid Region: A Case Study Around Veeranam Tank, Tamil Nadu, India

Stable isotope ratios of hydrogen and oxygen (δ18O and δD) were analysed for different water sources around Veeranam Tank in Cuddalore District of Tamil Nadu, India, to understand the groundwater recharge sources in the region. Water samples were collected from the tank, open wells, deep bore wells and the feeding stream (Vadavar River) in the vicinity of the Veeranam Tank for stable isotope measurements. δ18O of the water from open wells ranges from –5.07 to 1.25‰ and δD ranges from − 32.93 to 3.01‰ with the mean concentrations of δ18O and δD of − 1.84‰ and − 15.30‰, respectively. The δ18O and δD values of the deep bore wells range from − 5.23 to − 3.28‰ and − 37.21 to − 23.09‰, respectively. The mean concentrations of δ18O and δD in the deep bore well water are − 4.52‰ and − 31.25‰, respectively. In the tank water, δ18O ranges from 1.10 to 1.45‰ and δD ranges from 1.65‰ to 4.14‰ with the mean concentrations of δ18O and δD of 1.22‰ and 3.26‰, respectively. δ18O versus δD plot and d-excess value were interpreted to distinguish the predominant sources of recharge of wells in the location. The study identified the wells that are recharged predominantly by rain water and also by the tank. © 2023, The Institution of Engineers (India).