Isotope Evidence of Rainfall and Groundwater for Tracing Recharge Areas in Kaeng Khoi District, Saraburi Province, Thailand

Abstract

This study was conducted in the districts of Kaeng Khoi and Muang, located in the center of Saraburiprovince, Central Thailand. The purpose was to use a stable isotope technique to iden-tify recharge areas where rainfall infiltrates. Analysis of stable isotopes in groundwater, surface water and rainwater were conducted in September 2014. Isotope compositions of groundwater were found to have δD values that ranged from -37.55‰ to -48.04‰ while δ18O values ranged from -5.30‰ to -7.34‰. The Local Meteoric Water Line (LMWL) in the study area was indis-tinguishablefrom the Bangkok Local Meteoric Water Line (BKK LMWL), and the stable iso-tope values of rainwater in area were more depleted than BKK LMWL. The isotope compo-sitions of surface water revealed that the effect of evaporation could divide the groundwater into two groups, with the first group locally receiving rainfall and the second group interacting directly with surface water. Therefore, care must be taken to prevent groundwater contamination in the latter group due to polluted surface water caused by human activities.