A review of research dealing with isotope hydrology in Iran and the first Iranian meteoric water line

For more than half a century isotopes have been employed as a powerful tool in studying various aspects of water resources in a large number of countries. However, in developing countries like Iran the application of such techniques is in its infancy. The first research in Iran was carried out in 1975 to identify the source of saline groundwaters in south Iran, and the first national conference on the application of stable isotopes was held in 2013. Altogether, there are 70 publications which fall into seven categories, including the isotopic composition of precipitation/groundwater (35.75%), sources of salinization and hydrothermal water (18.57%), natural recharge and recharge areas of springs (17.14%), informative studies and groundwater modelling (11.42%), groundwater–surface water interaction (7.14%), karst development and hydrograph separation (5.71%), and pollution and pollutant transportation (4.28%). Nationwide, there are issues which require the application of isotopes (e.g., the determination of recharge areas of important springs and the identification of the sources of groundwater pollution) but a lack of laboratory facilities does not allow scientists to tackle these problems. In this research, we have also constructed the first Iranian meteoric water line, the slope and the deuterium excess of which are 6.89 and 6.57‰, respectively.