Determination of Recharge by Means of Isotopes and Water Chemistry in Shaqlawa-Harrir Basin, Kurdistan Region, Iraq

Abstract

Stable isotopes (2H, 18O), 14C determination, and chemical analysis of deep groundwater and surface waters (river and springs) were used to investigate the sources of ground- and surface water, groundwater recharge mechanisms as well as possible sources of ions in groundwater in the semi-arid Shaqlawa-Harrir basin in Kurdistan. One hundred water samples were taken during wet and dry season. The d-excess varies significantly depending on temperature and humidity at the vapor sources. The means of the δ18O and δ2H values in the groundwater samples are -6.8 and -36.8%, for the spring samples -6.3 and -34.5%, and for the river samples -9.2 and -51.3%, respectively. The depletion in the δ18O content of some water samples is due to the higher altitude of some recharge areas (altitude effect). 14C data ranges from 3.4, 71.4 and 82.7 pmC and shows that recharges rates and means residence times vary greatly in the study area. Groundwater was mainly classified as Ca-Mg-HCO3 and Mg-Ca-HCO3 type; only five well water samples belong to the  Na-Ca-HCO3 type. All water samples investigated are suitable to be used as both drinking water and irrigation water.