The Stable Isotope Characteristics of Precipitation in the Middle East Highlighting the Link between the Köppen Climate Classifications and the δ18O and δ2H Values of Precipitation

Abstract

The Middle East is faced with a water shortage crisis due to its semiarid and arid climate. In this paper, precipitation as an important part of the water cycle was evaluated in 43 stations across the Middle East using the stable isotope technique to study the parameters which influence the stable isotope content of precipitation. First, the stepwise regression model was applied to determine the main geographical and climatological factors affecting the stable isotopes in precipitation. Secondly, the stepwise model was also used to simulate the stable isotope values in precipitation. Furthermore, due to the notable climatic variations across the Middle East, the precipitation sampling stations were classified into six groups based on the Köppen climate zones. Significant variations in the stable isotope values of precipitation were observed in the stations of each climate zone. Finally, the Middle East meteoric water line was developed for the dry and wet periods based on the average stable isotopes in the studied stations. The developed lines showed a lower slope compared to the GMWL due to the higher air temperature and relative humidity in the Middle East compared to the average global conditions. To conclude, the stable isotope contents in precipitation showed significant temporal and spatial variations due to the notable climatic variations across the Middle East.