Space-Time Characteristics and Environmental Significance of the Stable Isotopes in Precipitation in the Gulang River Basin

Based on the precipitation samples and meteorological data simultaneously collected during individual precipitation events at the Gulang (2 085 m a.s.l.) and Anyuan stations (2 700 m a.s.l.) in Gulang, this article analyzes the temporal variation and local meteroic water lines and discusses the relationship between precipitation stable isotopes and temperature and precipitation and relative humidity. The results show that: ① Gulang and Anyuan have higher δ 18 O values in summer and autumn and lower δ 18 O values in spring and winter, respectively; ② The vaule of δ 18 O decreases with increasing altitude, while the value of the d-excess increases, reflecting the gradual depletion of stable isotopes of precipitation when the air mass is rising along the slope; ③ The slope and intercept of the local meteroic water lines deviate from that of the global meteroic water lines, showing that they may also be affected by local water vapor recirculation, except for the dry environment and strong evaporation effect; and ④ The temperature effect of Gulang in the low-altitude area is more significant than that of the Anyuan station and the Gulang River Basin does not show a precipitation effect. It has been proven that precipitation is not the fundamental factor determining the δ 18 O of the precipitation in arid areas. The results of this study are helpful to further understand the water circulation mechanism in the Gulang River Basin. © 2019, Science Press. All right reserved.