Spatial and Temporal Variation Characteristics of Stable Isotopes in Precipitation and Their Relationships with Meteorological Factors in the Shiyang River Basin in China

Stable isotopes of precipitation play an important role in understanding hydrological and climatic processes of arid inland river basins. In order to better understand the difference of regional water cycle and precipitation patterns, precipitation samples were collected in Shiyang River Basin from June 2018 to May 2020, and spatial and temporal variation characteristics of stable isotopes in precipitation and their relationships with meteorological factors were discussed. The results showed that stable isotopes in precipitation showed seasonal variation characteristics, that delta 2H and delta 18O values were higher in summer and autumn and lower in winter and spring, and d-excess values were higher in spring and autumn and lower in winter and summer. Slopes and intercepts of the local meteoric water lines gradually increased with elevation increasing. delta 18O significantly showed a positive correlation with temperature but a negative correlation with precipitation in summer. Contrary to below 15 hPa, delta 18O significantly showed a negative correlation with water vapor pressure above 15 hPa. Due to the influence of meteorological factors, there are significant differences in stable isotopes of precipitation in arid inland river basins, which were more influenced by local moisture recycling in upstream area but by below-cloud secondary evaporation in mid-downstream area.

Automated summary

Stable isotopes of precipitation play a crucial role in understanding hydrological and climatic processes in arid inland river basins. This study collected precipitation samples in the Shiyang River Basin from June 2018 to May 2020 to investigate the spatial and temporal variations of stable isotopes and their relationships with meteorological factors. The results indicate that stable isotopes exhibit seasonal variations, with higher values of delta 2H and delta 18O in summer and autumn, and lower values in winter and spring. The slopes and intercepts of the local meteoric water lines increase with elevation. Additionally, delta 18O shows a positive correlation with temperature and a negative correlation with precipitation in summer.