| Abstrakt: |
Seasonal variation and influencing factors of water isotopes were investigated in the Xiangjiang River basin, located in the East Asian monsoon region. This involved comprehensive sampling of precipitation and river water, as well as observing hydrometeorological factors spanning 13 hydrological years from January 2010 to December 2022. Key findings are as follows: River water δ²H (δ²HR) exhibited significant seasonal variation, with the most positive and negative δ²HR occurring in the spring flood period and summer drought, respectively, and generally aligned with those observed in precipitation. The correlations of the δ²HR with the corresponding hydrometeorological factors were generally weak and the reasons can be attributed to the seasonality of precipitation isotopes and mixing of various water bodies within the basin, but the changes in the runoff (ΔR) and δ²HR (Δδ²HR) between two contiguous samplings showed significant responses to the corresponding accumulated precipitation and evaporation. These results underscore the potential of Δδ²HR as a variable that reflects the seasonal variations in local environments, valuable for paleoclimate reconstruction. Prolonged rainless intervals with high evaporation rates in 2013 and 2022, as well as significant precipitation events in major flood periods in 2011 and 2017, notably had a significant impact on the δ²HR and runoff discharge. The most positive δ²HR values were primarily influenced by the precipitation input with the most enriched isotopes in the spring flood period, while the moderately isotope-depleted precipitation during limited basin wetness conditions led to the most negative δ²HR, thus caution is advised when interpreting extreme isotopic signals in river water. The spatial correlation analysis between water isotopes and hydrometeorological factors at the observing site and in the surrounding regions supported the representation of the Changsha site in the Xiangjiang River basin. Overall, these findings provide insights into the seasonal variation and influencing factors of δ²HR in the study area, shedding light on the complex dynamics of river water isotopes under different hydrometeorological conditions. [ABSTRACT FROM AUTHOR] |
