Research articles
ScienceAsia 44 (2018): 403-412 |doi:
10.2306/scienceasia1513-1874.2018.44.403
Study on the stable isotopes in surface waters of the
Naqu River basin, Tibetan Plateau
Guoqiang Donga,b, Baisha Wengb, Tianling Qinb, Denghua Yanb,*, Hao Wangb, Boya Gongb,
Wuxia Bib,c, Jianwei Wangb
ABSTRACT: To enhance our understanding of the regional hydroclimate in the Central Tibetan Plateau, different
types of water samples were collected across the Naqu River basin in the summer (July, August) and winter (January,
December) of 2017 for isotopic analysis. With Cuona Lake as the demarcation point, the ?18O values of the river water
increased initially and then decreased from upstream to downstream along the river?s mainstream. In the Naqu River
system, a general decrease of ?18O values in the trunk stream of the lower reaches (from the head of Cuona Lake)
was revealed owing to the gradual dilution of increased isotopically-depleted tributary inflow. Lakes play an important
role in regulating runoff and changes in the levels of stable isotopes in rivers or streams. Additionally, the decrease of
?18O is controlled by processes involved in the ?isotopic altitude effect?. Larger contributions of winter precipitation in
surface runoff at higher elevations would produce higher deuterium excess in stream water. On the regional scale, with
Cuona Lake as the demarcation point, one of the clearest findings was that the river/stream?s deuterium excess values
decreased first and then increased from the south to the north in the summer; but there was a positive linear increase
in the winter. From geographical and climatological perspectives, the changes of deuterium excess could result from
increasing effects of summertime, and the generation of continental/local recycled and monsoonal water vapor in the
surface runoff northward. The study area is at the critical transition between the Indian monsoon system in the South
and the Northern belt of the westerlies, as revealed by the intermediate deuterium excess values.
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| a |
College of Environmental Science and Engineering, Donghua University, Shanghai 201620 China |
| b |
State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of
Water Resources and Hydropower Research, Beijing 100038 China |
| c |
College of Hydrology and Water Resources, Hohai University, Nanjing 210098 China |
* Corresponding author, E-mail: 2327139543@qq.com
Received 30 Jan 2018, Accepted 3 Nov 2018
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