Unraveling of permafrost hydrological variabilities on Central Qinghai-Tibet Plateau using stable isotopic technique

Yuzhong Yang; Qingbai Wu; Yandong Hou; Zhongqiong Zhang; Jing Zhan; Siru Gao; Huijun Jin

doi:10.1016/j.scitotenv.2017.06.213

Unraveling of permafrost hydrological variabilities on Central Qinghai-Tibet Plateau using stable isotopic technique

Sci Total Environ. 2017 Dec 15:605-606:199-210. doi: 10.1016/j.scitotenv.2017.06.213. Epub 2017 Jun 28.

Authors

Yuzhong Yang¹, Qingbai Wu², Yandong Hou³, Zhongqiong Zhang¹, Jing Zhan¹, Siru Gao¹, Huijun Jin¹

Affiliations

¹ State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China.
² State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China; Beiluhe Observation Station of Frozen Soil Environment and Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China. Electronic address: qbwu@lzb.ac.cn.
³ School of Civil Engineering, Lanzhou University of Technology, China.

PMID: 28667847
DOI: 10.1016/j.scitotenv.2017.06.213

Abstract

Permafrost degradation on the Qinghai-Tibet Plateau (QTP) will substantially alter the surface runoff discharge and generation, which changes the recharge processes and influences the hydrological cycle on the QTP. Hydrological connections between different water bodies and the influence of thawing permafrost (ground ice) are not well understood on the QTP. This study applied water stable isotopic method to investigate the permafrost hydrological variabilities in Beiluhe Basin (BLB) on Central QTP. Isotopic variations of precipitation, river flow, thermokarst lake, and near-surface ground ice were identified to figure out the moisture source of them, and to elaborate the hydrological connections in permafrost region. Results suggested that isotopic seasonalities in precipitation is evident, it is showing more positive values in summer seasons, and negative values in winter seasons. Stable isotopes of river flow are mainly distributed in the range of precipitation which is indicative of important replenishment from precipitation. δ¹⁸O, δD of thermokarst lakes are more positive than precipitation, indicating of basin-scale evaporation of lake water. Comparison of δ_I values in different water bodies shows that hydrology of thermokarst lakes was related to thawing of permafrost (ground ice) and precipitation. Near-surface ground ice in BLB exhibits different isotopic characteristics, and generates a special δD-δ¹⁸O relationship (freezing line): δD=5.81δ¹⁸O-23.02, which reflects typical freezing of liquid water. From isotopic analysis, it is inferred that near-surface ground ice was mainly recharged by precipitation and active layer water. Stable isotopic and conceptual model is suggestive of striking hydrological connections between precipitation, river flow, thermokarst lake, and ground ice under degrading permafrost. This research provides fundamental comprehensions into the hydrological processes in permafrost regions on QTP, which should be considered in investigating the influence of thawing permafrost on the hydrological cycle on QTP.

Keywords: Ground ice; Permafrost hydrology; Qinghai-Tibet Plateau; Stable isotopes.