First comprehensive stable isotope dataset of diverse water units in a permafrost-dominated catchment on the Qinghai–Xizang Plateau

Abstract. Considered as the Asian water tower, the Qinghai–Xizang Plateau (QXP) processes substantial permafrost, where its hydrological environments are spatially differed and can be easily disturbed by changing permafrost and melting ground ice. Permafrost degradation compels melting permafrost to become an important source of surface runoff, changes the storage of groundwater, and greatly influences the hydrological processes in permafrost regions. However, the evidences linking permafrost degradation and hydrological processes on the QXP are lacking, which increase the uncertainties of the evaluation results of changing permafrost on the water resources. Stable isotopes offer valuable information on the connections between changing permafrost (ground ice) and water components. It is therefore particularly important to observe the changes in the stable isotopes of different waterbodies, which can vary over hourly to annual timescales and truly capture the thawing signals and reflect the influence of permafrost (ground ice) on the regional hydrological processes. The Beiluhe Basin (BLH) in the hinterland of QXP were selected, which well integrates all the water components related to hydrological cycles, and is an ideal site to study hydrological effect of permafrost change. This paper presents the temporal data of stable isotopes (δ18O, δD, and d-excess) in different water bodies (precipitation, stream water, thermokarst lake, and groundwater) in the BLH produced between 2017 and 2022. In special, the first detailed stable isotope data of ground ice at 17 boreholes and 2 thaw slumps are presented. A detailed description of the sampling processes, sample pretreating processes, and isotopic data quality control is given. The data firstly described the full seasonal isotope amplitude in the precipitation, stream, and thermokarst lakes, and delineated the depth isotopic variability in ground ice. Totally, 554 precipitation samples, 2402 lakes/ponds samples, 675 stream water samples, 102 supra-permafrost water samples, and 19 sub-permafrost water samples were collected during six years’ continuous sampling work. Importantly, 359 ground ice samples at different depths from 17 boreholes and 2 profiles were collected. This first data set provides a new basis for understanding the hydrological effects of permafrost degradation on the QXP. It also provides supports on the cryospheric study on the Northern Hemisphere.