Characteristics of water isotopes and ice-snowmelt quantification in the Tizinafu River, north Kunlun Mountains, Central Asia

The isotopic composition of river water, precipitation, and ice-snowmelt water have been measured in samples simultaneously collected at 29 sampling sites located at the junction of the principal river course and its tributaries. Distribution of stable isotopes, and temporal and spatial variations of δD and δ18O of river water and the sources of the Tizinafu River were investigated. The δ18O values of river water samples were near the GMWL and LMWL, which indicated similarity in constitution of water sources. We found significant seasonal effect in the water isotope, with maximum values in summer, and minimum values in winter. The d-excess changes in the opposite sense. Response of water isotope and d-excess towards temperature and elevation were assessed by correlation analysis. A negative relationship between elevation and δ18O was found, whereas little relationship was found for the elevation and d-excess. Furthermore, we quantitatively determined the ratio of ice-melt water using isotope hydrograph separation. Results showed the contribution of ice-snowmelt water varied from 25.96% to 68.87% for spatial characteristics, and from 28.31% to 65.43% for seasonal characteristics. The mean of the ice-snowmelt percentage is 43%, which meant that ice-snowmelt water was the main supplying water source for the Tizinafu River. The roles of ice-snowmelt water should be noted in water resource management in glacial rivers.