Quantifying future changes in glacier melt and river runoff in the headwaters of the Urumqi River, China.

Climate change is likely to have significant effects on the water cycle in glacierized basins. Here, the glacier-enhanced Soil and Water Assessment Tool (SWAT) was employed to simulate glacio-hydrological processes and to estimate the potential hydrological changes driven by downscaled future climate projections of five Global Circulation Models (GCMs) under three Representative Concentration Pathways (RCPs) in the headwaters of the Urumqi River, Tianshan Mountains, China. The evaluation indices indicated that the model performed well at simulating streamflow during the calibration and validation. The GCM-predicted mean temperature and precipitation both increase. The periods of 1966-1995, 2016-2045 and 2066-2095 were used as the baseline, the near future, and the far future periods, respectively. The results showed different runoff characteristics under various scenarios in the Urumqi Glacier No. 1 (UG1) sub-basin and Urumqi River Basin (URB) due to distinct melt water contributions. In the UG1 sub-basin, the ice melt and glacier melt are expected to reach peak water in the near future and sharply decline in the far future, and the sub-basin runoff would gradually decrease under all RCPs. In the URB, the ice melt and glacier melt rapidly decrease but the river runoff remains stable under RCP 2.6 and RCP 4.5, with a slight decrease under RCP 8.5. The grouped glacier area with small size class shows a rapid retreat rate. It was also found that melt water from three grouped glaciers exhibit different responses to future scenarios. [ABSTRACT FROM AUTHOR]