Abstract: The impact of climate change on local discharge is investigated in a glacierized high mountain catchment — the Tailan River basin in Tianshan Mountain region. Based on the hydrological and meteorological records at Tailan hydrologic station during 2003-2005, the optimum parameters in HBV model are obtained. Tailan River discharge is projected in the middle (2041-2060) and the end (2081-2100) of the 21st century, based on downscaling of RegCM3 under SRES A1B scenario and three scales of deglaciation. The results show that surface air temperature will significantly increase and there is no obvious change in precipitation in Tailan River basin in the two future periods. Three scenarios of glacier shrinkages are proposed at 15%, 20% and 25% in the middle, and 20%, 30%, 40% in the end of the 21st century, respectively. The discharge in Tailan River basin will increase under the glacier shrinkages, relative to the base period (1981-2000). In detail, the minimum increase in discharge will arrive at 17.3% and 18.6% in the middle and the end of the century, respectively. The largest ones will arrive at 45.9% and 66.0%. A moderate increase in discharge will be 28.9% and 41.5% estimated by the HBV model coupled with RegCM3. The seasonal discharge in the two future periods shows the same variation as the base period. The discharge will quickly increase in May in the future two periods. The discharge peak will occur in July in the middle of this century and August in the end of this century. It can be concluded that climate warming and the induced glacier shrinkage will increase the runoff amount, and will finally result in the allocation of the water resources in the catchment.

Key words: discharge estimation, HBV model, climate warming, glacier shrinkage, Tailan River basin