SWAT-Based Streamflow Estimation and Its Responses to Climate Change in the Kadongjia River Watershed, Southern Tibet

Runoff estimation and its response to climate change in ungauged or poorly gauged basins based on hydrological models are frontier research issues of the hydrological cycle. For the Kadongjia River watershed (KRW), a poorly gauged watershed located in southern Tibet, China, the Soil and Water Assessment Tool (SWAT) was adapted to model streamflow and its responses to climate change. The average annual streamflow was simulated to be roughly 124.6 mm with relatively small interannual variation during 1974-2010. The seasonal distribution of streamflow was uneven with a maximum in summer and a minimum in winter. Snowmelt, which was mainly produced in April-May, accounted for 4.0% of annual streamflow. Correlations and regression analysis between the interannual variations of major climatic and hydrological variables indicated that precipitation (temperature) had positive (negative) influence on the annual streamflow variation. For the interannual streamflow variations, warmer temperature was slightly more important than the variation of winter precipitation. Comparing streamflow changes in the current years (1980-99) with the future (2030-49), streamflow variations were more sensitive to changing climate in winter and spring than in the other two seasons. Model improvement is expected to enhance the simulation efficiency of SWAT and the analyses of hydrological responses to climatic change in KRW, thus supporting the model's credibility for hydrological cycle research in alpine regions.