Abstract:Climate changes can influence the water resources in the Loess Plateau greatly, and evaluating the impacts will provide helpful information for decision\|making of regional development. Based on the SWAT (soil and water Assessment Tools) model and four GCMs (General Circulation Models) under three emission scenarios, this study assessed the potential impacts of climate change on water resources in the Heihe watershed on the Loess Plateau during 2010-2039. Climate models predicted a -2.3% to 7.8% change in annual precipitation, 0.7℃ to 2.2℃ rises in maximum temperature, and 1.2℃ to 2.8 ℃ rises in minimum temperature. Climate change will affect the hydrologic situation of Heihe watershed; SWAT model predicted a -19.8% to 37.0% change for annual runoff, a -5.5% to 17.2% change for annual soil water content, and a 0.1% to 5.9% increase for annual evapotranspiration. Though the change trends of hydro\|meteorological variables are complex, T\|test showed that annual precipitation, runoff, soil water and evapotranspiration would increase with a high probability. For seasonal change, precipitation would possibly increase from December to July and in September while decrease in August and from October to November, runoff would increase from April to July and September to October while decrease in August and from November to March, soil water would possibly increase all the year, evapotranspiration would increase from November to June while decrease from July to October. Overall, the results showed that climate would change significantly and some countermeasures were necessary to reduce the adverse effects.