Global warming has become an indisputable fact over the past century, while much research has shown that the rate of potential evapotranspiration had been consistently decreasing throughout the world over the past 50 years. This phenomenon is called the “evaporation paradox.” In this study we tested the trends of potential evapotranspiration and air temperature, and analyzed the effects of climate change on streamflow. The conclusions include:
1) The potential evapotranspiration of the Lijiang watershed is significantly decreased at the 0.1 confidence level and temperature is significantly increased at the 0.01 confidence level.
2) Evaporation paradox exists in the Lijiang watershed, caused mainly by sunshine duration decrease.
3) The annual streamflow and precipitation of Lijiang watershed both showed a decreased trend: compared between the first decade of 1976-1985 and the last decade of 2006-2015, streamflow decreased 8.48% and precipitation decreased 7.65%.
4) The sensitivities of streamflow to precipitation and potential evapotranspiration were 1.4152 and -0.4152, respectively, and the effects of precipitation and potential evapotranspiration on streamflow were a 10.83% decrease and 1.67% increase, respectively.