Abstract: Based on hydrological cycle theory, this paper analyzed the intra-annual and inter-annual variation characteristics of precipitation, evaporation and temperature at Golmud River Catchment, Qinghai, China, in recent 60 years, by using trend analysis, Morlet wavelet function, and combining qualitative judgments and quantitative analysis. The results show:the climate of study area is transforming from cold-dry to warm-wet,and the temperature exhibited a wavelike rises trend. Since 1955, the temperature has risen 0.37℃; since 1967, the temperature rising rate of study area increased significantly. Since 1968, the precipitation of Golmud River Catchment increased significantly, with the average precipitation of 38.27 mm·a^-1; precipitation increase in July and August contributed most to the annual precipitation increase. The evaporation of study area has decreased from 3 278.2 mm·a^-1 in 1956 to 2 211.57 mm·a^-1 in 2014, with the average decrease rate of 18.08 mm·a^-1. Precipitation, temperature and evaporation all presented multi-time scale features. The precipitation had the periods of 14-16 a or 32-36 a oscillations, the evaporation had the periods of 9-12 a or 24-27 a oscillations and temperature had the periods of 7-8 a or 25-27 a oscillations. According to the characteristic of precipitation cycle, the precipitation will increase for few years from 2016 to 2030, but the evaporation will decrease in the next 10 a. The analysis results offer evidences to further study on water resources development and guides to exploit water resource reasonably.

Key words: precipitation, evaporation, temperature, Morlet wavelet, Golmud River Catchment