Abstract:

The Penman-Monteith model was applied to estimate the values of evapotranspiration (ET0) in the Qaidam Basin during the period of 1961-2017 based on the meteorological data from 8 meteorological stations. Then the values of surface humid index were derived, and the climate tendency rate, IDW interpolation, M-K test, Morlet wavelet and principal component analysis were used to analyze the spatiotemporal variation of humid index and its affecting factors in the study area. The results showed that the humid index in recent 57 years was in an increase trend 0.007·(10a) ^-1, which revealed that the regional climate became wetter in the Qaidam Basin, the interannual variation of the humid index was significant, and the variable coefficient was 30.73%. Seasonally, the humid indexes in spring, summer, autumn and winter were all in an increase trend, and the tendency rates were 0.003·(10a)^-1, 0.009·(10a)^-1, 0.004·(10a)^-1 and 0.003·(10a)^-1 respectively. Spatially, difference of the variation was very significant, and the increase of humid index in the eastern part of the basin was more significant than that in the western part. Mutation of humid index occurred in 1981 and 1986, and there were 2.8-and 3.6-year periods of humid index variation (α≥0.05), which was relatively identical with the 2-4-year periodicity of general atmospheric circulation. Principal component analysis showed that precipitation and average temperature were the main factors affecting the variation of humid index in the Qaidam Basin. In addition, the correlation coefficients between the humid index and the PVA, PVI, APVI and APVII were -0.46, -0.36, -0.49 and -0.47 (α≥0.01) respectively.

Key words: drought/wet event')">

drought/wet event, potential evapotranspiration, climate change, humid index, Penman-Monteith model, Qaidam Basin