Abstract: By applying the theory of wavelet transformation and the 1919-1996 natural runoff records of Lanzhou hydrometric station, the runoff variation along the upper reaches of the Yellow River is studied. The periods of runoff and points of abrupt change at different time scales are analyzed. The wavelet variance verification indicates that the main periods of the runoff variation along the upper reaches of the Yellow River are 22, 15, 4 and 37 years respectively in order of importance. Basing on the main period of 22 years, we predict that runoff will be in the dry period from about 1996 to about 2007.

Key words: upper reaches of Yellow River, runoff variation, wavelet analysis, period