A Multiple Time Scales Analysis of the Runoff Variation along the Upper Reaches of the Yellow River

摘要

By applying the theory of wavelet transformation and the 1919-1996 natural runoff 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 in dry period from about 1996 to about 2002.