Abstract:

Empirical Model Decomposition (EMD) was used to study the multitime scale analysis for the time series of the annual sediment yield of the Jiangjiagou debris flow between 1965 and 2004 in Dongchuan, Yunnan Province. The result shows that this annual sediment yield can be decomposed into three IMF components and one Res trend component. The analysis shows that the annual sediment yield of the Jiangjiagou debris flow reveals cyclical fluctuations, and there are fluctuations at 2-4 years, 6-10 years and 17-21 years time scale. Through the analysis of these components，we found that the amplitude of the fluctuations became larger after 1985, which indicated that the annual sediment yield of the Jiangjiagou debris flow varied greatly. And the rainfall affects the annual sediment yield of the Jiangjiagou debris flow and its cyclical fluctuations to some degree. The human activities have changed the local environment, providing the solid material for Jiangjiagou debris flow,thus make the cyclical fluctuations of the annual sediment discharge of debris flow in Jiangjiagou become more complex.

Key words: debris flow, annual sediment yield, empirical model decomposition(EMD), intrinsic mode function(IMF)