基于EMD的云南东川蒋家沟泥石流年输沙量多时间尺度分析

Multi-time Scale Analysis of Annual Sediment Yield of the Jiangjiagou Debris Flow in Dongchuan of Yunnan Based on Empirical Model Decomposition

基于经验模态分解(EMD)方法,对云南东川蒋家沟泥石流1965年至2004年40年的年输沙量时间序列进行多时间尺度分析,该时间序列分解成3个本征模函数(IMF)分量和趋势项(Res)分量。分析表明:蒋家沟泥石流的年输沙量存在多尺度的周期性波动,分别是2～4 a、6～10 a和17～21 a的准周期。通过对各IMF分量和Res趋势项分析发现,自1985年之后,波动的振幅开始变大,表明蒋家沟泥石流的年输沙量变化很大。降雨对蒋家沟泥石流的年输沙量及周期性波动有一定程度的影响。人类活动改变环境的同时,也为蒋家沟泥石流提供固体物质来源,这使得蒋家沟泥石流的年输沙量周期性波动变得更加复杂。

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.