Evolution Characteristics of Hydrological Time Series Based on S-transform
Wei Zhang · 2011
Multiple time scale analysis of hydrological time series has important significance for acquiring deeply understanding hydrological system evolution characteristics and mid-long term hydrological forecasting.But the common methods,such as Fourier transform,wavelet analysis and Hilbert-Huang transform,have disadvantages of their own.Stockwell-transform(S-transform),a tool of modern time-frequency analysis method,was introduced and applied to the case study of annual inflow series of Yuqiao Reservoir for the years 1956—2000.And therefore,the 3-dimension spectrogram of the series was drawn,which clearly displayed the multiple time scale evolution characteristics of the time series in the different periods.Furthermore,through analyzing the spectrogram's topological structure,the key characteristics of the Yuqiao Reservoir's annual inflow evolution process was obtained.The result shows that S-transform solves the frequency mixing problems which could be induced by the arbitrary number of decomposition layers of wavelet transform and Huang transform(EMD),which indicates that S-transform will have an extensive application prospect in the multiple time scale analysis and feature extraction of hydrological time series.