Runoff Characteristic in Flood and Dry Seasons in Source Regions of Changjiang River and Huanghe River Based on Wavelet Analysis

By decomposing and reconstructing the runoff information from 1965 to 2007 of the hydrologic stations of Tuotuohe,Zhimenda in the source region of Changjiang River,and Jimai,Tangnaihai in the source region of Huanghe River with db3 wavelet,the runoff data of different hydrologic stations were analysized.The result shows that the runoff declines in spring flood season,summer flood season and dry season except for those in Tuotuohe.The order of declining flood/dry season is summer spring dry.While runoff of Tuotuohe is always increasing in different stages from 1965 to 2007 with higher increase rate in summer flood season than that in spring one.Complex Morlet wavelet is selected to detect runoff periodicity of the four hydrologic stations mentioned above.Totally the periodicity is 11–12 years in the source region of Huanghe River,while 4–6 years in the spring flood season and 13–14 years in summer flood season in the source region of Changjiang River.The major periodicity in spring,summer and dry season is distinctive greatly in different basins.