Article

Long-periodic feature of runoff and its effect on riverbed in Qiantang estuary

Authors:
  • Zhejiang Institute of Hydraulics and Estuary
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Abstract

In accordance with the non-stationary hydrological time series, the wavelet method was adopted to analyze the periodic feature and the trend of the runoff in the Qiantang estuary. The complex Morlet function, whose basic characteristic was discussed, was selected to transform the standardized time-series of the annual runoff discharge. Based on the distribution of module and real of wavelet transform coefficients and wavelet variance, the prominent period of the annual runoff discharge in the Qiantang estuary is 21 years approximately, and it is predicted that the trend of the annual flow is in the low flow period from 2008 to 2010, and then the annual discharge is increase. Combined the observed topographical data, the relationships between the periodic variation of the runoff and riverbed deformation was analyzed. The results show there is a close relationship between them. The riverbed is scoured with straight alignment of river course during high flow period, and deposited with curved alignment of river course during low flow period.

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... The flood events substantially correlate with the Asian summer monsoon as well as the local climate and other regional factors such as geographical variation and local sources of aerosols Xia et al., 2016). Furthermore, it is characterized by the alternate wet and dry years on the interannual timescales, with the period around 20 years (Zeng et al., 2010). The sediment load from the Qiantang River correlates with the river discharge, varying between 1.4 × 10 6 -14.2 × 10 6 ton/a, with the mean being 5.7 × 10 6 ton/a (Fig. 2b). ...
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