Multi-scale analysis of the annual runoff records of lower nandujiang river within45 years based on morlet wavelet

摘要

Multi-scale continuous wavelet analysis is carried out for annual runoff of Lower Nandujiang River. The analysis is based on the runoff data observed at Longtang Hydrological Station of Nandujiang River from the year 1956 to 2000. Based on wavelet analysis, variation tendency of annual discharge in Lower Nandujiang River is predicted. Analysis results show that the Morlet wavelet applies well to natural runoff prediction in this area. The variation intensity of annual runoff of Lower Nandujiang River shows intensive fluctuations at time scales of 3-7 years, 9-19 years and 25~39 years. Besides, the periodic components of runoff time-series are identified and extracted according to wavelet variance. Quantitative analysis shows that the major period of runoff variation of Lower Nandujiang River is 13 years. Prediction results provide valuable information for urban planning of Haikou City, where Lower Nandujiang River flows into the sea.