Abstract. Hydrological time series (HTS) is the key basis of water conservancy project planning and construction. However, under the influence of climate change, human activities and other factors, the consistency of HTS has been destroyed and cannot meet the requirements in mathematical statistics. It is urgent to find a better way to divide HTS. Wavelet transform is an effective way to catch the evolution of HTS, but its accuracy is highly dependent on the mother wavelet (MWT). To address these issues, we constructed a potential changepoint set based on two traditional detection methods and wavelet changepoint detection (WTCPD). Then, the degree of change before and after the potential changepoint was calculated with the Kolmogorov-Smirnov test, and a changepoint detection framework (CPDF) was proposed. Finally, according to the difference of detection accuracy between MWT in WTCPD, a mother wavelet optimal framework (MWTOF) was proposed, and continuous wavelet transform was carried out to analyse HTS evolution. We used Pingshan Station and Yichang Station in the Yangtze River as study cases. The result shows: (1) CPDF can quickly locate potential changepoints, determine the change trajectory and complete the division of HTS. (2) MWTOF can select the MTW that conforms to HTS characteristics and ensure the accuracy and uniqueness of the transformation. This study analyses the HTS evolution and provides a better basis for hydrological and hydraulic calculation, which will improve the design flood estimation and the operation scheme preparation.

Abstract. Hydrological time series (HTS) are the key basis of water conservancy project planning and construction. However, under the influence of climate change, human activities and other factors, the consistency of HTS has been destroyed and cannot meet the requirements of mathematical statistics. Series division and wavelet transform are effective methods to reuse and analyse HTS. However, they are limited by the change-point detection and mother wavelet (MWT) selection and are difficult to apply and promote in practice. To address these issues, we constructed a potential change-point set based on a cumulative anomaly method, the Mann–Kendall test and wavelet change-point detection. Then, the degree of change before and after the potential change point was calculated with the Kolmogorov–Smirnov test, and the change-point detection criteria were proposed. Finally, the optimization framework was proposed according to the detection accuracy of MWT, and continuous wavelet transform was used to analyse HTS evolution. We used Pingshan station and Yichang station on the Yangtze River as study cases. The results show that (1) change-point detection criteria can quickly locate potential change points, determine the change trajectory and complete the division of HTS and that (2) MWT optimal framework can select the MWT that conforms to HTS characteristics and ensure the accuracy and uniqueness of the transformation. This study analyses the HTS evolution and provides a better basis for hydrological and hydraulic calculation, which will improve design flood estimation and operation scheme preparation.