Author(s): Jun Niu; Ji Chen; Bellie Sivakumar
Linked Author(s): Ji Chen, Jun Niu
Keywords: Flood; Drought; VIC model; Wavelet transform; Geomorphology factor; Yangtze River
Abstract: A river basin may reduce the high-frequency precipitation variability and memorize the low-frequency precipitation variability in manifesting the variability response by runoff or soil moisture. Knowledge of these response features is desirable for detection of the basin’s tendency to occurrence of floods or droughts. The possible basin tendencies may vary for different river basins, and, accordingly, for different sub-basins within a large-scale river basin. This study presents the use of wavelet-based analysis for evaluation of basin tendencies, at sub-basin basis, for the Yangtze River basin in China. The terrestrial hydrological processes over the basin are simulated using a macro-scale hydrological model, the Variable Infiltration Capacity (VIC), over the period 1951–2000. To capture the fluctuations embedded in the hydrological time series, the wavelet transform is employed to reveal the variability properties of hydrological variable in time-frequency domain. The variability response characteristics of different sub-basins are revealed for timescales ranging from 1/6 year to 9 years, with inspection on the wavelet power ratios of runoff and soil moisture to precipitation across these timescales. The flood or drought tendency for sub-basins is then investigated based on the frequency-dependent features associated with the effects of basin geomorphologic factors. The results provide useful information for devising adaptation and mitigation strategies in the face of extreme hydroclimatic events.