The Hydrology Bureau of Guangdong Province (HBGP) collected the flow data used in the study from four hydrological stations located in the main stream of Beijiang River (Figure 1 and Table 1). The quality of the flow data is strictly controlled by HBGP, which is officially responsible for the regional hydrological data. For each station, the annual peak flow series was obtained using the annual maximum value method (Mitosek et al. 2006). Therefore, there is only one maximum instant peak flow for each year for each station.