关键词: 洪水, 强度, 频率, 变化趋势, 气候变化, 珠江流域

Abstract: This study investigated the changes of extreme flood events with the long-term stream flow records of 1951-2010 at 23-typical cross-sections in the Pearl River basin. Flood magnitudes for return intervals larger than 10 years were defined as extreme flood events. Flood time series were derived from annual maximum (AM) series and peaks over threshold (POT) series respectively for 23 stream gauging stations in the main control sections. The Pearson type III distribution curve was selected for flood frequency analysis. Results indicate that the occurrence frequency of extreme flood events has increased after 1980s, specifically in recent two decades. Furthermore, the changes of extreme flood events were studied by comparing the flood frequency curves for the pre-1980 period (1951-1980) and post-1980 period (1981-2010). The flood extremes of 70% typical sections presented increasing tendencies in 1981-2010 compared with 1951-1980, with most of them in the Xijiang River basin, Beijiang River basin, and the western part of Guangdong Province. On the other hand, the rest 30 % sections, mainly concentrating in the Dongjiang River basin and the southern part of Guangxi Province, displayed decreasing tendencies.

Key words: flood, intensity, frequency, trend, climate change, Pearl River basin