Flood risks across the Pearl River basin, China, were evaluated using peak flood flow dataset covering a period of 1951-2014 from 78 stations and historical flood records of recent 1000 years. The General Extreme Value (GEV) model and the kernel estimation method were used to evaluate frequencies and risks of hazardous flood events. Results indicated that: (1) no abrupt changes or significant trends could be detected in peak flood flow series at most of the stations, and only 16 out of 78 stations exhibited significant peak flood flow changes with change points around 1990. Peak flood flow in the West River basin was increasing and significant increasing trends were identified during 1981-2010; decreasing peak flood flow was found in coastal regions and significant trends were observed during 1951-2014 and 1966-2014; (2) the largest three flood events were found to cluster in both space and time. Generally, basin-scale flood hazards can be expected in the West and North River basins; (3) the occurrence rate of floods was increasing in middle Pearl River basin but decreasing in the lower Pearl River basin. However, hazardous flood events were observed in the middle and lower Pearl River basin, and it is particularly true in recent 100 years. However, precipitation extremes were subject to moderate variations and human activities, such as building of levees, channelization of river systems and rapid urbanizations were the factors behind the amplification of floods in the middle and lower Pearl River basin, posing serious challenges for developing measures of mitigation of flood hazards in the lower Pearl River basin, particularly the Pearl River Delta (PRD) region.

More frequent flooding.pdf