Characteristics of extreme rainfall in South China during the late rice growth period

Extreme rainfall has significant impacts on human society and agricultural development, as well as severe effects on rice development. However, few studies have investigated the characteristics of extreme rainfall during different stages of rice growth period. Taking the South China region as a case study, the characteristics of extreme daily rainfall in the late rice growth period (July to November) from 1960 to 2009 were investigated using the percentile method. The results indicated that the extreme rainfall threshold varies between stages of rice growth period. The regional average extreme rainfall threshold exceeded the traditional heavy rainfall threshold (50 mm/day) during the seeding (60.6 mm/day), tillering (56.6 mm/day) and booting stage (51 mm/day) of late rice growth period. Regions with high extreme rainfall threshold are observed in coastal cities during each stage. Typhoons are the most important weather system that causes extreme rainfall, especially in the first three stages of the late rice growth period. Pronounced annual variability is found in a number of cases of extreme rainfall and typhoon-caused (TC) extreme rainfall. Extreme rainfall, ranging from 100-200 mm/day, is most common for cases with TC and none-typhoon-caused (NTC) extreme rainfall. Finally, flood risk regions more easily form in the coastal cities in cases of TC extreme rainfall, but for NTC extreme rainfall, the north-western region of South China is the main flood risk region.