Increase in flood and drought disasters during 1500-2000 in Southwest China

Climate change has had a huge impact on Southwest China, where extreme weather events have taken on an increasing trend. The region lies in the transition zone of three monsoons (East Asian, Indian, and Tibetan Plateau). We analyzed long-term trends of drought and flood disasters using sequential data on China's drought and flood incidence over 500 years (1501-2000), as well as precipitation records from 45 weather stations during 1961-2010. Results show that both types of disaster became more frequent. During 1501-2000, drought frequency rose from 2.12 to 4.15 per century to 9.03 and flood frequency from 2.06 to 5.09 per century to 11.94. For the 10 decades during 1900-2000, droughts exhibited a significant increasing trend (R (2) = 0.4491), while floods showed a slight increasing trend (R (2) = 0.0346). For extreme floods and droughts in 1961-2010, precipitation records revealed that most (2/3) areas in the region had increasing drought or flood frequencies. Generally, both frequency and intensity of these weather hazards conspicuously increased in Southwest China during 1501-2000.