Evolution characteristics of seasonal drought in the south of China during the past 58 years based on standardized precipitation index

Seasonal droughts have frequently taken place in the south of China in recent years, resulting of a serious impact on agricultural production. Therefore, analyzing the evolution characteristics and occurring rules are important to provide theory evidence for instituting policies about disaster prevention and mitigation under global climate change. Using standardized precipitation index (SPI) to describe drought, with precipitation data from weather stations in 15 provinces in the south of China, monthly drought indices in the recent 58yrs (from 1951 to 2008) were calculated, annual and seasonal change in station proportion of drought frequency were analyzed, which is the ratio of stations with drought occurring to overall stations, and the same for drought intensity. The results showed that drought in the south of China had increased with different magnitudes in the study period. Drought has become more serious in spring and autumn, though it’s the opposite in summer and winter. In the different zones of the study region, drought changes in the middle and lower reaches of Yangtze River, in Southwest China and in South China, were similar to the whole study region. Under the background of climate change, the drought change was bad for agricultural production. Comparing with other drought indices, SPI can catch basic features of the annual variations characteristics of seasonal drought in the south of China.