Early-Warning Signals of Drought-Flood State Transition over the Dongting Lake Basin Based on the Critical Slowing Down Theory

In this study, the standardized precipitation index (SPI) data in Hunan Province from 1961 to 2020 is adopted. Based on critical slowing down theory, moving t-test firstly used determine time of drought-flood state transition Dongting Lake basin. Afterwards, by means variance and autocorrelation coefficient that characterize phenomenon down, early-warning signals indicating basin are explored. The results show an obvious drought-to-flood (flood-to-drought) event occurred around 1993 (2003) recent 60 years. phenomena increases coefficient, which detected 5–10 years advance, can be considered as transition. Through studies related for basin, reliabilities coefficient-based abrupt changes demonstrated. It expected wide application method could provide important scientific technological support disaster prevention mitigation even middle lower reaches Yangtze River.