Early Warning Signals of Dry-Wet Transition Based on the Critical Slowing Down Theory: An Application in the Two-Lake Region of China

In recent years, the dry-wet transition (DWT), which often leads to regional floods and droughts, has become increasingly frequent in Poyang Lake basin Dongting (hereinafter referred as two-lake region). This study aims investigate early warning signals (EWSs) for DWT events. Firstly, based on standardized precipitation index (SPI) at 161 meteorological stations region from 1961 2020, is divided into four sub-regions by Rotational Empirical Orthogonal Function (REOF) analysis method. Then, occurrence time of events each sub-region determined moving t-test (MTT) technique. Finally, using two indicators (variance auto-correlation coefficient) describe critical slowing down (CSD) phenomenon, EWSs denoting all are investigated. The results reveal that there was a significant dry-to-wet (wet-to-dry) event around 1993 (2003) during last 60 years. phenomenon CSD, where coefficient variance increases found 10 years before DWT, suggests it can be taken an EWS confirms effectiveness applying theory investigating abrupt changes region, aiming provide theoretical basis effective prevention mitigation against disasters this region. Moreover, expected well-applied middle lower reaches Yangtze River.