Identifying and characterizing short-term drought with rapid onset based on the SAPEI in the Yangtze River basin

Study region: The Yangtze River basin (YRB) Study focus: This study presented a methodology for identifying short-term drought events, with a particular emphasis on rapid onset. The standardized antecedent precipitation evapotranspiration index (SAPEI) was adopted to detect drought at the grid level within a time series dataset, and a clustering algorithm was employed to identify drought events with three-dimensional structures, followed by a comprehensive analysis of their spatiotemporal characteristics and the factors contributing to spatial heterogeneity. New hydrological insights for the regions: The proposed method effectively captures the rapid intensification phase and the drought development processes. Short-term drought with rapid onset was predominantly observed in the northwestern region and the middle to lower reaches of the YRB from 1960 to 2014, exhibiting mild and moderate drought conditions. This spatial variability was related to the interactions among temperature, potential evapotranspiration, precipitation and wind. Furthermore, a total of 246 three-dimensional drought events were identified in the YRB. Among these events, centroid no-transfer events were prevalent, and the primary migration direction for centroid transfer events was from southeast to northwest. Additionally, short-term drought events displayed a characteristic evolution pattern, with the affected area remaining relatively stable while drought intensity exhibited a significant decrease which indicated the drought rapidly developed into more severe drought condition. This study can provide a reference for early warning and monitoring of short-term drought with rapid onset.