Atmospheric dryness and flash drought severity drive the shifts of different flash drought types into agricultural droughts

Flash droughts, characterized by their rapid onset and intensification, can evolve into long-term agricultural droughts, thereby amplifying adverse impacts on water resources, agriculture, and ecosystems. However, the propagation from short-term flash droughts to long-term agricultural droughts remains limited understood, particularly across different flash drought types. Here we developed an integrated framework that combined convergent cross mapping (CCM), the random forest model, and the copula-based Bayesian approach to investigate the propagation pathways and underlying mechanisms. We applied this framework to analyze the propagation of meteorological, soil, and evaporative flash droughts into agricultural droughts in the Middle and Lower Reaches of the Yangtze River Basin (MLRYRB) from 2000 to 2022. Our results revealed strong causal relationships between flash droughts and agricultural droughts, with an average propagation time of 36.8–48.8 days. Meteorological flash droughts showed the shortest propagation time, while evaporative flash droughts exhibited the longest. Soil flash droughts demonstrated the highest propagation frequency, rate, and sensitivity to agricultural droughts, while evaporative flash droughts showed the lowest translation rates to agricultural droughts. We further found that flash drought severity strongly influenced the propagation of all flash drought types, particularly soil flash droughts, with a threshold value of 11.2 ± 2.3. Additionally, precipitation and vapor pressure deficit (VPD) emerged as the most critical factor for meteorological and evaporative flash drought propagation, with threshold values of 14.3 ± 7.6 mm and 7.8 ± 2.3 hPa, respectively. These findings can advance our understanding of flash drought dynamics and mechanisms, offering important insights for effective drought mitigation. • Flash droughts exhibit strong causal relationships with agricultural droughts. • Soil flash droughts present the highest propagation number, rates, and sensitivity. • Precipitation, VPD, and severity dominate shifts of flash to agricultural droughts.