Agricultural rapid-onset droughts in southern China’s grain-producing regions: Spatiotemporal evolution and potential drought-crop risks

Flash droughts are intensifying under climate change, threatening global food security through their rapid onset and severe impacts on crop production. Yet crop-specific vulnerabilities to agricultural rapid-onset droughts across China’s major grain-producing regions remain poorly understood. Here, we investigated the spatiotemporal variations and seasonal characteristics of agricultural rapid-onset droughts across three major grain-producing regions in southern China: Middle-Lower Reaches of the Yangtze River Basin (MLRYR), Southwest China (SWC), and South China (SC), including frequency, duration, intensity, and development rate by using different root-zone soil moisture datasets. We further examined temporal coupling between agricultural rapid-onset drought onset and critical crop growth stages. Our analysis revealed significant spatial heterogeneity in different characteristics of agricultural rapid-onset droughts. Southern areas of MLRYR exhibited “high-frequency, short-duration, high-rate” characteristics (1.4–2.0 events per year, ∼25 days duration, >12 % per 5-day onset rate), while northern areas showed “low-frequency, long-duration, low-rate” patterns (0–1.4 events per year, 30–35 days duration, 8–10 % per 5-day onset rate). Spring and summer were identified as peak drought seasons with distinct patterns. Spring agricultural rapid-onset droughts exhibited “locally frequent” characteristics, while summer droughts showed “widespread occurrence” patterns. Critical crop-drought coupling risks were identified through phenological alignment analysis. Spring droughts coincided with winter wheat grain-filling periods in MLRYR and early rice nursery management in SC, while summer droughts threatened middle rice during tillering-to-booting transitions in MLRYR and reproductive stages of spring maize in SWC. These findings provide fundamental insights for developing targeted agricultural adaptation strategies to enhance food security with the intensification of flash droughts.