Event-scale investigation on spatiotemporal propagation dynamics between meteorological and agricultural drought

Meteorological drought can gradually propagate through land surface hydrological processes and further develop into agricultural drought, resulting in clear cascading propagation and time-lag responses between different drought types. In this study, the Pearl River Basin (PRB) was selected as the study area. A three-dimensional spatiotemporal clustering method was applied to identify drought events, and a spatiotemporal matching approach was further used to analyze drought propagation relationships and dynamic evolution characteristics between different drought types. The results showed that: (1) a total of 419 meteorological drought events and 154 agricultural drought events were identified in the PRB during 1982–2024, and agricultural drought generally showed longer duration, higher severity, and broader spatial extent than meteorological drought; (2) the most severe meteorological drought event occurred from August 2009 to April 2010, with a total severity of 204.05 × 10⁴·month·km², whereas the most severe agricultural drought event occurred from August 2022 to April 2024, with a total severity of 845.50 × 10⁴·month·km²; (3) 57 meteorological-agricultural drought-event pairs were successfully identified. Among them, one-to-one pairs accounted for the highest proportion (59.65%), while complex propagation patterns such as many-to-many relationships were also observed, indicating strong nonlinear characteristics in drought propagation. These findings reveal the propagation characteristics from meteorological drought to agricultural drought in the PRB from a three-dimensional spatiotemporal perspective, and provide a scientific basis for regional agricultural drought early warning and basin-scale water resources management.