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Yangtze River Basin, China As agricultural drought originates from meteorological drought, exploring the propagation from meteorological to agricultural drought is an important step in providing early warning of agricultural drought. In this study, Standardized Precipitation Index (SPI) and Improved Soil Moisture Anomaly Percentage Index (ISMAPI) were adopted to indicate meteorological and agricultural droughts, respectively. The propagation time from meteorological drought to agricultural drought was identified, and probabilistic linkages between the two types of drought were investigated using the copula function and Bayesian network. The average propagation time from meteorological to agricultural drought in the Yangtze River Basin (YRB) is 48 d. The propagation times in the summer and autumn are shorter than those in the spring and winter. The occurrence probability of more serious agricultural drought gradually increases with meteorological drought intensity. Agricultural and meteorological drought events were matched using the proposed drought event-matching method. In the YRB, approximately 72.4% of meteorological drought events may translate into agricultural drought events. Generally, an agricultural drought event that has the same drought category as that of the given meteorological drought event is most likely to occur. Regional differences in drought propagation time and occurrence probability of agricultural drought may be related to variations in climatic conditions across regions.
Xu et al. (Thu,) studied this question.