Identification of source regions of spatial drought propagation and assessment of their drought characteristics

초록

As extreme droughts intensify, investigating drought propagation is critical to mitigating damage. This study identified spatial drought propagation by aggregating meteorological drought onset times and characterized source and sink regions using the propagation potential (PP). We estimated the potential influence of source regions (PISR) to determine how droughts originating elsewhere affect specific areas. Accounting for spatial autocorrelation, we identified homogeneous clusters with significant propagation intensity. Source and sink regions accounted for approximately 86% and 14% of all basins, respectively. Notably, in 95% of the source regions, over half of the drought events had propagated from other source regions, highlighting their dual role in both absorbing and propagating drought events. To assess their impacts on drought characteristics, we performed a bivariate frequency analysis of these clusters using a copula model. At given severity and duration thresholds, source clusters had return periods of less than 2 years, whereas sink clusters extended up to 47 years. This divergence was most pronounced in the NRB (1.75 years for sources vs. 47.42 years for sinks), demonstrating that source regions are substantially more vulnerable to drought than sink regions. © 2026 The Authors.

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