Evaluating the propagation process of meteorological, hydrological, and agricultural drought dynamics in the Yellow river basin

The spatiotemporal evolution of drought patterns has drawn growing attention, particularly in the Yellow River Basin of northern China. However, the previous studies have primarily focused on unidirectional drought propagation. We extended the three-dimensional connectivity identification method to quantify the migration direction and distance between the centroids of drought initiation and termination, thereby improving the tracking and measurement of typical drought event trajectories. Furthermore, we systematically investigated the bidirectional dependencies and propagation characteristics among meteorological, hydrological, and agricultural droughts using Granger causality testing, drought propagation rate, and Maximum Cross-Correlation methods. The results illustrate that meteorological droughts were mainly in the middle-upper reaches, hydrological droughts in arid zones and upstream mountains, and agricultural droughts in semi-arid regions from 1981 to 2022. Hydrological droughts showed the longest migration distance. However, all drought types followed more complex pathways after 2010. Hydrological and agricultural drought exhibited consistent bidirectional dependence basin-wide. Propagation rates were generally high for meteorological-hydrological links except in upstream mountains, and notably strong for meteorological-agricultural propagation in the central-southern Wei River Basin. Seasonally, meteorological drought significantly impacted streamflow in spring and autumn, with hydrological drought lagging by 1–2 months across 72.4% of the basin. Agricultural systems responded within 1–5 months in summer and autumn. Hydrological-agricultural propagation showed similar seasonal patterns, with faster response from hydrological to agricultural drought (1–3 months) than the reverse (1–4 months).