Multidimensional Drought Relationships in the Yangtze River Basin: Causality, Propagation Thresholds, and Drought Resistance Capacity

A clear grasp of the interconnections among various drought types forms the foundation for effective drought mitigation policy-making. However, current research on the propagation of groundwater drought (GD) remains relatively limited. Therefore, this study employs a multi-source data approach, combining methods (such as Pearson correlation analysis, cross-convergence mapping systems, and Copula functions) to assess the characteristics and propagation patterns of meteorological (MD), agricultural (AD), and GD in the Yangtze River Basin (YRB). Findings demonstrated that (1) drought severity (mainly ranging from 3.25 to 6.49) and duration (mainly ranging from 2.6 to 5.4 months) in the upstream region (UR) of the YRB are relatively large. (2) A total of 79.92% of the regions showed a mutual feedback relationship between agricultural drought and groundwater drought. (3) The duration propagation threshold from MD to AD was relatively high in the source region (SR) (mainly ranging from 5.95 to 8.36) and the midstream region (MR) (mainly ranging from 5.68 to 7.39) under extreme drought conditions. The severity propagation threshold from AD to GD was relatively high in the MR (mainly ranging from 11.8 to 16.5) and the downstream region (DR) (mainly ranging from 14.5 to 20.2) under extreme drought conditions. This study is significant for the rational allocation of regional water resources and drought prevention policy formulation.