Tao et al. (2026) Drought Propagates Asynchronously Across Hydrological Compartments: Stage Differences in Propagation Time and Implications for Drought Monitoring

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Identification

• Journal: Hydrological Processes
• Year: 2026
• Date: 2026-09-01
• Authors: Hu Tao, Yibo Wang, Zhongyang Zhang, Zeyong Gao
• DOI: 10.1002/hyp.70683

Research Groups

Not specified in the provided text.

Short Summary

This study examines the timing and characteristics of drought propagation across meteorological, soil, and groundwater compartments in China, revealing that the transition from soil to groundwater is significantly slower than the transition from meteorological to soil conditions.

Objective

• To investigate and quantify the stage-specific differences in drought propagation between Stage 1 (meteorological-to-soil link) and Stage 2 (soil-to-groundwater link).

Study Configuration

• Spatial Scale: National scale (China), characterized as a hydroclimatically diverse domain.
• Temporal Scale: Analysis of lag times measured in months.

Methodology and Data

• Models used: Two-stage drought propagation framework, first-order autocorrelation (AC1), and partial-correlation diagnostics.
• Data sources: Standardized Precipitation Index (SPI), Standardized Soil moisture Index (SSI), and Groundwater Storage Anomaly Drought Severity Index (GWSA-DSI).

Main Results

• Propagation Lag Times: Stage 1 (meteorological $\rightarrow$ soil) is faster, with lags of 1.2–4.1 months; Stage 2 (soil $\rightarrow$ groundwater) is slower, with lags of 2.6–5.9 months.
• Persistence and Forcing: Stage 2 is characterized by lower short-term temporal persistence and weaker conditional associations with concurrent hydroclimatic forcing compared to Stage 1.
• Soil Moisture Influence: Antecedent soil moisture shows a strong, spatially consistent association with current SSI, but a weaker and more regionally heterogeneous relationship with GWSA-DSI.

Contributions

• Identifies a process-based asymmetry in drought propagation, demonstrating that deeper hydrological storage responds more slowly than near-surface indicators.
• Highlights that rapid recovery or development in near-surface indicators does not necessarily imply a corresponding change in deeper groundwater drought.

Funding

Not specified in the provided text.

Citation

@article{Tao2026Drought,
  author = {Tao, Hu and Wang, Yibo and Zhang, Zhongyang and Gao, Zeyong},
  title = {Drought Propagates Asynchronously Across Hydrological Compartments: Stage Differences in Propagation Time and Implications for Drought Monitoring},
  journal = {Hydrological Processes},
  year = {2026},
  doi = {10.1002/hyp.70683},
  url = {https://doi.org/10.1002/hyp.70683}
}