Wu et al. (2026) Linear time-lag effects and nonlinear interactions of global drought-flood abrupt alternation in responses to multiple factors

Identification

• Journal: Journal of Hydrology
• Year: 2026
• Date: 2026-02-17
• Authors: Bohua Wu, Ziqi Yan, Denghua Yan, Yaping Cheng, Jianzhu Li
• DOI: 10.1016/j.jhydrol.2026.135161

Research Groups

• State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation, Tianjin University, China
• State Key Laboratory of Water Cycle and Water Security, China Institute of Water Resources and Hydropower Research, China

Short Summary

This study investigated the linear time-lag effects and nonlinear interactions of multiple factors, including surface energy fluxes, on global drought-flood abrupt alternation (DFAA) events. It found that accounting for time-lag effects significantly increased the explanatory power of these factors on DFAA from 33.03% to 70.05%, revealing complex spatial heterogeneity and nonlinear threshold regulations.

Objective

• To systematically analyze the linear time-lag effects and nonlinear interactions of multiple factors (including surface energy fluxes) on global drought-flood abrupt alternation (DFAA) events across different lag times, moving beyond conventional linear frameworks.

Study Configuration

• Spatial Scale: Global, with specific analyses for continental, tropical, and arid climate zones.
• Temporal Scale: Analysis across different lag times; intra-annual seasonal signals were also considered and removed for specific analyses.

Methodology and Data

• Models used: Revised DFAA index (R-SDFAI), Pearson correlation coefficients, multiple linear regression, and interpretable machine learning models.
• Data sources: Implied data for multiple factors including surface energy fluxes (net radiation, heat flux), vapor pressure deficit, rainfall, and solar-induced chlorophyll fluorescence.

Main Results

• DFAA events were most frequent and intense in continental climate zones, with relatively low overall risk in tropical climate zones.
• Accounting for time-lag effects increased the explanatory power of multiple factors on DFAA from 33.03% to 70.05%, demonstrating clear spatial heterogeneity.
• In tropical climate zones, DFAA was bidirectionally influenced by vapor pressure deficit.
• In arid climate zones, net radiation exhibited bidirectional associations with DFAA.
• After removing intra-annual seasonal signals, the dominant relationship converged on the moisture component.
• Key nonlinear threshold regulations were identified, including negative impacts of high net radiation and low rainfall in tropical climate zones, and synergistic reversal driven by low heat flux and solar-induced chlorophyll fluorescence in arid climate zones.

Contributions

• Transcends conventional linear frameworks by incorporating linear time-lag effects and nonlinear interactions of multiple factors, including surface energy fluxes, to explain global DFAA.
• Significantly improves the understanding and explanatory power of DFAA drivers by demonstrating the importance of time-lag effects and nonlinear thresholds.
• Provides a scientific foundation for more accurate prediction and disaster prevention of DFAA events.

Funding

• Not explicitly mentioned in the provided text.

Citation

@article{Wu2026Linear,
  author = {Wu, Bohua and Yan, Ziqi and Yan, Denghua and Cheng, Yaping and Li, Jianzhu},
  title = {Linear time-lag effects and nonlinear interactions of global drought-flood abrupt alternation in responses to multiple factors},
  journal = {Journal of Hydrology},
  year = {2026},
  doi = {10.1016/j.jhydrol.2026.135161},
  url = {https://doi.org/10.1016/j.jhydrol.2026.135161}
}