Liu et al. (2025) Agricultural rapid-onset droughts in southern China’s grain-producing regions: Spatiotemporal evolution and potential drought-crop risks

Identification

• Journal: Agricultural Water Management
• Year: 2025
• Date: 2025-11-20
• Authors: Xiaoyin Liu, Peixin Li, Yifan Shen, Yuping Lv, Linxian Liao, Jia Wei, Junzeng Xu
• DOI: 10.1016/j.agwat.2025.109985

Research Groups

• College of Agricultural Science and Engineering, Hohai University, Nanjing, China
• Jiangsu Province Engineering Research Center for Agricultural Soil-Water Efficient Utilization, Carbon Sequestration and Emission Reduction, Hohai University, Nanjing, China
• College of Hydraulic Science and Engineering, Yangzhou University, Yangzhou, China
• Department of Land Surveying and Geo-Informatics, Research Institute for Sustainable Urban Development, Hong Kong Polytechnic University, Hong Kong, China
• College of Hydrology and Water Resources, Hohai University, Nanjing, China
• The National Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing, China

Short Summary

This study investigated the spatiotemporal evolution and seasonal characteristics of agricultural rapid-onset droughts and their coupling with critical crop growth stages across southern China's major grain-producing regions from 1950 to 2022. It revealed significant spatial heterogeneity in drought characteristics and identified critical crop-drought coupling risks during specific phenological windows, emphasizing the need for phenology-aligned drought management.

Objective

• To analyze the spatiotemporal evolution characteristics of four-dimensional agricultural rapid-onset drought parameters (frequency, duration, intensity, and onset rate) at pentad resolution across the Middle-Lower Reaches of the Yangtze River Basin (MLRYR), South China (SC), and Southwest China (SWC).
• To identify precise crop-drought coupling risks during spring and summer, providing a scientific basis for phenology-aligned drought monitoring and region-specific strategies to safeguard food security.

Study Configuration

• Spatial Scale: Three major grain-producing regions in southern China: Middle-Lower Reaches of the Yangtze River Basin (MLRYR), Southwest China (SWC), and South China (SC). Soil moisture data at 9 km resolution (ERA5-Land), resampled to 0.25° (approximately 25 km) for consistency. Crop distribution data at 1 km resolution.
• Temporal Scale: 1950–2022 (72 years) for drought analysis; 2000–2022 for reanalysis comparison. All temporal analyses of drought evolution are conducted on a pentad (5-day) basis.

Methodology and Data

• Models used: FAO Penman-Monteith equation (for potential evapotranspiration).
• Data sources:
  • Root-zone soil moisture (0–100 cm): ERA5-Land hourly dataset (9 km spatial resolution), Modern-Era Retrospective Analysis for Research and Applications Version 2 (MERRA2) (0.5° × 0.625° spatial resolution), and Global Land Data Assimilation System (GLDAS) Noah Land Surface Models (0.25° × 0.25° spatial resolution). All soil moisture datasets were resampled to a uniform 0.25° spatial resolution.
  • Meteorological variables: Daily precipitation, surface air temperature (mean, maximum, minimum), relative humidity, wind speed, and sunshine duration from the CN05.1 dataset (0.25° × 0.25° spatial resolution), based on observations from over 2400 meteorological stations across China.
  • Crop distribution data: National Ecosystem Science Data Center (1 km spatial resolution), derived from GLASS Leaf Area Index (LAI) data for maize, wheat, and rice cultivation during 2000–2019.

Main Results

• Agricultural rapid-onset droughts exhibit significant spatial heterogeneity across southern China. Southern MLRYR shows "high-frequency, short-duration, high-rate" characteristics (1.4–2.0 events per year, ~25 days duration, >12 % per 5-day onset rate), while northern MLRYR displays "low-frequency, long-duration, low-rate" patterns (0–1.4 events per year, 30–35 days duration, 8–10 % per 5-day onset rate).
• Spring and summer are identified as peak drought seasons with distinct patterns: spring droughts are "locally frequent," while summer droughts show "widespread occurrence."
• From 1950–2022, drought frequency significantly increased across all three regions (MLRYR, SWC, SC) (p < 0.01).
• Southwest China (SWC) experienced significant upward trends in drought frequency (p < 0.001), duration (p < 0.01), and intensity (p < 0.01), indicating a compound drought risk escalation (increases of approximately 0.35 events, 2.9 days, and 1.0 %ile units over 72 years). MLRYR and SC primarily faced an increase in occurrence rather than severity.
• Abrupt shifts in drought regimes were detected around 1990 across all three regions, coinciding with a broader transition to a warmer and drier background climate.
• Critical crop-drought coupling risks were identified through phenological alignment:
  • Spring droughts coincided with winter wheat grain-filling periods in MLRYR (north of the Yangtze River) and early rice nursery management/panicle differentiation in SC.
  • Summer droughts threatened middle rice during tillering-to-booting transitions in MLRYR and reproductive stages of spring maize in SWC.

Contributions

• Provides a comprehensive, high-resolution (pentad-scale) analysis of agricultural rapid-onset droughts, addressing the gap in understanding crop-specific vulnerabilities to these fast-developing events in southern China.
• Offers novel insights into the spatiotemporal evolution characteristics (frequency, duration, intensity, and onset rate) of agricultural rapid-onset droughts across major grain-producing regions.
• Highlights the critical temporal coupling between rapid-onset drought onset and sensitive crop growth stages, demonstrating that traditional monthly/seasonal assessments fail to capture these crucial vulnerability windows.
• Establishes a scientific rationale for transitioning towards precision, crop phenology-aligned drought monitoring and mitigation strategies, emphasizing the need for regionalized drought management frameworks.

Funding

• National Natural Science Foundation of China (52379037, 42307117, 52309064)
• Hong Kong Scholars Program (XJ2024046)

Citation

@article{Liu2025Agricultural,
  author = {Liu, Xiaoyin and Li, Peixin and Shen, Yifan and Lv, Yuping and Liao, Linxian and Wei, Jia and Xu, Junzeng},
  title = {Agricultural rapid-onset droughts in southern China’s grain-producing regions: Spatiotemporal evolution and potential drought-crop risks},
  journal = {Agricultural Water Management},
  year = {2025},
  doi = {10.1016/j.agwat.2025.109985},
  url = {https://doi.org/10.1016/j.agwat.2025.109985}
}

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