Chang et al. (2025) Historical evolution and future trend of meteorological drought in the upper Yangtze River basin

Identification

• Journal: Climate Dynamics
• Year: 2025
• Date: 2025-10-27
• Authors: Yu Chang, Wenxin Li, Cuishan Liu, Yun Wang, Ruimin He, Guoqing Wang
• DOI: 10.1007/s00382-025-07896-1

Research Groups

• Yangtze Institute for Conservation and Development, Hohai University
• College of Hydrology and Water Resources, Hohai University
• Research Centre for Climate Change, Ministry of Water Resources
• The National Key Laboratory of Water Disaster Prevention, Nanjing Hydraulic Research Institute
• China Electric Construction Group Northwest Survey and Design Institute Co.

Short Summary

This study analyzed historical (1961-2018) and projected future (2019-2099) meteorological drought trends in the upper Yangtze River basin using SPI and SPEI and CMIP6 models, finding a historical intensification of droughts post-2000 and a projected transition to significantly drier conditions with more frequent, longer, and more intense droughts after 2040 under higher emission scenarios.

Objective

• To examine the spatiotemporal patterns of meteorological drought characteristics (intensity, frequency, duration) in the upper Yangtze River basin from 1961 to 2018 using the Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI), and to project future drought trends from 2019 to 2099 using Coupled Model Intercomparison Project Phase 6 (CMIP6) models under different emission scenarios.

Study Configuration

• Spatial Scale: Upper Yangtze River basin (UYRB), spanning approximately 1 million square kilometers (90°32′–111°27′E, 24°27′–35°45′N).
• Temporal Scale: Historical analysis from 1961 to 2018 (58 years); Future projections from 2019 to 2099 (81 years), divided into near-term (2019–2039), mid-term (2040–2069), and long-term (2070–2099).

Methodology and Data

• Models used:
  • Drought Indices: Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI), calculated at 3-month (SPI3, SPEI3) and 12-month (SPI12, SPEI12) temporal resolutions.
  • Climate Models: Ensemble of 10 Coupled Model Intercomparison Project Phase 6 (CMIP6) models.
  • Statistical Methods: Sen’s Slope Estimator and Mann–Kendall Test for trend analysis; Run theory for drought event identification.
  • Potential Evapotranspiration Calculation: Penman–Monteith method (FAO).
• Data sources:
  • Historical (1961–2018): CN05.1 dataset from the National Climate Center, providing high-resolution daily meteorological data (precipitation, temperature, potential evapotranspiration) interpolated from over 2400 meteorological stations across China.
  • Future Projections (2019–2099): Data from 10 CMIP6 models, standardized to a spatial resolution of 0.5° × 0.5°, under three Shared Socioeconomic Pathways (SSPs): SSP1-2.6 (low forcing), SSP2-4.5 (moderate forcing), and SSP5-8.5 (high forcing).

Main Results

• Historical Trends (1961–2018):
  • Annual mean temperature increased significantly at 0.22 °C per decade, with the highest warming in the northwest (up to 0.5 °C per decade) and the strongest seasonal warming in winter (0.34 °C per decade).
  • Annual precipitation showed an insignificant upward trend (2.22 mm per decade), with spatial variability: increases in northwestern areas (up to 40 mm per decade) and declines in central regions (down to -40 mm per decade).
  • Drought intensity increased notably after 2000, particularly in summer and autumn, with the Yangtze River Source Region (YRSR) and surrounding areas experiencing higher frequency and longer duration of dry conditions.
  • SPEI generally indicated more pronounced drought extremes than SPI due to its inclusion of temperature and evapotranspiration.
• Future Projections (2019–2099) using SPEI:
  • Drought Intensity: The basin is projected to transition from relatively wet conditions (2019–2039) to increasing aridity after 2040. By 2070–2099, widespread droughts are expected, with moderate to severe droughts dominating under SSP2-4.5 (mean SPEI -0.7) and severe to extreme droughts under SSP5-8.5 (mean SPEI -1.1).
  • Drought Frequency: Drought occurrence is projected to remain low (<5%) in the near-term (2019–2039) but will intensify significantly after 2040. By 2070–2099, mean drought frequencies are expected to exceed 50% under moderate (SSP2-4.5) and high-emission (SSP5-8.5) scenarios.
  • Drought Duration: Drought durations are projected to increase across all scenarios after 2040. By 2070–2099, mean durations are expected to exceed 6 months under SSP2-4.5 and more than 21 months under SSP5-8.5, with some zones facing prolonged, year-round droughts (up to 24 months).
  • Overall: A progressive transition towards longer, more frequent, and more intense droughts is projected after 2040, with the most severe changes occurring under higher emission scenarios.

Contributions

• Provides a comprehensive assessment of historical (1961-2018) and future (2019-2099) meteorological drought characteristics (intensity, frequency, duration) in the upper Yangtze River basin using both SPI and SPEI.
• Utilizes an ensemble of 10 CMIP6 models under three SSP scenarios to project future drought trends, addressing existing literature limitations regarding temporal drought pattern assessment and projections of water stress characteristics (magnitude, recurrence, persistence).
• Offers detailed analysis of geographical variability in drought attributes and territory-specific manifestations of water stress classifications.
• Generates analytical outcomes intended to inform policy frameworks and intervention protocols for drought management in the region under evolving climate patterns.

Funding

• The National Key R&D Program of China (2023YFC3206004, 2022YFC3202301)
• The National Natural Science Foundation of China (52121006)
• The Academy of Engineering Consultancy Projects (2022-JB-02-04, 2023-JB-04-08)
• The Special Funding for Basic Research Operations of Central Public Welfare Research Institutions (Y522013)

Citation

@article{Chang2025Historical,
  author = {Chang, Yu and Li, Wenxin and Liu, Cuishan and Wang, Yun and He, Ruimin and Wang, Guoqing},
  title = {Historical evolution and future trend of meteorological drought in the upper Yangtze River basin},
  journal = {Climate Dynamics},
  year = {2025},
  doi = {10.1007/s00382-025-07896-1},
  url = {https://doi.org/10.1007/s00382-025-07896-1}
}

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