Sun et al. (2026) Interdecadal variability and future persistence of meteorological drought in Yunnan, Southwest China (1961–2021)

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2026
• Date: 2026-01-06
• Authors: Wenjun Sun, Zhiqiang Lin, chaojun chen, Jian Zhang, Mingqiang Liang, Yao Wu, Hongming Yan, Junyun Li, Tingyong Li
• DOI: 10.1016/j.ejrh.2025.103071

Research Groups

• Yunnan Key Laboratory of Plateau Geographical Processes & Environmental Changes, Faculty of Geography, Yunnan Normal University, Kunming, China
• GIS Technology Engineering Research Centre for West-China Resources and Environment of Educational Ministry, Faculty of Geography, Yunnan Normal University, Kunming, China
• Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan
• Earth and Climate Research Center, Earth and Life Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium
• Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany
• Yunnan Climate Center, Kunming, China
• Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing, China

Short Summary

This study investigates the interdecadal variability and future persistence of meteorological drought in Yunnan, Southwest China, from 1961 to 2021. It reveals a persistent drying trend with an abrupt shift around 2002, projected to continue for the next three decades, driven by a combination of climatic and anthropogenic factors.

Objective

• To quantify the interdecadal variation characteristics of meteorological drought in Yunnan Province.
• To elucidate the mechanisms governing the wet–dry transition process under varying climatic conditions.
• To project the future evolution and persistence of meteorological drought in Yunnan in the context of global warming.

Study Configuration

• Spatial Scale: Yunnan Province, Southwest China (area of 394,100 km²), utilizing data from 124 meteorological stations.
• Temporal Scale: Historical analysis from 1961 to 2021 (61 years), with future projections for the next three decades.

Methodology and Data

• Models used:
  • Standardized Precipitation Evapotapotranspiration Index (SPEI-12) (calculated using the Penman-Monteith model for potential evapotranspiration).
  • Theil-Sen median slope estimator.
  • Mann-Kendall (M-K) nonparametric statistical test.
  • Intensity analysis (interval, category, and transition levels).
  • Hurst exponent (using Rescaled Range (R/S) analysis).
  • Linear regression method.
  • Inverse Distance Weighted (IDW) method for spatial interpolation.
  • Empirical Orthogonal Function (EOF) analysis.
  • Random Forest importance analysis.
  • Morlet wavelet analysis.
• Data sources:
  • Monthly meteorological observations (precipitation, mean air temperature) from 124 national meteorological stations across Yunnan Province (1961–2021), obtained from the Yunnan Climate Center.
  • Potential Evapotranspiration (PET) data from the high-resolution Climatic Research Unit Gridded Time Series (CRU TS v4.07) dataset (0.5° × 0.5° resolution, 1961–2021).
  • Long-term socio-economic indicators (population, gross domestic product (GDP), urbanization rate) from the China Economic and Social Big Data Research Platform (1961–2021).
  • ERA5 reanalysis (for validation).
  • Six standardized monsoon indices: East Asian Summer Monsoon Index (EASMI), South Asian Summer Monsoon Index (SASMI), South China Sea Summer Monsoon Index (SCSMI), Western North Pacific Monsoon Index (WNPMI), Indian Summer Monsoon Index (ISMI), and Webster–Yang Monsoon Index (WYMI).

Main Results

• The SPEI-12 in Yunnan Province exhibited an overall decreasing trend from 1961 to 2021, with an average annual decline rate of -0.014 per year.
• A significant abrupt shift towards intensified drought occurred around 2002, with the period 2010–2021 identified as the driest.
• Drought frequency increased by approximately 27% after 2000 compared to the 1960s, while wet frequency declined by about 16%.
• Spatially, a pronounced decline in SPEI-12 was observed in the eastern, western, and southwestern regions, indicating regional drought intensification.
• EOF analysis revealed a dominant spatial pattern of consistent aridity across the entire region (EOF1, 55.70% variance) and a secondary dipolar pattern highlighting contrasting drought–wet variations between northwestern and southeastern regions (EOF2, 13.75% variance).
• Wavelet analysis detected significant oscillations in the SPEI-12 series with periods of approximately 36 years, 23 years, and 13 years.
• Intensity analysis indicated an acceleration in the rate of transition between wet and dry states over time, particularly after 2000, with drought categories showing rapid expansion.
• The mean Hurst exponent (H) across Yunnan Province was 0.68, suggesting strong persistence in drought–wet sequences, with 99.2% of stations exhibiting H > 0.5.
• Future projections, based on the Hurst exponent and historical trends, indicate a likely continuation and intensification of arid conditions in most parts of Yunnan, with 49.07% of the province projected to experience statistically significant decreases in SPEI-12.
• Precipitation was the predominant factor influencing SPEI-12 variability (57.07% importance), followed by potential evapotranspiration (13.02%), Atlantic Multidecadal Oscillation (AMO) (11.83%), temperature (11.68%), and Pacific Decadal Oscillation (PDO) (6.40%).
• Weakened South Asian Summer Monsoon Index (SASMI), Webster–Yang Monsoon Index (WYMI), and Indian Summer Monsoon Index (ISMI) were strongly correlated with the post-2000 drought intensification.
• Anthropogenic influences, including urbanization, population growth, and land-use change, indirectly amplified regional drought severity by modifying climate variables and contributing to a "dry island effect."

Contributions

• Provides an integrated and systematic assessment of interdecadal meteorological drought variability in Yunnan Province using SPEI-12, addressing existing gaps in research on decadal-scale changes, detailed wet-dry transition processes, and future drought trends under global warming.
• Integrates multiple advanced analytical methods (intensity analysis, Hurst exponent, Mann-Kendall test, wavelet analysis, EOF, Random Forest) with high-resolution PET data from CRU TS v4.07 for a comprehensive investigation.
• Elucidates the combined climatic and human mechanisms shaping long-term aridification in a climate-sensitive region.
• Offers a scientific foundation for improving drought early-warning systems, sustainable water resource planning, and adaptive policy design in monsoon-affected regions.

Funding

• Yunnan Fundamental Research Projects (Grant 202201AS070022)
• Young and Middle-age Academic and Technical Leader in Yunnan Province (No. 202205AC160025)
• National Natural Science Foundation of China (NSFC, No. 42272214, 42172204, and 42401189)

Citation

@article{Sun2026Interdecadal,
  author = {Sun, Wenjun and Lin, Zhiqiang and chen, chaojun and Zhang, Jian and Liang, Mingqiang and Wu, Yao and Yan, Hongming and Li, Junyun and Li, Tingyong},
  title = {Interdecadal variability and future persistence of meteorological drought in Yunnan, Southwest China (1961–2021)},
  journal = {Journal of Hydrology Regional Studies},
  year = {2026},
  doi = {10.1016/j.ejrh.2025.103071},
  url = {https://doi.org/10.1016/j.ejrh.2025.103071}
}