Nguyen‐Xuan et al. (2025) Assessment of future droughts in Vietnam using high-resolution downscaled CMIP6 projections

Identification

• Journal: Natural Hazards
• Year: 2025
• Date: 2025-09-05
• Authors: Thanh Nguyen‐Xuan, Dzung Nguyen‐Le, Quan Tran-Anh, Tung Nguyen‐Duy, Thanh Ngo‐Duc
• DOI: 10.1007/s11069-025-07651-z

Research Groups

• Department of Space and Earth Sciences, University of Science and Technology of Hanoi (USTH), Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam
• Faculty of Environment, Hanoi University of Mining and Geology (HUMG), Hanoi, Vietnam
• Oxford University Clinical Research Unit, Ho Chi Minh city, Vietnam

Short Summary

This study assesses future drought conditions in Vietnam using high-resolution downscaled CMIP6 projections and the Standardized Precipitation-Evapotranspiration Index (SPEI). It finds that while significant warming is projected, precipitation is the dominant factor for SPEI trends, with overall milder drought characteristics expected, though severity and intensity may worsen in specific regions under worst-case scenarios and higher return periods.

Objective

• To investigate future drought conditions in Vietnam and its seven sub-climatic regions using the Standardized Precipitation-Evapotranspiration Index (SPEI) derived from high-resolution downscaled CMIP6 projections.

Study Configuration

• Spatial Scale: Vietnam and its seven sub-climatic regions, at a 10-kilometer resolution.
• Temporal Scale: Reference period: 1985–2014; Future period: 2015–2099. Daily data were used for SPEI derivation.

Methodology and Data

• Models used:
  • CMIP6 global models (statistically downscaled to create the CMIP6-VN dataset).
  • Standardized Precipitation-Evapotranspiration Index (SPEI) for drought assessment.
  • Copula analysis for evaluating drought event characteristics (duration and severity) under higher return periods.
• Data sources:
  • CMIP6-VN dataset, providing daily, high-resolution (10-kilometer) precipitation and temperature products.
  • Three Shared Socioeconomic Pathways (SSPs): SSP1-2.6, SSP2-4.5, and SSP5-8.5.

Main Results

• The performance of 22 CMIP6-VN models was confirmed for accurately representing precipitation and temperature characteristics during the 1985–2014 reference period.
• Significant warming is projected across Vietnam for the 2015–2099 period under all three SSPs (SSP1-2.6, SSP2-4.5, and SSP5-8.5).
• Precipitation projections remain uncertain, though most areas are anticipated to experience slightly increased rainfall.
• Precipitation significantly influences SPEI trends more than temperature, accounting for approximately 75% of the SPEI trend under SSP5-8.5.
• Drought characteristics, with the exception of intensity, are projected to become milder in the future across Vietnam.
• The central coastal area is projected to exhibit the most pronounced and statistically significant changes in drought characteristics.
• Further analysis of six models showing the most pronounced increasing drought trends revealed that drought severity and intensity could worsen under worst-case scenarios, particularly in northern Vietnam and the Central Highlands.
• Copula analysis indicates that drought events with higher return periods are projected to be more prolonged and severe in the future.

Contributions

• Provides critical scientific evidence for informing national adaptation strategies and regional water resource planning in Vietnam under future climate change.
• Utilizes a high-resolution (10-kilometer) downscaled CMIP6 dataset (CMIP6-VN) for a comprehensive assessment of future drought conditions across Vietnam's sub-climatic regions.
• Quantifies the relative influence of precipitation and temperature on SPEI trends under different SSPs.
• Investigates drought characteristics under various global warming levels (GWLs) and employs copula analysis to assess changes in drought severity and duration for events with higher return periods.

Funding

• 2nd phase of the GEMMES Vietnam project, funded by the French Development Agency (AFD) through Facility 2050.
• Vietnam National Foundation for Science and Technology Development (NAFOSTED) under Grant 105.06-2021.14.

Citation

@article{NguyenXuan2025Assessment,
  author = {Nguyen‐Xuan, Thanh and Nguyen‐Le, Dzung and Tran-Anh, Quan and Nguyen‐Duy, Tung and Ngo‐Duc, Thanh},
  title = {Assessment of future droughts in Vietnam using high-resolution downscaled CMIP6 projections},
  journal = {Natural Hazards},
  year = {2025},
  doi = {10.1007/s11069-025-07651-z},
  url = {https://doi.org/10.1007/s11069-025-07651-z}
}