Tran et al. (2025) Evaluating Drought Evolution in Vietnam Using Cmip6-Vn Climate Projections

Identification

• Journal: Inżynieria Mineralna
• Year: 2025
• Date: 2025-10-10
• Authors: Tuan Anh Tran, Thu Nguyen, T. Tran
• DOI: 10.29227/im-2025-02-19

Research Groups

• Faculty of Environment, Hanoi University of Mining and Geology, Hanoi, Vietnam
• Faculty of Natural Resources and Environment, Vietnam National University of Agriculture, Hanoi, Vietnam

Short Summary

This study evaluates drought evolution across Vietnam's seven climatic sub-regions from 1985 to 2099 using the one-month Standardized Precipitation Evapotranspiration Index (SPEI) derived from the 10-km resolution CMIP6-VN dataset under three Shared Socioeconomic Pathways (SSPs). It projects increasing drought intensity and severity, particularly in central and northern regions, driven by amplified evapotranspiration outpacing precipitation gains, highlighting the need for adaptive water management.

Objective

• To evaluate the evolution of drought characteristics (intensity, frequency, and severity) across Vietnam's seven climatic sub-regions from 1985 to 2099 under three Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP5-8.5), utilizing the one-month Standardized Precipitation Evapotranspiration Index (SPEI) derived from the high-resolution CMIP6-VN dataset.

Study Configuration

• Spatial Scale: Vietnam's mainland territory, divided into seven climatic sub-regions (Northwest, Northeast, Red River Delta, North Central, South Central, Central Highland, and South). Data resolution is 0.1° × 0.1° (approximately 10 km).
• Temporal Scale: Historical (1985–2014), Near-future (2015–2039), Mid-century (2040–2069), and Far-future (2070–2099). Total period analyzed: 1985–2099.

Methodology and Data

• Models used:
  • 22 CMIP6 Global Climate Models (GCMs) downscaled to the CMIP6-VN dataset.
  • Potential Evapotranspiration (PET) estimated using the Hargreaves-Samani method.
  • Drought assessment using the one-month Standardized Precipitation Evapotranspiration Index (SPEI).
  • Temporal trend analysis using the Mann-Kendall test.
  • Model projection uncertainty quantified using the Signal-to-Noise Ratio (SNR) method.
• Data sources:
  • CMIP6-VN dataset: High-resolution (10-km) downscaled near-surface temperature (T2m), maximum/minimum daily temperature (Tmax/Tmin), and precipitation (Pr) data for Vietnam.
  • Validation data: 157 ground-based meteorological stations for temperature and 481 for precipitation across Vietnam.

Main Results

• Temperature Projections: Consistent warming trends across all regions and scenarios. National average temperatures are projected to increase by 1.4 °C (SSP1-2.6), 2.6 °C (SSP2-4.5), and 4.5 °C (SSP5-8.5) by the end of the century relative to the 1985–2014 baseline. Northern regions (R1–R4) show enhanced warming (up to 5.1 °C in R1) compared to southern regions (4.0 °C in R7).
• Precipitation Projections: General increases across all scenarios, with SSP2-4.5 showing the largest rise (7.2% by 2070–2099). However, precipitation projections exhibit higher uncertainty (approximately ±20%) compared to temperature.
• Drought Evolution (SPEI):
  • Near-future (2015–2039): Drought frequency decreases (e.g., 40.9% reduction under SSP1-2.6), but intensity (mean SPEI during droughts: -1.31, a 19.1% increase) and severity (duration: 9.4 months/event, a 23.7% increase) rise, driven by temperature increases (0.5–0.82 °C) despite near-stable precipitation (±1–2%). Southern Vietnam (R6, R7) experiences a 22.7% intensity increase under SSP2-4.5.
  • Mid-century (2040–2069): A hydroclimatic transition towards wetter conditions is observed, most pronounced under SSP1-2.6 (13/22 models show wetting trends, SPEI = +0.2 to +0.5).
  • Late-century (2070–2099): Renewed drought stress with a national average increase of approximately 5 events (29.2%) across all scenarios. Northern regions (R1–R3) exhibit stronger wetting (SPEI = +0.6) than southern regions (R6, R7). Central region R4 faces the most extreme severity, with drought durations reaching 15.7 months/event (a 106.6% increase) under SSP2-4.5.
• Uncertainty: Model agreement is high in the near term, particularly in regions R2, R4, and R5 (15/22 models under SSP1-2.6). However, uncertainty increases towards the end of the century and under high-emission scenarios, with SSP5-8.5 showing the least model agreement.

Contributions

• Provides the first comprehensive national assessment of drought trends across Vietnam using the high-resolution (10-km) CMIP6-VN downscaled dataset, filling critical gaps in national-scale, high-resolution analyses.
• Utilizes the Standardized Precipitation Evapotranspiration Index (SPEI), which integrates temperature-driven evapotranspiration, offering a more realistic assessment of drought under climate warming compared to previous studies relying on precipitation-only indices.
• Covers long-term projections from the near-future (2015) to the far-future (2099) across three Shared Socioeconomic Pathways (SSP1-2.6, SSP2-4.5, SSP5-8.5), providing robust insights for both short- and long-term adaptation planning.
• Offers a transformative understanding of future drought patterns in Vietnam, supporting evidence-based strategies for sustainable water resource management and agricultural resilience.

Funding

• Research No. T25-35 of Hanoi University of Mining and Geology.

Citation

@article{Tran2025Evaluating,
  author = {Tran, Tuan Anh and Nguyen, Thu and Tran, T.},
  title = {Evaluating Drought Evolution in Vietnam Using Cmip6-Vn Climate Projections},
  journal = {Inżynieria Mineralna},
  year = {2025},
  doi = {10.29227/im-2025-02-19},
  url = {https://doi.org/10.29227/im-2025-02-19}
}