Moon et al. (2025) An Analysis of Drought Characteristics in Busan Based on the Standardized Precipitation Evapotranspiration Index Reflecting Climate Change Trends

Identification

• Journal: Korean Society of Hazard Mitigation
• Year: 2025
• Date: 2025-10-28
• Authors: Ji Hyun Moon, Ji Yoon Kang, Raehyun Kim, Keewook Kim
• DOI: 10.9798/kosham.2025.25.5.57

Research Groups

• Busan Development Institute, Republic of Korea
• Department of Civil Engineering, Pusan National University, Republic of Korea
• Gimhae Research Institute, Republic of Korea
• Yooshin Co., Ltd., Republic of Korea

Short Summary

This study projected future drought characteristics in Busan, Republic of Korea, by calculating the Standardized Precipitation Evapotranspiration Index (SPEI) under RCP 4.5 and 8.5 climate change scenarios. The analysis revealed a significant increase in the frequency and intensity of extreme short-term droughts, particularly a 1,560% rise in 1-month extreme droughts, alongside shifts in seasonal drought patterns and reduced variability across most seasons.

Objective

• To project future drought characteristics in the Busan region by calculating the Standardized Precipitation Evapotranspiration Index (SPEI) reflecting climate change trends from future climate scenarios (RCP 4.5 and 8.5) for the target year 2030.

Study Configuration

• Spatial Scale: Busan Metropolitan City, Republic of Korea, encompassing 13 standard watersheds with a total area of 1,246.62 square kilometers (60.5% within Busan city limits).
• Temporal Scale:
  • Historical period: 1966–2018 (53 years)
  • Future projection period: 2021–2030 (10 years)
  • Drought durations analyzed: 1-month, 6-month, and 12-month.

Methodology and Data

• Models used:
  • Standardized Precipitation Evapotranspiration Index (SPEI) for drought assessment.
  • Penman-Monteith method for calculating potential evapotranspiration (PET).
  • Log-logistic probability distribution function for SPEI calculation.
  • Bias correction method (Lee and Kim, 2016; Hawkins et al., 2013) for dew point temperature.
  • Mann-Kendall test for trend analysis of seasonal drought frequency.
• Data sources:
  • Historical daily meteorological data (1966–2018) from 13 synoptic observation stations provided by the Korea Meteorological Administration.
  • Future climate scenarios (2021–2030) based on Representative Concentration Pathways (RCP) 4.5 and 8.5, obtained from the Korea Meteorological Administration Climate Information Portal.
  • Watershed names and areas from the Water Resources Management Information System (http://wamis.go.kr).

Main Results

• Shorter drought durations, especially 1-month droughts, occurred significantly more frequently than longer durations.
• As drought duration increased, the difference between upper and lower quartiles decreased, indicating reduced variability.
• Climate change led to a drastic increase in extreme droughts (SPEI < -2), with a 1,560% increase in 1-month extreme droughts.
• Overall, 12-month droughts showed an approximate 6.7% increase in occurrence.
• Spatially, 1-month droughts were most frequent, with higher occurrences in the outskirts of Busan City compared to the central area.
• Under the RCP 8.5 scenario, areas experiencing over 2.5 months of 1-month droughts increased, and areas with increased 6- and 12-month droughts also expanded, including the relatively less drought-prone central city areas.
• Seasonally, drought months in spring and autumn increased significantly (from 0.58 to 0.90 months for spring; 0.61 to 1.23 months for autumn), while those in summer and winter decreased (from 0.57 to 0.08 months for summer; 0.60 to 0.29 months for winter).
• Except for winter, all seasons showed reduced variability (coefficient of variation) in drought months as climate change intensified, suggesting increased temporal concentration of precipitation.

Contributions

• Provides a novel projection of future drought characteristics for the Busan region by integrating climate change trends (2021-2030) into historical meteorological data (1966-2018) for SPEI calculation.
• Offers a detailed, multi-scalar analysis of drought patterns (duration, intensity, spatial distribution, seasonal trends) under different climate change scenarios (RCP 4.5 and 8.5) for a major urban area.
• Highlights the specific vulnerability of urban areas to increasing extreme short-term droughts and shifts in seasonal drought occurrences due to climate change.
• Generates foundational data crucial for informed water resource management, disaster preparedness, and long-term climate change adaptation strategies in urban environments.

Funding

• Ministry of Interior and Safety (MOIS), Republic of Korea
• Korea Institute of Industrial Technology Planning and Evaluation (KEIT), Republic of Korea
• Project Name: Development and Demonstration of Advanced Urban Retention Technology for Reducing Urban Flood Damage
• Project Code: RS-2024-00415937

Citation

@article{Moon2025Analysis,
  author = {Moon, Ji Hyun and Kang, Ji Yoon and Kim, Raehyun and Kim, Keewook},
  title = {An Analysis of Drought Characteristics in Busan Based on the Standardized Precipitation Evapotranspiration Index Reflecting Climate Change Trends},
  journal = {Korean Society of Hazard Mitigation},
  year = {2025},
  doi = {10.9798/kosham.2025.25.5.57},
  url = {https://doi.org/10.9798/kosham.2025.25.5.57}
}