An Analysis of Drought Characteristics in Busan Based on the Standardized Precipitation Evapotranspiration Index Reflecting Climate Change Trends

This study calculated the Standardized Precipitation Evapotranspiration Index (SPEI) based on future climate scenarios (RCPs 4.5 and 8.5) to evaluate drought characteristics. The analysis of the annual average drought occurrence showed that shorter drought durations occurred more frequently. In particular, 1-month droughts occurred significantly more often than droughts of other durations. Additionally, as drought duration increased, the difference between the upper and lower quartiles decreased, indicating reduced variability. The analysis of drought frequency by intensity revealed that climate change caused changes in drought patterns, causing extreme droughts, with less than -2 of SPEI, to increase by 1,560%. The spatial distribution analysis showed that 1-month droughts were the most frequent, with higher occurrences on the outskirts of Busan City than in the central area. Under the RCP 8.5 scenario, areas experiencing over 2.5 months of 1-month droughts increased, and areas with 6- and 12-month droughts also increased. Specifically, even the central area of the city, which had relatively low drought occurrences, showed a gradual increase as climate change intensified. Seasonally, the drought months of spring and autumn increased from 0.58 and 0.61 months to 0.90 and 1.23 months, respectively, while those of summer and winter decreased from 0.57 and 0.60 months to 0.08 and 0.29 months, respectively. Furthermore, except for winter, all seasons showed reduced variability in drought months as climate change intensified, indicating that precipitation may become more concentrated over time with less variability as climate change progresses.