Many farmers struggled with extreme drought and heat wave this year. The social and economic impacts of droughts are nothing new. Because Korea’s Joseon Dynasty (1392-1910) was agrarian and heavily dependent on rice cultivation, the country was particularly sensitive to drought and torrential rains, and went to great lengths to minimize damage.
Professor Jonghun Kam (Environmental Science and Engineering) of POSTECH and Chang-Kyun Park, researcher at the Institute of Environmental and Energy Technology, have developed a self-calibrating effective drought index (scEDI) through joint research. This new index allowed them to examine 250 years of drought data, starting from the late Joseon Dynasty to the present day, and to compare and analyze rainfall records.
The EDI, a typical tool for determining the severity of drought, is used for daily monitoring and characterization of drought conditions. The index uses daily precipitation records for the last 30 years. In other words, the reference period determines the EDI values, making it difficult to compare values over a long recording period.
Professor Kam’s research team is the first to propose a self-calibrating EDI and use it to analyze the daily rainfall observed in Seoul from 1777 to 2020 with the same intensity and frequency.
Specifically, this research used the historical records of the Annals of the Joseon Dynasty (Joseon Wangjo Sillok) and daily precipitation data as measured by the Joseon Rain Gauge (chukwookee). The study demonstrated the value of the unprecedentedly meticulous records left by the Koreans from this period.
Comparing Joseon-era records with online search results today implies that our predecessors were more sensitive to drought. Most drought damage records and peaks in public interest in drought coincide with moderate (-1.4 by scEDI) and severe drought (-2.0), respectively.
The results suggest that the socio-economic impact of drought depends on the socio-economic structure. As a valuable tool for the quantitative assessment of drought consequences, the scEDI has the potential to identify droughts with social consequences in advance.
Professor Kam explained: “The scEDI proposed in this study has an automatic calibration that corresponds to the climate of the reference period and allows for the temporal detection and comparison of droughts (in terms of severity, duration and intensity). This establishes a new research methodology for social droughts that have been difficult to study compared to other drought-related categories: meteorological, agricultural, and hydrological. He added, “Understanding both the social impacts of droughts and how they have been addressed will provide the Korean public with action plans to be prepared for future droughts in advance.”
Recently published in Journal of HydrologyThe study was supported by the National Research Foundation of Korea (Sejong Science Fellowship Program and Mid-career Researcher Program) and the National Disaster Management Research Institute (Cooperative Research Method and Safety Management Technology in National Disaster).
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Materials provided by Pohang University of Science and Technology (POSTECH). Note: Content can be edited for style and length.
