Prediction of drought is important for efficient water management, as the occurrence of droughts affects large areas over a long period. According to various climate change scenarios, it is reported that in the future, Korea's climate is likely to increase in temperature with increasing rainfall. This increase in temperature will have a big impact on the evapotranspiration. The occurrence of drought begins mainly with two causes: lack of rainfall or an increase in evapotranspiration. Therefore, in this study, the impact of climate change on future droughts is revealed through the standardized precipitation index and the evaporative demand drought index. Two drought indices with different characteristics are used to examine the trend of future drought, and the SDF curve was derived to quantitatively analyze the depth of future drought. Future droughts are projected by applying future climate data generated from various climate models.
Studies using drought index to examine return levels of drought can be classified into two approaches: univariate frequency analysis using annual series extracted from drought index time series and multivariate frequency analysis that simultaneously reflects various characteristics of drought. In the case of drought analysis, it is important to properly consider the duration, so, in this study, univariate frequency analysis is performed using the partial duration series. In addition, a bivariate frequency analysis is performed using a relatively simple bivariate exponential distribution to give a more realistic return level to major drought events in the past while reflecting the correlation between drought severities and durations. The drought severity–duration–frequency curves using each of the two frequency analyses are derived, and these curves are used to examine how the drought phenomenon currently in progress is evolving. From this, the advantages and disadvantages of the two approaches, as well as the points to be aware of in application, are discussed. Finally, using the two approaches to the proposed drought frequency analysis, the behavior of Korea’s future extreme droughts is investigated under the conditions of various future climate change scenarios.
Drought monitoring is necessary for water resource management. The drought monitoring currently operated by the Korea Meteorological Administration (KMA) is heavily dependent on the Standard Precipitation Index (SPI), which considers only precipitation. However, since SPI does not account for meteorological variables other than precipitation, it cannot account for the impacts of increases in evapotranspiration due to climate change. In order to overcome this limitation, studies on various drought indices that can reflect changes in potential evapotranspiration ( ) have been undertaken, and a new -based drought index, the Evaporative Demand Drought Index (EDDI), has recently been established. In this study, the applicability of EDDI for drought monitoring in South Korea was evaluated using meteorological data from the KMA for the period 1981-2017. The temporal behaviors of EDDI and SPI were investigated by comparing EDDI and SPI over various timescales. The results indicated that EDDI reproduced past drought events well and showed high correlation with SPI. Therefore, EDDI is expected to be effective for drought monitoring.
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