Characteristics of Drought Propagation from Meteorological to Hydrological Drought Using Sensor-Based Drought Indices

Sustained meteorological drought can lead to hydrological drought, which is known as drought propagation. Propagated drought events are more devastating than non-propagated events. Therefore, investigating their propagation characteristics is critical. In this study, we characterized drought propagation using sensor-based drought indices calculated from observed precipitation and reservoir storage. The study area was classified into 29 clusters based on its primary water source, which served as a standard for calculating the hydrological drought index. We then determined the propagation between meteorological and hydrological droughts and investigated the propagation characteristics (attenuation, lag, and lengthening) and their corresponding damage patterns. The average numbers of meteorological and hydrological drought occurrences were 85 and 18, respectively, and the average propagation rate from meteorological to hydrological droughts was approximately 14%. Among the propagated events, 92% exhibited lengthening characteristics with an average lag time of 5.04 weeks. For the Boryeong Dam basin, the meteorological drought in 2012 propagated into a hydrological drought, but attenuated into a weaker hydrological drought, which resulted in no damage. Conversely, the meteorological drought in 2016 propagated with a lag and lengthening. This event damaged the water supply and agriculture in the four regions, affecting 3,760 people and 703 ha. These cluster-specific propagation characteristics and corresponding damage patterns can be used to establish region-specific drought response policies.