Exploring the influence of climate change-induced drought propagation on wetlands

Drought has been one of the most ominous natural hazards for the last century. However, it is a big challenge to identify the progression of drought, because, unlike other natural disasters, its progress is very slow. This study examined the impact of climate change on drought-related hydro-meteorological variables (precipitation, soil moisture, and streamflow) and drought propagation from meteorological to agricultural and hydrological drought based on the emission scenario representative concentration pathway (RCP) 8.5. The multi-model ensemble (MME) projection of five general circulation models (GCMs) was made, and Sen's slope test was used to identify the trend embedded in the hydro-meteorological variables. Drought characteristics (duration, severity, and frequency) of meteorological, agricultural, and hydrological drought were also investigated spatially and temporally under the climate change scenario. A probabilistic graphical model (PGM) was used to estimate the propagation probability of different states of meteorological drought to agricultural and hydrological droughts, whereas the joint propagation probability of meteorological and agricultural drought to hydrological drought was investigated in the Nakdong River basin of South Korea. The drought characteristics (duration and severity) of meteorological, agricultural, and hydrological drought were projected to increase across the basin, except for the north and northwestern parts, for the period of 2021 to 2060, whereas drought frequency was projected to increase in the whole basin in all future periods. The results of drought propagation showed that the propagation probability of severe and extreme states of meteorological drought resulting in severe and extreme states of agricultural and hydrological drought ranged from 0.36–0.57 and 0.48–0.72, respectively; whereas the propagation probability of severe and extreme states of agricultural drought resulting in severe and extreme states of hydrological drought varied from 0.26–0.42 on average. The joint propagation probability of severe and extreme states of meteorological and agricultural droughts given severe and extreme states of hydrological drought ranged from 0.49–0.83 on average. The results of this study provide valuable information for drought-associated decision-making and will be helpful in management and restoration of wetlands; however, it is necessary to keep in mind that our findings depend on emission scenario.