Climate change enhances the severity and variability of drought in the Pearl River Basin in South China in the 21st century

Drought is expected to increase in frequency, severity, and duration in the future due to global warming and this will greatly threaten the future socio-economic development. This study evaluates the spatiotemporal variation of future drought (2016-2100) in the Pearl River Basin (PRB) using the Palmer drought severity index (PDSI), the Variable Infiltration Capacity (VIC) model, and future climate projections based on the general circulation models (GCMs) from phase 5 of the Coupled Model Intercomparison Project (CMIP5) under three representative concentration pathway (RCP) scenarios. The results show that future drought conditions are expected to be more serious than historical (1960-2015) drought conditions in the PRB, especially under RCP8.5. The severity and variability of future drought conditions are also higher than for the historical period. The west Guangxi and South Guizhou provinces exhibit the highest increment in drought severity under the three RCP scenarios. At the seasonal scale, drought severity shows the highest increment in the winter with little change in summer; the summer drought severity increases in most areas of the PRB but the increment of the drought severity is lower than the winter. The number of future drought events is expected to decrease but the duration and severity are expected to increase, especially in the mid-west PRB and under high greenhouse gas (GHG) emission scenarios. In summary, in most areas of the PRB, the severity and variability of drought are expected to increase in the 21 st century, especially in the mid-west PRB and an increase in evapotranspiration is assumed to be the main underlying cause. Irrigation projects and agricultural production in the PRB might face serious threats of drought in the future.