Influence of evapotranspiration on future drought risk using bivariate drought frequency curves

This study investigated the influence of evapotranspiration on future drought risk using bivariate drought frequency curves. Two different drought indices were used; SPI (Standardized Precipitation Index) which considers precipitation variation only and SPEI (Standardized Precipitation Evapotranspiration Index) which takes into account both precipitation and evapotranspiration variations. After generating the drought indices under the Representative Concentration Pathway (RCP) 8.5 scenario used in the Fifth Assessment Report (AR5) of IPCC, drought frequency analyses were performed and drought risks were estimated based on the joint quantiles of drought duration and severity. As a result, significant differences of drought risk were identified between SPI- and SPEIbased drought analyses using RCP 8.5 projections; mainly, the SPEI-based drought risk increases entirely across South Korea compared with the SPI-based drought risk. The outcomes of this study would be useful to develop comprehensive drought mitigation plans to cope with future climate change.