Projecting meteorological, hydrological and agricultural droughts for the Yangtze River basin

Abstract

Drought is a multifaceted natural hazard that occurs in virtually any component of the hydrological cycle. Drought monitoring and prediction from multiple viewpoints are essential for reliable risk planning and management. This study presents a joint prognosis of meteorological (M-drought), hydrological (H-drought) and agricultural (A-drought) droughts for the period 2021–2100 over the Yangtze River basin (YRB). The prognosis uses an ensemble of 10 models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) for two future emission scenarios (RCP4.5 and RCP8.5). Precipitation, runoff, and soil moisture are used to quantify M-drought, H-drought, and A-drought, respectively. The results indicate that the raw CMIP5 multimodel ensemble for the YRB generally overestimates precipitation while underestimating temperature. The precipitation, runoff, and soil moisture are all projected to increase in the coming decades at the spatial scale of the entire YRB. Moreover, the magnitudes of drought shift from moderate and severe in the past (1954–2013) to extreme and exceptional in the future. The durations of drought are anticipated to prolong in the future, especially for the A-droughts. A-droughts are projected to be more severe than M- and H-droughts. Furthermore, the headwater areas and the areas surrounding the intersection of Sichuan, Guizhou and Chongqing are anticipated to increase in A-drought severity. These findings provide insight to inform drought planning and management in the YRB, and improve our understanding of the ability of precipitation, runoff, and soil moisture to describe droughts under global warming scenarios.