Widespread enhancement and slower occurrence of agricultural drought events in drylands of the Yellow River Basin

Study region: The Yellow River Basin in China Study focus: Agricultural drought (AD) poses a serious threat to national food security, however, responses to AD to meteorological drought (MD), factoring in influences of climate change and human activity, are not well understood. This study employed the Standardized Precipitation Evapotranspiration Index and the Standardized Soil Moisture Index to characterize the evolution of MD and AD. The drought propagation time (PT) was calculated with maximum correlation coefficients under full-crop-cycle, seasonal, and multi-threshold modes for spring and winter wheat in the Yellow River Basin (YRB; China). New hydrological insights for the region: Both spring and winter wheat faced increasing magnitude agricultural drought events (ADEM), with winter wheat being affected more severely from 1950-2021. Increasing temperature enhanced ADEM, while human activities had a more uncertain. The PT was generally prolonged for all propagation modes, with spring wheat having a longer PT except for in multi-threshold mode. The full-crop-cycle mode showed the entire period of crop growth propagation characteristics, the seasonal mode showed different propagation characteristics by month, and the multi-threshold mode showed the propagation characteristics at different degrees of AD. Sunspot Index had the highest influence on PT among all teleconnection factors, and human activities had increasing impact. The results of this study provide a basis for better understanding the agricultural drought propagation.