Evolution properties between meteorological, agricultural and hydrological droughts and their related driving factors in the Luanhe River basin, China

To fully reveal drought propagation mechanism and effectively mitigate drought, it is of importance to synthesize investigating different types of droughts; specifically, the propagation from meteorological to agricultural droughts and from agricultural to hydrological droughts, as well as their potential driving factors. The results suggested that: (1) the Standardized Precipitation Evapotranspiration Index (SPEI) is a better indicator for detecting drought onset, the Standardized Soil Index (SSI) can better describe drought persistence, and the Standardized Runoff Index (SRI) can depict the termination of drought; (2) the propagation time from meteorological to agricultural droughts, as well as that from agricultural to hydrological droughts, showed remarkable seasonal characteristics in the Luanhe River basin; (3) the significant influence of the Nino 1+2+3+4, Nino 3.4, Southern Oscillation Index (SOI), Multivariate ENSO Index (MEI), and Atlantic Multidecadal Oscillation (AOM) on meteorological drought was concentrated in the 16-88-month periods, as well as the decadal scale of 99-164-month periods, the significant influence of Nino 4, Nino 3.4, MEI, and SOI on agricultural drought was concentrated in the 16-99-month periods, as well as the decadal scale of 99-187-month periods, and the significant influence of Nino 4 and AOM on hydrological drought was concentrated in the 16-64-month periods, as well as the decadal scale of 104-177-month periods.