Association and driving factors of meteorological drought and agricultural drought in Ningxia, Northwest China

Under global warming, drought problems have become increasingly prominent, which has seriously affected the ecological environment's protection and social and economic development at global and regional scales. Ningxia is an arid region in northwest China with serious water problems, and droughts further exacerbate its water security and hinder ecological and socio-economic development. Therefore, this study explored the temporal and spatial distribution characteristics of meteorological and agricultural droughts and their driving factors in Ningxia during 2002-2021 by combining wavelet analysis and grey relational analysis. The main conclusions are as follows: (1) precipitation, soil moisture (SM), and evapotranspiration (ET) in Ningxia increased significantly, while the main meteorological drought events in Ningxia appeared around 2006, 2011, and 2015, and the agricultural drought first became stronger and then weaker; (2) precipitation and ET were correlated with meteorological drought in Ningxia, with a coefficient above 0.8, while the correlation between agricultural drought and precipitation, ET, and gross primary production (GPP) were very significant; and (3) precipitation, ET, and GPP were not all included in the drivers of meteorological drought in Ningxia, whereas agricultural drought had a grey correlation with precipitation, ET, and GPP according to the grey relational analysis. This study is of great significance for revealing the spatiotemporal characteristics and driving factors of drought in Ningxia as well as the early warning and risk management.