Analysis of drought events in the Jiziwan region of the Yellow River basin and their responses to atmospheric circulation factors on the basis of a three-dimensional identification algorithm

Study region Jiziwan region of the Yellow River basin, China. Study focus In the Yellow River basin, ecological protection and the development of high-quality infrastructure are of great strategic significance for China. To date, the ecological protection of the Yellow River basin has faced severe challenges, among which frequent droughts have become key limiting factors. However, the spatiotemporal structure and occurrence pattern of drought in the Jiziwan region of the Yellow River basin are difficult to accurately represent, and the mechanisms by which the driving factors affect drought are unknown. Therefore, in this study, the temperature–vegetation drought index (TVDI), 3D drought identification algorithm, structural equation modelling (SEM) system and multivariate cross-wavelet transform were used to reveal the spatiotemporal characteristics of drought events and their response mechanisms to driving factors New hydrological insights for the region From 2001–2020, the annual TVDI increased significantly (0.011/year), with a spatial distribution showing a pattern of higher values in the west and lower values in the east. Seasonal differences were evident, with spring being the most severe drought season and winter showing the fastest increase in TVDI (0.012/year). A total of 15 drought events were identified, with the 2015–2016 event being the most severe (24-month duration, 52.58% of the area affected, and an intensity of 4.635 ×10 5 km²·month). Soil moisture mitigates drought through direct and indirect pathways, while surface temperature and solar radiation exacerbate drought via energy balance processes. Precipitation is the key negative moderator of drought, with the largest total impact (-0.69), highlighting its critical role in alleviating drought. Atmospheric circulation factors (AO, DMI, PNA) interact with drought (TVDI) through multiple timescale resonance cycles (4–56 months), collectively influencing drought development by altering regional water-heat balance.