Drought Variations in the Yili Basin, Northwest China since AD 1673 Based on Tree-Ring Width

The Yili Basin represents a typical region influenced by the Westerlies, and as a result of the substantial precipitation delivered by these winds, it has emerged as a significant hub for agricultural and animal husbandry activities in Central Asia. This study established a 419-year tree-ring width chronology, utilizing living Picea schrenkiana samples from two sampling sites in the Yili Basin. Correlation analysis showed that the standard tree-ring width chronology had the best correlation with the Palmer Drought Severity Index from the previous August to the current May (PDSI_P8C5) (r = 0.614, n = 59, p < 0.001). Therefore, we reconstructed PDSI_P8C5 variations from 1673 to 2018. The reconstruction results reveal eight wet and seven dry periods during the past 346 years. In the reconstructed series, droughts are particularly pronounced around 1770 and 1920, and the PDSI shows a significant long-term wetting trend since the 1980s. The solar activity, North Atlantic Oscillation (NAO), and Atlantic Multidecadal Oscillation (AMO) jointly influenced the regional moisture variation.