西北地区中西部, 干旱, 标准化降水蒸散指数, NDVI

Systematically investigating drought evolution characteristics and vegetation responses to drought is crucial for drought prevention, disaster mitigation, water resource management, and policy formulation. Our study focuses on Xinjiang, Qinghai, and Gansu provinces in mid-western Northwest China. Using the CN05.1 dataset from 1963 to 2022 to calculate the standardized precipitation evapotranspiration index (SPEI), combined with the normalized difference vegetation index (NDVI) from 2003 to 2022, we applied run theory, Theil-Sen slope estimator, Mann-Kendall trend test, and regression analysis to analyze drought evolution across multiple temporal scales and explore drought impacts on vegetation. The results indicate that over the past 60 years, the study area exhibited a drying trend on decadal and interannual scales, with 1998 identified as a significant drought mutation year. Pronounced drying trends were observed in eastern and southern Xinjiang, the Qaidam Basin, and the Hexi Corridor, where light and moderate droughts were predominant. The Hexi Corridor experienced a significantly higher frequency of moderate droughts (greater than 15.00%) than other regions. Drought variability exhibited periodic characteristics of 12-year, 30-year, and 46-year cycles, with notable seasonal differences. In spring, summer, and autumn, the mid-western Northwest China showed significant drying trends, with the most rapid decline in autumn (SPEI rate: −0.034 yr⁻¹). The Hexi Corridor exhibited SPEI decline rates below −0.030 yr⁻¹ across all three seasons, indicating high risks of consecutive droughts, alongside prolonged duration, higher peak intensity, and mean drought intensity. The Tarim Basin also faced severe drought conditions in spring and autumn. Drought exerted measurable impacts on vegetation dynamics. Compared to 2003-2012, NDVI degradation areas increased by approximately 3.52% during 2013-2022. Over the past two decades, vegetation degradation was concentrated in western Xinjiang, eastern and southern Qinghai, where NDVI and SPEI were positively correlated.

Mid-western Northwest, drought, standardized precipitation evapotranspiration index, NDVI