Interannual Variability and Key Influencing Factors of Drought in China over the Past 120 Years
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Graphical Abstract
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Abstract
This study examines the long-term patterns of drought in China over the past 120 years using datasets from three drought indices: the Standardized Precipitation Index (SPI-12), Standardized Precipitation Evapotranspiration Index (SPEI-12), and self-calibrated Palmer Drought Severity Index (scPDSI) covering the period from 1901 to 2020. The research investigates the reasons behind the inconsistencies observed in these indices. The results reveal a significant drying trend in Southwest China, the Loess Plateau, southern Northeast China, and southern Xinjiang while wetting trends are notable in eastern Northwest China, northern Northeast China, and North China. Drought events in Northeast China and Northwest China are characterized by prolonged duration and higher intensity, although there is a general trend of decreasing drought, particularly evident in eastern Northwest China and northern Northeast China. In contrast, southern Northeast China exhibits a decreasing trend of drought duration and intensity. Every year, about 2.82×106 km2 of land areas experience drought, with about 3.05×104 km2 of land areas threatened by extreme drought. Drought-affected areas of varying severity have increased over time, showing rapid growth after the mid-1990s. Additionally, the drought area exhibits significant interannual and decadal variabilities, with periods of 2–3 years and 18–22 years. In humid regions, the three drought indices show good consistency, while in semi-arid and arid regions, their consistency is relatively low. In humid areas, wet–dry variation is primarily influenced by precipitation. In semi-arid and arid areas, in addition to precipitation, temperature and soil characteristics also play important roles in drought variations. Therefore, more attention should be paid to drought index selection over arid and semi-arid areas in the context of global warming.
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