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Arid Land Geography ›› 2024, Vol. 47 ›› Issue (2): 214-227.doi: 10.12118/j.issn.1000-6060.2023.070

• Climatology and Hydrology • Previous Articles     Next Articles

Evolution and driving factors of megadrought and pluvial events in the Qilian Mountains during the past 500 years

REN Zijian1,2(), WANG Jianglin1(), XU Henian1,2, QIN Chun1   

  1. 1. Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, Gansu, China
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2023-02-21 Revised:2023-04-12 Online:2024-02-25 Published:2024-03-14
  • Contact: WANG Jianglin E-mail:renzijian21@mails.ucas.ac.cn;wangjianglin2011@lzb.ac.cn

Abstract:

Qilian Mountains is a climate-sensitive area in the arid areas of northwest China, where extreme megadrought events considerably impact vegetation, frozen soil, and other ecological elements. This paper uses three hydroclimate reconstruction datasets to analyze the occurrence, evolution, and possible driving mechanism of megadrought and pluvial events in the Qilian Mountains over the past 500 years. The results showed that the climate in the Qilian Mountains has shown a clear wetting trend since the recent decades, and the wetness trend after 1951 has exceeded the range of natural variability in the historical period. The RAP dataset provided a good representation of the historical dry and wet conditions in the study area. Significant variations were observed in precipitation during the past seven megadrought events in the region, with the highest severity occurring during the drought period of 1786—1796. Furthermore, considerable variations were noted in the duration of the four megapluvial events, with the longest duration being a wet event that lasted for 42 years from 1968 to 2009. Megadrought and pluvial events were influenced by climate forcing and internal variability of sea surface temperatures (SST). The decadal SST modes in the Pacific and Atlantic Oceans and their phase combinations were key factors regulating the megadrought and pluvial events in the Qilian Mountains. Solar radiation exhibited an in-phase variation with the precipitation in the Qilian Mountains, while volcanic activity primarily affected megadrought events. This study highlights the importance of a long-term perspective for assessing current hydroclimate anomalies in the Qilian Mountains and including possible roles of external forcing and sea surface temperature variability in assessing the future megadrought and pluvial risks in this region.

Key words: megadrought/pluvial events, Little Ice Age, driving factors, Qilian Mountain