PROGRESS IN GEOGRAPHY ›› 2020, Vol. 39 ›› Issue (4): 591-601.doi: 10.18306/dlkxjz.2020.04.006

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Spatiotemporal changes of droughts and heatwaves on the Loess Plateau during 1960-2016

SUN Yijie, LIU Xianfeng*(), REN Zhiyuan, DUAN Yifang   

  1. School of Geography and Tourism, Shaanxi Normal University, Xi'an 710119, China
  • Received:2019-03-25 Revised:2019-05-25 Online:2020-04-28 Published:2020-06-28
  • Contact: LIU Xianfeng E-mail:liuxianfeng7987@163.com
  • Supported by:
    National Natural Science Foundation of China(41801333)

Abstract:

Based on daily maximum temperature and monthly precipitation data of 49 meteorological stations on the Loess Plateau during 1960-2016 and using the 90th percentile of the temperature as extreme temperature thresholds and standardized precipitation index (SPI), this study examined the spatiotemporal variation characteristics of heatwaves and droughts and the dynamics of concurrent droughts and heatwaves across the Loess Plateau. The results show that: 1) The occurrence frequency of heatwaves presented an increasing trend on the Loess Plateau during the recent 57 years with a liner tendency of 0.29 times/a, of which a significant increasing trend was detected after 1995. The significantly increasing areas were mainly distributed in the northeast of Shanxi Province, eastern Qinghai Province, and southern and central Gansu Province. 2) Standardized precipitation index (SPI) showed a downward trend in the recent 57 years, indicating a trend from water-logging to drought, and the early 1990s was a turning point. Particularly, areas with the declining trend of SPI12 accounted for 62% of the whole study area, and regions with significant drought were mainly distributed in the south of the gully areas of the Loess Plateau, the southern part of Northern Shaanxi, the south of Shanxi Province, and the east of Gansu Province. 3) The simultaneous occurrence frequency of droughts and heatwaves showed an overall increasing trend, with a growth rate of 0.66 times/10 a. From 1960 to 1979 it showed a declining trend of -0.26 times/a, then an increasing trend of 0.52 times/a from 1980 to 2002, while a steady increasing trend was detected after 2003. Spatially, the high incidence of droughts and heatwaves was observed in the eastern of Shanxi, the south of Northern Shaanxi, and the southwest of Gansu; areas with increasing trend were mainly concentrated in the northeast of Shanxi, central and eastern Gansu, and northern Ningxia.

Key words: heatwave, drought, concurrent extremes, spatiotemporal variations, Loess Plateau