| The characteristics of seasonal drought’s comprehensive index in Gansu Province |
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| DOI：10.7606/j.issn.1000-7601.2018.04.40 |
| Key Words: drought comprehensive index seasonal drought standardized Z-index drought intensity Gansu Province |
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| Abstract: |
| Based on the annual and monthly precipitation of 71 meteorological stations in Gansu province from 1971 to 2013, with the help of the Z index, the drought comprehensive index was constructed as the evaluation index based on the drought frequency and the drought intensity. The drought characteristics at different time scales were analyzed based on the seasonal drought and the seasonal continuous drought. The results showed significant difference in seasonal drought degree (MK<0) and drought range (%). In spring, the Longdong plateau is -0.154 (100%), and the heavy drought areas are Lingtai (-0.238*), Ningxian (-0.180), and Zhenyuan (-0.178); in summer, Gansu corridor is -0.081(73.7%), and the heavy drought areas are Mazongshan (-0.271*), Anxi (-0.255*) and Dunhuang (-0.171); in autumn, Longzhong plateau is -0.017 (50.9%), and the heavy drought area is Huining (-0.186). The seasonal drought comprehensive index of heavy drought period showed spring in 1995 (Longdong, 0.481), summer in 1997 (Longnan, 0.405), autumn in 1972 (Gannan, 0.366), winter in 1998 (Longdong, 0.586) and in 2009 (Gannan, 0.449). The high value areas of the continuous drought in two seasons were in Baiyin, Huining, Gulang, Maqu, Lingtai, Yongden, Huachi, Jingning, etc (>0.030), with the most severe drought in autumn and winter (0.0274). The high value areas of the continuous drought in three seasons were Huining, Gulang, Jingning, Baiyin and Yongdeng, etc (>0.020), among which, the drought degree of summer-autumn-winter is severest (0.017 5). The high value areas of the continuous drought in four seasons were Huining, Gulang, Xifeng, Lingtai, Jingchuan, etc (>0.015). All the seasonal continuous drought were significant (>0.009) except the winter-spring-summer-autumn drought.The research results of the seasonal drought comprehensive index can provide scientific basis for regional drought assessment and disaster prevention and reduction. |
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