| Drought characteristics and trend in Longdong Loess Plateau in recent 50 years |
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| DOI：10.7606/j.issn.1000-7601.2017.02.42 |
| Key Words: longdong loess plateau standardized precipitation evapotranspiration index(SPEI) wavelet analysis R/S methods markov chain |
| Author Name | Affiliation | | ZHANG Yao-zong | College of Geography and History, Longdong University, Qingyang, Gansu 745000, China
College of Geography and Environmental Science, Northwest Normal University, Lanzhou, Gansu 730070, China
Qingyang Centre for the Management and Combat of Desertification, Qingyang, Gansu 745000, China | | ZHANG Bo | College of Geography and Environmental Science, Northwest Normal University, Lanzhou, Gansu 730070, China | | LIU Yan-yan | College of Geography and History, Longdong University, Qingyang, Gansu 745000, China
Qingyang Centre for the Management and Combat of Desertification, Qingyang, Gansu 745000, China | | ZHANG Duo-yong | College of Geography and History, Longdong University, Qingyang, Gansu 745000, China
Qingyang Centre for the Management and Combat of Desertification, Qingyang, Gansu 745000, China | | JIA Yan-qing | College of Geography and Environmental Science, Northwest Normal University, Lanzhou, Gansu 730070, China | | TANG Min | College of Geography and Environmental Science, Northwest Normal University, Lanzhou, Gansu 730070, China | | WANG Guo-qiang | College of Geography and Environmental Science, Northwest Normal University, Lanzhou, Gansu 730070, China | | MA Bin | College of Geography and Environmental Science, Northwest Normal University, Lanzhou, Gansu 730070, China |
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| Abstract: |
| Based on monthly precipitation and temperature data from 13 meteorological stations,the characteristics of drought in Longdong Loess Plateau were studied by means of different scales of Standard Precipitation Evapotranspiration Index, Mann-kendall test, R/S methods and Markov chain. The results showed that over the past 50 years, linear trend of SPEI in Longdong Loess Plateau was less than 0, which indicated the drought trend was very obvious, especially since 1990 s. Mann-kendall abrupt analysis confirmed that the drought trend was significant since 1990s. According to the wavelet analysis, the main periods of the SPEI in interannual scale were 19 a, 11 a, 7 a, 4 a, 2 a; the main periods of the SPEI in the monthly scale were 17, 25, 35, 10 and 6 months. Hurst of SPEI12 in R/S prediction analysis, was 0.64>0.5, and auto correlation coefficient was Rt>0. So in the next period of time, the drought trend would continue. According to Markov model, the probability of drought extremes would increase in the evolution process of drought state, and Persistenceof severe drought state would increase. |
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