| Analysis of spatio-temporal distribution of drought characteristics based on SPEI in Gansu Province |
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| DOI：10.7606/j.issn.1000-7601.2019.03.34 |
| Key Words: drought SPEI temporal and spatial characteristics EOF REOF Gansu Province |
| Author Name | Affiliation | | LI Liang | Key Laboratory of Agricultural Soil and Water Engineering of Northwest A & F University, Yangling, Shaanxi 712100, China
The Chinese Arid Area Research Institute of Water-saving Agriculture, Northwest A & F University, Yangling, Shaanxi 712100, China
College of Water Resources and Architectural Engineering, Northwest A & F University, Yangling, Shaanxi 712100, China | | Pich Linvolak | Key Laboratory of Agricultural Soil and Water Engineering of Northwest A & F University, Yangling, Shaanxi 712100, China
The Chinese Arid Area Research Institute of Water-saving Agriculture, Northwest A & F University, Yangling, Shaanxi 712100, China
College of Water Resources and Architectural Engineering, Northwest A & F University, Yangling, Shaanxi 712100, China | | CAI Huan-jie | Key Laboratory of Agricultural Soil and Water Engineering of Northwest A & F University, Yangling, Shaanxi 712100, China
The Chinese Arid Area Research Institute of Water-saving Agriculture, Northwest A & F University, Yangling, Shaanxi 712100, China
College of Water Resources and Architectural Engineering, Northwest A & F University, Yangling, Shaanxi 712100, China |
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| Abstract: |
| To better understand the spatio-temporal distribution of drought characteristics under climate change in different time scales in Gansu Province, daily data from 33 meteorological stations for the period of 1951-2015 were used in this study. The standardized precipitation evapotranspiration index (SPEI) was established combining with Mann-Kendall mutation test, complex wavelet analysis, empirical orthogonal function (EOF) and rotated empirical orthogonal function (REOF) method to analyse the spatial and temporal patterns of drought in the past 65 a in Gasnu Province. The results showed that in terms of the inter-annual SPEI changes, it showed a trend to become humid and then dry, and in recent years the drought trend has gradually increased. On the other hand, it was getting wet from dry firstly and then being dry in all of seasons, especially spring (P<0.05) from the seasonal perspective. The drought coverage and the intensity of drought appeared as the features of the local slight drought and domain moderate drought mainly at the annual scale in Gansu. In the time cycle, the time periods in Gansu were 39, 13, 7 a and 22 a in turn decrease on periodicity, but it appeared different oscillation of dry and wet in different time scales. Spatially, the northwestern regions had a humid trend, but it was drier in the southeastern part of Gansu on the contrary. Most regions were getting dry in spring (P<0.05) and winter, and it was similar of dry and wet zones in summer as well as autumn in terms of spatial distribution. According to the strength of arid sensitivity in Gansu, it can be divided into 4 sub-regions: Eastern district of southeastern region (I sub-region), northwestern region (Ⅱ sub-region), central region (Ⅲ sub-region) and western district of southeastern region (Ⅳ sub-region). Drought in Ⅲ sub-region was gradually alleviated, and others showed a trend of being drier. |
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