CAO Er-jia, XUE Yu, LI Hong-ying, GONG Jie, XU Cai-xian
China Rural Water and Hydropower. 2019, (11):
165-171.
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In this paper, daily meteorological data from 1980 to 2017 of 20 meteorological stations in and around Ulanqab the typical region of the farming-pastoral ecotone in central Inner Mongolia were used to calculate the relative moisture index(M) to reveal the drought change trend. Based on the inverse distance weight interpolation method (IDW), anomaly and accumulated anomaly method, Mann-Kendall trend test method, partial correlation analysis method, the spatial distribution characteristics, the variation trend and the cause of drought in the crop growing season (April to September) of Ulanqab in the latest 38 years were analyzed, and Hurst index was used to analyze the trend of drought in the future. The results showed that: (1) The spatial distribution of drought in Ulanqab is became drier gradually from the southern to the northern parts, among which Liangcheng, Zhuozi and Fengzhen are wetter, and Siziwang is drier. In the past 38 years, the average value of the M in the growing season was -0.575, indicating light drought. (2) From April to September, the M increased first and then decreased. In the past 38 years, the region became slightly dry, especially in August, which showed the most significant drying trend (α=0.01). (3) Partial correlation analysis of potential evapotranspiration (ET0) and various meteorological elements showed that the wind speed impacted on ET0 significantly, followed by the relative humidity, sunshine duration and average temperature. The main factors which that enhanced the drought are the decrease of precipitation and relative humidity, followed by the increase of average temperature, while the decrease of wind speed and sunshine hours can also alleviate the aggravation of drought. Hurst index indicated that the growing season will continue to dry in this region, and August will continue to dry strongly.