Temporal and Spatial Variation Characteristics of Drought in Yibin City Based on MCI Index

Based on the meteorological data of 10 national meteorological stations in Yibin from 1971 to 2020 and the meteorological drought comprehensive index (MCI) calculated by FAO Penman Monteith model, this paper studies and analyzes the temporal and spatial characteristics of drought in Yibin in recent 50 years. The results pass the M-K mutation test of MCI drought index. The results show that: The annual average number of drought days in Yibin fluctuated greatly from 1970s to 2010s, and the number of drought days increased then decreased. The number of drought days increased in winter and summer, and decreased in spring and autumn. From the late 1970s to the mid-2010s, the number of drought days in Yibin City showed an upward trend. In particular, there was an abnormal drought from 1995 to 2015, and the number of drought days was outside the critical value of significant level 0.05 (± 1.96), and the mutation point was 1975.