Vegetation Cover Dynamic Changes of Minxian Before and After Minxian-Zhangxian M_S6.6 Earthquake in Gansu Province

Using the Landsat8 remote sensing image data, the imidiate pixel model was used to estimate the vegetation coverage of Minxian county before and after the Minxian-Zhangxian M_S6.6 earthquake, and combined with elevation and slope data, the effects of topographic factors on vegetation damage and restoration were studied. The results showed that: The vegetation coverage of Minxian County in the three periods was mainly medium and high vegetation coverage, reflecting the good vegetation coverage in the study area. ① In terms of spatial distribution, the medium-high and high-vegetation coverage is mainly distributed in the high-altitude areas in the southwest and southeast of Jixian County, and the low-vegetation coverage area is extended along the residential areas from the location of the Jixian County to the northwest. ② From 2013 to 2014, the average vegetation coverage decreased by 0.09, and the damaged area reached 96.53%, mainly due to the damage of vegetation with high vegetation coverage. Vegetation damage is mainly distributed in the elevation of 2 344~3 283 m, and the slope of 5°~35° is the main area of vegetation damage. ③From 2014 to 2017, the average vegetation coverage rose to 0.43, and the restored area reached 2 901.93 km². Vegetation restoration was dominated by vegetation restoration with high vegetation coverage, followed by low vegetation coverage. The vegetation restoration showed an increasing trend at an elevation of 2 031~2 970 m, and then began to decline. The vegetation restoration area showed an increasing trend at a slope of 0°~25°, and then decreased.