Assessment of vegetation damage by three typhoons (Bavi, Maysak, and Haishen) in Northeast China in 2020

Typhoons usually bring natural disasters and economic losses. Satellite-based vegetation monitoring approaches largely improve our understanding of monitoring and assessing the area damaged by typhoons at high temporal and spatial scales, but it is still unclear which approach could achieve a greater robustness in assessing typhoon damages. From August 27 to September 8, 2020, three typhoons of Bavi, Maysak, and Haishen successively passed through the Northeast China, covering Liaoning, Jilin, and Heilongjiang provinces, and caused great damages to local vegetation and crops. Here, we employed two top-recognized approaches, i.e., the Normalized Difference Infrared Index (NDII) and the Disturbance Index (DI) derived from the moderate-resolution imaging spectroradiometer, to assess impacts three typhoons of Northeast China on the local vegetation and crops. With the help of Google Earth high-resolution images, this study demonstrated that the DI-based assessment gave a more accurate performance with an overall accuracy of 83% compared with NDII in typhoon-induced damages. DI was therefore used for spatial monitoring and assessment of three typhoon impacts. The DI-based results revealed that the damaged area of vegetation and crops in Northeast China was over 1.24 x 10(5) km(2), including croplands, forests, and grasslands with the damaged area of 4.74 x 10(4) km(2) (38.23% of total damaged area), 3.41 x 10(4) km(2) (27.5%), and 0.12 x 10(4) km(2) (0.97%), respectively. The damaged proportions were 14.13%, 13.19%, and 3.11% accounting for croplands, forests, and grasslands, respectively, of entire Northeast China. This study proves that DI-based vegetation damage assessment has more potential in large-scale monitoring of typhoon damages.