An evaluation of vegetation loss due to the super typhoon Sarika in Hainan Island of China

Abstract

With the continued strengthening of global climate change, various extreme climate events have become increasingly prominent. Typhoons are the most disastrous weather event that cause severe losses to the economy, agriculture, transportation, communication, and ecosystem in coastal regions. The super typhoon Sarika that hit Hainan Island on October 18, 2016, lasted for 15 h, and it was the most severe typhoon that hit this island in October since 1970. The coastal land of Hainan Island experienced gales with an average speed of 35 m/s. In this study, we evaluated the impact of the super typhoon Sarika on vegetation by performing normalized difference vegetative index (NDVI) difference analysis using MODIS multi-temporal images acquired before and after the typhoon. The assessment of typhoons depends on the land-use types and landscape topography of slope, aspect, and altitude. The results indicated that the super typhoon Sarika seriously hit forestry, agriculture, shrubs, plantations, and orchards on Hainan Island. Overall, 79% of vegetation exhibited a negative change, whereas only 21% of vegetation exhibited a positive change in NDVI after the super typhoon Sarika. Agriculture was most severely impacted by the typhoon, where more than 81% of areas exhibited a decrease in NDVI, followed by plantations and orchards, where 77% of areas exhibited a decrease in NDVI. Additionally, the impact of the typhoon on vegetation was affected by the degree of NDVI decrease with the altitude, slope, and aspect. In conclusion, vegetation damage is associated with land cover types, altitude, aspect, and slope. NDVI decreased more in low-altitude plain and coastal areas than in higher altitude montane forest areas.