Mangrove Normalized Difference Vegetation Index (NDVI) Method for mapping healthiness of mangrove forests in Kilim, Langkawi / Nor Hajaratun Fatin Mohamad Nor

Mangrove forests are present in the intertidal zone, located within small groups of trees and shrubs in the harsh interface between sea and land. Nevertheless, the health of mangrove trees has been impacted by changes in the seasons and the level of disturbance in the mangrove habitat. Mangrove erosion is caused by a variety of indirect effects of climate change. For this purpose, two Sentinel 2A images from 2019 to 2023 were used in this research to identify mangrove areas and extract NDVI values. More interestingly, Object Based Image Analysis (OBIA) is used in this research to classify the mangrove area. There are 10 categories for classifying images. The findings indicate that mangrove area is 707.751 hectares in 2019 and 599,464 hectares in 2023. Research results show that the mangrove area has decreased up to 108.287 hectares, or 8%. The Natural Breaks (Jenks) method was initially utilised to compute the NDVI values to categorise the NDVI map. The value of the healthiness of mangrove trees is then evaluated using a Difference NDVI map between 2019 and 2023 to determine whether it is positive or negative. The results show the range of NDVI values in 2019 is between -0.5 and 0.9, while the range in 2023 is between -0.07 and 0.60. The research provides information on the state of the mangrove ecosystems that can be used to inform future conservation and management initiatives.