Assessing the impacts of the 2004 tsunami on mangroves using GIS and remote sensing techniques: A case study of Phang Nga, Thailand

On December 26, 2004, the biggest earthquake in the past 40 years occurred under the sea near the west of Sumatra. Tsunamis never occurred before in the Indian Ocean, yet the earthquake created a powerful tsunami that killed more than 200,000 people and affected millions when it hit 11 countries around the Indian Ocean, including Thailand. While tsunami characteristics and effects are not fully understood, there are reports suggesting that mangroves, acting as a barrier, may be able to significantly reduce the devastation caused by the waves.; In this study, we choose the worst-hit province in Thailand, Phang Nga, as our study area. The study focuses on the spatial association between mangrove forests and the damage. Using GIS and remote sensing techniques, we compile the data from various sources and detect the land cover changes to determine the level of damage in regions with and without mangroves. The proposed novel approach integrates GIS proximity analysis and change detection with remote sensing techniques to creatively delineated buffer zones from the coastline into four homogenous sub-regions. These techniques can provide an easy way to compare the patterns of damage in areas with different land characteristics and different distances from the coastline. The results show that the obvious damage of the tsunami is within the distance of 3 kilometers from the coastline. The areas near the coastline of all sub-regions show levels of damage with an average of 26.87%. In this study, we observe that mangroves can withstand the force of tsunami much better than regular vegetation and the areas behind mangrove forests also benefit from the protection. Our results could be useful for mangrove replantation and management in the future. Moreover, this study could be a prototype for studying impacts of the tsunami in other affected countries.