ESTIMATION OF ABOVEGROUND BIOMASS IN MANGROVE FOREST DAMAGED BY THE MAJOR TSUNAMI DISASTER IN 2004 IN THAILAND USING HIGH RESOLUTION SATELLITE DATA

摘要

The Indian Ocean Major Earthquake off the Coast of Sumatra and Tsunami in the Indian Ocean, which occurred on 26 December 2004, caused much victims and heavy damages in coastal zones. Some studies reported that mangrove forests filled the role of mitigation of the damage by the Tsunami. On the other hand, mangrove forests themselves suffered both direct and collateral damages by the Tsunami. Direct damages resulted from fierce impacts of the Tsunami and objects damaged by it, and vibration of trunks of mangrove trees by repetitious waves of the Tsunami and respiratory disorders from roots due to sedimentation of sands, which were brought by them, caused collateral damages. This study aims to estimate of aboveground biomass in mangrove forest damaged by the major Tsunami disaster in 2004 in Thailand using high resolution satellite data. The study area is located in the coastal zone of Ranong, Thailand. Thirty-six 0.04-ha plots were established in the study area and stem diameter and tree height (partly and using the height-diameter equation for the rest of them) were investigated in the field. IKONOS and QuickBird multi-spectral and panchromatic data were acquired for this study. Mangrove extent was extract from both IKONOS and QuickBird data using the object-oriented classification. Panchromatic data of IKONOS and QuickBird before and after the Tsunami disaster were used to identify individual crown size of mangrove using the watershed method after masking non-crown area. Allometric equations between stem diameter and sunny-crown area for every mangrove species were derived. Sunny-crown areas were extracted from IKONOS and QuickBird panchromatic data. The highest digital numbers of each band of IKONOS and QuickBird data within each extracted sunny-crown area were used to identify mangrove species. The aboveground biomass was estimated in each plot as a function of stem diameter derived from the sunny-crown area using the allometric equations. The distribution of aboveground biomass was mapped from the result.