MAPPING REEF ZONATIONS OF THE ATOLLS IN TRUONG SA ISLANDS BY USING LANDSAT 8OLI IMAGERY
Keywords:Reef zonations, Truong Sa islands, Landsat 8OLI data, depth-invariance index
The Truong Sa islands play an essential part in military, security and defense, and socio-economic purposes. Truong Sa consists of many islands and atolls. However, the reef zonations or geomorphic zones of coral reefs of the atolls are poorly documented because of the absence of field measurement data, especially in disputed areas. The authors use Landsat 8OLI satellite imagery and the Support vector machine (SVM) classification method to classify the atolls' reef zonation in the paper. The authors also experienced the DII index for bands 2, 3, 4 of the Landsat 8OLI image to correct the water column in the pre-processing image step, which are the input data of the classification processing. The classification accuracy achieved 97.8% and 98.3%. The study area is at Toc Tan island and Thuyen Chai island.