DETERMINING THE SEAGRASS AREA IN THE LAGOON REGION OF THUA THIEN HUE PROVINCE USING LANDSAT 8 IMAGE

Abstract

The objective was to identify classification indices for seagrass based on Landsat 8 imagery to map its distribution in the lagoon region of ​​Thua Thien Hue province. Graph analysis and empirical statistical methods were employed to develop a set of object - based imagery classification indices and to analyze the ​​seagrass areas on satellite image. The Kappa index was applied to evaluate the accuracy of the seagrass distribution map. The study shows that a threshold of 10,000 for channel 5 can be used as an index to classify terrestrial and water surface objects. Additionally, the total value of channel 3 and channel 4 greater than 17,300 can be used as an index to classify the water surface areas with seagrass and those without. The interpretation results indicated that the ​​seagrass area was 840 ha in the Tam Giang - Cau Hai lagoon and 65 ha in the Lap An lagoon, respectively. Scientifically, the breakthrough of this study lies in developing a set of classification indices for seagrass areas using Landsat 8 satellite images and effectively applying object-oriented classification techniques to map seagrass distribution. Practically, the study successfully created a seagrass distribution map in the lagoon region of ​​Thua Thien Hue province, achieving a Kappa coefficient of 0.7, which helps assess the changes in seagrass areas.