MAPPING OF SHALLOW WATER SEAGRASSES IN THE COAST OF SURIGAO DEL SUR, PHILIPPINES USING REMOTE SENSING TECHNIQUES

摘要

The Province of Surigao del Sur, located along the northeastern coast of Mindanao facing the Pacific Ocean, is one of the provinces in the Caraga Region which have the largest coastal area and marine life biodiversity. This region is also one of the study area of Phil-LiDAR 2.B.14 Project in which one of the objectives is mapping of benthic habitats and marine aquaculture. Among the benthic habitats that are dominant in Surigao del Sur are seagrasses which are known to be highly productive ecosystem that provides shelter and serves as food source to diverse species of young and adult fish, marine invertebrates and marine mammals. Hence, this study is conducted in accordance to the objective of the project and also to assess the vastness of the seagrasses in the shallow water areas in the coast of Surigao del Sur by employing remote sensing techniques. Landsat 8 image is used in seagrass mapping by means of unsupervised ISODATA classification method. Landsat 8 images have been found to be efficient and could be an alternative in conducting benthic mapping because of its additional coastal blue band. The satellite image was radiometrically calibrated and atmospherically corrected using Fast Line-of-Sight Atmospheric Analysis of Hypercubes (FLAASH) method. Unsupervised ISODATA classification was then applied with minimum and maximum classes of 20 and 30, respectively. The seagrasses classification was clustered into two classes, namely, dense seagrass and sparse seagrass. Accuracy assessment of the classified features was performed using the validation points collected from the actual field survey. The classification has an overall accuracy of 87.5% and kappa coefficient of 0.84. It is then concluded that the classification method used is reliable and efficient in mapping spatial extents of seagrasses.