SATELLITE-BASED BENTHIC HABITAT MAPPING USING LANDSAT 8 IN NUSA LEMBONGAN AND NUSA CENINGAN ISLAND, BALI

摘要

The Island of Nusa Lembongan and Nusa Ceningan are two of three islands in Nusa Penida waters, Bali Province, with 296 species of reefs biodiversity at depth less than 30 meters. LANDSAT 8, with 14 days of temporal resolution and spatial resolution of 30 m2, has becoming an efective and sustainable alternative in satellite-based benthic habitat mapping activies in regional scale. Equipped with the 430-450 nm coastal blue band, the first four channels on LANDSAT 8 now can be used to identify objects in shallow water because of their penetration ability. This study will determine the most effective band combinations used to create RGB composites to calculate the zonation of benthic habitat. Satellite image is geometrically corrected based on the Indonesia Coastal Environment map scale 1:50,000 provided by Geospatial Information Agency (BIG). Atmospheric correction method and water coloumn correction performed using Fast Line-of-sight Atmospheric Analysis of Hypercubes (FLAASH) method and Lyzenga algoritm for reducing the atenuation effect. The combination used to create RGB composite with the best effectiveness is determined by comparing the results of the shallow water habitat map using a combination of clustered into three classes of coral reef, vegetation, and benthic substrate using the unsupervised ISODATA classification method. Analysis of the result conducted by qualitative approach based on the benthic coverage data provided by Marine Research Institute and Observatory (BPOL), as well as several existing web-based GIS of coral reef's databases. The band combination of 123 on LANDSAT 8 stated to be able to provide more effective area information of benthic habitat in the study area consists of 1,618,200 m~2 of coral reefs, 1,684,800 m~2 of vegetation such as seagrass or algae, and 776,600 m~2 of benthic substrate, with total area of 4,080,600 m~2 and ratio between habitat to benthic substrate is 2.1 : 2.2 : 1.