Coral Reef Habitat Change Detection Using Landsats 5, 7 and 8: A Case Study in the Red Sea (Hurghada, Egypt)

Abstract:

Coral reefs suffer major deterioration and degradation due to natural and man-made impacts worldwide. Close monitoring is needed to save such vital components of our environment. Remote-sensing technology has shown its ability to monitor and survey remote areas of coral reefs. In this study, coral reef habitats in Hurghada, Egypt were examined using Landsat imageries over a 26-year period. The change detection analysis was adopted to identify the alterations in coral reef habitats between 1987 and 2013. Three images, acquired from Landsat-5 TM on August 14^th 1987, Landsat-7 ETM+ on September 10^th 2000, and Landsat-8 OLI on July 20^th 2013, were used in the change detection analysis. Different processing techniques were applied to the three images, including but not limited to rectification, masking, water column correction, classification, and change detection statistics. The supervised classifications performed over the three scenes show five significant marine-related classes: coral, sand subtidal, sand intertidal, macro-algae, and seagrass. The change detection statistics obtained from the classified scenes of 1987 and 2000 revealed a significant increase in the macro-algae and seagrass classes (93% and 47%, respectively), accompanied by a major decline in the sand intertidal, coral, and sand subtidal classes (41%, 40%, and 37%, respectively). On the other hand, the change detection statistics obtained from the classified scenes of 2000 and 2013 revealed an increase in the sand subtidal and macro-algae classes (14% and 19%, respectively), while a major decrease in the sand intertidal, coral, and seagrass classes (49%, 46% and 74%, respectively).