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Proceedings Paper

Monitoring of coral reefs on Ishigaki Island in Japan using multitemporal remote sensing data
Author(s): Tsuneo Matsunaga; Akira Hoyano; Yosei Mizukami
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Paper Abstract

In recent years environmental problems in the coral reefs attract both scientific and social attentions. However, most coral reefs have few maps showing the reef topography and the distributions of various benthic habitats in the reef. Satellite remote sensing can be used for coral reef mapping because satellites can observe the reefs scattered in tropical oceans in a short time repeatedly. Simple comparison between satellite images acquired on two different days is, however, strongly affected by the changes of the tidal level. Applying conventional classification algorithms to such satellite images often results in misclassification. We developed Bottom Index (BI) algorithm to minimize the water depth effect on satellite data. BI is a modified reflectance ratio between two bands in satellite data and corresponds to the proportion of benthic community cover in a pixel. In this study we applied this algorithm to Landsat TM data acquired during 1984 - 1996 on Ishigaki coral reefs, Japan, and evaluated its accuracy. We also developed the method for the separation of sand and coral/ algae/seagrass habitat using BI. We also found that the extinction coefficient ratio between two TM bands that is necessary for BI algorithm was basically constant there. And temporal variations of the sea floor cover type in Ishigaki during 1984 - 1996 were indicated by BI maps. Sea truth survey was conducted in August 2000 to validate the BI maps.

Paper Details

Date Published: 5 January 2001
PDF: 11 pages
Proc. SPIE 4154, Hyperspectral Remote Sensing of the Ocean, (5 January 2001); doi: 10.1117/12.411677
Show Author Affiliations
Tsuneo Matsunaga, Tokyo Institute of Technology (Japan)
Akira Hoyano, Tokyo Institute of Technology (Japan)
Yosei Mizukami, Tokyo Institute of Technology (Japan)

Published in SPIE Proceedings Vol. 4154:
Hyperspectral Remote Sensing of the Ocean
Robert J. Frouin; Hiroshi Kawamura; Motoaki Kishino, Editor(s)

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