Digital and Visual Analyses of IRS Satellite Data for Zonation and change deduction of coral reefs in Gulf of Mannar marine biosphere reserve

Coral reefs are highly sensitive and productive marine ecosystem. The increasing human population and their activities and other natural factors have caused the degradation of coral reefs. The IRS LISSII (1988) and IRS LISSIII (1998) satellite data with GIS and ERDAS software were used for mapping coral reef, change detection and of coral reef zonations. Digital and visual techniques were used to map the coral reefs. Visual classification shows that 25 km 2 of coral reef area in Gulf of Mannar has been lost over a period of ten years. Digital classification of IRS LISSIII date using Principle Component Analysis was found to be more suitable for coral reef zonation.