Mangrove monitoring using sequences of Landsat imagery in the Mary River wetlands

Mangroves have expanded in the Mary River wetlands in the Northern Territory of Australia due to the widening and headward extension of tidal channels as a result of saltwater intrusion. Approximately 240 km/sup 2/ of freshwater wetlands have been altered over the past 50 years, with further alteration anticipated. A mangrove monitoring method has been implemented based on summaries of change in a greenness index from a time series of calibrated Landsat TM/ETM imagery covering the years 1987-2000. Field verification was carried out in 2000. Results indicate that this method can be used to detect the extent and rate of mangrove expansion in these wetlands over the past decade. It has been estimated that over 100 km of mangroves have been established on tidal creek extensions during this period. These results not only offer further insight into the environmental processes occurring in this region but also demonstrate the value of temporal datasets for deducing changes in land use and associated impacts.