A three decade assessment of forest cover changes in Nijhum dwip national park using remote sensing and GIS

Abstract

Forest cover loss has a crucial impact on global climate change. The Nijhum Dwip National Park (NDNP), a deltaic part of the Sundarbans mangrove forest, has changed significantly over the decades. The goal of this study was to detect the decadal changes in forest cover using freely available satellite remote sensing data and GIS tools. A maximum likelihood classification technique was used to classify the Landsat images of 1990, 2001, 2011 and 2020. The potential of NDVI and SAVI-based classification for detection of forest cover changes in comparison to supervised classification was also evaluated. More than 42% of the total forest cover area (1781 ha) has been deforested over the decades between 1990 and 2011. The study also reported that nearly 1235 ha and over 856 ha of forest area disappeared from 4217.5 ha in 1990 to 2982.5 ha and 2126.16 ha in 2001 and 2011, respectively. In contrast, an increase of 310 ha of forest area has been recorded in the last decade, from 2011 to 2020. NDVI performed better in forest cover change detection than SAVI. This research will be invaluable for this type of research continuity and proper monitoring of this protected mangrove forest area, along with providing useful information to decision makers.