Analysis of Vegetation Health of the Sundarbans Region Using Remote Sensing Methods

The world’s largest mangrove region, Sundarban, plays a vital role in sustaining the ecological balance in the Ganga–Brahmaputra deltic region. It spans two neighboring countries, namely India and Bangladesh. In this article, we strive to assess the vegetation health of the Sundarbans region. We rely on the satellite images from Landsat 8 from January 2014 to January 2020. The vegetation health assessment is based on two indices, normalized difference vegetation index (NDVI) and forest canopy density (FCD) analysis of the interest area. NDVI consists of two bands: red and infrared band, showing a negative trend of 0.0085 per year. The image difference technique is employed further to study the vegetation health of the area of interest. NDVI difference marks the coastal regions with a higher depletion rate of vegetation than the regions away from the sea coasts. The histogram of the NDVI difference shows a negative shift from the central zero axis, which is the zone of no change in the vegetation cover. Being an early model to study vegetation health, NDVI has some disadvantages. It tends to quickly saturates at high biomass content and blurs the difference between moderately high plant cover from very high plant cover. So, we have taken another model, FCD, to compare the results of NDVI with it. It highlights the sharp depletion of highly forested cover. Nearly, 80% of the highly forested region has been depleted and joins the medium forested area. The overall mangrove cover is likely to dip more in the ensuing decades if governments of the two countries do not take necessary measures.