ASSESSMENT OF HALF-DECADAL VARIABILITY OF MANGROVE HEALTH COVER OVER THE INDIAN SUNDARBAN REGION USING REMOTE SENSING AND GIS TECHNIQUE

The present study aims to assess changes of mangrove vegetation with their cause and impact over a period of 30 years, from 1990 to 2019. The density of mangrove variability in half decadal level was calculated based on Normalized Differential Vegetation Index (NDVI) composites derived using 30m spatial resolution temporal Landsat Thematic Mapper (TM) & Operational Land Imager (OLI) data pertaining to Indian part of Sundarban Mangrove Forest. Further, variability of Half Decadal Change of Mangrove Density (HDCMD) was calculated using the consecutive NDVI composites. The results of HDCMD have shown large spatio-temporal variability, maximum HDCMD recorded during 1995, 2000 & 2014 with strong positive correlation (0.85) with Net Rainfall Change (NRC) and negative correlation (-0.82) with bio-carbon flux. The dense and healthy mangroves contribute in sinking bio-carbon from atmosphere, acting as good source sink. A net change in the HDCMD reveals overall improvement in the mangrove cover during 1989-2019. However, the threat of coastal erosion on mangrove environ along the southern sea fronts persists. Besides, the mangrove cover increased in prevailing depositional environments of islands and banks of creeks. The outcomes of such study are useful in sustainable coastal zone management, planning, environment and climate change.