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Coastal wetlands in tropical and subtropical regions around the world are dominated by mangrove ecosystems. For coastal environment mangroves are utmost important bio-resources. It provides services in aspect of economic and ecological, such as preventing coastal erosion, providing habitat for fish and shrimp breeding, supplying building materials and medicinal ingredients, and attracting tourists. At the same time, for the purpose of agriculture, aquaculture, tourism, urban development etc. they are getting exploited which result in their decline. Over the past century, India's mangrove area decreased by 40%. Therefore, it is crucial to evaluate the situation and trends of mangroves in India.
Remote sensing is a tool that can provide spatio-temporal information on mangrove ecosystem distribution, species differentiation, health status, and ongoing changes in mangrove populations in order to analyse the mangrove. To assess the mangrove of Cauvery deltaic region in between 2001 and 2021 we have used the Landsat 5 and Landsat 8 data which offered 30m resolution. We have assessed the trends of mangrove area by generating Land Use Land Cover map in the region during 2011 to 2021 and found that the area of mangrove forest has increased from 5.27 sq. km to 10.48 sq. km. We have done fragmentation analysis (using Fragstat) to check the spatial heterogeneity within the region, which shows the increase of NP, PD, TE, and ED in between 2001 and 2011 implies that the amount of disturbance over the landscape increased through the period of time and for 2011-2021 it decreases which may be due to that the forest is put under protected area which suggest the vulnerability decreases. To check the health condition of the vegetation cover we have calculated Vegetation Health Index by combining NDVI, TNDVI, GCI, CVI, SAVI and ARVI indices which shows that the areas with healthy vegetation increased from 2.31 percent in 2001 to 6.90 percent in 2021. The moderate vegetation decreased from 24.27 percent to 12.66 percent in between 2001 and 2011 and later in 2021 it shows rise of 12.09% of the total area. The areas with No vegetation slightly increased in 2011 then decreases in 2021 maybe because the area now comes under protected area. The findings of this study could be beneficial to the ecological and scientific communities. The new maps presented in this study will serve as a good resource and guide for the organisation in charge of coastal management.
