Coastal Wasteland Identification and Mapping Using Satellite Data

Abstract

Coastal salt-affected lands are often associated with seasonal fluctuation of the shallow, brackish water table. Impeded drainage typical of coastal ambience is the root cause of salinisation /alkalinisation, which poses severe impediment to sustained irrigated agriculture. Present study was done on a small portion of the Indian side of world’s biggest estuarine belt called ‘Sundarbans’ encompassing the mouth of the sea, Bay of Bengal, spanning through India and Bangladesh. Multi-temporal satellite data were investigated to evaluate the spatial extent of costal wasteland in Sandeshkhali block, North 24 Parganas district in West Bengal, India. Landsat 8 Operational Land Imager (OLI) data of different seasons were used. The coastal wetlands were demarcated through field-based investigation and geographic location of each point was recorded. Normalized Difference Water Index was used to extract the water bodies from the satellite data. Supervised classification technique was adopted to classify coastal wetlands. The total area of wasteland is estimated as 130.86 km2, which is approximately 34.36% of the total geographical area. Coastal wastelands namely wetlands, coastal sand, salt pan, coastal swamp, scrub land, surface waterlogged areas and tidal salt marsh were identified in the study area. The overall accuracy of the classification results showed 88% along with the overall kappa statistics of 0.84. The study demonstrated high performance of the proposed approach in the surface wasteland identification.