Coastal morphological changes: Assessing long-term ecological transformations across the northern Bay of Bengal

Abstract

Major rivers from the Himalayas carry a high volume of sedimentation, and deposit it across the Bay of Bengal in Bangladesh. This has caused significant changes in the morphology of the bay, including the development of islands across the bay area. However, few studies have been carried out on the morphological changes, especially the development of new islands across the northern Bay of Bengal. This study, therefore, aimed to assess the coastal morphological changes and ecological succession of the newly formed islands of the bay area. We used state of the art cloud computing technologies, using the Google Earth Engine (GEE) platform. Publicly available annual composites of Landsat 8, Landsat ETM+, and TM data from 1989 to 2018 were used for analysis. The findings showed significant changes in the morphology of the coastal area over a period of 30 years. There was a 1.15% increase in land area between 1989 and 2018. New islands were formed across the bay, and a few old islands disappeared between 1989 and 2018. The majority of the offshore islands developed in the estuary of the Meghna River. Among the quickly grown islands, Bhashan Char, Char Nizam, Jahajerchar, and Urir Char are prominent. Initially, the islands appeared as barren areas without any vegetation, but different types of vegetation have been observed growing on the newly formed islands recently. The findings of this study are important for the conservation and development planning of newly formed islands.