Impacts of morphological change on coastal landscape dynamics in Monpura Island in the northern Bay of Bengal, Bangladesh

Abstract

Coastal morphological change and landscape dynamics have been creating a new window for taking immediate sustainable management strategies for coastal resources management. The dynamic nature of coastal morphological response includes erosion/accretion of landmass, development of an island by sedimentation, movement of the island, and change in geometry and shape. The objectives of the study illustrate morphological change, driver, and mechanism of morphological change, and the effects of morphological change on coastal landscape dynamics. The study also explores spatio-temporal landscape dynamics effects on coastal ecosystem services and livelihood pattern of the coastal community. The novelty of the present research is that how morphological change influence in response to landscape dynamics and its ecosystem services by exploring historical data including shoreline change, century scale erosion and accretion, stability of the islands since 1776 to 2021. In this study, historical maps (i.e., Rennell’s map in 1776 and Tassin map in 1840), Topographic Survey map (1943) and remotely sensed digital image (i.e., Landsat TM in 1990, 2000 and 2010, and Landsat OLI in 2021) have been used to quantify coastal geomorphological change and landscape dynamics through RS and GIS tools and techniques. The finding of the study showed remarkable change occurred in geomorphology of the Monpura Island over the period of 245 years. The spatial coverage of the island has been declined dramatically, which is quantified ∼2905 ha from 1776 to 2021. In the century scale from 1840 to 1943, erosion is observed higher than accretion, and the statistics showing that 8963.40 ha eroded along the east flank of Island. In the northern flank of the Island, Net Shoreline Movement (NSM) and the rate of shoreline movement which expressed by EPR showed highest and flowed by ∼4 km and -126.55 m/y toward landmass. During the epoch 1990–2021, because of morphological change and anthropogenic interventions, the crop land of the Island has been significantly declined by ∼38%, while the rivers and settlement spatial coverage have been increased by ∼768% and ∼153%, with an annual rate of change ∼25% and ∼5% respectively. These outcomes and prepared maps of the current research will be supportive for the local inhabitant, coastal morphologist, and environmental resources management manager, national and international policy advisor, government and non-movement stakeholder, researcher to observe coastal morpho-dynamics including shoreline dynamics, coastal erosion and accretion and its impacts on landscape and ecosystem services.