Shoreline Change Detection of Nizam Island, Bangladesh (1997–2022) Using GIS and Remote Sensing Techniques

Abstract

Coastal shoreline changes are a natural process that forms and reshapes the coastal zone through sedimentation over time and space. Addressing the changes of the coastal shoreline in the Bay of Bengal, one can observe the magnitude of coastal changes over time. The aim of the study is to analysis the shoreline changes detection of Nizam Island. The satellite images were obtained from Landsat Satellite imagery, where 1997 and 2010 years of Landsat 4-5 Thematic Mapper (TM) and 2022 year of Landsat 8-9 Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) were obtained. The data processing and analysis was done on ArcGIS 10.7 software application. The island showed considerable growth from 1997 to 2010, where the high accretion was 31.28 km²/year, accretion rate was 2.41 km²/year, with net sediment flux of 27.74 km²/year respectively. From 2010 to 2022 year, the accretion rate had declined, and stable land area was found to be consistent of 29.81 km² in the study period. The accretion was 8.62 km² being lower than erosion of 12.25 km² from 2010 to 2022 year. Although net sediment flux for the 25-year study period is very high and favorable for stability and existence of Nizam Island. Vegetation growth has been prominent in the region as the NDVI values had shown. The evolution of Nizam Island and increasing growth and stability can indicate further sedimentation in the south of Bangladesh and the cause of heavy sedimentation in the region. The development and stability of Nizam Island signifies the sedimentation process in the Bay of Bengal region.