Monitoring Coastline Changes in the Coastal Belt of Chittagong in Bangladesh Using GIS and Remote Sensing

Abstract

Coastal zones are the most dynamic feature of earth surface in which lithosphere, hydrosphere and atmosphere gets into contact with each other. Such dynamic process should be monitored with great importance as a large portion of the world’s population is living along the coastal zones. This paper focuses on delineation of the changes in the coastal land areas of Chittagong in Bangladesh through the shifting of coastline. Chittagong coastal area is around 245 km with an unbroken 125 km gently slopped sandy sea beach in Cox’s Bazar. However, due to both the natural phenomenon and human interventions, coastline in these areas has been changing gradually. These changes have occurred in relation to land biomass, erosion and accretion rate. Therefore, shoreline geometry analysis can help understand such dynamic coastal process. Several satellite images from Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM) were used for the long term coastline change analysis. The digital shoreline analysis (DSA) using ArcGIS 10.1, and image rectification, atmospheric correction, edge separation techniques between earth surface and water surface using ENVI software were used in this analysis. DSAS was used as a reliable statistical approach for the rate of coastline change.  The result shows that changes in dynamic changes due to erosion and accretion have been impacting the morph-dynamics in the study area. The maximum accession rate was 3.6 km and 1.9 km at different section points and on the contrary the maximum erosion at several section points was 0.37 km and 3.3 km at the time interval of 1989 to 2009 and 2009 to 2014, respectively. Overall, it was found that the area was affected with huge rate of accretion and increase in the landmass of the Chittagong area till the year 2009 but later on till the date of 2014 the erosion rate of the area again increased. The findings of this study can help policy makers to make decisions in delineating new islands emerging at the sea boundary of Bangladesh and planning for better coastal management.