Assessing the shoreline dynamics of Hatiya Island of Meghna estuary in Bangladesh using multiband satellite imageries and hydro-meteorological data

Abstract

Hatiya is the largest and one of the most significant offshore islands in the Meghna river estuary. Which is very dynamic in nature as it is part of an active delta, where erosion and accretion process is active simultaneously. The present study attempts to assess the shoreline shifting and erosion-accretion measurement of Hatiya island and make an attempt to understand the impact of water level, temperature and rainfall on shoreline movement and erosion-accretion using GIS and remote sensing technique. Digital Shoreline Analysis System (DSAS) extension for ArcGIS has been used for calculation of shoreline movement. Net Shoreline Movement (NSM) showed that the island is moving, the maximum seaward movement is 6.1 km and the maximum landward movement is about 12.62 km. In its addition, End Point Rate (EPR) is calculated for quantifying the shoreline shifting which revealed that maximum rate of seaward shifting is about 138.5 m/year and landward shifting rate is about 285.38 m/year. The island has shown its dynamic movement towards land in southern part while the seaward movement found in most other parts of the island. About 8 sq. km of land eroded in last 45 years and 1.62 km of shoreline has depleted during this period. The tidal flat is also showed a dynamic nature that is more active prior to the dominant land accretion. Hydro-meteorological data also showed that the local climate is changing and changes in rainfall and water level affect the erosion and accretion process. The DSAS technique is an effective tool for continuous monitoring of dynamics shorelines like Hatiya island.