Monitoring bank-line movements of the rivers flowing across the Sundarbans using remote sensing and GIS techniques

Abstract

Sundarbans is the largest mangrove forest decussated by a network of alluvial rivers upon the Ganges–Brahmaputra–Meghna basin outlined by recurrent bank erosion and accretion leading to channel pattern modification. Standing against various natural disasters, frequent bank-line changes associated with land loss or gain were observed along the main rivers of Sundarbans, causing major changes in river patterns over decades. Monitoring the morphological changes of the river is the main purpose of this research. The present study has undertaken steps to investigate the bank-line shifting of the eight main rivers located within Sundarbans over the past thirty years. The courses of main rivers from Baleswar to Bidyadhari were analyzed using a combined approach of remote sensing and GIS. Landsat images from USGS Earth Explorer were collected, sorted based on almost identical tidal conditions and digitized along the river banks to quantify and observe the dynamic behaviors of the river bank lines. Critical zones were observed in some parts of the river banks which were classified based on large lateral movements along both the left and right banks. The lateral movement of the river banks observed ranging between 160–1600 meters. Analysis has shown that most of the river banks have shifted land-ward which indicates loss of land except Pussur, Arpangasia and few regions of Baleswar River. The collected satellite data provided useful information on river bank configuration as well as changes in river morphology within the Sundarbans.