Quantification of erosion patterns in the Brahmaputra-Jamuna River using geographical information system and remote sensing techniques

There is significant evidence of frequent and rapid erosion and fast rates of bank line retreat along the river Brahmaputra-Jamuna within Bangladesh. This study is aimed at quantifying the actual rates of bank erosion along the river based on time series analysis of satellite images and historical maps. Analysis shows that the erosion rates in the Brahmaputra-Jamuna River were 160 m year(-1) between 1973 and 1992, indicating the severity of erosion hazard along the river. This study also revealed the fact that the river has migrated westwards at an average movement rate of 50 m year(-1) during the period of 1830-1992. In 1830, the river had an average width of 6.2 km, but by 1992 the average width had increased to 10.6 km. The channel has widened at an average rate of 27 m year(-1) during 1830-1914. After that, it has widened at an average rate of 65 m year(-1). The average width of the river has increased about 130 m year(-1) since 1973. Analysis of the Landsat images shows that, over the whole river, riverine islands most often persist from 1 to 7 years, but 30% have lasted for 14 years or more. Accretion has taken place in the middle and lower reaches north of the east bank and in the extreme north of the west bank between 1973 and 1992. The rate of accretion is not comparable with the rate of bank erosion of the Brahmaputra-Jamuna River. Copyright (C) 2003 John Wiley Sons, Ltd.