Assessing the long-term planform dynamics of Ganges–Jamuna confluence with the aid of remote sensing and GIS

Abstract

The confluence of the Ganges, Jamuna, and Padma rivers is one of the most dynamic in the world, an internationally important research area because of the confluence of two of the world's major rivers, the Ganges and the Brahmaputra. Morphological changes in this area have resulted in severe erosion along the banks. Riverbank erosion is one of Bangladesh's most critical issues, requiring a substantial solution. Riverbank erosion affects millions of people in Bangladesh each year because of erosion in this confluence zone. Consequently, understanding the morphological shifting pattern of the confluence is crucial. The research aims to quantify actual bank shifting near the confluence of the Ganges, Jamuna, and Padma rivers in terms of shifting rate and area during a 25-year period (1990–2015). The acquired satellite images were geo-referenced, and bank lines were digitized to carry out this research. The bank line is the linear construction that separates the outside boundary of the river channel from the floodplains. To assess channel width fluctuation, the distance between the extreme borders of the left and right banks, including mid-channel sandbars, was measured. This period is split into five stages, each lasting 5 years, to measure the maturity of change. Furthermore, the long-term trend from 1972 to 2015 is qualitatively discernible. Landsat satellite pictures were used to investigate this morphological change. The study provides current and reliable information on the planform dynamics of the Ganga–Jamuna confluence. This study will help design and implement drainage development plans and erosion control techniques in this crucial confluence zone.