Plan form changes of the Ganges-Jamuna confluence and its relation to flood

Abstract

Abstract This paper presents the plan form changes of the Ganges-Jamuna confluence based on morphological changing processes (erosion, accretion), confluence point and junction angle and investigates the relationship of the changes with nation-wide flood events. Decadal remotely sensed images have been used for deriving the confluence morphology dataset. The study reveals that the Ganges-Jamuna confluence is morphologically highly unstable. Only about 18% of the confluence area was stable in terms of net change over the whole study period. In decadal scale, percentages of stable confluence area were within sixties and erosion and accretion range from 16% to 25% and 12%–26%, respectively. Gross movement of the confluence over the study period was about 10.25\xa0km with an average rate of movement of about 0.228\xa0km/year. This movement also depicts the morphological instability of the confluence. The plan form changes of the confluence are seen to be influenced by flood events. Erosion in higher extent was the short term impact and in decadal time scale flood introduced extended accretion in the confluence. The rate of confluence point movement is related to the extent of flood in more or less consistent way. Inferences from this study lead to qualitatively predict the future movement of the confluence.