Major elements of morphological dynamics in the Brahmaputra River

Abstract

This paper documents the bankline dynamics of the Brahmaputra River along the India and Bangladesh region during the period 1976 to 2018. Multiple approaches, including satellite image-based interpretations, fieldwork, and meta-analysis, are performed to explore the factors responsible for the morphological dynamics of the river. Results suggest that the Brahmaputra River has lost ~2686 sq. km of land in the last four decades. Brahmaputra river has also widened ~1.7 km (mean value over the studied reach) during the period. We identified five active erosional sections along the river. The high erosions along these sections are promoted by the past avulsion and the lowlands areas in the floodplain of Brahmaputra. Interestingly, progressive erosions along the active sections of the Brahmaputra River have been sustained for decades to centuries. Sustained and dominant peripheral second order channels (dominant channels) have largely decided such progressive erosions. Interpretation based on historical maps suggests that the observed morphological changes of the Brahmaputra River are the continuation of the river’s recent planform evolution that can be traced back to 2-3 centuries. These rapid morphological changes in Brahmaputra River are conceivably due to high sediment flux, where seismic activities look to be a pragmatic factor.