PLANFORM CHANGES OF THE LARGE BRAIDED RIVER BRAHMAPUTRA: A SHORT TERM STUDY USING RS-GIS
Planform changes are extremely significant in a large braided river system such as the Brahmaputra's. The morphodynamics of the river greatly affects the floodplains in the Assam valley. Numerous protected areas of in situ conservation are situated in the floodplains of Brahmaputra, and the river has a significant role in operating and sustaining the ecological system. However these areas are significantly influenced and altered by periodic floods and changes in the planform of the river. The present study focuses on recent decadal (2008-2018) planform changes in the Brahmaputra River along the reach of the Kaziranga National Park (KNP)-a UNESCO World Heritage Site using geoinformatic techniques. For this decadal investigation the Landsat images of 2008 and 2018 are utilised and the data is analysed in GIS environment. The results show a dominance of erosion on the southern bank and a dominance of deposition on the northern bank. It suggests the southward expansion of the river in the last 10 years. The result also signifies the spatial variability in planform parameters along the reach. There is considerable decrease in the number and areas of mid-channel and side bars during the period of study. Braiding Index has also decreased which is attributed to the changes in the morphodynamics of the tributaries. These riverine processes not only affect areal dimensions but also the wildlife of the KNP.
Keywords: Planform changes, Kaziranga National Park, Brahmaputra River, Morphodynamics, Biodiversity