Contours In Motion: Spatio-Temporal Analysis Of The Brahmaputra River Morphodynamics

Abstract

The River Brahmaputra, a major and highly dynamic transboundary river in Southeast Asia, causes significant riverbank erosion and deposition in Assam, posing substantial natural hazards to land, infrastructure, livelihoods, and the regional economy. This research analyses spatio-temporal changes in the riverbank line between 1997 and 2023 using Landsat satellite imagery and Geographic Information System (GIS), methods like Normalized Difference Water Index (NDWI) and overlay analysis, validated with historical imagery from Google Earth software and field visits. Over the past 26 years, the river has undergone significant morphological shifts. Approximately 1077 sq.km. were lost due to erosion, but 1482 sq. km were gained via deposition, indicating a net deposition overall. Erosion impacts were most severe in upper Assam, particularly Dibrugarh district (173.66 sq.km.), while deposition was greatest in lower Assam, led by Barpeta district (174.21 sq.km.). Districts experienced varied net changes, with Dhemaji facing a significant loss and Barpeta gaining the most land. River gradients, monsoons, sediment loads, and human activities influence these dynamics. Given the profound environmental, ecological, and socio-economic consequences, the study stresses the need for integrated, region-specific river management approaches, including sustainable land use, continuous monitoring, community participation, and engineering solutions to mitigate hazards and improve resilience.