Post-earthquake Sedimentation Changed the Morphology of the Brahmaputra River

The Eurasian plate is being pushed upwards by the Indian Plate and is moving northeast and uplifting the Himalayan Mountain.Brahmaputra plain is one of most important geological areas, who experienced tectonic evolution, so that area is very seismically unstable.The 1897 and 1950 earthquakes, which had a Richter magnitude of 8.7, were among the worst ever in recorded history.This study primarily focuses on the morphological changes that have taken place in response to the 1950 Great Assam Earthquake's disruption of the fluvial system.We have chosen an area between Pasighat, Bhupen Hazarika, and Bogibeel Bridge for this study.Post-great-Assam-earthquake of 1950 has supplied Around 45 billion m3 of sediments in Brahmaputra River and its tributaries.Due to this riverbed rode by 1.5m at Dibrugarh immediately after the earthquake and thereafter a significant number of debris-silt continued enter to river and riverbed rose by 3m in 1955 , of Dibrugarh town eroded, and between 1953 -2022 approx.approx. 3 Km 2 of areas have been eroded.Fine fraction of sediment (silt and clay) travelled quickly through the system, without disturbing the morphology of the channels, but course fraction (sand) had taken half century to travel through the system and continuous changing the river morphology.During the past century, Brahmaputra River in Assam has expanded from 6-Km to 9-Km, and between 1973 and 2022, it has increased by 0.53-Km.Interpretation based on historical maps suggests that the observed morphological changes of the Brahmaputra River are a continuation of the recent planform evolution of the river which can be observed over 2-3 centuries.