River terraces assessment to evaluate the regional tectonic activity of the fore parts of Mishmi Block and Manabhum Anticline, North-east India: A conjunctive approach using Field Mapping and Satellite imagery

Abstract

Terraces are the remains of a river's old floodplain. They are created when a river channel is downcut into its former floodplain, which is then deserted and subjected to lateral erosion. A former floodplain's downcutting, abandonment and lateral erosion can be caused by local or regional tectonic uplift, changes in the climate and changes in the river's discharge or a combination of these. The 1950 Mw 8.6 Great Assam Earthquake, which completely wrecked the region, occurred in the Mishmi Hills. The study area lacks tectonics research, therefore understanding the region's undulations requires a thorough understanding of terraces. Using ArcGIS 10.4, a digital elevation model (DEM) with a 30m resolution and satellite images form Google Earth Pro was superimposed on the Survey of India's topographic map for this investigation. The goal of the study is to use terrace analysis to comprehend the regional tectonic activity of the entire frontal and foothills of the Mishmi Hills. The Lohit, Dibang and Noa Dihing River are the most notable rivers in the research area. The rivers possess incised valleys and tributaries where different level of terraces may be identified. The terraces of the said rivers and tributaries are the subject of this study. Since the terrace levels vary from valley to valley, it is impossible to correlate adjacent valleys. The terraces are typically found where one of these rivers and one of its tributaries converge. The tectonic influence on various features in the studied area is typically defined through the study of terraces.