Publication Date

4-1-2022

Advisor(s) - Committee Chair

Nahid Gani (Director), Royhan Gani, Jun Yan, Liang Xue

Degree Program

Department of Earth, Environmental, and Atmospheric Sciences

Degree Type

Master of Science

Abstract

Tectonic activity continues to shape and create challenges for human populations in tectonically active areas. The Bengal Basin is one of the most important sedimentary basins of the Eastern Himalayan Range, aiding in one of the densely populated regions of the world. The basin is part of the tectonically active Himalayan Orogen that is undergoing oblique subduction between the Eurasian Plate and the Indian Plate. As a result of this subduction-related convergence, the eastern part of the Basin, particularly the Chittagong-Tripura Fold Belt (CTFB) and western part of the Indo-Burman Range (IBR) has structurally deformed into a series of mostly compressional fold and thrust belts including strike-slip faults. The CTFB and IBR are characterized by a network of river channels that are incising through thick sedimentary rocks and crossing and/or flowing parallel to this fold and thrust belt. This study analyzed channel morphology using quantitative stream-power law-driven river longitudinal profile models extracted from high-resolution DEMs to investigate the bedrock river response to ongoing tectonics. Analyzing several channel geomorphic metrics (ksn, χ, and knickpoints) and river profile forms revealed (1) several convex and double-concave reaches of major bedrock rivers and their tributaries. These forms of profile reaches are primarily indicative of the transient state of the rivers as a result of ongoing tectonics; (2) the presence of upstream propagating iv knickpoints and distinct knickzone in the profile reaches also suggest a transient state of rivers; (3) two different ksn zones in the CTFB and IBR; the high ksn zone to the east and the low ksn zone to the west. These zones are thought to be associated with the differential uplift rate of the two east-dipping thrust fault systems such as the Kaladan Fault and Chittagong Cox’s Bazar Fault (CCF); and (4) the χ- map shows the occasional transient state of drainage divide where the divided migration is to the east, west, and northeast, and χ – vs. elevation plots display disequilibrium state of the rivers. This migrating nature of the drainage divides suggests that the river basins are not in a steady-state condition, rather these basins are likely adjusting with the overall ongoing tectonic activities. The findings of this study provide a new perspective on understanding the riverscape evolution in such a landscape undergoing active tectonics.

Disciplines

Earth Sciences | Geographic Information Sciences | Geography | Geology | Geomorphology | Physical Sciences and Mathematics | Remote Sensing | Tectonics and Structure

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