160-10 Historical channel shifting, alluvial geomorphology, and sediment characteristics of the River Ganges (Padma) in northwest Bangladesh

Session: Advances in Fluvial Processes and Sediment Transport, Part I

Presenting Author:

Ashraf Uddin

Authors:

Uddin, Ashraf¹, Halim (Deceased), Mohammad Abdul², Huque (Deceased), Md Anamul³, Hoque (Deceased), Monirul⁴, Miah (Deceased), Mohammad Moniruzzaman⁵, Uddin, Md Riaz⁶, Shamsudduha, Mohammad⁷, Alam, Md Iftekhar⁸, Chowdhury, Nur Uddin Md Khaled⁹, Jahan, Shakura¹⁰, Munim, Mustuque Ahmed¹¹

(1) Department of Geosciences, Auburn University, Auburn, AL, USA, (2) Environmental Engineering Program, Stevens Institute of Technology, Hoboken, NJ, USA; Department of Geology and Mining, Rajshahi University, Rajshahi, Bangladesh, (3) Department of Geology, University of Dhaka, Dhaka, Bangladesh, (4) Department of Geology, University of Dhaka, Dhaka, Bangladesh, (5) Department of Geography & Environment, University of Dhaka, Dhaka, Bangladesh, (6) Department of Geosciences, Auburn University, Auburn, AL, USA, (7) Department of Risk and Disaster Reduction, University College London, London, United Kingdom, (8) Department of Geological Sciences, Cal Poly Pomona, Pomona, CA, USA, (9) Chemistry, Geoscience and Physics, Tarleton State University, Stephenville, TX, USA, (10) Department of Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL, USA, (11) Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA, USA,

Abstract:

The river Ganges, also known locally as the Padma, in the Chapai-Nawabganj and Rajshahi districts, is a natural laboratory to study various aspects of deposited sediments along with the river valley morphology. Channel shifting is a common phenomenon in the area. The recent history of the river indicates migration towards the northwest; the local trends are, however, toward north-northeast. Among the two schools of thought regarding the prime flow of the river 4000 years back, one is in favor of the river Bhagirathi, its first distributary, whereas the other supports the present course.

The Ganges in the study area covers only 88 kilometers out of a total length of about 2500 kilometers. The river is apparently structurally controlled, being marginal and parallel to a fold belt in the upstream and to an impervious Pleistocene inlier in the study area. The sinuosity value, numerous mid-stream bars, and abundant channel scours of the river designate this to be a braided, but in totality, this has been a meandering river. The flow regime of the river in the study area ranges from low in the dry season to moderate-to high during the monsoon.

Comparison of several historical maps, such as, Ptolemy (150), Gastaldi (1561), Sanson (1652), Rennel (1778), and Google Earth (2020) show shifting and narrowing of the Ganges in the study area. Most shifting (up to 25 km) has been noticed in areas near the river’s 1^st entrance to Bangladesh and the least (<1 km) has been seen near the mid-part of the study area around Godagari and Bidirpur. The limited shifting may be due to the position of the river adjacent to a geomorphic barrier of Pleistocene uplands.

The arroyo of the Ganges in the area exhibits several bedforms and sedimentary structures, including small, mega and giant ripples, dunes, horizontal, cross, and herring bone strata, mud cracks and clay galls from the fine-to-medium grained very well to well-sorted sediments the river has been transporting. Garnet, kyanite, staurolite and epidote are the dominant heavy minerals in the river sediments suggesting draining through mostly metamorphic source terranes. Palynological data of the river sediments reveal the presence of angiosperms, pteridophytes, and gymnosperms in order of abundance, suggesting derivation from terranes of varying elevations.  

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10810

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