Study of Lithofacies, Radar Facies and Satellite Images of the River Bars: Implication for Regulation Structures on the Tista River of Eastern Himalaya
Document Type
Book Chapter
Publication Title
Surface Environments and Human Interactions Reflections from Asia
Abstract
The study examines the sedimentary facies of the Tista River bars in the foothill alluvial plain of the Eastern Himalaya. We have used, following our earlier work, a scheme of classification of the river bars in pre-dam (TOL) and post-dam (TNL) category based on the study of the last 31 years’ satellite images. The present study explores if the pre-dam bars differ in their sedimentary facies and overall architecture from that of the post-dam bars. For this purpose, we studied the cutbank sections of selected pre-dam and post-dam bars and conducted Ground Penetrating Radar (GPR) survey of the bars of these two categories. We defined eight facies and four facies associations from the surface exposures of the Tista bars and categorized the GPR signals into eight radar facies. The study reveals contrasting patterns of structure and architecture of the pre-dam and post-dam bars. The typical bar building architecture (like upstream or downstream accreting surfaces, bar top channel incision, fining and thinning upward succession) and evidence of remarkable flow fluctuation have been recorded in the TOL bars. In contrast, the TNL bars appear to be entirely different with monotonously aggrading cosets of trough cross strata forming sheet-like units as the sole feature of these bars. We interpret the internal features of TNL bars and their architecture to be the product of controlled artificial discharge from upstream dams and barrage. The grain size comparison of these two temporal categories of bars also demonstrates fining of grain size in the TNL bars. Recognition of these kinds of contrasting bar architecture allows recognition of the effect of the engineering structures in the natural streams and provides means to assess the hydrological changes during the post-dam period.
First Page
105
Last Page
137
DOI
10.1007/978-981-97-0112-4_7
Publication Date
1-1-2024
Recommended Citation
Ghosh, Kausik and Chakraborty, Tapan, "Study of Lithofacies, Radar Facies and Satellite Images of the River Bars: Implication for Regulation Structures on the Tista River of Eastern Himalaya" (2024). Book Chapters. 287.
https://digitalcommons.isical.ac.in/book-chapters/287