Assessing channel migration dynamics and vulnerability (1977–2018) of the Torsa River in the Duars and Tal region of eastern Himalayan foothills, West Bengal, India

Oniticellini Kolbe, 1905 is a paucispecific tribe of the scarab beetle subfamily Scarabaeinae. The tribe is composed of 256 described species worldwide, while from India, 26 species were recorded to date. Beetles belonging to this tribe are commonly known as paracoprid dung beetles and perform some remarkable ecological functions. Nevertheless, there is a dearth of knowledge on the occurrence of these beetles in the mega diverse tropical forests of the Himalayan foothills located in the north of the West Bengal state of India. A first faunistic account of the tribe Oniticellini Kolbe, 1905 from Baikunthapur Forest, located at the Himalayan foothills of the West Bengal state of India is presented. A total of five species of the tribe distributed over two genera Tiniocellus and Liatongus were recorded during multiple surveys of the scarab fauna of the Forest. All taxa were recorded for the first time from the area, while Tiniocellus spinipes (Roth, 1851) is a new record for the West Bengal State of India. Additionally, a preliminary checklist of Indian species of the tribe is also provided.

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Development of Channel Characteristics during Post-Avulsion Period-A Case Study on a Part of Torsa River, West Bengal

Asian Journal of Research in Social Sciences and Humanities ◽

10.5958/2249-7315.2016.00208.2 ◽

2016 ◽

Vol 6 (6) ◽

pp. 225

Author(s):

Ujwal Deep Saha ◽

Soma Bhattacharya

Keyword(s):

West Bengal ◽

Channel Characteristics ◽

Torsa River

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An assessment on the nature of channel migration of River Diana of the sub-Himalayan West Bengal using field and GIS techniques

Arabian Journal of Geosciences ◽

10.1007/s12517-014-1594-5 ◽

2014 ◽

Vol 8 (8) ◽

pp. 5649-5661 ◽

Cited By ~ 12

Author(s):

Subhankar Chakraborty ◽

Sutapa Mukhopadhyay

Keyword(s):

West Bengal ◽

Channel Migration ◽

Gis Techniques

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Reconstructing the channel shifting pattern of the Torsa River on the Himalayan Foreland Basin over the last 250 years

Bulletin of Geography Physical Geography Series ◽

10.2478/bgeo-2019-0007 ◽

2019 ◽

Vol 16 (1) ◽

pp. 99-114

Author(s):

Ujwal Deep Saha ◽

Soma Bhattacharya

Keyword(s):

Satellite Images ◽

Foreland Basin ◽

Tectonic Activity ◽

Channel Migration ◽

Colonial Literature ◽

Fluvial Dynamics ◽

Himalayan Foreland Basin ◽

Channel Shifting ◽

Seasonal Discharge ◽

Torsa River

Abstract The varied physiography, incidences of high seasonal discharge, influences of neo-tectonic activity and the young geological foundation with less consolidated cohesive and non-cohesive sediment have left the Himalayan foreland basin a formidable ground, where silt-laden rivers tend to migrate frequently. A set of maps prepared after 1764, space photographs captured in 1970 and current satellite images from 2015 and 2017 were studied to reconstruct the fluvial dynamics of the Torsa River on the foreland basin of Sikkim-Bhutan Himalaya considering a time span of nearly 250 years. Evidence collected from colonial literature, the above-mentioned satellite images and a field survey, were combined to verify results taken from the old maps used as the base of the study. The application of satellite remote sensing and analysis of the topographic signatures of the palaeo-courses in the form of the palaeo-levee, abandoned courses and ox-bow lakes were the major operational attributes in this study. As a consequence of the channel migration of Torsa River since 1764, the historical floodplain of Torsa has been topographically marked by beheaded old distributaries, a misfit channel system and the presence of abandoned segments. Morphometric changes in the old courses, major flood events and neo-tectonic activity guided an overall trend of channel migration eastwards and has led to a couple of channel oscillation events in the Torsa River over the last 250 years. The mechanism of the avulsion events was thoroughly driven by sedimentation-induced channel morphometric changes and occasional high discharge.

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