Longitudinal profiles and geomorphic indices analysis on tectonic evidence of fluvial form, process and landform deformation of Eastern Himalayan Rivers, India

Abstract

The drainage pattern and the morphology of the piedmont zone of the Himalayas are clear indicators of the active orogenic belt of most recent origin formed by the collision of Indian and Eurasian plate. The foothills of the Himalayas in West Bengal are zones of active tectonics drained by the rivers belonging to the Brahmaputra system. The present study is conducted for the left bank tributaries and sub-tributaries of Tista which bear the imprint of active tectonics of the region as they lie in the zone of Himalayan Frontal Fault, the most active thrust belt of Himalayas. Data and subsequent field experiences which showed that the region is constantly acted upon by recent diastrophism. Various tectonic indices were calculated to evaluate the evidence of tectonism. This include hypsometric integral (HI), fractal dimension (FD), basin asymmetry factor (AF), basin shape index (Bs), stream-length gradient (SL), mountain front sinuosity (Smf) and valley-floor width to valley height ratio (Vf). The results of these indices are used to prepare an index of active tectonics with three classes which is represented in a map. Then the field evidences of deformed landscape are matched with the areas showing high tectonic index values.

Formation, Migration, and Morphodynamic Alteration of 50 Channel Bars in Darjeeling Himalayan Piedmont Zone, India

“…Alluvial rivers in the Himalayan foothill region are very dynamic, 47,48,62 especially in terms of deposition. 10 The mobile deposition is a common feature of the riverbed in Darjeeling Himalayan foothill zone.…”

“…All these rivers are a part of the Ganga-Brahmaputra subsystem and are much younger in age as they are present in the piedmont zone of the Himalayas. 47,48 All these rivers originate at a very high elevation of above 1500 to 2000 m and end jointly at around 50 to 300 m elevation. Considering the geomorphological and hydrological disparity, the piedmont area of Darjeeling Himalayas has been classified into 3 specific zones: Upper (>150 m), Middle (150-100 m), and Lower (<100 m) ( Figure 2; Table 1).…”

“…Being a part of the Himalayan Foreland Basin, it contains the most active fault, that is, the Main Frontal Thrust. 48 This fault line passes through the course of these rivers which is one of the reasons for the development of several minor faults in the course of these rivers, [49][50][51] and at many places, the channels take straight and right-angle bends. The foreland basin is characterised by axial and traverse drainage patterns.…”

Drainage Density and Its Controlling Factors on the Eastern Margin of the Qinghai–Tibet Plateau

“…In recent years, with the development of Remote Sensing and Geographic Information System (GIS), many digital elevation model (DEM)-derived geomorphic indexes have been developed, and they are now widely used for quantitatively describing the shape and dimension of the Earth's landforms and analyzing the geomorphic evolution and the surface process (Mahmood and Gloaguen, 2012;Liu et al, 2019;Radaideh and Mosar, 2019;Ayaz and Dhali, 2020;Kumar and Singh, 2021). Among them, the drainage density (D d ), defined as the ratio between the cumulative length of channels and the area of the drained basin (Horton, 1932), is one of the many physiographic properties of basins considered as an index of surface processes and the basic parameter to control and influence the hydrological characteristics of any basin (Horton, 1945).…”

Assessment of Neotectonic Landscape Deformation in Evia Island, Greece, Using GIS-Based Multi-Criteria Analysis

“…The parameters of the first two categories are useful in the identification of tectonically active areas and in the determination of the variation of the relative tectonic activity, while the geological factors are important in the sense that they affect the other parameters [1]. The wide and extensive use of these parameters in morphotectonic analyses (e.g., [27,[47][48][49][50]) proves that their selection for the assessment of the landscape deformation is correct and rational. The most commonly used morphotectonic parameters are the Amplitude of relief (Ar), which is defined as the maximum difference in elevation within a 1 km 2 unit area [51], and the normalized Stream Length gradient index (SLk), which is linked to stream power-the ability of a stream to erode its bed and transport sediment from the highest part of its drainage basin to the lower point of the basin [14].…”