The present study tried examining the role of tectonic perturbations on the fluvial processes through an array of morphotectonic indices coupled with channel longitudinal form analysis in the Neora River catchment. ALOS Palsar 12.5 m DEM is used to derive the channel longitudinal profile along with the Stream Length Gradient Index (SL), and thereafter, calculate the morphotectonic indices. Using the entropy weightage method (EWM), an aggregated tectonic index (ATI) has been prepared to map the degree of tectonic controls at sub-catchment scale. Furthermore, Principal Component Analysis (PCA) groupings and Kernel Density Estimate (KDE) plots have been performed on the sub-basins—indicating the localized effects of surface deformation—based on the morphotectonic parameters to evaluate the localised nature of tectonic activity. The tectonic deformities have been strongly reflected in the channel longitudinal profile with distinct differences in channel responses related to notable lithological variations. The knickpoint distribution and its correspondence with structural deformities and the nature of sub-catchments in-terms of morpho-tectonic signatures defines segment specific dominance of either tectonic deformation and lithological composition. Within the segment above Himalayan thrusts, lithology was seemed to be dominant force governing catchment forms while on the HFB, localised surface deformations and relative channel adjustments is the dominant phenomenon.

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Geomorphic Assessment of Tectonic Influence on the Neora River Basin, Darjiling-Sikkim Himalaya

  • Bikramjit Roy,
  • Sohini Neogy,
  • Ujwal Deep Saha,
  • Rachita Chakraborty

摘要

The present study tried examining the role of tectonic perturbations on the fluvial processes through an array of morphotectonic indices coupled with channel longitudinal form analysis in the Neora River catchment. ALOS Palsar 12.5 m DEM is used to derive the channel longitudinal profile along with the Stream Length Gradient Index (SL), and thereafter, calculate the morphotectonic indices. Using the entropy weightage method (EWM), an aggregated tectonic index (ATI) has been prepared to map the degree of tectonic controls at sub-catchment scale. Furthermore, Principal Component Analysis (PCA) groupings and Kernel Density Estimate (KDE) plots have been performed on the sub-basins—indicating the localized effects of surface deformation—based on the morphotectonic parameters to evaluate the localised nature of tectonic activity. The tectonic deformities have been strongly reflected in the channel longitudinal profile with distinct differences in channel responses related to notable lithological variations. The knickpoint distribution and its correspondence with structural deformities and the nature of sub-catchments in-terms of morpho-tectonic signatures defines segment specific dominance of either tectonic deformation and lithological composition. Within the segment above Himalayan thrusts, lithology was seemed to be dominant force governing catchment forms while on the HFB, localised surface deformations and relative channel adjustments is the dominant phenomenon.