loading page

Investigation of Flexural bulge of the Indian Plate for Controls on Landscape Evolution
  • Parv Kasana,
  • Vimal Singh,
  • Rahul Devrani
Parv Kasana
University of Delhi

Corresponding Author:[email protected]

Author Profile
Vimal Singh
University of Delhi
Author Profile
Rahul Devrani
Wadia Institute of Himalayan Geology
Author Profile


The morphology of a river channel is driven by multiple forcing factors that can be either external or internal. The internal factors, such as the variation in rock strength, lineament orientation, and fracture density can be an impelling force in the landscape evolution of a slow uplifting terrain. The spatial variation in the internal factors may result in heterogeneity in fluvial erosion rates, which may produce false signals of active tectonics in a terrain. The Himalayan orogeny has resulted in an upward flexure in the Indian crust known as a peripheral forebulge. The uplifted Vindhayan plateau is proposed as the depiction of this flexure. The bending of the Indian plate has resulted in the generation of tensile forces in this area. These forces have resulted in the formation of large-scale lineaments, which are roughly aligned parallel to the axial plane of the forebulge. This study highlights the role of lineaments, rock strength, and fluvial erodibility in the tectonics of forebulge. We used N-type Schmidt hammer to measure the intact rock strength of lithologies met in the Vindhayan plateau. We calculated the Normalized steepness index (Ksn) to assess the fluvial erodibility of the channels. We calculated swath profiles and local relief distribution to understand topographic variation. Further, we looked at the knickpoint distribution and tried to correlate it with major lineaments and lithological boundaries. Finally, we tried to understand the relationship between the lineament distribution and regional tectonics of the forebulge. We find that there is a significant difference in fluvial erodibility between the weakest and strongest lithologies. We observed that the lineaments act as the conduits for rapid erosion and knickpoint formation. The Ksn values are relatively high where we encountered the hard lithologies, resulting in the formation of vertical knickpoints (waterfalls). We have observed a correlation between, Rock strength variation, topographic relief, knickpoints, and Normalized steepness index. Our results suggest that spatial variation in rock strength and lineament pattern is playing a crucial role in the landscape evolution of the Vindhayan plateau. We finally propose a model to relate lineament orientations and lithological variations with slow uplift of the forebulge.